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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2015	Jan. 31, 2016	Jun. 30, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	QUALYS, INC.
Entity Central Index Key	0001107843
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		34,432,373
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1,006

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 91,698	$ 76,504
Short-term investments	87,268	50,714
Accounts receivable, net of allowance of $769 and $590 at December 31, 2015 and 2014, respectively	42,325	32,993
Prepaid expenses and other current assets	7,945	6,528
Total current assets	229,236	166,739
Long-term investments	43,277	39,448
Property and equipment, net	31,329	26,618
Deferred tax assets, net	16,079	22,639
Intangible assets, net	1,360	2,001
Goodwill	317	317
Other noncurrent assets	1,916	2,262
Total assets	323,514	260,024
Current liabilities:
Accounts payable	2,368	5,661
Accrued liabilities	11,786	10,353
Deferred revenues, current	98,025	81,147
Total current liabilities	112,179	97,161
Deferred revenues, noncurrent	14,564	10,064
Other noncurrent liabilities	1,205	972
Total liabilities	127,948	108,197
Commitments and contingencies (Note 5)
Stockholders’ equity:
Preferred stock: $0.001 par value; 20,000,000 shares authorized, no shares issued and outstanding at December 31, 2015 and 2014	0	0
Common stock, $0.001 par value; 1,000,000,000 shares authorized, 34,414,631 and 33,594,285 shares issued and outstanding at December 31, 2015 and 2014, respectively	34	34
Additional paid-in capital	223,228	195,133
Accumulated other comprehensive income (loss)	(211)	10
Accumulated deficit	(27,485)	(43,350)
Total stockholders’ equity	195,566	151,827
Total liabilities and stockholders’ equity	$ 323,514	$ 260,024

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for Doubtful Accounts Receivable	$ 769	$ 590
Preferred Stock, Par Value (in dollars per share)	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001	$ 0.001
Common Stock, Shares Authorized	1,000,000,000	1,000,000,000
Common Stock, Shares, Issued	34,414,631	33,594,285
Common Stock, Shares, Outstanding	34,414,631	33,594,285

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Revenues	$ 164,284	$ 133,579	$ 107,962
Cost of revenues	33,885	28,963	24,660
Gross profit	130,399	104,616	83,302
Operating expenses:
Research and development	29,451	26,320	21,678
Sales and marketing	49,569	48,049	42,523
General and administrative	26,573	21,000	16,792
Total operating expenses	105,593	95,369	80,993
Income from operations	24,806	9,247	2,309
Other income (expense), net:
Interest expense	(6)	(9)	(43)
Interest income	570	452	375
Other expense, net	(850)	(1,077)	(600)
Total other expense, net	(286)	(634)	(268)
Income before income taxes	24,520	8,613	2,041
Provision for (benefit from) income taxes	8,655	(21,631)	500
Net income	15,865	30,244	1,541
Net income attributable to common stockholders	$ 15,865	$ 30,244	$ 1,539
Net income per share attributable to common stockholders:
Basic (usd per share)	$ 0.47	$ 0.92	$ 0.05
Diluted (usd per share)	$ 0.42	$ 0.81	$ 0.04
Weighted average shares used in computing net income per share attributable to common stockholders:
Basic (in shares)	34,050	32,979	31,914
Diluted (in shares)	38,184	37,170	35,973

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 15,865	$ 30,244	$ 1,541
Change in net unrealized gain (loss) on investments, net of tax	(202)	0	38
Less: reclassification adjustment for net realized gain included in net income	(19)	(28)	(8)
Net change, net of tax	(221)	(28)	30
Other comprehensive income (loss), net	(221)	(28)	30
Comprehensive income	$ 15,644	$ 30,216	$ 1,571

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income	$ 15,865	$ 30,244	$ 1,541
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	14,360	11,897	9,612
Bad debt expense	851	470	307
Loss on disposal of property and equipment	5	324	12
Stock-based compensation	17,494	10,549	5,506
Amortization of premiums and accretion of discounts on investments	594	565	282
Excess tax benefits from stock-based compensation	(487)	(259)	(150)
Impairment of intangible assets	255	0	0
Deferred income taxes	6,564	(22,599)	(66)
Changes in operating assets and liabilities:
Accounts receivable	(10,183)	(4,882)	(4,343)
Prepaid expenses and other assets	(1,011)	(3,456)	610
Accounts payable	(3,293)	2,332	(100)
Accrued liabilities	3,339	1,622	437
Deferred revenues	21,378	14,817	11,281
Other noncurrent liabilities	229	(201)	152
Net cash provided by operating activities	65,960	41,423	25,081
Cash flows from investing activities:
Purchases of investments	(146,707)	(157,660)	(145,263)
Sales and maturities of investments	105,509	157,339	138,124
Purchases of property and equipment	(20,051)	(13,914)	(13,650)
Capitalized software development costs	(99)	(98)	0
Release of restricted cash	0	0	114
Net cash used in investing activities	(61,348)	(14,333)	(20,675)
Cash flows from financing activities:
Proceeds from exercise of stock options	10,095	7,639	4,073
Proceeds from early exercise of stock options	0	0	40
Excess tax benefits from stock-based compensation	487	259	150
Principal payments under capital lease obligations	0	(805)	(1,186)
Net cash provided by financing activities	10,582	7,093	3,077
Effect of exchange rate changes on cash and cash equivalents	0	(48)	1
Net increase in cash and cash equivalents	15,194	34,135	7,484
Cash and cash equivalents at beginning of period	76,504	42,369	34,885
Cash and cash equivalents at end of period	91,698	76,504	42,369
Supplemental disclosures of cash flow information
Cash paid for interest expense	6	9	43
Cash paid for income taxes, net of refunds	995	347	390
Non-cash investing and financing activities
Purchases of property and equipment recorded in accounts payable and accrued liabilities	0	1,399	487
Vesting of early exercised common stock options	$ 19	$ 47	$ 262

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2012	$ 91,555	$ 31	$ 166,651	$ 8	$ (75,135)
Balance (in shares) at Dec. 31, 2012		31,420,028
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,541				1,541
Change in net unrealized gain (loss) on investments	30			30
Issuance of common stock upon exercise of stock options	$ 4,073	$ 1	4,072
Issuance of common stock upon exercise of stock options (shares)	952,871	952,871
Vesting of early exercised common stock options	$ 262		262
Excess tax benefits from stock-based compensation	150		150
Repurchase of unvested early exercised stock options	0
Repurchase of unvested early exercised stock options (shares)		(500)
Issuance of common stock in exchange for services	41		41
Issuance of common stock in exchange for services (shares)		2,900
Stock-based compensation	5,465		5,465
Balance at Dec. 31, 2013	103,117	$ 32	176,641	38	(73,594)
Balance (in shares) at Dec. 31, 2013		32,375,299
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	30,244				30,244
Change in net unrealized gain (loss) on investments	(28)			(28)
Issuance of common stock upon exercise of stock options	$ 7,639	$ 2	7,637
Issuance of common stock upon exercise of stock options (shares)	1,216,710	1,216,710
Vesting of early exercised common stock options	$ 47		47
Excess tax benefits from stock-based compensation	259		259
Repurchase of unvested early exercised stock options	0
Repurchase of unvested early exercised stock options (shares)		(125)
Issuance of common stock in exchange for services	50		50
Issuance of common stock in exchange for services (shares)		2,401
Stock-based compensation	10,499		10,499
Balance at Dec. 31, 2014	151,827	$ 34	195,133	10	(43,350)
Balance (in shares) at Dec. 31, 2014		33,594,285
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,865				15,865
Change in net unrealized gain (loss) on investments	(221)			(221)
Issuance of common stock upon exercise of stock options	10,095	$ 0	10,095
Issuance of common stock upon vesting of restricted stock units	$ 0
Issuance of common stock upon vesting of restricted stock units (in shares)		12,500
Issuance of common stock upon exercise of stock options (shares)	807,846	807,846
Vesting of early exercised common stock options	$ 19		19
Excess tax benefits from stock-based compensation	487		487
Stock-based compensation	17,494		17,494
Balance at Dec. 31, 2015	$ 195,566	$ 34	$ 223,228	$ (211)	$ (27,485)
Balance (in shares) at Dec. 31, 2015		34,414,631

The Company and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2015

Accounting Policies [Abstract]

The Company and Summary of Significant Accounting Policies



NOTE 1.	The Company and Summary of Significant Accounting Policies

Description of Business

Qualys, Inc. (the “Company”) was incorporated in the state of Delaware on December 30, 1999. The Company is headquartered in Redwood City, California and has majority-owned subsidiaries throughout the world. The Company is a pioneer and leading provider of cloud-based security and compliance solutions that enable organizations to identify security risks to their IT infrastructures, help protect their IT systems and applications from ever-evolving cyber-attacks and achieve compliance with internal policies and external regulations. The Company’s cloud solutions address the growing security and compliance complexities and risks that are amplified by the dissolving boundaries between internal and external IT infrastructures and web environments, the rapid adoption of cloud computing and the proliferation of geographically dispersed IT assets. Organizations can use the Company’s integrated suite of solutions delivered on its Qualys Cloud Platform to cost-effectively obtain a unified view of their security and compliance posture across globally-distributed IT infrastructures.

Basis of Presentation

The accompanying consolidated financial statements and footnotes have been prepared by the Company in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) as well as the instructions to Form 10-K and the rules and regulations of the U.S. Securities and Exchange Commission ("SEC"). In the opinion of management, the accompanying consolidated financial statements include all adjustments necessary for the fair presentation of the Company’s consolidated financial position, results of operations and cash flows for the periods presented. The accompanying consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries. All significant intercompany transactions and balances have been eliminated upon consolidation.

Certain prior year amounts related to income taxes have been reclassified to conform to the current year presentation related to Accounting Standards Update (ASU) No. 2015-17, Balance Sheet Classification of Deferred Taxes, which requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non-current on the balance sheet. The Company adopted this standard retrospectively. These reclassifications did not change previously reported total assets, liabilities, stockholders' equity, income from operations or net income.

Use of Estimates

The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported results of operations during the reporting period. The Company’s management regularly assesses these estimates, which primarily affect revenue recognition, the valuation of accounts receivable, goodwill and intangible assets, stock-based compensation and the provision for income taxes. Actual results could differ from those estimates and such differences may be material to the accompanying consolidated financial statements.

Concentration of Credit Risk

The Company invests its cash and cash equivalents with major financial institutions. Cash balances with any one institution at times may be in excess of federally insured limits. Cash equivalents are invested in high-quality investment grade financial instruments and are diversified. The Company has not experienced any losses in such accounts and believes it is not exposed to any significant credit risk.

Credit risk with respect to accounts receivable is dispersed due to the large number of customers. Collateral is not required for accounts receivable. The Company maintains an allowance for potential credit losses based upon the expected collectability of accounts receivable. The Company writes off its receivables once collection efforts are unsuccessful. As of December 31, 2015 and 2014, no customer or channel partner accounted for more than 10% of the Company's accounts receivable balance.

Cash, Cash Equivalents, Short-Term and Long-Term Investments

Cash and cash equivalents include cash held in banks, highly liquid money market funds, commercial paper, and fixed-income U.S. government agency securities, all with original maturities of three months or less when acquired. The Company’s investments consist of fixed-income U.S. government agency securities, corporate bonds, asset-backed securities and commercial paper. Management determines the appropriate classification of the Company's investments at the time of purchase and reevaluates such designation at each balance sheet date. The Company classifies its investments as either short-term or long-term based on each instrument's underlying contractual maturity date.

Cash equivalents are stated at cost, which approximates fair market value. Short-term and long-term investments are classified as available-for-sale and are carried at fair value. Unrealized gains and losses in fair value are reported in other comprehensive income (loss). When the available-for-sale securities are sold, cost is based on the specific identification method, and the realized gains and losses are included in other income (expense) in the consolidated statements of operations. Short-term and long-term investments are reviewed quarterly for impairment that is deemed to be other-than-temporary. An investment is considered other-than-temporarily impaired when its fair value is below its amortized cost and (1) there is an intent to sell the security, (2) it is “more likely than not” that the security will be sold before recovery of its amortized cost basis or (3) the present value of expected cash flows from the investment is not expected to recover the entire amortized cost basis. Declines in value that are considered to be other-than-temporary and adjustments to amortized cost for the amortization of premiums and the accretion of discounts are recorded in other income (expense). Interest and dividends are recorded in interest income as earned.

Accounts Receivable

Accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts represents the Company’s best estimate of the amount of probable credit losses and is determined based on a review of existing accounts receivable by aging category to identify significant customers or invoices with collectability issues. For those invoices not specifically reviewed, the reserve is calculated based on the age of the receivable.

Any change in the assumptions used in analyzing a specific account receivable may result in an additional provision for doubtful accounts being recognized in the period in which the change occurs. When the Company ultimately concludes that a receivable is uncollectible, the balance is written off against the allowance for doubtful accounts. Payments subsequently received on such receivables are credited back to the allowance for doubtful accounts.

Property and Equipment, net

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which range from three to five years. Leasehold improvements are amortized on a straight-line basis over the lesser of the estimated useful life of the asset or the lease term.

The Company purchases physical scanner appliances and other computer equipment that are provided on a subscription basis. This equipment is recorded within property and equipment on the accompanying consolidated balance sheet, and the depreciation is recorded to cost of revenues over an estimated useful life of three years.

Upon retirement or disposal, the cost of assets and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in the consolidated statements of operations. Repairs and maintenance that do not extend the life of an asset are expensed as incurred and major improvements are capitalized as property and equipment.

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets, which consist of property and equipment, and intangible assets subject to amortization, for indicators of possible impairment when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Impairment exists if the carrying amounts of such assets exceed the estimates of future undiscounted cash flows expected to be generated by such assets. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s estimated fair value. As of December 31, 2015, the Company has not written down any of its long-lived assets as a result of impairment.

Goodwill and Intangible Assets

Goodwill represents the excess of the purchase price over the fair value of the net tangible and identifiable intangible assets acquired in a business combination and is not subject to amortization. Goodwill and other intangible assets with indefinite lives are not amortized, but tested for impairment annually or if certain circumstances indicate a possible impairment may exist. These tests are performed at the reporting unit level. The Company’s operations are organized as one reporting unit.

In testing for a potential impairment of goodwill, the Company first performs a qualitative assessment of its reporting unit to determine if it is more likely than not (a more than 50% likelihood) that the fair value of the reporting unit is less than its carrying amount. If the fair value is not considered to be less than the carrying amount, no further evaluation is necessary. The Company performed the annual qualitative assessment for the year ended December 31, 2015 and concluded there was no impairment of goodwill.

In testing for a potential impairment of intangible assets with indefinite lives that are not subject to amortization, the Company first performs a qualitative assessment to determine if it is more likely than not (a more than 50% likelihood) that the fair value of the indefinite-lived intangible assets is less than the carrying amount. If the fair value is not considered to be less than the carrying amount, no further evaluation is necessary. The Company performed the annual qualitative assessment in 2015 and concluded that as of December 31, 2015, there was an impairment of certain indefinite-lived intangible assets.

If the qualitative assessment indicates there is more than a 50% likelihood that the fair value is less than the carrying amount, the Company would perform a two-step test. In the first step, the carrying value of the reporting unit or intangible asset is compared to its estimated fair value. If the estimated fair value is less than the carrying value, then potential impairment exists. In the second step, for goodwill, the Company calculates the amount of any impairment by determining the implied fair value of goodwill using a hypothetical purchase price allocation, similar to that which would be applied if it were an acquisition and the purchase price was equivalent to fair value as calculated in the first step. Impairment is equivalent to any excess of goodwill carrying value over its implied fair value. For indefinite-lived intangible assets, the Company performs the currently prescribed quantitative impairment test by comparing the fair value of the indefinite-lived intangible asset with its carrying value. In 2015, the Company determined there was an impairment of certain indefinite-lived intangible assets and recorded a write-off of $0.3 million, recorded in other expense, net.

Certain other intangible assets acquired are amortized over their estimated useful lives and tested for impairment if certain circumstances indicate an impairment may exist. The Company’s intangible assets are comprised primarily of existing technology, patent license, and non-competition agreements and are amortized over periods ranging from three to fourteen years on a straight-line basis. As of December 31, 2015, the Company has not written down any of these intangible assets as a result of impairment.

Software Development Costs

The Company capitalizes qualifying software costs developed or obtained for internal use. These costs generally include internal costs, such as payroll and benefits of those employees directly associated with the development of the software, and other consulting expenses. During each of the years ended December 31, 2015 and 2014, the Company capitalized software development costs of $0.1 million. Total capitalized development costs are $0.4 million and $0.3 million at December 31, 2015 and 2014, respectively, and the related accumulated amortization is $0.3 million at December 31, 2015 and 2014.

Derivative Financial Instruments

Derivative financial instruments are utilized by the Company to reduce foreign currency exchange risks. The Company uses foreign currency forward contracts to mitigate the impact of foreign currency fluctuations of certain non-U.S. dollar denominated asset positions, primarily cash and accounts receivable. These contracts are recorded within prepaid expenses and other current assets in the consolidated balance sheets. Gains and losses resulting from currency exchange rate movements on these forward contracts are recognized in other income (expense) in the accompanying consolidated statements of operations in the period in which the exchange rates change and offset the foreign currency gains and losses on the underlying exposure being hedged. The Company does not enter into derivative financial instruments for trading or speculative purposes.

At December 31, 2015, the Company had two outstanding forward contracts with notional amounts of 6.1 million Euros and 2.6 million British Pounds, which expired on January 31, 2016. At December 31, 2014, the Company had two outstanding forward contracts with notional amounts of 6.0 million Euros and 2.1 million British Pounds, which expired on January 31, 2015. These forward contracts were entered into as of December 31, 2015 and 2014, respectively, and thus the fair value of the contracts was $0 at both December 31, 2015 and 2014. In 2015, the Company recorded a net gain of $0.6 million from forward contracts, which was offset by foreign currency transaction losses of $1.0 million for the year. In 2014, the Company recorded a net gain of $0.7 million from forward contracts, which was offset by foreign currency transaction losses of $1.4 million for the year. These derivatives did not meet the criteria to be designated as hedges.

Stock-Based Compensation

The Company recognizes the fair value of its employee stock options and restricted stock units (RSUs) over the requisite service period for those awards ultimately expected to vest. The fair value of each option is estimated on date of grant using the Black-Scholes option pricing model and the fair value of each restricted stock unit is based on the fair value of the Company's stock on the date of grant. Forfeitures are estimated on the date of grant and revised if actual or expected forfeiture activity differs materially from original estimates.

Option grants to non-employees are accounted for at the fair value of the equity instrument issued, as calculated using the Black-Scholes option-pricing model and the expense is recognized over the vesting periods of the options. The value of options granted to non-employees is remeasured as they vest over a performance period.

Revenue Recognition

The Company derives revenues from subscriptions that require customers to pay a fee in order to access the Company’s cloud solutions. Customers generally enter into one year renewable subscriptions. The subscription fee entitles the customer to an unlimited number of scans for a specified number of networked devices or web applications and, if requested by a customer as part of their subscription, a specified number of physical or virtual scanner appliances. The Company’s physical and virtual scanner appliances are requested by certain customers as part of their subscriptions in order to scan IT infrastructures within their firewalls and do not function without, and are not sold separately from, subscriptions for the Company’s solutions. In some limited cases, the Company also provides certain computer equipment used to extend its Qualys Cloud Platform into its customers’ private cloud environment. Customers are required to return physical scanner appliances and computer equipment if they do not renew their subscriptions.

The Company recognizes revenues when all of the following conditions are met:


•	There is persuasive evidence of an arrangement.


•	The service has been provided to the customer.


•	The collection of the fees is reasonably assured.


•	The amount of fees to be paid by the customer is fixed or determinable.

Subscriptions are recognized ratably over the subscription period. The Company recognizes revenues from subscriptions that include physical scanner appliances and other computer equipment ratably over the period of the subscription. Because the customer’s access to the Company’s cloud solutions are delivered at the same time as or within close proximity to the delivery of physical scanner appliances and the terms are commensurate for these services and equipment, the Company considers these elements as a single unit of accounting recognized ratably over the subscription period.

Deferred revenues consist of revenues billed or received that will be recognized in the future under subscriptions existing at the balance sheet date. The current portion of deferred revenues represents amounts that are expected to be recognized within one year of the balance sheet date.

Costs of shipping and handling charges incurred by the Company associated with physical scanner appliances and other computer equipment are included in cost of revenues.

Sales taxes and other taxes collected from customers to be remitted to government authorities are excluded from revenues.

Advertising Expenses

Advertising costs are expensed as incurred and include costs of advertising, trade show costs and promotional materials. The Company incurred advertising costs of $6.1 million, $5.3 million, and $4.2 million for 2015, 2014 and 2013, respectively.

Income Taxes

The Company provides for the effect of income taxes in its consolidated financial statements using the asset and liability method which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, net operating loss carryovers, and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date.

Income tax expense or benefit is recognized for the amount of taxes payable or refundable for the current year, and for deferred tax assets and liabilities for the tax consequences of events that have been recognized in an entity’s financial statements or tax returns. The Company must make significant assumptions, judgments and estimates to determine its current provision (benefit) for income taxes, its deferred tax assets and liabilities, and any valuation allowance to be recorded against its deferred tax assets. The Company's judgments, assumptions and estimates relating to the current provision (benefit) for income taxes include the geographic mix and amount of income (loss), its interpretation of current tax laws, and possible outcomes of current and future audits conducted by foreign and domestic tax authorities. The Company's judgments also include anticipating the tax positions the Company will record in the consolidated financial statements before actually preparing and filing the tax returns. The Company's estimates and assumptions may differ from the actual results as reflected in its income tax returns and the Company records the required adjustments when they are identified or resolved. Changes in the Company's business, tax laws or the Company's interpretation of tax laws, and developments in current and future tax audits, could significantly impact the amounts provided for income taxes in the Company's results of operations, financial position, or cash flows.

Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to tax benefit carry-forwards and to differences between the financial statement amounts of assets and liabilities and their respective tax basis. The Company regularly reviews its deferred tax assets for recoverability and establishes a valuation allowance if it is more likely than not that some portion or all of the deferred tax assets will not be realized. To make this assessment, the Company takes into account predictions of the amount and category of taxable income from various sources and all available positive and negative evidence about these possible sources of taxable income. The weight given to the potential effect of negative and positive evidence is commensurate with the extent to which the strength of the evidence can be objectively verified.

The Company applies a two-step approach to determining the financial statement recognition and measurement of uncertain tax positions. The Company only recognizes an income tax expense or benefit with respect to uncertain tax positions in its financial statements that the Company judges is more likely than not to be sustained solely on its technical merits in a tax audit, including resolution of any related appeals or litigation processes. To make this judgment, the Company must interpret complex and sometimes ambiguous tax laws, regulations and administrative practices. If an income tax position meets the more likely than not recognition threshold, then the Company must measure the amount of the tax benefit to be recognized by determining the largest amount of tax benefit that has a greater than a 50% likelihood of being realized upon effective settlement with a taxing authority that has full knowledge of all of the relevant facts. It is inherently difficult and subjective to estimate such amounts, as this requires the Company to determine the probability of various possible settlement outcomes. To determine if a tax position is effectively settled after a tax examination has been completed, the Company must also estimate the likelihood that another taxing authority could review the respective tax position. The Company must also determine when it is reasonably possible that the amount of unrecognized tax benefits will significantly increase or decrease in the 12 months after each fiscal year-end. These judgments are difficult because a taxing authority may change its behavior as a result of the Company's disclosures in its financial statements. The Company must reevaluate its income tax positions on a quarterly basis to consider factors such as changes in facts or circumstances, changes in tax law, effectively settled issues under audit, and new audit activity. Such a change in recognition or measurement would result in recognition of a tax benefit or an additional charge to the tax provision. The Company's policy is to recognize interest and penalties related to unrecognized tax benefits as a component of the provision for income taxes.

Comprehensive Income (Loss)

Other comprehensive income (loss) consists of unrealized gains (losses) on available-for-sale investments, net of tax, which are not included in the Company’s net income. Total comprehensive income includes net income and other comprehensive income (loss) and is included in the consolidated statements of comprehensive income.

Foreign Currency Transactions

The Company’s operations are conducted in various countries around the world and the financial statements of its foreign subsidiaries are reported in the U.S. dollar as their respective functional currency. Monetary assets and liabilities denominated in foreign currencies have been remeasured into U.S. dollars using the exchange rates in effect at the balance sheet date, and income and expenses are remeasured at average exchange rates during the period. Foreign currency remeasurement gains and losses and foreign currency transaction gains and losses are recognized in other income (expense), net. The Company recorded total foreign currency transaction losses of $0.4 million $0.7 million and $0.7 million during 2015, 2014 and 2013, respectively.

Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. For certain of the Company’s financial instruments, including certain cash equivalents, accounts receivable, accounts payable, and other current liabilities, the carrying amounts approximate their fair value due to the relatively short maturity of these balances.

The Company measures and reports certain cash equivalents, investments and derivative foreign currency forward contracts at fair value in accordance with the provisions of the authoritative accounting guidance that addresses fair value measurements. This guidance establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. The hierarchy is broken down into three levels based on the reliability of inputs as follows:

Level 1—Valuations based on quoted prices in active markets for identical assets or liabilities.

Level 2—Valuations based on other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3—Valuations based on inputs that are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability.

The Company's financial instruments consist of assets measured using Level 1 and 2 inputs. Level 1 assets include a highly liquid money market fund, which is valued using unadjusted quoted prices that are available in an active market for an identical asset. Level 2 assets include fixed-income U.S. government agency securities, commercial paper, corporate bonds, asset-backed securities and derivative financial instruments consisting of foreign currency forward contracts. The securities, bonds and commercial paper are valued using prices from independent pricing services based on quoted prices in active markets for similar instruments or on industry models using data inputs such as interest rates and prices that can be directly observed or corroborated in active markets. The foreign currency forward contracts are valued using observable inputs, such as quotations on forward foreign exchange points and foreign interest rates. See Note 2 for more information regarding the fair value measurement of the Company's financial instruments.

Net Income Per Share Attributable to Common Stockholders

The Company computes net income attributable to common stockholders using the two-class method required for participating securities. Common stock subject to repurchase resulting from the early exercise of stock options are considered to be participating securities since they contain non-forfeitable rights to dividends or dividend equivalents in the event the Company declares a dividend for common stock. In accordance with the two-class method, earnings allocated to these participating securities are subtracted from net income after deducting preferred stock dividends, if any, to determine total undistributed earnings to be allocated to common stockholders.

Basic net income per share attributable to common stockholders is computed by dividing net income attributable to common stockholders by the weighted-average number of common shares outstanding during the period. All participating securities are excluded from basic weighted average common shares outstanding. In computing diluted net income attributable to common stockholders, undistributed earnings are reallocated to reflect the potential impact of dilutive securities. Diluted net income per share is computed by dividing net income attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, adjusted for the effects of potentially dilutive common shares, which comprise of outstanding stock options. The dilutive potential common shares are computed using the treasury stock method or the as-if converted method, as applicable. The effects of outstanding stock options are excluded from the computation of diluted net income per common share in periods in which the effect would be antidilutive.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (FASB) issued an Accounting Standards Update (ASU) amending revenue recognition guidance and requiring more detailed disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. In August 2015, the FASB issued an ASU to defer the effective date of ASU 2014-09 for all entities by one year. Thus, ASU 2014-09 will be effective for fiscal years, and interim periods within those years, beginning after December 15, 2017, but entities will be permitted to early adopt the standard only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. The new revenue standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized on date of adoption. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements.

In April 2015, the FASB issued an ASU amending existing guidance which clarifies that software licenses contained in a cloud computing arrangement should be capitalized if the customer has the right to take possession of the software and the ability to run the software outside of the cloud computing arrangement. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract under existing guidelines. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. A reporting entity may apply the amendments prospectively to all arrangements entered into or materially modified after the effective date or retrospectively. Early adoption is permitted. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements.

In November 2015, the FASB issued an ASU which requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non-current on the balance sheet. As a result, each jurisdiction will only have one net non-current deferred tax asset or liability. The guidance does not change the existing requirement that allows for offsetting of deferred tax assets and liabilities within the same jurisdiction. Although the new guidance is effective for public business entities in fiscal years beginning after December 15, 2016, earlier adoption is permitted for all entities as of the beginning of the current interim or annual reporting period. Furthermore, the standard permits prospective or retrospective application for all deferred tax assets and liabilities (i.e., by reclassifying the comparative balance sheet). The Company has early adopted retrospectively, and, accordingly, has applied the new guidance to its deferred taxes for the years ended December 31, 2015 and 2014. As a result of the adoption, the Company made the following adjustments to the consolidated balance sheet as of December 31, 2014: an $8.5 million decrease to current deferred tax assets and total current assets; and an $8.5 million increase to non-current deferred tax assets.

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments



NOTE 2.	Fair Value of Financial Instruments

The Company's cash and cash equivalents, short-term investments, and long-term investments consist of the following:



	December 31, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	61,372	$	—	$	—		$	61,372
Money market funds	3,980		—		—			3,980
U.S. government agencies	8,999		1		—			9,000
Commercial paper	17,345		1		—			17,346
Total	91,696		2		—			91,698
Short-term investments:
Commercial paper	10,447		1		—			10,448
Corporate bonds	12,448		—		(13		)	12,435
U.S. government agencies	64,422		3		(40		)	64,385
Total	87,317		4		(53		)	87,268
Long-term investments:
Asset-backed securities	7,007		—		(18		)	6,989
U.S. government agencies	32,683		—		(142		)	32,541
Corporate bonds	3,751		—		(4		)	3,747
Total	43,441		—		(164		)	43,277
Total	$	222,454	$	6	$	(217	)	$	222,243



	December 31, 2014
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	36,024	$	—	$	—		$	36,024
Money market funds	39,180		—		—			39,180
U.S. government agencies	300		—		—			300
Commercial paper	1,000		—		—			1,000
Total	76,504		—		—			76,504
Short-term investments:
Commercial paper	4,998		1		—			4,999
Corporate bonds	12,438		6		(6		)	12,438
U.S. government agencies	33,280		3		(6		)	33,277
Total	50,716		10		(12		)	50,714
Long-term investments:
Asset-backed securities	16,092		5		(3		)	16,094
U.S. government agencies	20,243		22		(10		)	20,255
Corporate bonds	3,101		—		(2		)	3,099
Total	39,436		27		(15		)	39,448
Total	$	166,656	$	37	$	(27	)	$	166,666

The following table sets forth by level within the fair value hierarchy the fair value of the Company's available-for-sale securities measured on a recurring basis, excluding cash and money market funds:



	December 31, 2015
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	27,794	$	—	$	27,794
U.S. government agencies	—		105,926		—		105,926
Corporate bonds	—		16,182		—		16,182
Asset-backed securities	—		6,989		—		6,989
Total	$	—	$	156,891	$	—	$	156,891



	December 31, 2014
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	5,999	$	—	$	5,999
U.S. government agencies	—		53,832		—		53,832
Corporate bonds	—		15,537		—		15,537
Asset-backed securities	—		16,094		—		16,094
Total	$	—	$	91,462	$	—	$	91,462

The following summarizes the fair value of securities classified as available-for-sale by contractual maturity:



	December 31, 2015
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	27,794	$	—	$	—	$	27,794
U.S. government agencies	73,385		32,541		—		105,926
Corporate bonds	12,435		3,747		—		16,182
Asset-backed securities	—		3,411		3,578		6,989
Total	$	113,614	$	39,699	$	3,578	$	156,891



	December 31, 2014
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	5,999	$	—	$	—	$	5,999
U.S. government agencies	33,577		20,255		—		53,832
Corporate bonds	12,438		3,099		—		15,537
Asset-backed securities	—		7,327		8,767		16,094
Total	$	52,014	$	30,681	$	8,767	$	91,462

At December 31, 2015 and 2014, derivative financial instruments, consisting of foreign currency forward contracts, were valued at $0 as the contracts were entered into on the last day of the respective reporting periods. These instruments were valued using Level 2 inputs.

There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy, as determined at the end of each reporting period.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Property and Equipment, Net

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

Property and Equipment, net



NOTE 3.	Property and Equipment, Net

Property and equipment consists of the following:



	December 31,
	2015			2014
	(in thousands)
Computer equipment	$	48,192		$	35,576
Computer software	12,484			10,899
Furniture, fixtures and equipment	2,804			2,931
Scanner appliances	22,627			19,861
Leasehold improvements	3,367			2,622
Total property and equipment	89,474			71,889
Less: accumulated depreciation and amortization	(58,145		)	(45,271		)
Property and equipment, net	$	31,329		$	26,618

Physical scanner appliances and other computer equipment that are or will be subject to subscriptions by customers have a net carrying value of $8.4 million and $6.0 million at December 31, 2015 and 2014, respectively, including assets that have not been placed in service of $1.4 million and $1.4 million, respectively. Other fixed assets not placed in service at December 31, 2015 and 2014, included in computer equipment and leasehold improvements, were $4.3 million and $2.8 million, respectively. Depreciation and amortization expense relating to property and equipment was $13.9 million, $11.5 million and $9.2 million for 2015, 2014 and 2013, respectively.

Goodwill and Intangible Assets, Net

12 Months Ended

Dec. 31, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets Disclosure [Text Block]



NOTE 4.	Goodwill and Intangible Assets, Net

Intangible assets consist primarily of existing technology, patent license and non-competition agreements acquired in business combinations. Acquired intangibles are amortized on a straight-line basis over the respective estimated useful lives of the assets.

The carrying values of intangible assets are as follows (in thousands):



				December 31,
				2015					2014
	Estimated Lives	Cost		Accumulated Amortization			Net Book Value		Accumulated Amortization			Net Book Value
Existing technology	7 years	$	1,910	$	(1,456	)	$	454	$	(1,183	)	$	727
Patent license	14 years	1,388		(522		)	866		(422		)	966
Non-competition agreements and other	3 years	171		(171		)	—		(158		)	13
Total intangibles subject to amortization		$	3,469	$	(2,149	)	1,320		$	(1,763	)	1,706
Intangible assets not subject to amortization							40					295
Total intangible assets, net							$	1,360				$	2,001

Intangibles amortization expense for each of 2015, 2014 and 2013 was $0.4 million. In 2015, the Company wrote off $0.3 million related to the impairment of certain intangible assets that were not subject to amortization.

As of December 31, 2015, the Company expects amortization expense in future periods to be as follows (in thousands):



2016	$	373
2017	282
2018	100
2019	100
2020	100
2021 and thereafter	365
Total expected future amortization expense	$	1,320

Goodwill, which is not subject to amortization, totaled $0.3 million as of December 31, 2015 and 2014.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2015

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies



NOTE 5.	Commitments and Contingencies

Leases

The Company leases certain computer equipment and its corporate office and data center facilities under noncancelable operating leases for varying periods through 2020.

The following are the minimum annual lease payments due under operating leases at December 31, 2015 (in thousands):



2016	$	3,892
2017	2,377
2018	944
2019	566
2020	339
Total minimum lease payments	$	8,118

Rent expense was $6.6 million, $6.2 million and $5.4 million for 2015, 2014 and 2013, respectively. Although certain of the operating lease agreements provide for escalating rent payments over the terms of the leases, rent expense under these agreements is recognized on a straight-line basis. As of December 31, 2015 and 2014, the Company has accrued $0.5 million of deferred rent related to these agreements, which is reflected in accrued liabilities and other noncurrent liabilities in the accompanying consolidated balance sheets.

Indemnifications

The Company from time to time enters into certain types of contracts that contingently require it to indemnify various parties against claims from third parties. These contracts primarily relate to (i) the Company's by-laws, under which it must indemnify directors and executive officers, and may indemnify other officers and employees, for liabilities arising out of their relationship, (ii) contracts under which the Company must indemnify directors and certain officers for liabilities arising out of their relationship, and (iii) contracts under which the Company may be required to indemnify customers or resellers from certain liabilities arising from potential infringement of intellectual property rights, as well as potential damages caused by limited product defects. To date, the Company has not incurred and has not recorded any liability in connection with such indemnifications.

The Company maintains director and officer insurance, which may cover certain liabilities arising from its obligation to indemnify its directors.

Contingencies

From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable a loss has been incurred and such loss can be reasonably estimated. At December 31, 2015, the Company has not recorded any material liabilities in accordance with accounting for contingencies.

Stockholders' Equity

12 Months Ended

Dec. 31, 2015

Stockholders' Equity Attributable to Parent [Abstract]

Stockholders' Equity



NOTE 6.	Stockholders' Equity

Common Stock

The Company had reserved shares of common stock for future issuance as of December 31, 2015:



Options and RSUs outstanding under equity incentive plans
2000 Equity Incentive Plan⁽¹⁾		3,527,674
2012 Equity Incentive Plan ⁽¹⁾		4,098,884
Shares available for future grants under an equity incentive plan
2012 Equity Incentive Plan⁽¹⁾		1,618,861
Total shares reserved for future issuance		9,245,419

(1) See Note 7 for a description of these plans.

Preferred Stock

Effective October 3, 2012, the Company is authorized to issue 20,000,000 shares of undesignated preferred stock with a par value of $0.001 per share. Each series of preferred stock will have such rights and preferences including dividend rights, dividend rate, conversion rights, voting rights, rights and terms of redemption (including sinking fund provisions), redemption price, and liquidation preferences as determined by the Board. As of December 31, 2015 and 2014, there are no issued or outstanding shares of preferred stock.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Section 50
-Paragraph 4
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
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-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

+ Details

Employee Stock and Benefit Plans

12 Months Ended

Dec. 31, 2015

Share-based Compensation [Abstract]

Employee Stock and Benefit Plans



NOTE 7.	Employee Stock and Benefit Plans

Stock Options

2012 Equity Incentive Plan

The 2012 Equity Incentive Plan (the 2012 Plan) was adopted and approved in September 2012 and became effective on September 26, 2012. Under the 2012 Plan, the Company is authorized to grant to eligible participants incentive stock options (ISOs), nonstatutory stock options (NSOs), stock appreciation rights (SARs), restricted stock awards (RSAs), restricted stock units (RSUs), performance units and performance shares equivalent to up to 6,348,478 shares of common stock as of December 31, 2015. The number of shares of common stock available for issuance under the 2012 Plan includes an annual increase on January 1 of each year by an amount equal to the least of 3,050,000 shares; 5% of the outstanding shares of stock as of the last day of the immediately preceding fiscal year; or an amount determined by the board of directors. Options may be granted with an exercise price that is at least equal to the fair market value of the Company's stock at the date of grant and are exercisable when vested. Options granted generally vest over a period of up to four years, with a maximum term of ten years. ISOs may only be granted to employees and any subsidiary corporations' employees. All other awards may be granted to employees, directors and consultants and subsidiary corporations' employees and consultants. Options, SARs, RSAs, RSUs, performance units and performance awards may be granted with vesting terms as determined by the board of directors and expire no more than ten years after the date of grant or earlier if employment or service is terminated. As of December 31, 2015, 1,618,861 shares were available for grant under the 2012 Plan.

2000 Equity Incentive Plan

Under the 2000 Equity Incentive Plan (the 2000 Plan), the Company was authorized to grant to eligible participants either ISOs or NSOs. The ISOs were granted at a price per share not less than the fair market value at the date of grant. The NSOs were granted at a price per share not less than 85% of the fair market value at the date of grant. Options granted generally vest over a period of up to four years, with a maximum term of ten years. The 2000 Plan was terminated in connection with the closing of the IPO, and accordingly, no shares are currently available for issuance under the 2000 Plan. The 2000 Plan continues to govern outstanding awards granted thereunder.

Options granted under the 2000 Plan were immediately exercisable, and unvested shares are subject to repurchase by the Company. Upon termination of employment of an option holder, the Company has the right to repurchase at the original purchase price any issued but unvested common shares. The amounts paid for shares purchased under an early exercise of stock options and subject to repurchase by the Company are not reported as a component of stockholders’ equity (deficit) until those shares vest. The amounts received in exchange for these shares are recorded as an accrued liability in the accompanying consolidated balance sheets and will be reclassified to common stock and additional paid-in capital as the shares vest.

Employee Stock-based Compensation

Stock-based compensation for employee stock options is included in the consolidated statements of operations as follows:



	Year Ended December 31,
	2015		2014		2013
	(in thousands)
Cost of revenues	$	1,250	$	757	$	421
Research and development	4,936		2,463		1,038
Sales and marketing	3,867		2,394		1,244
General and administrative	6,325		4,217		1,842
Total stock-based employee compensation	$	16,378	$	9,831	$	4,545

Compensation cost is recognized on a straight-line basis over the service period. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

As of December 31, 2015, the Company had $25.2 million of total unrecognized employee compensation cost related to unvested awards that it expects to recognize over a weighted-average period of 2.3 years.

The fair value of each option granted to employees is estimated on the date of grant using the Black-Scholes option-pricing model based on the following assumptions:



	Year Ended December 31,
	2015	2014	2013
Expected term (in years)	4.9 to 5.9	5.3 to 5.9	5.4 to 6.1
Volatility	45% to 48%	48% to 52%	52% to 53%
Risk-free interest rate	1.3% to 1.7%	1.5% to 1.7%	0.7% to 1.5%
Dividend yield	—	—	—

The expected term of the options is based on evaluations of historical and expected future employee exercise behavior. The risk-free interest rate is based on the U.S. Treasury rates at the date of grant with maturity dates approximately equal to the expected term at the grant date. Volatility is based on historical volatility of several public entities that are similar to the Company, as the Company does not have sufficient historical transactions in its own shares on which to base expected volatility. The Company has not historically declared any dividends and does not expect to in the future.

Non-Employee Stock-based Compensation

The Company records compensation representing the fair value of stock options granted to non-employees. Stock-based non-employee compensation was $0.6 million, $0.7 million and $0.9 million for 2015, 2014 and 2013, respectively. Non-employee stock-based compensation is recognized over the vesting periods of the options. The value of options granted to non-employees is remeasured as they vest over a performance period.

Stock Option Plan Activity

A summary of the Company’s stock option activity is as follows:



	Outstanding Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
						(in thousands)
Balance as of December 31, 2012	6,513,508		$	4.39	6.6	$	67,711
Granted	2,001,400		15.78
Exercised	(952,871	)	4.32
Canceled	(522,944	)	10.71
Balance as of December 31, 2013	7,039,093		7.17		6.5	112,312
Granted	2,744,150		26.16
Exercised	(1,216,710	)	6.28
Canceled	(961,126	)	16.91
Balance as of December 31, 2014	7,605,407		12.93		6.5	188,743
Granted	1,526,450		39.50
Exercised	(807,846	)	12.50
Canceled	(744,953	)	27.67
Balance as of December 31, 2015	7,579,058		16.88		5.9	131,345
Vested and expected to vest—December 31, 2015	7,111,282		15.69		5.7	130,208
Exercisable—December 31, 2015	5,195,339		9.78		4.8	121,098

The following table summarizes the outstanding and vested stock options at December 31, 2015:



	Outstanding				Vested
Exercise Price	Number of Shares	Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (Years)	Number of Shares	Weighted Average Exercise Price Per Share
$1.40 - $1.40	156,259	$	1.40	0.5	156,259	$	1.40
$1.90 - $1.90	940,082	1.90		1.1	940,082	1.90
$2.10 - $2.80	415,220	2.63		2.9	415,220	2.63
$3.80 - $3.80	1,117,235	3.80		3.9	1,117,235	3.80
$4.10 - $8.90	868,867	6.16		5.4	842,958	6.08
$9.40 - $16.68	786,624	13.13		6.9	606,364	12.95
$19.26 - $26.86	1,156,772	24.00		8.1	575,066	23.69
$30.58 - $30.58	827,997	30.58		8.7	423,645	30.58
$34.97 - $37.28	824,344	36.31		8.7	14,381	37.18
$40.68 - $52.14	485,658	45.13		8.9	75,635	41.39
	7,579,058	16.88		5.9	5,166,845	9.79

The weighted-average grant date fair value of the Company’s stock options granted during 2015, 2014 and 2013 was $16.51, $12.07 and $7.62, respectively. The aggregate grant date fair value of the Company’s stock options granted during 2015, 2014 and 2013 was $25.2 million, $33.1 million and $15.2 million, respectively.

The intrinsic value of options exercised was $22.7 million, $25.7 million and $11.1 million during 2015, 2014 and 2013, respectively. Intrinsic value of an option is the difference between the fair value of the Company’s common stock at the time of exercise and the exercise price paid.

Restricted Stock

The terms and conditions of RSUs and RSAs, including vesting criteria and timing are set by the board of directors. The cost of RSUs and RSAs is determined using the fair value of the Company’s common stock on the date of the grant. Compensation cost is recognized on a straight-line basis over the requisite service period of each grant adjusted for estimated forfeitures.

During 2015, the Company granted 60,000 units of restricted stock with a grant date fair value of $37.28. The Company did not issue restricted stock units in 2014 and 2013. The Company recorded compensation expense of $0.5 million in 2015. During 2015, 12,500 units were vested and released, and there were no cancellations or forfeitures. The restricted stock units outstanding and expected to vest as of December 31, 2015 is 47,500 units.

As of December 31, 2015, the Company has $1.8 million of unrecognized compensation cost related to unvested awards that it expects to recognize over a weighted-average period of 1.6 years.

401(k) Plan

The Company’s 401(k) Plan (the “401(k) Plan”) was established in 2000 to provide retirement and incidental benefits for its employees. As allowed under section 401(k) of the Internal Revenue Code, the 401(k) Plan provides tax-deferred salary deductions for eligible employees. Contributions to the 401(k) Plan are limited to a maximum amount as set periodically by the Internal Revenue Service. To date, the Company has not made any contributions to the 401(k) Plan.

Other Income (Expense), Net

12 Months Ended

Dec. 31, 2015

Other Income and Expenses [Abstract]

Other Income (Expense), Net



NOTE 8.	Other Income (Expense), Net

Other income (expense), net consists of the following:



	Year Ended December 31,
	2015			2014			2013
	(in thousands)
Foreign exchange losses	$	(444	)	$	(664	)	$	(679	)
Other income (expense)	(406		)	(413		)	79
Other expense, net	$	(850	)	$	(1,077	)	$	(600	)

Income Taxes

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Income Taxes



NOTE 9.	Income Taxes

The Company’s geographical breakdown of income before income taxes is as follows:



	Year Ended December 31,
	2015		2014		2013
	(in thousands)
Domestic	$	22,540	$	7,384	$	947
Foreign	1,980		1,229		1,094
Income before income taxes	$	24,520	$	8,613	$	2,041

The provision for (benefit from) income taxes consists of the following:



	Year Ended December 31,
	2015			2014			2013
	(in thousands)
Current
Federal	$	115		$	—		$	(40	)
State	1,041			317			154
Foreign	693			651			452
Total current provision	1,849			968			566
Deferred
Federal	7,115			(22,184		)	6
State	(247		)	(433		)	—
Foreign	(62		)	18			(72		)
Total deferred provision (benefit)	6,806			(22,599		)	(66		)
Total provision for (benefit from) income taxes	$	8,655		$	(21,631	)	$	500

The reconciliation of the statutory federal income tax rate to the Company’s effective tax rate is as follows:



	Year Ended December 31,
	2015		2014		2013
Federal statutory rate	35.0	%	35.0	%	34.0	%
State taxes	2.2		1.4		5.1
Stock-based compensation	0.5		1.3		9.1
Foreign source income	0.6		3.9		1.9
Change in valuation allowance	1.3		(270.5	)	(28.4	)
Incremental federal rate benefit previously not recognized	—		(7.0	)	—
Federal and state research and development credit	(3.9	)	(11.3	)	—
Other	(0.4	)	(3.9	)	2.8
Provision for (benefit from) income taxes	35.3	%	(251.1	)%	24.5	%

Deferred income taxes reflect the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The components of the Company’s deferred tax assets and liabilities are as follows:



	December 31,
	2015			2014
	(in thousands)
Deferred tax assets
Net operating loss carryforwards	$	1,936		$	12,849
Research and development credit carryforwards	6,508			6,392
Accrued liabilities	614			583
Deferred revenues	3,838			3,291
Deferred rent	142			191
Intangible assets	246			401
Stock-based compensation	8,301			4,149
Other	1,396			903
Gross deferred tax assets	22,981			28,759
Valuation allowance	(3,303		)	(3,079		)
Net deferred tax assets	19,678			25,680
Deferred tax liabilities
Fixed assets	(3,599		)	(3,039		)
Intangible assets	—			(2		)
Total deferred tax liabilities	(3,599		)	(3,041		)
Net deferred tax assets	$	16,079		$	22,639

Realization of deferred tax assets is dependent upon future earnings, if any, and the timing and amount of such assets are uncertain. Prior to the fourth quarter of 2014, the Company had provided a valuation allowance for its U.S. federal and state deferred tax assets that it believed were not more likely than not realizable. Management determined that the objective and verifiable negative evidence, such as relatively low U.S. operating income and uncertainty of sustaining or growing future operating profits, continued to outweigh positive evidence that would be necessary to reduce the valuation allowance.

In the fourth quarter of 2014, the Company recorded a $23.7 million tax benefit for the recognition of its U.S. federal and certain state deferred tax assets, primarily due to the increased and expected sustainable profitability in its U.S. operations. In reaching this conclusion, management considered the Company's increasing realized profitability in the fourth quarter of 2014, forecasted future profitability, its ability to better absorb uncertainties in future profits, and the cumulative effect of changes in the macro-economic environment surrounding the IT security industry, which ultimately resulted in increased demand for its solutions.

The Company believes it is more likely than not that its California deferred tax assets will not be realized because the income attributed to California is not expected to be sufficient to recognize these deferred tax assets. Accordingly, the Company continues to record the valuation allowance of $3.3 million as of December 31, 2015 for its California deferred tax assets During the year ended December 31, 2015, the valuation allowance had increased by $0.2 million to $3.3 million.

At December 31, 2015, the Company had federal and state net operating loss carryforwards of approximately $35.6 million and $4.8 million respectively, available to reduce federal and state taxable income. The excess tax benefits included in net operating loss carryforwards but not reflected in deferred tax assets for federal and state are $30.8 million and $0.2 million, respectively. The Company’s federal net operating losses expire in the years 2022 to 2035, and its state net operating losses expire from 2016 to 2035. Utilization of the Company’s net operating loss carryforwards may be subject to a substantial annual limitation due to the ownership change limitations provided by the Internal Revenue Code and similar state provisions. Such an annual limitation could result in the expiration of the net operating loss carryforwards before utilization. As of December 31, 2015, the Company had federal and state research and development credits of $5.0 million and $5.7 million, respectively. Federal research and development credits expire in the years 2023 to 2035. State research and development credits do not expire.

U.S. income taxes and foreign withholding taxes have not been provided on undistributed earnings for non-U.S. subsidiaries. The Company intends to continue to reinvest the earnings of these foreign subsidiaries indefinitely. The Company’s share of undistributed earnings of foreign subsidiaries that could be subject to additional U.S. income tax if remitted was approximately $8.7 million and $6.8 million as of December 31, 2015 and 2014, respectively. Determination of the amount of unrecognized deferred tax liability for temporary differences related to investments in these non-U.S. subsidiaries that are essentially permanent in duration is not practicable. If the undistributed earnings are remitted to the U.S. these amounts would be taxable in the U.S. at the current federal and state tax rates net of foreign tax credits. Also, depending on the jurisdiction any distribution would potentially be subject to withholding taxes at rates applicable to that jurisdiction.

The evaluation of a tax position is a two-step process. The first step requires the Company to determine whether it is more likely than not that a tax position will be sustained upon examination based on the technical merits of the position. The second step requires the Company to recognize in the financial statement each tax position that meets the more likely than not criteria, measured at the amount of benefit that has a greater than fifty percent likelihood of being realized.

A reconciliation of the Company’s unrecognized tax benefits is as follows:



	Year Ended December 31,
	2015			2014			2013
	(in thousands)
Unrecognized tax benefits beginning balance	$	3,330		$	3,255		$	2,647
Gross increase for tax positions of prior years	20			—			241
Gross decrease for tax positions of prior years	(171		)	(127		)	—
Gross increase for tax positions of current year	418			332			446
Lapse of statute of limitations	(91		)	(130		)	(79		)
Total unrecognized tax benefits	$	3,506		$	3,330		$	3,255

The unrecognized tax benefits, if recognized, would impact the income tax provision by $2.1 million, $2.1 million and $1.0 million as of December 31, 2015, 2014 and 2013, respectively.

The Company has elected to include interest and penalties as a component of income tax expense. The amounts were not material for 2015, 2014 and 2013.

The Company files income tax returns in the United States, including various state jurisdictions. The Company’s subsidiaries file tax returns in various foreign jurisdictions. The tax years 2010 to 2015 remain open to examination by the major taxing jurisdictions in which the Company is subject to tax, with the exception of France which remains open to examination for the 2012 through 2015 tax years only. As of December 31, 2015, the Company was not under examination by the Internal Revenue Service or any state tax jurisdictions.

A retroactive and permanent reinstatement of the federal research and development tax credit was signed into law on December 18, 2015 in accordance with the Protecting Americans from Tax Hikes Act of 2015. The Company recorded a 2015 federal research and development credit of $0.6 million, net of reserves, in the fourth quarter of 2015. The California research and development credit estimated for 2015, net of reserves, is $0.5 million.

Segment Information and Information about Geographic Area

12 Months Ended

Dec. 31, 2015

Segment Reporting [Abstract]

Segment Information and Information about Geographic Area



NOTE 10.	Segment Information and Information about Geographic Area

The Company operates in one segment. The Company’s chief operating decision maker is the Chairman, President and Chief Executive Officer, who makes operating decisions, assesses performance and allocates resources on a consolidated basis. All of the Company’s principal operations and decision-making functions are located in the United States. Revenues by geographic area, based on the location of the customer, are as follows:



	Year Ended December 31,
	2015		2014		2013
	(in thousands)
United States	$	115,384	$	93,425	$	75,485
Foreign	48,900		40,154		32,477
Total revenues	$	164,284	$	133,579	$	107,962

Property and equipment, net, by geographic area, are as follows:



	December 31,
	2015		2014
	(in thousands)
United States	$	25,623	$	23,650
Foreign	5,706		2,968
Total property and equipment, net	$	31,329	$	26,618

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Section 50
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Topic 280
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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+ Details

Net Income Per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2015

Earnings Per Share [Abstract]

Net Income Per Share Attributable to Common Stockholders



NOTE 11.	Net Income Per Share Attributable to Common Stockholders

The computations for basic and diluted net income per share attributable to common stockholders are as follows:



	Year Ended December 31,
	2015		2014		2013
	(in thousands, except per share data)
Numerator:
Net income	$	15,865	$	30,244	$	1,541
Net income attributable to participating securities	—		—		(2		)
Net income attributable to common stockholders - basic	15,865		30,244		1,539
Net income attributable to common stockholders - diluted	$	15,865	$	30,244	$	1,539
Denominator:
Weighted-average shares used in computing net income per share attributable to common stockholders - basic	34,050		32,979		31,914
Effect of potentially dilutive securities:
Common stock options	4,134		4,191		4,059
Weighted-average shares used in computing net income per share attributable to common stockholders - diluted	38,184		37,170		35,973
Net income per share attributable to common stockholders
Basic	$	0.47	$	0.92	$	0.05
Diluted	$	0.42	$	0.81	$	0.04

Potentially dilutive securities not included in the calculation of diluted net income per share because doing so would be antidilutive are as follows:



	Year Ended December 31,
	2015	2014	2013
	(in thousands)
Common stock options	1,582	1,689	952

Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information (Unaudited)



NOTE 12.	Quarterly Financial Information (Unaudited)

The following table sets forth unaudited consolidated statements of operations data for each of the quarters in the two-year period ended December 31, 2015. The unaudited quarterly consolidated statements of operations data set forth below have been prepared on the same basis as the audited consolidated financial statements included elsewhere in this Annual Report on Form 10-K and, in the opinion of management, reflect all necessary adjustments, which consist only of normal recurring adjustments, necessary for a fair presentation of such data. Historical results are not necessarily indicative of the results for the full year or any other period. This data should be read together with the consolidated financial statements and the related notes included elsewhere in this Annual Report on Form 10-K.



	Three Months Ended
	Mar. 31, 2014			Jun. 30, 2014		Sep. 30, 2014			Dec. 31, 2014			Mar. 31, 2015			Jun. 30, 2015		Sep. 30, 2015			Dec. 31, 2015
	(unaudited)
	(in thousands, except per share data)
Revenues	$	30,356		$	32,302	$	34,348		$	36,573		$	37,493		$	39,877	$	42,469		$	44,445
Cost of revenues	6,846			7,175		7,421			7,521			7,964			8,157		8,762			9,002
Gross profit	23,510			25,127		26,927			29,052			29,529			31,720		33,707			35,443
Operating expenses:
Research and development	6,404			6,411		6,490			7,015			7,150			7,205		7,564			7,532
Sales and marketing	12,492			11,845		11,774			11,938			11,443			12,776		12,282			13,068
General and administrative	4,875			5,081		5,156			5,888			6,016			6,427		6,983			7,147
Total operating expenses	23,771			23,337		23,420			24,841			24,609			26,408		26,829			27,747
Income (loss) from operations	(261		)	1,790		3,507			4,211			4,920			5,312		6,878			7,696
Other income (expense), net	12			41		(119		)	(568		)	(77		)	128		(154		)	(183		)
Income (loss) before income taxes	(249		)	1,831		3,388			3,643			4,843			5,440		6,724			7,513
Provision for (benefit from) income taxes⁽¹⁾	182			174		283			(22,270		)	1,841			2,124		2,601			2,089
Net income (loss)	$	(431	)	$	1,657	$	3,105		$	25,913		$	3,002		$	3,316	$	4,123		$	5,424
Net income (loss) per share:
Basic	$	(0.01	)	$	0.05	$	0.09		$	0.77		$	0.09		$	0.10	$	0.12		$	0.16
Diluted	$	(0.01	)	$	0.04	$	0.08		$	0.69		$	0.08		$	0.09	$	0.11		$	0.14

⁽¹⁾ Provision for income taxes consists primarily of taxes on income in foreign jurisdictions and state income taxes in the U.S. In the fourth quarter of 2014, the Company recorded a tax benefit of $23.7 million to recognize its U.S. federal and certain state deferred tax assets.

Schedule II Schedule of Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2015

Valuation and Qualifying Accounts [Abstract]

Schedule II Schedule of Valuation and Qualifying Accounts

SCHEDULE II

SUPPLEMENTARY CONSOLIDATED FINANCIAL STATEMENT SCHEDULE

VALUATION AND QUALIFYING ACCOUNTS

(in thousands)



			Additions
	Balance at Beginning of Year		Charged to Costs and Expenses		Deductions and Other ⁽¹⁾			Balance at End of Year
Allowance for Doubtful Accounts
Year Ended December 31, 2015	$	590	$	851	$	(672	)	$	769
Year Ended December 31, 2014	$	389	$	470	$	(269	)	$	590
Year Ended December 31, 2013	$	331	$	307	$	(249	)	$	389

⁽¹⁾Primarily represents write-offs of uncollectible accounts, net of recoveries.

The Company and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2015

Accounting Policies [Abstract]

Description of Business

Basis of presentation

Basis of Presentation

Use of estimates

Use of Estimates

Concentration of credit risk

Concentration of Credit Risk

Cash, cash equivalents and short-term and long-term investments

Cash, Cash Equivalents, Short-Term and Long-Term Investments

Accounts receivable

Accounts Receivable

Property and equipment, net

Property and Equipment, net

Impairment of long-lived assets

Impairment of Long-Lived Assets

Goodwill and intangible assets

Goodwill and Intangible Assets

Software development cost

Software Development Costs

Derivative financial instruments

Derivative Financial Instruments

Share-based compensation

Stock-Based Compensation

Revenue recognition

Revenue Recognition

The Company recognizes revenues when all of the following conditions are met:


•	There is persuasive evidence of an arrangement.


•	The service has been provided to the customer.


•	The collection of the fees is reasonably assured.


•	The amount of fees to be paid by the customer is fixed or determinable.

Costs of shipping and handling charges incurred by the Company associated with physical scanner appliances and other computer equipment are included in cost of revenues.

Sales taxes and other taxes collected from customers to be remitted to government authorities are excluded from revenues.

Advertising expenses

Advertising Expenses

Income taxes

Income Taxes

Comprehensive income (loss)

Comprehensive Income (Loss)

Foreign currency translation and transactions

Foreign Currency Transactions

Fair value measurement

Fair Value Measurements

Level 1—Valuations based on quoted prices in active markets for identical assets or liabilities.

Net income per share attributable to common stockholders

Net Income Per Share Attributable to Common Stockholders

Recent accounting pronouncements

Recent Accounting Pronouncements

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Schedule of Cash and Cash Equivalents, Available-for-sale Securities Reconciliation

The Company's cash and cash equivalents, short-term investments, and long-term investments consist of the following:



	December 31, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	61,372	$	—	$	—		$	61,372
Money market funds	3,980		—		—			3,980
U.S. government agencies	8,999		1		—			9,000
Commercial paper	17,345		1		—			17,346
Total	91,696		2		—			91,698
Short-term investments:
Commercial paper	10,447		1		—			10,448
Corporate bonds	12,448		—		(13		)	12,435
U.S. government agencies	64,422		3		(40		)	64,385
Total	87,317		4		(53		)	87,268
Long-term investments:
Asset-backed securities	7,007		—		(18		)	6,989
U.S. government agencies	32,683		—		(142		)	32,541
Corporate bonds	3,751		—		(4		)	3,747
Total	43,441		—		(164		)	43,277
Total	$	222,454	$	6	$	(217	)	$	222,243



	December 31, 2014
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	36,024	$	—	$	—		$	36,024
Money market funds	39,180		—		—			39,180
U.S. government agencies	300		—		—			300
Commercial paper	1,000		—		—			1,000
Total	76,504		—		—			76,504
Short-term investments:
Commercial paper	4,998		1		—			4,999
Corporate bonds	12,438		6		(6		)	12,438
U.S. government agencies	33,280		3		(6		)	33,277
Total	50,716		10		(12		)	50,714
Long-term investments:
Asset-backed securities	16,092		5		(3		)	16,094
U.S. government agencies	20,243		22		(10		)	20,255
Corporate bonds	3,101		—		(2		)	3,099
Total	39,436		27		(15		)	39,448
Total	$	166,656	$	37	$	(27	)	$	166,666

Schedule of Assets Measured on Recurring Basis



	December 31, 2015
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	27,794	$	—	$	27,794
U.S. government agencies	—		105,926		—		105,926
Corporate bonds	—		16,182		—		16,182
Asset-backed securities	—		6,989		—		6,989
Total	$	—	$	156,891	$	—	$	156,891



	December 31, 2014
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	5,999	$	—	$	5,999
U.S. government agencies	—		53,832		—		53,832
Corporate bonds	—		15,537		—		15,537
Asset-backed securities	—		16,094		—		16,094
Total	$	—	$	91,462	$	—	$	91,462

Schedule of Investments Classified by Contractual Maturity

The following summarizes the fair value of securities classified as available-for-sale by contractual maturity:



	December 31, 2015
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	27,794	$	—	$	—	$	27,794
U.S. government agencies	73,385		32,541		—		105,926
Corporate bonds	12,435		3,747		—		16,182
Asset-backed securities	—		3,411		3,578		6,989
Total	$	113,614	$	39,699	$	3,578	$	156,891



	December 31, 2014
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	5,999	$	—	$	—	$	5,999
U.S. government agencies	33,577		20,255		—		53,832
Corporate bonds	12,438		3,099		—		15,537
Asset-backed securities	—		7,327		8,767		16,094
Total	$	52,014	$	30,681	$	8,767	$	91,462

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

Property and equipment

Property and equipment consists of the following:



	December 31,
	2015			2014
	(in thousands)
Computer equipment	$	48,192		$	35,576
Computer software	12,484			10,899
Furniture, fixtures and equipment	2,804			2,931
Scanner appliances	22,627			19,861
Leasehold improvements	3,367			2,622
Total property and equipment	89,474			71,889
Less: accumulated depreciation and amortization	(58,145		)	(45,271		)
Property and equipment, net	$	31,329		$	26,618

Goodwill and Intangible Assets, Net (Tables)

12 Months Ended

Dec. 31, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

Carrying value of intangible assets

The carrying values of intangible assets are as follows (in thousands):



				December 31,
				2015					2014
	Estimated Lives	Cost		Accumulated Amortization			Net Book Value		Accumulated Amortization			Net Book Value
Existing technology	7 years	$	1,910	$	(1,456	)	$	454	$	(1,183	)	$	727
Patent license	14 years	1,388		(522		)	866		(422		)	966
Non-competition agreements and other	3 years	171		(171		)	—		(158		)	13
Total intangibles subject to amortization		$	3,469	$	(2,149	)	1,320		$	(1,763	)	1,706
Intangible assets not subject to amortization							40					295
Total intangible assets, net							$	1,360				$	2,001

Intangible assets future periods amortization expense

As of December 31, 2015, the Company expects amortization expense in future periods to be as follows (in thousands):



2016	$	373
2017	282
2018	100
2019	100
2020	100
2021 and thereafter	365
Total expected future amortization expense	$	1,320

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2015

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Lease Payments for Operating Leases

The following are the minimum annual lease payments due under operating leases at December 31, 2015 (in thousands):



2016	$	3,892
2017	2,377
2018	944
2019	566
2020	339
Total minimum lease payments	$	8,118

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2015

Stockholders' Equity Attributable to Parent [Abstract]

Schedule of shares reserved for future issuance

The Company had reserved shares of common stock for future issuance as of December 31, 2015:



Options and RSUs outstanding under equity incentive plans
2000 Equity Incentive Plan⁽¹⁾		3,527,674
2012 Equity Incentive Plan ⁽¹⁾		4,098,884
Shares available for future grants under an equity incentive plan
2012 Equity Incentive Plan⁽¹⁾		1,618,861
Total shares reserved for future issuance		9,245,419

(1) See Note 7 for a description of these plans.

Employee Stock and Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2015

Share-based Compensation [Abstract]

Stock-based employee compensation

Stock-based compensation for employee stock options is included in the consolidated statements of operations as follows:



	Year Ended December 31,
	2015		2014		2013
	(in thousands)
Cost of revenues	$	1,250	$	757	$	421
Research and development	4,936		2,463		1,038
Sales and marketing	3,867		2,394		1,244
General and administrative	6,325		4,217		1,842
Total stock-based employee compensation	$	16,378	$	9,831	$	4,545

Fair value assumptions of options granted to employees

The fair value of each option granted to employees is estimated on the date of grant using the Black-Scholes option-pricing model based on the following assumptions:



	Year Ended December 31,
	2015	2014	2013
Expected term (in years)	4.9 to 5.9	5.3 to 5.9	5.4 to 6.1
Volatility	45% to 48%	48% to 52%	52% to 53%
Risk-free interest rate	1.3% to 1.7%	1.5% to 1.7%	0.7% to 1.5%
Dividend yield	—	—	—

Stock option activity

A summary of the Company’s stock option activity is as follows:



	Outstanding Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
						(in thousands)
Balance as of December 31, 2012	6,513,508		$	4.39	6.6	$	67,711
Granted	2,001,400		15.78
Exercised	(952,871	)	4.32
Canceled	(522,944	)	10.71
Balance as of December 31, 2013	7,039,093		7.17		6.5	112,312
Granted	2,744,150		26.16
Exercised	(1,216,710	)	6.28
Canceled	(961,126	)	16.91
Balance as of December 31, 2014	7,605,407		12.93		6.5	188,743
Granted	1,526,450		39.50
Exercised	(807,846	)	12.50
Canceled	(744,953	)	27.67
Balance as of December 31, 2015	7,579,058		16.88		5.9	131,345
Vested and expected to vest—December 31, 2015	7,111,282		15.69		5.7	130,208
Exercisable—December 31, 2015	5,195,339		9.78		4.8	121,098

Schedule of exercise price range, outstanding and vested

The following table summarizes the outstanding and vested stock options at December 31, 2015:



	Outstanding				Vested
Exercise Price	Number of Shares	Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (Years)	Number of Shares	Weighted Average Exercise Price Per Share
$1.40 - $1.40	156,259	$	1.40	0.5	156,259	$	1.40
$1.90 - $1.90	940,082	1.90		1.1	940,082	1.90
$2.10 - $2.80	415,220	2.63		2.9	415,220	2.63
$3.80 - $3.80	1,117,235	3.80		3.9	1,117,235	3.80
$4.10 - $8.90	868,867	6.16		5.4	842,958	6.08
$9.40 - $16.68	786,624	13.13		6.9	606,364	12.95
$19.26 - $26.86	1,156,772	24.00		8.1	575,066	23.69
$30.58 - $30.58	827,997	30.58		8.7	423,645	30.58
$34.97 - $37.28	824,344	36.31		8.7	14,381	37.18
$40.68 - $52.14	485,658	45.13		8.9	75,635	41.39
	7,579,058	16.88		5.9	5,166,845	9.79

Other Income (Expense), Net (Tables)

12 Months Ended

Dec. 31, 2015

Other Income and Expenses [Abstract]

Schedule of Other Nonoperating Income (Expense)

Other income (expense), net consists of the following:



	Year Ended December 31,
	2015			2014			2013
	(in thousands)
Foreign exchange losses	$	(444	)	$	(664	)	$	(679	)
Other income (expense)	(406		)	(413		)	79
Other expense, net	$	(850	)	$	(1,077	)	$	(600	)

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Schedule of Geographical Breakdown of Income (Loss) Before Provision for (Benefit From) Income Taxes

The Company’s geographical breakdown of income before income taxes is as follows:



	Year Ended December 31,
	2015		2014		2013
	(in thousands)
Domestic	$	22,540	$	7,384	$	947
Foreign	1,980		1,229		1,094
Income before income taxes	$	24,520	$	8,613	$	2,041

Schedule of Provision for (Benefit From) Income Taxes

The provision for (benefit from) income taxes consists of the following:



	Year Ended December 31,
	2015			2014			2013
	(in thousands)
Current
Federal	$	115		$	—		$	(40	)
State	1,041			317			154
Foreign	693			651			452
Total current provision	1,849			968			566
Deferred
Federal	7,115			(22,184		)	6
State	(247		)	(433		)	—
Foreign	(62		)	18			(72		)
Total deferred provision (benefit)	6,806			(22,599		)	(66		)
Total provision for (benefit from) income taxes	$	8,655		$	(21,631	)	$	500

Schedule of Effective Income Tax Rate Reconciliation

The reconciliation of the statutory federal income tax rate to the Company’s effective tax rate is as follows:



	Year Ended December 31,
	2015		2014		2013
Federal statutory rate	35.0	%	35.0	%	34.0	%
State taxes	2.2		1.4		5.1
Stock-based compensation	0.5		1.3		9.1
Foreign source income	0.6		3.9		1.9
Change in valuation allowance	1.3		(270.5	)	(28.4	)
Incremental federal rate benefit previously not recognized	—		(7.0	)	—
Federal and state research and development credit	(3.9	)	(11.3	)	—
Other	(0.4	)	(3.9	)	2.8
Provision for (benefit from) income taxes	35.3	%	(251.1	)%	24.5	%

Schedule of Deferred Tax Assets and Liabilities

The components of the Company’s deferred tax assets and liabilities are as follows:



	December 31,
	2015			2014
	(in thousands)
Deferred tax assets
Net operating loss carryforwards	$	1,936		$	12,849
Research and development credit carryforwards	6,508			6,392
Accrued liabilities	614			583
Deferred revenues	3,838			3,291
Deferred rent	142			191
Intangible assets	246			401
Stock-based compensation	8,301			4,149
Other	1,396			903
Gross deferred tax assets	22,981			28,759
Valuation allowance	(3,303		)	(3,079		)
Net deferred tax assets	19,678			25,680
Deferred tax liabilities
Fixed assets	(3,599		)	(3,039		)
Intangible assets	—			(2		)
Total deferred tax liabilities	(3,599		)	(3,041		)
Net deferred tax assets	$	16,079		$	22,639

Schedule of Unrecognized Tax Benefits

A reconciliation of the Company’s unrecognized tax benefits is as follows:



	Year Ended December 31,
	2015			2014			2013
	(in thousands)
Unrecognized tax benefits beginning balance	$	3,330		$	3,255		$	2,647
Gross increase for tax positions of prior years	20			—			241
Gross decrease for tax positions of prior years	(171		)	(127		)	—
Gross increase for tax positions of current year	418			332			446
Lapse of statute of limitations	(91		)	(130		)	(79		)
Total unrecognized tax benefits	$	3,506		$	3,330		$	3,255

Segment Information and Information about Geographic Area (Tables)

12 Months Ended

Dec. 31, 2015

Segment Reporting [Abstract]

Revenues and property and equipment, net, by geographic area

Revenues by geographic area, based on the location of the customer, are as follows:



	Year Ended December 31,
	2015		2014		2013
	(in thousands)
United States	$	115,384	$	93,425	$	75,485
Foreign	48,900		40,154		32,477
Total revenues	$	164,284	$	133,579	$	107,962

Property and equipment, net, by geographic area, are as follows:



	December 31,
	2015		2014
	(in thousands)
United States	$	25,623	$	23,650
Foreign	5,706		2,968
Total property and equipment, net	$	31,329	$	26,618

Net Income Per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2015

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The computations for basic and diluted net income per share attributable to common stockholders are as follows:



	Year Ended December 31,
	2015		2014		2013
	(in thousands, except per share data)
Numerator:
Net income	$	15,865	$	30,244	$	1,541
Net income attributable to participating securities	—		—		(2		)
Net income attributable to common stockholders - basic	15,865		30,244		1,539
Net income attributable to common stockholders - diluted	$	15,865	$	30,244	$	1,539
Denominator:
Weighted-average shares used in computing net income per share attributable to common stockholders - basic	34,050		32,979		31,914
Effect of potentially dilutive securities:
Common stock options	4,134		4,191		4,059
Weighted-average shares used in computing net income per share attributable to common stockholders - diluted	38,184		37,170		35,973
Net income per share attributable to common stockholders
Basic	$	0.47	$	0.92	$	0.05
Diluted	$	0.42	$	0.81	$	0.04

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

Potentially dilutive securities not included in the calculation of diluted net income per share because doing so would be antidilutive are as follows:



	Year Ended December 31,
	2015	2014	2013
	(in thousands)
Common stock options	1,582	1,689	952

Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information



	Three Months Ended
	Mar. 31, 2014			Jun. 30, 2014		Sep. 30, 2014			Dec. 31, 2014			Mar. 31, 2015			Jun. 30, 2015		Sep. 30, 2015			Dec. 31, 2015
	(unaudited)
	(in thousands, except per share data)
Revenues	$	30,356		$	32,302	$	34,348		$	36,573		$	37,493		$	39,877	$	42,469		$	44,445
Cost of revenues	6,846			7,175		7,421			7,521			7,964			8,157		8,762			9,002
Gross profit	23,510			25,127		26,927			29,052			29,529			31,720		33,707			35,443
Operating expenses:
Research and development	6,404			6,411		6,490			7,015			7,150			7,205		7,564			7,532
Sales and marketing	12,492			11,845		11,774			11,938			11,443			12,776		12,282			13,068
General and administrative	4,875			5,081		5,156			5,888			6,016			6,427		6,983			7,147
Total operating expenses	23,771			23,337		23,420			24,841			24,609			26,408		26,829			27,747
Income (loss) from operations	(261		)	1,790		3,507			4,211			4,920			5,312		6,878			7,696
Other income (expense), net	12			41		(119		)	(568		)	(77		)	128		(154		)	(183		)
Income (loss) before income taxes	(249		)	1,831		3,388			3,643			4,843			5,440		6,724			7,513
Provision for (benefit from) income taxes⁽¹⁾	182			174		283			(22,270		)	1,841			2,124		2,601			2,089
Net income (loss)	$	(431	)	$	1,657	$	3,105		$	25,913		$	3,002		$	3,316	$	4,123		$	5,424
Net income (loss) per share:
Basic	$	(0.01	)	$	0.05	$	0.09		$	0.77		$	0.09		$	0.10	$	0.12		$	0.16
Diluted	$	(0.01	)	$	0.04	$	0.08		$	0.69		$	0.08		$	0.09	$	0.11		$	0.14

The Company and Summary of Significant Accounting Policies (Details) € in Millions, £ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2015 GBP (£) customer contract	Dec. 31, 2015 EUR (€) customer contract	Dec. 31, 2015 USD ($) customer contract	Dec. 31, 2014 GBP (£) customer	Dec. 31, 2014 EUR (€) customer	Dec. 31, 2014 USD ($) customer
Goodwill and Intangible Assets
Impairment of intangible assets		$ 255,000	$ 0	$ 0
Software Development Costs
Capitalized software development costs		99,000	98,000	0
Cost of intangible assets							$ 3,469,000			$ 3,469,000
Accumulated amortization of intangible assets							$ 2,149,000			1,763,000
Derivative Financial Instruments
Derivative, number of instruments held \| contract					2	2	2
Foreign currency contract, asset, fair value disclosure							$ 0			0
Foreign currency transaction loss, before tax		1,000,000	1,400,000
Advertising Expenses
Advertising expense		6,100,000	5,300,000	4,200,000
Foreign exchange losses		$ (444,000)	(664,000)	$ (679,000)
Income Taxes
Noncurrent deferred tax assets							16,079,000			22,639,000
Effect of early adoption of accounting guidance
Income Taxes
Current deferred tax assets										(8,500,000)
Noncurrent deferred tax assets										8,500,000
Minimum
Property Equipment, Net
Property, plant and equipment, useful life		3 years
Goodwill and Intangible Assets
Finite-lived intangible asset, useful life	3 years
Maximum
Property Equipment, Net
Property, plant and equipment, useful life		5 years
Goodwill and Intangible Assets
Finite-lived intangible asset, useful life	14 years
Scanner appliances
Property Equipment, Net
Property, plant and equipment, useful life		3 years
Forward contracts
Derivative Financial Instruments
Derivative, notional amount					£ 2.6	€ 6.1		£ 2.1	€ 6.0
Foreign currency contract, asset, fair value disclosure							0			0
Derivative instruments not designated as hedging instruments, gain		$ 600,000	$ 700,000
Software and software development costs
Software Development Costs
Cost of intangible assets							400,000			300,000
Accumulated amortization of intangible assets							$ 300,000			$ 300,000
Customer concentration risk \| Accounts receivable
Concentration of Credit Risk
Concentration risk, number of customers \| customer					0	0	0	0	0	0

Fair Value of Financial Instruments (Cash and Cash Equivalents, Available-for-sale Securities, Restricted Cash Reconciliation) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	$ 222,454	$ 166,656
Unrealized Gains	6	37
Unrealized Losses	(217)	(27)
Fair value	222,243	166,666
Cash and Cash Equivalents
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	91,696	76,504
Unrealized Gains	2	0
Unrealized Losses	0	0
Fair value	91,698	76,504
Cash and Cash Equivalents \| Cash
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	61,372	36,024
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair value	61,372	36,024
Cash and Cash Equivalents \| Money market funds
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	3,980	39,180
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair value	3,980	39,180
Cash and Cash Equivalents \| U.S. government agencies
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	8,999	300
Unrealized Gains	1	0
Unrealized Losses	0	0
Fair value	9,000	300
Cash and Cash Equivalents \| Commercial paper
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	17,345	1,000
Unrealized Gains	1	0
Unrealized Losses	0	0
Fair value	17,346	1,000
Short-term Investments
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	87,317	50,716
Unrealized Gains	4	10
Unrealized Losses	(53)	(12)
Fair value	87,268	50,714
Short-term Investments \| U.S. government agencies
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	64,422	33,280
Unrealized Gains	3	3
Unrealized Losses	(40)	(6)
Fair value	64,385	33,277
Short-term Investments \| Commercial paper
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	10,447	4,998
Unrealized Gains	1	1
Unrealized Losses	0	0
Fair value	10,448	4,999
Short-term Investments \| Corporate bonds
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	12,448	12,438
Unrealized Gains	0	6
Unrealized Losses	(13)	(6)
Fair value	12,435	12,438
Long-Term Investments
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	43,441	39,436
Unrealized Gains	0	27
Unrealized Losses	(164)	(15)
Fair value	43,277	39,448
Long-Term Investments \| U.S. government agencies
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	32,683	20,243
Unrealized Gains	0	22
Unrealized Losses	(142)	(10)
Fair value	32,541	20,255
Long-Term Investments \| Corporate bonds
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	3,751	3,101
Unrealized Gains	0	0
Unrealized Losses	(4)	(2)
Fair value	3,747	3,099
Long-Term Investments \| Asset-backed securities
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Amortized cost, total	7,007	16,092
Unrealized Gains	0	5
Unrealized Losses	(18)	(3)
Fair value	$ 6,989	$ 16,094

Fair Value of Financial Instruments (Fair Value Hierarchy) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	$ 156,891	$ 91,462
Recurring Basis \| Fair Value
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	156,891	91,462
Level 1 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	0	0
Level 2 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	156,891	91,462
Level 3 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	0	0
Commercial paper
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	27,794	5,999
Commercial paper \| Recurring Basis \| Fair Value
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	27,794	5,999
Commercial paper \| Level 1 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	0	0
Commercial paper \| Level 2 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	27,794	5,999
Commercial paper \| Level 3 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	0	0
U.S. government agencies
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	105,926	53,832
U.S. government agencies \| Recurring Basis \| Fair Value
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	105,926	53,832
U.S. government agencies \| Level 1 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	0	0
U.S. government agencies \| Level 2 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	105,926	53,832
U.S. government agencies \| Level 3 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	0	0
Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	16,182	15,537
Corporate bonds \| Recurring Basis \| Fair Value
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	16,182	15,537
Corporate bonds \| Level 1 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	0	0
Corporate bonds \| Level 2 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	16,182	15,537
Corporate bonds \| Level 3 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	0	0
Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	6,989	16,094
Asset-backed securities \| Recurring Basis \| Fair Value
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	6,989	16,094
Asset-backed securities \| Level 1 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	0	0
Asset-backed securities \| Level 2 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	6,989	16,094
Asset-backed securities \| Level 3 \| Recurring Basis
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities, fair value	$ 0	$ 0

Fair Value of Financial Instruments (Contractual Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Mature within One Year	$ 113,614	$ 52,014
After One Year through Two Years	39,699	30,681
Over Two Years	3,578	8,767
Fair Value	156,891	91,462
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Mature within One Year	27,794	5,999
After One Year through Two Years	0	0
Over Two Years	0	0
Fair Value	27,794	5,999
U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Mature within One Year	73,385	33,577
After One Year through Two Years	32,541	20,255
Over Two Years	0	0
Fair Value	105,926	53,832
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Mature within One Year	12,435	12,438
After One Year through Two Years	3,747	3,099
Over Two Years	0	0
Fair Value	16,182	15,537
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Mature within One Year	0	0
After One Year through Two Years	3,411	7,327
Over Two Years	3,578	8,767
Fair Value	$ 6,989	$ 16,094

Fair Value of Financial Instruments (Narrative) (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contract, asset, fair value disclosure	$ 0	$ 0
Forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contract, asset, fair value disclosure	$ 0	$ 0

Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment	$ 89,474	$ 71,889
Less: accumulated depreciation and amortization	(58,145)	(45,271)
Property and equipment, net	31,329	26,618
Depreciation and amortization expense	13,900	11,500	$ 9,200
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	48,192	35,576
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment	12,484	10,899
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Property and equipment	2,804	2,931
Scanner appliances
Property, Plant and Equipment [Line Items]
Property and equipment	22,627	19,861
Scanner appliances and other computer equipment subject to subscription
Property, Plant and Equipment [Line Items]
Property and equipment, net	8,400	6,000
Scanner appliances and other computer equipment not placed in service
Property, Plant and Equipment [Line Items]
Property and equipment	1,400	1,400
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	3,367	2,622
Other fixed assets not placed in service
Property, Plant and Equipment [Line Items]
Property and equipment	$ 4,300	$ 2,800

Goodwill and Intangible Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Goodwill and Intangible Assets [Line Items]
Cost	$ 3,469	$ 3,469
Accumulated Amortization	(2,149)	(1,763)
Net Book Value	1,320	1,706
Intangible assets not subject to amortization	40	295
Total intangible assets, net	1,360	2,001
Amortization of intangible assets	400	400	$ 400
Impairment of intangible assets	255	0	$ 0
Goodwill	$ 317	317
Existing technology
Schedule of Goodwill and Intangible Assets [Line Items]
Estimated Lives	7 years
Cost	$ 1,910	1,910
Accumulated Amortization	(1,456)	(1,183)
Net Book Value	$ 454	727
Patent license
Schedule of Goodwill and Intangible Assets [Line Items]
Estimated Lives	14 years
Cost	$ 1,388	1,388
Accumulated Amortization	(522)	(422)
Net Book Value	$ 866	966
Non-competition agreements and other
Schedule of Goodwill and Intangible Assets [Line Items]
Estimated Lives	3 years
Cost	$ 171	171
Accumulated Amortization	(171)	(158)
Net Book Value	$ 0	$ 13

Goodwill and Intangible Assets, Net (Future Amortization) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
2016	$ 373
2017	282
2018	100
2019	100
2020	100
2021 and thereafter	365
Net Book Value	$ 1,320	$ 1,706

Commitments and Contingencies (Future Minimum Lease Payments) (Details) $ in Thousands	Dec. 31, 2015 USD ($)
Operating Leases
2016	$ 3,892
2017	2,377
2018	944
2019	566
2020	339
Total minimum lease payments	$ 8,118

Commitments and Contingencies (Additional Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 6.6	$ 6.2	$ 5.4
Deferred rent credit, noncurrent	$ 0.5	$ 0.5

Stockholders' Equity (Details) - $ / shares	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 03, 2012
Common Stock
Options and RSUs outstanding under equity incentive plans	7,579,058	7,605,407	7,039,093	6,513,508
Total shares reserved for future issuance	9,245,419
Preferred Stock
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, par value per share (in dollars per share)	$ 0.001	$ 0.001
Preferred Stock
Preferred Stock
Preferred stock, shares authorized					20,000,000
Preferred stock, par value per share (in dollars per share)					$ 0.001
2000 Equity Incentive Plan
Common Stock
Options and RSUs outstanding under equity incentive plans	3,527,674
2012 Equity Incentive Plan
Common Stock
Options and RSUs outstanding under equity incentive plans	4,098,884
Shares available for future grants under an equity incentive plan	1,618,861

Employee Stock and Benefit Plans (Plan Information) (Details) - shares		12 Months Ended
	Sep. 26, 2012	Dec. 31, 2015
2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized		6,348,478
Number of shares available for grant		1,618,861
2012 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years
2012 Equity Incentive Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Term of award	10 years
2000 Equity Incentive Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Term of award		10 years
Number of shares available for issuance		0
2000 Equity Incentive Plan \| Stock Options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award strike price as a percentage of market value		85.00%
Increase of Number of Shares Option \| 2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plan annual increase (in shares)	3,050,000
Increase of Percentage of Shares Outstanding Option \| 2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plan, annual increase, percent of shares outstanding	5.00%

Employee Stock and Benefit Plans (Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based employee compensation	$ 16,378	$ 9,831	$ 4,545
Unrecognized employee compensation cost	$ 25,200
Unrecognized employee compensation cost, period for recognition	2 years 3 months 18 days
Non-employee share-based compensation expense	$ 600	700	900
Cost of revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based employee compensation	1,250	757	421
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based employee compensation	4,936	2,463	1,038
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based employee compensation	3,867	2,394	1,244
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based employee compensation	$ 6,325	$ 4,217	$ 1,842

Employee Stock and Benefit Plans (Fair Value Assumptions, Stock Options) (Details) - Stock Options	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	4 years 10 months 24 days	5 years 3 months 7 days	5 years 4 months 24 days
Volatility	45.00%	48.00%	52.00%
Risk-free interest rate	1.30%	1.50%	0.70%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	5 years 10 months 7 days	5 years 10 months 7 days	6 years 1 month 6 days
Volatility	48.00%	52.00%	53.00%
Risk-free interest rate	1.70%	1.70%	1.50%

Employee Stock and Benefit Plans (Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Outstanding Shares
Beginning balance (in shares)	7,605,407	7,039,093	6,513,508
Granted (in shares)	1,526,450	2,744,150	2,001,400
Exercised (in shares)	(807,846)	(1,216,710)	(952,871)
Canceled (in shares)	(744,953)	(961,126)	(522,944)
Ending balance (in shares)	7,579,058	7,605,407	7,039,093	6,513,508
Vested and Expected to vest (in shares)	7,111,282
Exercisable (in shares)	5,195,339
Weighted Average Exercise Price
Weighted average exercise price, beginning balance (in dollars per share)	$ 12.93	$ 7.17	$ 4.39
Weighted average exercise price, granted (in dollars per share)	39.50	26.16	15.78
Weighted average exercise price, exercised (in dollars per share)	12.50	6.28	4.32
Weighted average exercise price, canceled (in dollars per share)	27.67	16.91	10.71
Weighted average exercise price, ending balance (in dollars per share)	16.88	$ 12.93	$ 7.17	$ 4.39
Vested and Expected to vest, weighted average exercise price (in dollars per share)	15.69
Exercisable, Weighted average exercise price (in dollars per share)	$ 9.78
Weighted Average Remaining Contractual Life (Years)
Weighted average remaining contractual life	5 years 10 months 24 days	6 years 6 months 7 days	6 years 6 months	6 years 7 months 6 days
Vested and Expected to vest, weighted average remaining contractual life	5 years 8 months 12 days
Exercisable, weighted average remaining contractual life	4 years 9 months 18 days
Aggregate Intrinsic Value
Aggregate intrinsic value	$ 131,345	$ 188,743	$ 112,312	$ 67,711
Vested and Expected to vest, aggregate intrinsic value	130,208
Exercisable, aggregate intrinsic value	$ 121,098

Employee Stock and Benefit Plans (Options Outstanding and Vested) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of shares, outstanding	7,579,058
Weighted average exercise price per share, outstanding (in dollar per share)	$ 16.88
Weighted average remaining contractual life, outstanding	5 years 10 months 24 days
Number of shares, vested	5,166,845
Weighted average exercise price per share, vested (in dollar per share)	$ 9.79
Stock Options
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average grant date fair value (in dollars per share)	$ 16.51	$ 12.07	$ 7.62
Aggregate grant date fair value	$ 25.2	$ 33.1	$ 15.2
Intrinsic value of options exercised	$ 22.7	$ 25.7	$ 11.1
$1.40 - $1.40
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	$ 1.40
Exercise price range, upper limit (in dollar per share)	$ 1.40
Number of shares, outstanding	156,259
Weighted average exercise price per share, outstanding (in dollar per share)	$ 1.40
Weighted average remaining contractual life, outstanding	5 months 26 days
Number of shares, vested	156,259
Weighted average exercise price per share, vested (in dollar per share)	$ 1.40
$1.90 - $1.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	1.90
Exercise price range, upper limit (in dollar per share)	$ 1.90
Number of shares, outstanding	940,082
Weighted average exercise price per share, outstanding (in dollar per share)	$ 1.90
Weighted average remaining contractual life, outstanding	1 year 25 days
Number of shares, vested	940,082
Weighted average exercise price per share, vested (in dollar per share)	$ 1.90
$2.10 - $2.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	2.10
Exercise price range, upper limit (in dollar per share)	$ 2.80
Number of shares, outstanding	415,220
Weighted average exercise price per share, outstanding (in dollar per share)	$ 2.63
Weighted average remaining contractual life, outstanding	2 years 10 months 27 days
Number of shares, vested	415,220
Weighted average exercise price per share, vested (in dollar per share)	$ 2.63
$3.80 - $3.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	3.80
Exercise price range, upper limit (in dollar per share)	$ 3.80
Number of shares, outstanding	1,117,235
Weighted average exercise price per share, outstanding (in dollar per share)	$ 3.80
Weighted average remaining contractual life, outstanding	3 years 10 months 20 days
Number of shares, vested	1,117,235
Weighted average exercise price per share, vested (in dollar per share)	$ 3.80
$4.10 - $8.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	4.10
Exercise price range, upper limit (in dollar per share)	$ 8.90
Number of shares, outstanding	868,867
Weighted average exercise price per share, outstanding (in dollar per share)	$ 6.16
Weighted average remaining contractual life, outstanding	5 years 4 months 27 days
Number of shares, vested	842,958
Weighted average exercise price per share, vested (in dollar per share)	$ 6.08
$9.40 - $16.68
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	9.40
Exercise price range, upper limit (in dollar per share)	$ 16.68
Number of shares, outstanding	786,624
Weighted average exercise price per share, outstanding (in dollar per share)	$ 13.13
Weighted average remaining contractual life, outstanding	6 years 10 months 24 days
Number of shares, vested	606,364
Weighted average exercise price per share, vested (in dollar per share)	$ 12.95
$19.26 - $26.86
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	19.26
Exercise price range, upper limit (in dollar per share)	$ 26.86
Number of shares, outstanding	1,156,772
Weighted average exercise price per share, outstanding (in dollar per share)	$ 24.00
Weighted average remaining contractual life, outstanding	8 years 1 month 17 days
Number of shares, vested	575,066
Weighted average exercise price per share, vested (in dollar per share)	$ 23.69
$30.58 - $30.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	30.58
Exercise price range, upper limit (in dollar per share)	$ 30.58
Number of shares, outstanding	827,997
Weighted average exercise price per share, outstanding (in dollar per share)	$ 30.58
Weighted average remaining contractual life, outstanding	8 years 7 months 27 days
Number of shares, vested	423,645
Weighted average exercise price per share, vested (in dollar per share)	$ 30.58
$34.97 - $37.28
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	34.97
Exercise price range, upper limit (in dollar per share)	$ 37.28
Number of shares, outstanding	824,344
Weighted average exercise price per share, outstanding (in dollar per share)	$ 36.31
Weighted average remaining contractual life, outstanding	8 years 8 months 12 days
Number of shares, vested	14,381
Weighted average exercise price per share, vested (in dollar per share)	$ 37.18
$40.68 - $52.14
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollar per share)	40.68
Exercise price range, upper limit (in dollar per share)	$ 52.14
Number of shares, outstanding	485,658
Weighted average exercise price per share, outstanding (in dollar per share)	$ 45.13
Weighted average remaining contractual life, outstanding	8 years 10 months 17 days
Number of shares, vested	75,635
Weighted average exercise price per share, vested (in dollar per share)	$ 41.39

Employee Stock and Benefit Plans (Restricted Stock) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based employee compensation	$ 16,378	$ 9,831	$ 4,545
Unrecognized employee compensation cost, period for recognition	2 years 3 months 18 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted (in shares)	60,000
Weighted-average grant date fair value (usd per share)	$ 37.28
Stock-based employee compensation	$ 500
Units vested and released in period (in shares)	12,500
Units cancelled and forfeited during period (in shares)	0
Units outstanding and expected to vest (in shares)	47,500
Unrecognized employee compensation cost	$ 1,800
Unrecognized employee compensation cost, period for recognition	1 year 6 months 29 days

Other Income (Expense), Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Income and Expenses [Abstract]
Foreign exchange losses	$ (444)	$ (664)	$ (679)
Other income (expense)	(406)	(413)	79
Other income (expense), net	$ (850)	$ (1,077)	$ (600)

Income Taxes (Income Before Provision for (Benefit From) Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income (Loss) from Continuing Operations
Domestic									$ 22,540	$ 7,384	$ 947
Foreign									1,980	1,229	1,094
Income before income taxes	$ 7,513	$ 6,724	$ 5,440	$ 4,843	$ 3,643	$ 3,388	$ 1,831	$ (249)	$ 24,520	$ 8,613	$ 2,041

Income Taxes (Provision For (Benefit From) Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current
Federal									$ 115	$ 0	$ (40)
State									1,041	317	154
Foreign									693	651	452
Total current provision									1,849	968	566
Deferred
Federal									7,115	(22,184)	6
State									(247)	(433)	0
Foreign									(62)	18	(72)
Total deferred provision (benefit)									6,806	(22,599)	(66)
Provision for (benefit from) income taxes	$ 2,089	$ 2,601	$ 2,124	$ 1,841	$ (22,270)	$ 283	$ 174	$ 182	$ 8,655	$ (21,631)	$ 500

Income Taxes (Tax Rate Reconciliation) (Details)	12 Months Ended
Income Taxes (Tax Rate Reconciliation) (Details)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Federal statutory rate	35.00%	35.00%	34.00%
State taxes	2.20%	1.40%	5.10%
Stock-based compensation	0.50%	1.30%	9.10%
Foreign source income	0.60%	3.90%	1.90%
Change in valuation allowance	1.30%	(270.50%)	(28.40%)
Incremental federal rate benefit previously not recognized	0.00%	(7.00%)	0.00%
Federal and state research and development credit	(3.90%)	(11.30%)	(0.00%)
Other	(0.40%)	(3.90%)	2.80%
Provision for (benefit from) income taxes	35.30%	(251.10%)	24.50%

Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets
Net operating loss carryforwards	$ 1,936	$ 12,849
Research and development credit carryforwards	6,508	6,392
Accrued liabilities	614	583
Deferred revenues	3,838	3,291
Deferred rent	142	191
Intangible assets	246	401
Stock-based compensation	8,301	4,149
Other	1,396	903
Gross deferred tax assets	22,981	28,759
Valuation allowance	(3,303)	(3,079)
Net deferred tax assets	19,678	25,680
Deferred tax liabilities
Fixed assets	(3,599)	(3,039)
Intangible assets	0	(2)
Total deferred tax liabilities	(3,599)	(3,041)
Net deferred tax assets	$ 16,079	$ 22,639

Income Taxes (Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits beginning balance	$ 3,330	$ 3,255	$ 2,647
Gross increase for tax positions of prior years	20	0	241
Gross decrease for tax positions of prior years	(171)	(127)	0
Gross increase for tax positions of current year	418	332	446
Lapse of statute of limitations	(91)	(130)	(79)
Total unrecognized tax benefits	$ 3,506	$ 3,330	$ 3,255

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax [Line Items]
Provision for (benefit from) income taxes	$ 2,089	$ 2,601	$ 2,124	$ 1,841	$ (22,270)	$ 283	$ 174	$ 182	$ 8,655	$ (21,631)	$ 500
Valuation allowance	3,303				3,079				3,303	3,079
Undistributed earnings of foreign subsidiaries	8,700				6,800				8,700	6,800
Unrecognized tax benefits that would impact effective tax rate	2,100				2,100				2,100	$ 2,100	$ 1,000
Internal Revenue Service (IRS) [Member]
Income Tax [Line Items]
Operating loss carryforwards	35,600								35,600
Deferred tax asset not recognized, net operating loss carryforwards	30,800								30,800
Internal Revenue Service (IRS) [Member] \| Research and Development Credits [Member]
Income Tax [Line Items]
Tax credit carryforward	5,000								5,000
State and Local Jurisdiction [Member]
Income Tax [Line Items]
Valuation allowance	3,303								3,303
Operating loss carryforwards	4,800								4,800
Deferred tax asset not recognized, net operating loss carryforwards	200								200
State and Local Jurisdiction [Member] \| Research and Development Credits [Member]
Income Tax [Line Items]
Tax credit carryforward	5,700								$ 5,700
Research and development tax credit	500
Federal and State Jurisdictions [Member]
Income Tax [Line Items]
Provision for (benefit from) income taxes					$ (23,700)
Federal and State Jurisdictions [Member] \| Research and Development Credits [Member]
Income Tax [Line Items]
Research and development tax credit	$ 600

Segment Information and Information about Geographic Area (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments \| segment									1
Revenues	$ 44,445	$ 42,469	$ 39,877	$ 37,493	$ 36,573	$ 34,348	$ 32,302	$ 30,356	$ 164,284	$ 133,579	$ 107,962
Property and equipment, net	31,329				26,618				31,329	26,618
United States
Segment Reporting Information [Line Items]
Revenues									115,384	93,425	75,485
Property and equipment, net	25,623				23,650				25,623	23,650
Foreign
Segment Reporting Information [Line Items]
Revenues									48,900	40,154	$ 32,477
Property and equipment, net	$ 5,706				$ 2,968				$ 5,706	$ 2,968

Net Income Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net income	$ 5,424	$ 4,123	$ 3,316	$ 3,002	$ 25,913	$ 3,105	$ 1,657	$ (431)	$ 15,865	$ 30,244	$ 1,541
Net income attributable to participating securities									0	0	(2)
Net income attributable to common stockholders - basic									15,865	30,244	1,539
Net income attributable to common stockholders - diluted									$ 15,865	$ 30,244	$ 1,539
Denominator:
Weighted-average shares used in computing net income per share attributable to common stockholders - basic									34,050	32,979	31,914
Effect of potentially dilutive securities:
Common stock options (in shares)									4,134	4,191	4,059
Weighted - average shares used in computing net income (loss) per share attributable to common stockholders - diluted (in shares)									38,184	37,170	35,973
Basic (usd per share)	$ 0.16	$ 0.12	$ 0.10	$ 0.09	$ 0.77	$ 0.09	$ 0.05	$ (0.01)	$ 0.47	$ 0.92	$ 0.05
Diluted (usd per share)	$ 0.14	$ 0.11	$ 0.09	$ 0.08	$ 0.69	$ 0.08	$ 0.04	$ (0.01)	$ 0.42	$ 0.81	$ 0.04
Stock Options
Antidilutive Securities
Common stock options (in shares)									1,582	1,689	952

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Revenues	$ 44,445	$ 42,469	$ 39,877	$ 37,493	$ 36,573	$ 34,348	$ 32,302	$ 30,356	$ 164,284	$ 133,579	$ 107,962
Cost of revenues	9,002	8,762	8,157	7,964	7,521	7,421	7,175	6,846	33,885	28,963	24,660
Gross profit	35,443	33,707	31,720	29,529	29,052	26,927	25,127	23,510	130,399	104,616	83,302
Operating expenses:
Research and development	7,532	7,564	7,205	7,150	7,015	6,490	6,411	6,404	29,451	26,320	21,678
Sales and marketing	13,068	12,282	12,776	11,443	11,938	11,774	11,845	12,492	49,569	48,049	42,523
General and administrative	7,147	6,983	6,427	6,016	5,888	5,156	5,081	4,875	26,573	21,000	16,792
Total operating expenses	27,747	26,829	26,408	24,609	24,841	23,420	23,337	23,771	105,593	95,369	80,993
Income from operations	7,696	6,878	5,312	4,920	4,211	3,507	1,790	(261)	24,806	9,247	2,309
Other income (expense), net	(183)	(154)	128	(77)	(568)	(119)	41	12	(286)	(634)	(268)
Income before income taxes	7,513	6,724	5,440	4,843	3,643	3,388	1,831	(249)	24,520	8,613	2,041
Provision for (benefit from) income taxes	2,089	2,601	2,124	1,841	(22,270)	283	174	182	8,655	(21,631)	500
Net income	$ 5,424	$ 4,123	$ 3,316	$ 3,002	$ 25,913	$ 3,105	$ 1,657	$ (431)	$ 15,865	$ 30,244	$ 1,541
Earnings Per Share [Abstract]
Basic (in usd per share)	$ 0.16	$ 0.12	$ 0.10	$ 0.09	$ 0.77	$ 0.09	$ 0.05	$ (0.01)	$ 0.47	$ 0.92	$ 0.05
Diluted (usd per share)	$ 0.14	$ 0.11	$ 0.09	$ 0.08	$ 0.69	$ 0.08	$ 0.04	$ (0.01)	$ 0.42	$ 0.81	$ 0.04
Federal and State Jurisdictions [Member]
Operating expenses:
Provision for (benefit from) income taxes					$ (23,700)

Schedule II Schedule of Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 590	$ 389	$ 331
Charged to Costs and Expenses	851	470	307
Deductions and Other	(672)	(269)	(249)
Balance at End of Year	$ 769	$ 590	$ 389