Mobileiron 10-K 22 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Feb. 15, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Registrant Name	MOBILEIRON, INC.
Entity Central Index Key	1,470,099
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 282
Entity Common Stock, Shares Outstanding		106,793,168
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 104,613	$ 85,833
Short-term investments	1,000	6,797
Accounts receivable, net of allowance for doubtful accounts of $425 and $475 at December 31, 2018 and December 31, 2017, respectively	60,994	50,629
Deferred commissions-current	8,265	9,285
Prepaid expenses and other current assets	8,367	5,510
TOTAL CURRENT ASSETS	183,239	158,054
Property and equipment-net	7,046	8,812
Deferred commissions-noncurrent	9,066	9,123
Goodwill	5,475	5,475
Other assets	5,561	2,976
TOTAL ASSETS	210,387	184,440
Current liabilities:
Accounts payable	2,154	1,369
Accrued expenses	27,347	25,070
Unearned revenue - current	74,177	55,105
Customer arrangements with termination rights	19,367	19,546
TOTAL CURRENT LIABILITIES	123,045	101,090
Long-term liabilities:
Unearned revenue - noncurrent	31,660	21,917
Other long-term liabilities	1,565	1,881
TOTAL LIABILITIES	156,270	124,888
Commitments and contingencies (Note 12)
Stockholders’ equity:
Common stock, $0.0001 par value, 300,000,000 shares authorized, 107,028,433 and 97,203,950 shares issued, and 106,206,545 and 97,203,950 shares outstanding at December 31, 2018 and 2017, respectively	11	10
Additional paid-in capital	462,004	420,525
Treasury stock	(3,831)
Accumulated deficit	(404,067)	(360,983)
TOTAL STOCKHOLDERS’ EQUITY	54,117	59,552
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 210,387	$ 184,440

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Accounts receivable, allowance	$ 425	$ 475
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	107,028,433	97,203,950
Common stock, shares outstanding	106,206,545	97,203,950

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue
Revenue	$ 193,192	$ 179,758	$ 166,182
Cost of revenue
Restructuring charge		311	181
Total cost of revenue	34,922	30,537	30,548
Gross profit	158,270	149,221	135,634
Operating expenses:
Research and development	78,047	75,350	67,398
Sales and marketing	94,204	96,807	102,327
General and administrative	28,880	28,091	29,695
Litigation settlement charge		1,143
Restructuring charge		1,038	871
Total operating expenses	201,131	202,429	200,291
Operating loss	(42,861)	(53,208)	(64,657)
Other income (expense) - net	1,124	988	145
Loss before income taxes	(41,737)	(52,220)	(64,512)
Income tax expense	1,347	1,142	982
Net loss	$ (43,084)	$ (53,362)	$ (65,494)
Net loss per share, basic and diluted (in dollars per share)	$ (0.42)	$ (0.57)	$ (0.76)
Weighted-average shares used to compute net loss per share, basic and diluted (in shares)	102,527	93,770	85,845
License
Revenue
Revenue	$ 59,338	$ 64,035	$ 66,347
Cost of revenue
Cost of revenue	3,270	2,203	2,896
Cloud services
Revenue
Revenue	50,714	38,728	31,093
Cost of revenue
Cost of revenue	12,719	8,847	8,374
Software support and services
Revenue
Revenue	83,140	76,995	68,742
Cost of revenue
Cost of revenue	$ 18,933	$ 19,176	$ 19,097

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Deficit	Total
BALANCE at Dec. 31, 2015	$ 8	$ 343,336		$ (242,127)	$ 101,217
BALANCE (in shares) at Dec. 31, 2015	81,326,237
Issuance of common stock for stock option exercises, net of repurchases		2,468			$ 2,468
Issuance of common stock for stock option exercises, net of repurchases (in shares)	1,040,902				1,040,902
Vesting of early exercised stock options and restricted stock		43			$ 43
Vesting of early exercised stock options and restricted stock (in shares)	9,957
Issuance of common stock for pursuant to the Employee Stock Purchase Plan		4,851			4,851
Issuance of common stock for pursuant to the Employee Stock Purchase Plan (in shares)	1,799,341
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans	$ 1	5,638			5,639
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans (in shares)	1,653,371
Vesting of restricted stock units (in shares)	3,236,223
Stock-based compensation		26,857			26,857
Net loss				(65,494)	(65,494)
BALANCE at Dec. 31, 2016	$ 9	383,193		(307,621)	75,581
BALANCE (in shares) at Dec. 31, 2016	89,066,031
Issuance of common stock for stock option exercises, net of repurchases		3,287			$ 3,287
Issuance of common stock for stock option exercises, net of repurchases (in shares)	1,172,409				1,172,409
Vesting of early exercised stock options and restricted stock (in shares)	2,477
Issuance of common stock for pursuant to the Employee Stock Purchase Plan		4,562			$ 4,562
Issuance of common stock for pursuant to the Employee Stock Purchase Plan (in shares)	1,676,158
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans		8,272			8,272
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans (in shares)	1,688,097
Shares withheld for net settlement of Stock-Settled Bonus Plans and equity awards		(3,149)			(3,149)
Shares withheld for net settlement of Stock-Settled Bonus Plans and equity awards (in shares)	(677,547)
Vesting of restricted stock units	$ 1				1
Vesting of restricted stock units (in shares)	4,276,325
Stock-based compensation		24,360			24,360
Net loss				(53,362)	(53,362)
BALANCE at Dec. 31, 2017	$ 10	420,525		(360,983)	59,552
BALANCE (in shares) at Dec. 31, 2017	97,203,950
Issuance of common stock for stock option exercises, net of repurchases		6,520			$ 6,520
Issuance of common stock for stock option exercises, net of repurchases (in shares)	2,488,544				2,488,544
Issuance of common stock for pursuant to the Employee Stock Purchase Plan		4,548			$ 4,548
Issuance of common stock for pursuant to the Employee Stock Purchase Plan (in shares)	1,597,778
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans	$ 1	9,621			9,622
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans (in shares)	1,973,386
Shares withheld for net settlement of Stock-Settled Bonus Plans and equity awards		(6,376)			$ (6,376)
Shares withheld for net settlement of Stock-Settled Bonus Plans and equity awards (in shares)	(1,294,360)				(1,294,360)
Repurchase of common stock			$ (3,831)		$ (3,831)
Repurchase of common stock (in shares)	(821,888)				(821,888)
Vesting of restricted stock units (in shares)	5,059,135
Stock-based compensation		27,166			$ 27,166
Net loss				(43,084)	(43,084)
BALANCE at Dec. 31, 2018	$ 11	$ 462,004	$ (3,831)	$ (404,067)	$ 54,117
BALANCE (in shares) at Dec. 31, 2018	106,206,545

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (43,084)	$ (53,362)	$ (65,494)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	38,436	33,731	34,389
Depreciation	3,846	3,389	3,348
Amortization of intangible assets	100	545	616
Amortization (accretion) of premium of investment securities	(50)	(57)	(14)
Provision for doubtful accounts	199	149	77
Loss (gain) on disposal of equipment	25	(16)	99
Changes in operating assets and liabilities:
Accounts receivable	(10,564)	(4,916)	(1,947)
Deferred commissions	1,078	329	570
Other current and noncurrent assets	(5,535)	(1,006)	(807)
Accounts payable	715	439	(1,297)
Unearned revenue	28,815	16,434	10,574
Customer arrangements with termination rights	(179)	5,348	6,520
Accrued expenses and other long-term liabilities	355	2,029	1,637
Net cash provided by (used in) operating activities	14,157	3,036	(11,729)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(1,956)	(6,454)	(2,930)
Proceeds from maturities of investment securities	15,900	38,015	94,631
Purchase of investment securities	(10,053)	(8,570)	(79,134)
Net cash provided by investing activities	3,891	22,991	12,567
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from Employee Stock Purchase Plan	4,424	4,798	4,332
Proceeds from exercise of stock options	6,514	4,114	1,639
Taxes paid for net settlement of equity awards	(4,862)	(3,149)
Amounts withheld for net settlement of equity awards	(1,513)
Repurchases of common stock	(3,831)
Net cash provided by financing activities	732	5,763	5,971
NET CHANGE IN CASH AND CASH EQUIVALENTS	18,780	31,790	6,809
CASH AND CASH EQUIVALENTS-Beginning of period	85,833	54,043	47,234
CASH AND CASH EQUIVALENTS-End of period	104,613	85,833	54,043
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for income taxes	1,419	1,189	1,021
SUPPLEMENTAL DISCLOSURES OF NONCASH FINANCING ACTIVITIES:
Value of shares issued under Bonus Plans	5,898	5,123	5,639
Value of shares issued under the Employee Stock Purchase Plan	4,548	4,562	$ 4,851
Unpaid property and equipment purchases	$ 148	$ 228

Description of Business and Sig

Description of Business and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Description of Business and Significant Accounting Policies
Description of Business and Significant Accounting Policies	1. Description of Busines Description of Business MobileIron, Inc. and its wholly owned subsidiaries, collectively, the “Company”, “we”, “us” or “our”, provides a purpose-built mobile IT platform that enables enterprises to manage and secure mobile applications, content and devices while providing their employees with device choice, privacy and a native user experience. We were incorporated in Delaware in July 2007 and are headquartered in Mountain View, California, with additional sales and support presence in North America, Europe, the Middle East, Asia and Australia and employees in India primarily focused on research and development. Basis of Presentation and Consolidation The accompanying audited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, and include the accounts of our wholly owned subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation. Foreign Currency Translation Our reporting currency is the U.S. dollar. The functional currency of all our international operations is the U.S. dollar. All monetary asset and liability accounts are translated into U.S. dollars at the period-end rate, nonmonetary assets and liabilities are translated at historical exchange rates, and revenue and expenses are translated at the weighted-average exchange rates in effect during the period. Translation adjustments arising are recorded as foreign currency gains (losses) in the consolidated statements of operations. We recognized a foreign currency loss of $471,000 in 2018, a foreign currency gain of $242,000 in 2017, and a foreign currency loss of $339,000 in 2016, in other income (expense)—net in our consolidated statements of operations. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. These estimates include, but are not limited to, revenue recognition, stock-based compensation, commissions, goodwill and accounting for income taxes. Actual results could differ from those estimates. Concentrations of Credit Risk Financial instruments that potentially subject us to a concentration of credit risk consist of cash, money market funds and fixed income investments. Although we deposit our cash with multiple financial institutions, our deposits, at times, exceed federally insured limits. We invest in fixed income securities that are of high-credit quality. Substantially all of our money market funds, or $36.6 million, are held in five funds that are rated “AAA.” We generally do not require collateral or other security in support of accounts receivable. Allowances are provided for individual accounts receivable when we become aware of a customer’s inability to meet its financial obligations, such as in the case of bankruptcy, deterioration in the customer’s operating results, or change in financial position. If circumstances related to customers change, estimates of the recoverability of receivables would be further adjusted. We also consider broader factors in evaluating the sufficiency of our allowances for doubtful accounts, including the length of time receivables are past due, significant one-time events and historical experience. Activity in our allowance for doubtful accounts was as follow (in thousands): Balance at Bad Write-offs, Balance at Beginning Debt Net of End of Period Expense Recoveries of Period Balance as of December 31, 2018 $ 475 199 (249) $ 425 Balance as of December 31, 2017 $ 433 149 (107) $ 475 Balance as of December 31, 2016 $ 628 77 (272) $ 433 One reseller accounted for 11% (1% as an end customer), 14% (1% as an end customer) and 15% (1% as an end customer) of total revenue in 2018, 2017 and 2016, respectively. The same reseller accounted for 7% and 16% of net accounts receivable as of December 31, 2018 and 2017, respectively. There were no other resellers or end-user customers that accounted for 10% or more as a percentage of our revenue or net accounts receivable for any period presented. Segments We have one reportable segment. Summary of Significant Accounting Policies Revenue Recognition Revenue Presentation License revenue includes sales of perpetual software licenses, software licenses sold as part of on-premises term subscriptions, and appliances. Cloud services include sales of cloud-based solutions that allow customers to use hosted software over a contract period without taking possession of our software and are typically provided on a subscription or usage basis. Software support and services revenue includes sales of software support sold as part of on-premises term subscriptions, software support for perpetual licenses, and professional services. Revenue Recognition Revenue is recognized upon transfer of control of promised products or services to customers in an amount that reflects the consideration we expect to receive in exchange for those products or services. We enter into contracts that can include various combinations of products and services, which are generally capable of being distinct and accounted for as separate performance obligations. Revenue is recognized net of allowances for returns and any taxes collected from customers, which are subsequently remitted to governmental authorities. Nature of Products and Services Licenses for on-premises software provide the customer with a right to use the software as it exists when made available to the customer. Customers may purchase on-premises software licenses as perpetual licenses or as part of subscriptions. On-premises licenses are considered distinct performance obligations and revenue from the licenses is recognized upfront when the software is made available to the customer. Software support and services convey rights to the upgrades released over the contract period and provide support and tools to help customers deploy and use our products more efficiently. Revenue allocated to software support and services is generally recognized ratably over the contract period as customers simultaneously consume and receive benefits, given that the software support and services comprises a distinct performance obligation that is satisfied over time. On-premises subscriptions and software support and services occasionally contain termination rights. We recognize revenue from those arrangements, including the distinct licenses contained therein, as the termination rights for the performance obligation expire. See also Unearned Revenue and Customer Arrangements with Termination Rights below. Cloud services, which allow customers to use hosted software over a contract period without taking possession of our software, are provided on a subscription or usage basis. Revenue related to cloud services provided on a subscription basis is recognized ratably over the contract period and revenue related to cloud services based on usage is generally recognized as the usage occurs. Professional services include consulting, deployment and training services. Our professional services represent distinct performance obligations as our customers benefit from the services separately or together with other readily available resources. Professional services revenue is recognized as services are delivered. Appliance revenue was less than 5% of total revenue for all periods presented and is included as a component of license revenue within the consolidated statements of operations. Refer to Note 14 – Segment and Disaggregated Revenue Information for further information. Significant Judgments Our contracts with customers often include promises to transfer multiple products and services to a customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment. Judgment is required to determine whether a software license is considered distinct and accounted for separately, or not distinct and accounted for together with the software support and services and recognized over time. Judgment is required to determine the standalone selling price (“SSP”) for each distinct performance obligation. We use a range of amounts to estimate the SSP for items that are not sold separately, including on-premises licenses sold with software support and services. In instances where SSP is not directly observable, such as when we do not sell the product or service separately, we determine the SSP using information that may include other observable inputs. We typically have more than one SSP for individual products and services due to the stratification of those products and services by customer classes and circumstances. In these instances, we may use information such as the size and type of customer in determining the SSP. Contract Balances Timing of revenue recognition may differ from the timing of invoicing customers. We record a receivable when revenue is recognized prior to invoicing, or unearned revenue when revenue will be recognized after invoicing. For multi-year agreements, we either invoice our customer in full at the inception of the contract or annually at the beginning of each annual period. We record an unbilled receivable related to revenue recognized for multi-year on-premises licenses invoiced annually when we have an unconditional right to invoice and receive payment in the future for those licenses or when we have the right to invoice future monthly periods under committed monthly recurring charge (“MRC”) agreements. The majority of our MRC agreements are for a month to month term (“non-committed”) or usage-based. Payment terms and conditions vary by contract type, although terms generally include a requirement to pay within 30 to 60 days. In instances where the timing of revenue recognition differs from the timing of invoicing, we have determined our contracts generally do not include a significant financing component. The primary purpose of our invoicing terms is to provide customers with simplified and predictable ways of purchasing our products and services, not to receive financing from our customers or to provide customers with financing. This includes invoicing at the beginning of a subscription term with revenue recognized ratably over the contract period or multi-year on-premises licenses that are invoiced annually with a portion of the revenue recognized upfront. As of December 31, 2018 and 2017, the balance of accounts receivable, net of the allowance for doubtful accounts, included $1.4 million and $2.5 million, respectively, of unbilled receivables from upfront recognition of revenue for certain multi-period on-premises software subscriptions that include both distinct software licenses and software support and services. As of December 31, 2018 and 2017, unbilled receivables included in other long-term assets on our consolidated balance sheets were $592,000 and $977,000, respectively. Unearned Revenue and Customer Arrangements with Termination Rights We generally invoice our customers upfront for subscriptions and software support and services associated with perpetual licenses. Unearned revenue from those upfront billings is comprised of unearned revenue from cloud-based subscriptions, software support and services for on-premises subscriptions, software support and services associated with perpetual licenses, and professional services to be performed in the future. Because some of our arrangements with customers contain termination rights, the arrangements do not meet the definition of a contract under Accounting Standard Codification, or ASC, Topic 606, Revenue Recognition from Contracts with Customers, or ASC 606, and are not recorded as unearned revenue and instead are recorded as “customer arrangements with termination rights” on our consolidated balance sheets. Refer to Note 13 – Unearned Revenue for further information on unearned revenue, changes in unearned revenue during the period, and customer arrangements with termination rights. Deferred Commissions We recognize an asset for the incremental costs of obtaining a contract with a customer. We have determined that certain sales incentive programs meet the requirements to be capitalized and we include those costs in current and non-current deferred commissions on our consolidated balance sheets. Deferred commissions are amortized over the period commensurate with revenue recognition. Changes in deferred commissions were as follows (in thousands): Year ended December 31, 2018 2017 Balance, beginning of the period $ 18,408 $ 18,738 Deferral of commissions earned 15,312 17,470 Recognition of commission expense (16,240) (17,621) Impairment of deferred commissions (149) (179) Balance, end of the period $ 17,331 $ 18,408 Cash Equivalents We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents. As of December 31, 2018 and 2017, cash and cash equivalents consisted of cash deposited with banks, money market funds and investments that mature within three months of their purchase. Held-To-Maturity Investments We determine the appropriate classification of our fixed income investments at the time of purchase and reevaluate their classifications each reporting period. Investments are classified as held-to-maturity since the Company has positive intent and the ability to hold the securities to maturity. Held-to-maturity securities are stated at amortized cost. Comprehensive Loss Comprehensive loss includes all changes in equity (net assets) during a period from non-owner sources. In 2018, 2017 and 2016, there were no differences between net loss and comprehensive loss. Therefore, the consolidated statements of comprehensive loss have been omitted. Net Loss per Share of Common Stock Basic net loss per common share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and potentially dilutive securities outstanding for the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, convertible preferred stock, unvested restricted stock, restricted stock units and stock options are considered to be potentially dilutive securities. Because we have reported a net loss for 2018, 2017 and 2016, the number of shares used to calculate diluted net loss per common share is the same as the number of shares used to calculate basic net loss per common share for those periods presented because the potentially dilutive shares would have been anti-dilutive if included in the calculation. Software Development Costs Incurred in Connection with Software to be Sold or Marketed The costs to develop new software products and enhancements to existing software products are expensed as incurred until technological feasibility has been established. We consider technological feasibility to have occurred when all planning, designing, coding and testing have been completed according to design specifications. Once technological feasibility is established, any additional costs would be capitalized. We believe our current process for developing software is essentially completed concurrent with the establishment of technological feasibility, and accordingly, no costs have been capitalized. Internal Use Software We capitalize costs incurred during the application development stage related to our internally used software. Such costs are primarily incurred by third-party vendors and consultants. Costs related to preliminary project activities and post-implementation activities are expensed as incurred. Amounts capitalized in all periods presented were not significant. All software development costs incurred in connection with our cloud offering, or SaaS, are also sold or marketed to partners or end customers, therefore we start capitalizing costs when technological feasibility is achieved. No costs were capitalized in any periods presented as we believe that our current process for developing software is essentially completed concurrent with the establishment of technological feasibility. Property and Equipment Property and equipment are stated at cost. Depreciation is computed using the straight-line method over the estimated useful life of the property and equipment, determined to be three years for computers and equipment and software, five years for furniture and fixtures, and the lesser of the remaining lease term or estimated useful life for leasehold improvements. Expenditures for repairs and software support are charged to expense as incurred. Upon disposition, the cost and related accumulated depreciation are removed from the accounts and the resulting gain or loss is reflected as operating expenses in the consolidated statements of operations. Goodwill and Intangible Assets We record the excess of the acquisition purchase price over the fair value of the tangible and identifiable intangible assets acquired as goodwill. We perform an impairment test of our goodwill in the third quarter of our fiscal year, or more frequently if indicators of potential impairment arise. We have a single reporting unit and consequently evaluate goodwill for impairment based on an evaluation of the fair value of the Company as a whole. We record purchased intangible assets at their respective estimated fair values at the date of acquisition. Purchased intangible assets were amortized using the straight-line method over their remaining estimated useful lives, which ranged from three to five years. We have determined that our intangible assets were not impaired during the years ended December 31, 2018, 2017 and 2016. Long-Lived Assets with Finite Lives Long-lived assets are reviewed for possible impairment whenever events or circumstances indicate that the carrying amount of these assets may not be recoverable. We evaluate the recoverability of each of our long-lived assets, including property and equipment, by comparison of its carrying amount to the future discounted cash flows we expect the asset to generate. If we consider the asset to be impaired, we measure the amount of any impairment as the difference between the carrying amount and the fair value of the impaired asset. Stock-Based Compensation We use the estimated grant-date fair value method of accounting in accordance with ASC Topic 718 Compensation—Stock Compensation . Fair value is determined using the Black-Scholes Model using various inputs, including our estimates of expected volatility, term and future dividends. We estimated the forfeiture rate in 2018, 2017 and 2016 based on our historical experience for annual grant years where the majority of the vesting terms have been satisfied. We recognize compensation costs for awards with service and performance vesting conditions and for our Employee Stock Purchase Plan, or ESPP, on an accelerated method over the requisite service period of the award. For stock options or restricted stock grants with no performance condition, we recognize compensation costs on a straight-line basis over the requisite service period of the award, which is generally the vesting term of four years. Research and Development Research and development, or R&D, costs are charged to expense as incurred. Advertising Advertising costs are expensed and included in sales and marketing expense when incurred. Advertising expense in 2018, 2017 and 2016 was $204,000, $102,000 and $305,000, respectively. Income Taxes We account for income taxes in accordance with ASC Topic 740, Income Taxes , under which deferred tax liabilities and assets are recognized for the expected future tax consequences of temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities and net operating loss and tax credit carryforwards. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. We use a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. A tax position is recognized when it is more likely than not that the tax position will be sustained upon examination, including resolution of any related appeals or litigation processes. A tax position that meets the more-likely-than-not recognition threshold is measured at the largest amount of benefit that is greater than 50% likely of being realized upon ultimate settlement with a taxing authority. The standard also provides guidance on derecognition of tax benefits, classification on the balance sheet, interest and penalties, accounting in interim periods, disclosure and transition. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board, or FASB, or other standard setting bodies and adopted by us as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on our financial position or results of operations upon adoption. Guidance Not Yet Adopted Financial Instruments – Credit Losses In June 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses – Measurement of Credit Losses on Financial Instruments, which introduces a model based on expected losses to estimate credit losses for most financial assets and certain other instruments. In addition, for available-for-sale debt securities with unrealized losses, the losses will be recognized as allowances rather than reductions in the amortized cost of the securities. The standard is effective for annual reporting periods beginning after December 15, 2019, with early adoption permitted for annual reporting periods beginning after December 15, 2018. Entities will apply the standard’s provisions by recording a cumulative-effect adjustment to retained earnings. We are evaluating the impact of the adoption on our consolidated balance sheet, results of operations, cash flows and disclosures . We intend to adopt ASU No. 2016-13 effective January 1, 2020. Leases In February 2016, the FASB finalized ASU 2016-02, Leases. ASU 2016-02 requires lessees to recognize the assets and liabilities on the balance sheet for the rights and obligations created by most leases and continue to recognize expenses on the income statements over the lease term. It will also require disclosure designed to give financial statement users information on the amount, timing, and uncertainly of cash flows arising from leases. The guidance is effective for annual reporting periods beginning after December 15, 2018 and interim periods within those fiscal years. We adopted ASU 2016-02 effective January 1, 2019 and, as permitted by ASU 2018-11, we do not plan to recast our prior periods. As a result of this new standard, we expect to record a lease commitment liability of approximately $18.0 million and corresponding right-of-use asset of approximately $16.5 million at March 31, 2019 for our leases designated as operating leases in Note 12, “Commitments and Contingencies,” upon adoption . We do not expect the new standard to materially impact our results of operations. Recently Adopted Guidance Revenue from Contracts with Customers In May 2014, the FASB, jointly with the International Accounting Standards Board, issued a comprehensive new standard, ASC 606. The standard’s core principle is that a reporting entity will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In addition, the standard requires disclosure of the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The guidance permitted two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (modified retrospective method). We adopted the standard using the full retrospective method and restated each prior reporting period presented. The standard was effective for us beginning January 1, 2018. In preparation for adoption of the standard, we implemented internal controls and key system functionality to enable the preparation of financial information and reached conclusions on key accounting assessments related to the standard, including our assessment of the impact of accounting for costs incurred to obtain a contract. The most significant impact of the standard relates to the elimination of the requirement to have vendor specific objective evidence, or VSOE, of fair value to separate and recognize revenue for products and services in a contract. The elimination of the VSOE requirement causes a significant change to the timing of revenue recognition for on-premises software term license revenue and other multiple-element arrangements with products or services that lacked VSOE of fair value. Our on-premises term license agreements include distinct software licenses and software support and services. Under ASC 606, we recognize the software license revenue at the time of delivery and recognize the software support and services revenue ratably over the term of the subscription agreements. Under Accounting Standard Codification Topic 605, Revenue Recognition, or ASC 605, we recognized all revenue from those arrangements ratably over the term of the subscription agreements. Due to the complexity of certain of our revenue contracts, the actual revenue recognition treatment required under the new standard depends on contract-specific terms and in some instances may vary from recognition at the time of delivery. The timing of revenue recognized from our cloud offerings, perpetual licenses, professional services and appliances remain substantially unchanged. In addition, Accounting Standards Codification Subtopic 340-40, Other Assets and Deferred Costs - Contracts with Customers, or ASC 340, requires us to recognize an asset for the incremental costs of obtaining a contract with a customer if our sales incentive programs meet the requirements for capitalization. Previously we recorded these incremental costs of obtaining a contract as commission expense when we booked a sales transaction; whereas under ASC 340, we record an asset for the incremental cost to obtain a contract and recognize the cost over the period commensurate with revenue recognition. In connection with our adoption of ASC 606 on January 1, 2018, there was a decrease to our deferred income tax liabilities and an offsetting increase in the valuation allowance recorded against deferred tax assets. No income tax impact was recorded to retained earnings upon adoption as a result of the full valuation allowance on United States deferred tax assets. In 2018, we recorded no income tax expense or benefit as a result of the adoption of the ASC 606. Adoption of the standard resulted in the recognition of additional revenue of $3.3 million and $2.3 million in 2017 and 2016, respectively, primarily due to an increase in revenue recognized from on-premises software subscriptions delivered and recognized in 2017 and 2016 and earlier recognition from other arrangements that lacked VSOE of fair value under ASC 605, partially offset by lower on-premises software subscription revenue from amounts billed prior to 2016. The new standard for accounting for costs to obtain a contract resulted in an increase in sales and marketing expense of $330,000 and $570,000 in 2017 and 2016, respectively, primarily due to the net impact of the capitalization of commissions earned in 2017 and 2016 and the amortization expense from commissions capitalized prior to 2016. The new standard did not have a material impact on net cash provided by (used in) operating, financing, or investing activities in our consolidated cash flow statements. Adoption of the standard resulted in an increase in accounts receivable and other assets of $3.4 million as of December 31, 2017, driven primarily by unbilled receivables from upfront recognition of revenue for certain multi-period on-premises software subscriptions that include both distinct software licenses and software update and support services. Unearned revenue was reduced by $35.5 million as of December 31, 2017 due to (a) cumulative changes to revenue and (b) a reclassification of approximately $19.5 million as of December 31, 2017 for arrangements with customers which contain termination rights. Because of the termination rights, the arrangements did not meet the definition of a contract under ASC 606 and were not recorded as unearned revenue but they were instead recorded as “customer arrangements with termination rights” on our consolidated balance sheets. Total capitalized costs to obtain a contract included in current and non-current prepaid and other current assets on our consolidated balance sheets were $9.3 million and $9.1 million, respectively, as of December 31, 2017. The following tables show the impact of adoption of the standards related to revenue recognition on our reported results (in thousands except per share information): Year ended December 31, 2017 New Revenue Standard As Statement of Operations: As Reported Adjustment Adjusted Revenue $ 176,491 $ 3,267 $ 179,758 Total operating expenses 202,099 330 202,429 Net loss (56,299) 2,937 (53,362) Net loss per share, basic and diluted (0.60) 0.03 (0.57) Year ended December 31, 2016 New Revenue Standard As Statement of Operations: As Reported Adjustment Adjusted Revenue $ 163,926 $ 2,256 $ 166,182 Total operating expenses 199,721 570 200,291 Net loss (67,180) 1,686 (65,494) Net loss per share, basic and diluted (0.78) 0.02 (0.76) December 31, 2017 New Revenue Standard As Balance Sheets: As Reported Adjustment Adjusted Assets Accounts receivable, net $ 48,171 $ 2,458 $ 50,629 Deferred commissions-current — 9,285 9,285 Deferred commissions-noncurrent — 9,123 9,123 Other assets 1,999 977 2,976 Liabilities and stockholders' equity Accrued expenses 24,995 75 25,070 Unearned revenue-current 84,467 (29,362) 55,105 Unearned revenue-noncurrent 28,034 (6,117) 21,917 Customer arrangements with termination rights — 19,546 19,546 Total stockholders' equity 21,851 37,701 59,552

Significant Balance Sheet Compo

Significant Balance Sheet Components	12 Months Ended
	Dec. 31, 2018
Significant Balance Sheet Components
Significant Balance Sheet Components	2. Significant Balance Sheet Components Accounts Receivable, Net —Accounts receivable, net at December 31, 2018 and 2017 consisted of the following (in thousands): December 31, 2018 December 31, 2017 Accounts receivable - billed $ 60,037 $ 48,646 Accounts receivable - unbilled 1,382 2,458 Allowance for doubtful accounts (425) (475) Accounts receivable, net $ 60,994 $ 50,629 Property and Equipment —Property and equipment at December 31, 2018 and 2017 consisted of the following (in thousands): As of December 31, 2018 2017 Computers and appliances $ 13,517 $ 13,178 Purchased software 4,711 4,063 Furniture and fixtures 1,695 1,734 Leasehold improvements 3,503 3,226 Total property and equipment 23,426 22,201 Accumulated depreciation and amortization (16,380) (13,389) Total property and equipment—net $ 7,046 $ 8,812 Accrued Expenses —Accrued expenses at December 31, 2018 and 2017 consisted of the following (in thousands): As of December 31, 2018 2017 Accrued commissions $ 4,398 $ 3,989 Accrued stock-settled bonus 9,355 7,705 Employee Stock Purchase Plan liability 1,923 2,047 Other accrued payroll-related expenses 3,630 4,285 Accrued royalties 3,596 733 Other accrued liabilities 4,445 6,311 Total accrued expenses $ 27,347 $ 25,070

Fair Value Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2018
Fair Value Measurement
Fair Value Measurement	3. Fair Value Measurement With the exception of our held-to-maturity fixed income investments, we report financial assets and liabilities and nonfinancial assets and liabilities that are recognized or disclosed at fair value in the consolidated financial statements on a recurring basis in accordance with ASC 820 (formerly FASB Statement No. 157, Fair Value Measurements ). ASC 820 defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities, which are required to be recorded at fair value, we consider the principal or most advantageous market in which we would transact and the market-based risk measurements or assumptions that market participants would use in pricing the asset or liability, such as inherent risk, transfer restrictions and credit risk. ASC 820 also establishes a fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value into three levels. A financial instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is available and significant to the fair value measurement. ASC 820 establishes and prioritizes three levels of inputs that may be used to measure fair value: · Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. · Level 2—Inputs are quoted prices for similar assets and liabilities in active markets or inputs other than quoted prices that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments. · Level 3—Inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value. The inputs require significant management judgment or estimation. Our financial assets that are carried at fair value include cash and money market funds. We had no financial liabilities, or nonfinancial assets and liabilities that were required to be measured at fair value on a recurring basis, or that were measured at fair value as of December 31, 2018 or 2017. Our financial instruments measured at fair market value as of December 31, 2018 and 2017 were as follows: As of December 31, 2018 (in thousands) Level 1 Level 2 Level 3 Total Money market funds $ 36,617 $ — $ — $ 36,617 Corporate debt securities — 6,555 — 6,555 Commercial paper — 53,598 — 53,598 Total $ 36,617 $ 60,153 $ — $ 96,770 As of December 31, 2017 (in thousands) Level 1 Level 2 Level 3 Total Money market funds $ 10,583 $ — $ — $ 10,583 Corporate debt securities — 7,076 — 7,076 Commercial paper — 51,796 — 51,796 Total $ 10,583 $ 58,872 $ — $ 69,455

Investments

Investments	12 Months Ended
	Dec. 31, 2018
Investments
Investments	4. Investments Our portfolio of fixed income securities consists of commercial paper and corporate debt securities. All our investments in fixed income securities are classified as held-to-maturity. These investments are carried at amortized cost. Our investments in fixed income securities as of December 31, 2018 and 2017 were as follows: As of December 31, 2018 Amortized Fair (in thousands) cost Gains Losses Value Corporate debt securities $ 6,556 $ — $ (1) $ 6,555 Commercial paper 53,600 1 (3) 53,598 Total $ 60,156 $ 1 $ (4) $ 60,153 As of December 31, 2017 Amortized Fair (in thousands) cost Gains Losses Value Corporate debt securities $ 7,078 $ — $ (2) $ 7,076 Commercial paper 51,805 — (9) 51,796 Total $ 58,883 $ — $ (11) $ 58,872 The following table summarizes the balance sheet classification of our investments: As of December 31, (in thousands) 2018 2017 Cash equivalents $ 59,156 $ 52,086 Short-term investments 1,000 6,797 Total investments $ 60,156 $ 58,883 The gross amortized cost and estimated fair value of our held-to-maturity investments at December 31, 2018 and 2017 by contractual maturity are shown below. Actual maturities may differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties. As of December 31, 2018 2017 Gross Gross Amortized Fair Amortized Fair (in thousands) Cost Value Cost Value Due in one year or less $ 60,156 60,153 $ 58,883 $ 58,872 Due after one year through five years — — — — Total $ 60,156 $ 60,153 $ 58,883 $ 58,872 We monitor our investment portfolio for impairment on a periodic basis. In order to determine whether a decline in fair value is other-than-temporary, we evaluate, among other factors: the duration and extent to which the fair value has been less than the carrying value; our financial condition and business outlook, including key operational and cash flow metrics, current market conditions and future trends in our industry; our relative competitive position within the industry; and our intent and ability to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value. A decline in the fair value of the security below amortized cost that is deemed other-than-temporary is charged to earnings, resulting in the establishment of a new cost basis for the affected securities. In 2018, we had an insignificant amount of unrealized gains or losses, and we did not recognize any other-than-temporary impairments .

Goodwill and Intangibles

Goodwill and Intangibles	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	5. Goodwill and Intangibles The following table reflects intangible assets subject to amortization as of December 31, 2017 (in thousands): December 31, 2017 Gross Carrying Accumulated Net Book Amount Amortization Impairment Value Technology $ 3,080 $ (2,980) — $ 100 Total $ 3,080 $ (2,980) $ — $ 100 The net book value of intangible assets subject to amortization was zero at December 31, 2018. Amortization of the technology intangible assets of $100,000, $545,000 and $616,000 in 2018, 2017 and 2016, respectively, was recorded in cost of revenue. At December 31, 2018 and 2017, the carrying value of goodwill was $5.5 million.

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2018
Restructuring Charges
Restructuring Charges	6. Restructuring Charges We initiated business restructuring plans in 2016 and 2017 to reduce our cost structure through workforce reductions and, in 2017, to exit an office facility. The following table sets forth a summary of restructuring activities which took place during the years ended December 31, 2018, 2017 and 2016 (in thousands): Severance and Related Costs Balance, December 31, 2015 $ — Provision for restructuring charges 1,052 Cash payments (1,037) Balance, December 31, 2016 $ 15 Provision for restructuring charges 1,349 Cash payments (867) Balance, December 31, 2017 $ 497 Provision for restructuring charges — Cash payments (497) Balance, December 31, 2018 $ —

Line of Credit

Line of Credit	12 Months Ended
	Dec. 31, 2018
Line of Credit
Line of Credit	7. Line of Credit We have a $20.0 million revolving line of credit with a financial institution that can be used to (a) borrow for working capital and general business requirements, (b) issue letters of credit, and (c) enter into foreign exchange contracts. Amounts borrowed accrue interest at a floating per annum rate equal to the prime rate. A default interest rate shall apply during an event of default at a rate per annum equal to 5% above the otherwise applicable interest rate. The line of credit is collateralized by substantially all of our assets, except intellectual property, and requires us to comply with working capital, net worth and other covenants, including limitations on indebtedness and restrictions on dividend distributions, among others, and the borrowing capacity is limited to eligible accounts receivable. We are required to maintain an adjusted quick ratio (defined as the ratio of current assets to current liabilities minus short-term unearned revenue and customer obligations with termination rights) of at least 1.25. In May 2015, we issued a letter of credit for $1.5 million as a security deposit for a new Mountain View facility lease and in November 2017 we issued a bank guarantee to a customer of approximately $3.0 million that can be drawn if we become insolvent or bankrupt. The issuances of the letter of credit and bank guarantee reduced the borrowing capacity under our line of credit to approximately $15.5 million. In June 2018, we amended our revolving line of credit which currently matures in June 2019. There were no outstanding amounts under the line of credit at December 31, 2018 and 2017 and we were in compliance with all financial covenants.

Preferred Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2018
Preferred Stock
Preferred Stock	8. Preferred Stock We were authorized to issue up to 10,000,000 shares of convertible preferred stock as of December 31, 2018 and 2017. No shares of convertible preferred stock were issued and outstanding as of December 31, 2018 and 2017.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2018
Common Stock
Common Stock	9. Common Stock We were authorized to issue 300,000,000 shares of common stock with a par value of $0.0001 per share as of December 31, 2018 and 2017. Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends from funds available, when and if declared by the board of directors, subject to the approval and priority rights of holders of all classes of preferred stock outstanding. As of December 31, 2018 and 2017, we reserved shares of common stock for issuance as follows: As of December 31, 2018 2017 Options outstanding 4,496,557 7,738,496 Unvested restricted stock units outstanding 12,303,913 12,906,030 Shares available for grant under the 2014 equity plan and 2015 inducement plan 2,337,545 1,859,997 Shares available for purchase under the Employee Stock Purchase Plan 364,762 990,501 Total 19,502,777 23,495,024 Repurchase Program In October 2018, our Board of Directors approved a common stock repurchase program (“Repurchase Program”) whereby the Company is authorized to purchase up to a maximum of $25 million of its common stock, subject to compliance with applicable law and the limitations in the Company’s credit facilities on stock repurchases. The authorization allows repurchases from time to time in the open market or in privately negotiated transactions. The amount and timing of repurchases made under the Repurchase Program will depend on a variety of factors, including available liquidity, cash flow and market conditions. Shares can be purchased through the Repurchase Program through October 2020, unless extended or shortened by our Board of Directors. The Repurchase Program does not obligate us to acquire any particular amount of common stock and the program may be modified or suspended at any time at our discretion. The repurchases would be funded from available working capital and are subject to compliance with the terms and limitations of the Company’s credit facilities. In 2018, we repurchased 821,888 shares of common stock at an average price of $4.66 per share for a total cost of $3.8 million under the Repurchase Program.

Share Based Awards

Share Based Awards	12 Months Ended
	Dec. 31, 2018
Share Based Awards
Share Based Awards	10. Share Based Awards 2008 Plan The 2008 Stock Plan, or 2008 Plan, which expired on June 12, 2014, provided for the grant of incentive and nonstatutory stock options to employees, nonemployee directors and consultants of the Company. Options granted under the 2008 Plan generally become exercisable within three to four years following the date of grant and expire 10 years from the date of grant. When options are subject to our repurchase right, we may buy back any unvested shares at their original exercise price in the event of an employee’s termination prior to full vesting. Our 2008 Plan was terminated following the date our 2014 Equity Incentive Plan, or the 2014 Plan, became effective. Any outstanding stock awards under our 2008 Plan will continue to be governed by the terms of our 2008 Plan and applicable award agreements. 2014 Equity Incentive Plan Our board of directors adopted our 2014 Plan on April 17, 2014, and our stockholders subsequently approved the 2014 Plan on May 27, 2014. The 2014 Plan became effective on the date that our registration statement was declared effective by the SEC. The 2014 Plan is the successor to and continuation of our 2008 Plan. Upon the effective date of the 2014 Plan, no further grants can be made under our 2008 Plan. Our 2014 Plan provides for the grant of incentive stock options, or ISOs, within the meaning of Section 422 of the Internal Revenue Code, or the Code, to our employees and our parent and subsidiary corporations’ employees, and for the grant of nonstatutory stock options, or NSOs, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance-based stock awards, and other forms of equity compensation to our employees, directors and consultants. Additionally, our 2014 Plan provides for the grant of performance cash awards to our employees, directors and consultants. The initial number of shares of our common stock available to be issued under our 2014 Plan was 8,142,857, which number of shares will be increased by any shares subject to stock options or other stock awards granted under the 2008 Plan that would have otherwise returned to our 2008 Plan (such as upon the expiration or termination of a stock award prior to vesting), not to exceed 16,312,202. The number of shares of our common stock reserved for issuance under our 2014 Plan automatically increase on January 1 of each year, beginning on January 1, 2015 and continuing through and including January 1, 2024, by 5% of the total number of shares of our capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by our board of directors. On January 1, 2019, we increased the number of shares of common stock reserved for issuance under our 2014 Plan by 5,310,327 shares, which was 5% of the total number of shares of capital stock outstanding at December 31, 2018. 2015 Inducement Plan On December 20, 2015, our board of directors adopted our 2015 Inducement Plan, or the Inducement Plan, to reserve 1,600,000 shares of our common stock to be used exclusively for grants of awards to individuals that were not previously employees or directors of the Company. The terms and conditions of the Inducement Plan are substantially similar to our stockholder-approved 2014 Plan. On January 5, 2016 our board of directors approved the amendment and restatement of the Inducement Plan to increase the share reserve under the 2015 Inducement Plan to 1,970,000 shares of our common stock. As of December 31, 2018 there were 1,000,000 options and restricted stock units outstanding under the Amended and Restated 2015 Inducement Plan. 2014 Employee Stock Purchase Plan Our board of directors adopted our 2014 Employee Stock Purchase Plan, or ESPP, on April 17, 2014, and our stockholders subsequently approved the ESPP on May 27, 2014. The ESPP became effective immediately upon the execution and delivery of the underwriting agreement related to our IPO. Subsequently, on June 14, 2017, our shareholders approved the amendment of the ESPP. The purpose of the ESPP is to secure the services of new employees, to retain the services of existing employees and to provide incentives for such individuals to exert maximum efforts toward our success and that of our affiliates. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the Code. The ESPP permits eligible employees to purchase our common stock through payroll deductions, which may not exceed 15% of the employee’s base compensation. Stock may be purchased under the plan at a price equal to 85% of the fair market value of our common stock on either the first day of the offering or the last day of the applicable purchase period, whichever is lower. As of December 31, 2018 and 2017 , 364,762 and 990,501 shares of common stock were available for future issuance under our ESPP, respectively. The number of shares of our common stock reserved for issuance under our ESPP increase automatically each year, beginning on January 1, 2015 and continuing through and including January 1, 2024, by the lesser of (i) 1% of the total number of shares of our common stock outstanding on December 31 of the preceding calendar year; (ii) 2,142,857 shares of common stock; or (iii) such lesser number as determined by our board of directors. Shares subject to purchase rights granted under our ESPP that terminate without having been exercised in full will not reduce the number of shares available for issuance under our ESPP. On January 1, 2019, we increased the number of shares available for issuance under the ESPP by 1,062,065 shares, which was 1% of the total number of shares of common stock outstanding at December 31, 2018. Restricted Stock Units In 2014 we began granting restricted stock units under our 2014 Plan. For stock-based compensation expense, we measure the value of the restricted stock units based on the fair value of our common stock on the date of grant. Our restricted stock unit grants are subject to service conditions and we expense the fair value of those shares on a straight-line basis over their vesting periods. Our restricted stock unit activity for 2016, 2017 and 2018 was as follows: Restricted Stock Units Weighted- Average Number of Grant Date Shares Fair Value Unvested, December 31, 2015 7,832,962 $ 6.66 Granted 10,724,225 3.36 Vested (4,889,594) 4.99 Cancelled/Forfeited (3,192,618) 5.39 Unvested, December 31, 2016 10,474,975 $ 4.45 Granted 11,017,278 5.04 Vested (5,964,422) 4.70 Cancelled/Forfeitures (2,621,801) 5.01 Unvested, December 31, 2017 12,906,030 $ 4.72 Granted 10,224,832 4.63 Vested (7,032,521) 4.88 Cancelled/Forfeitures (3,794,428) 4.48 Unvested, December 31, 2018 12,303,913 $ 4.63 Bonus Plans In 2015, our board of directors approved the 2015 Executive Bonus Plan and 2015 Non-Executive Bonus Plan, or 2015 Bonus Plan, which provided for the issuance of shares of unrestricted common stock to employees based on meeting certain Company metrics. We issued 1,653,371 shares of unrestricted common stock in the first quarter of 2016 based on amounts earned under the 2015 Non-Executive Bonus Plan. No shares were issued under the 2015 Executive Bonus Plan. In 2016, our compensation committee approved the 2016 Executive Bonus Plan and 2016 Non-Executive Bonus Plan, or collectively, the 2016 Bonus Plans, each effective as of January 1, 2016, which provided for the issuance of shares of unrestricted common stock to employees based on meeting certain Company metrics. We issued 1,010,550 shares of unrestricted common stock in the first quarter of 2017, after withholding 677,547 shares to cover employee payroll taxes which we paid in cash, for amounts earned under the 2016 Bonus Plans. In 2017, the Compensation Committee of our board of directors approved the 2017 Executive Bonus Plan and 2017 Non-executive Bonus Plan, or collectively, the 2017 Bonus Plans, each effective as of January 1, 2017, which provided for the issuance of shares of unrestricted common stock to employees based on meeting certain Company metrics. We issued 1,220,822 shares of unrestricted common stock in the first quarter of 2018, after withholding 752,564 shares to cover employee payroll taxes which we paid in cash, for amounts earned under the 2017 Bonus Plans. In March 2018, the Compensation Committee of our board of directors approved the 2018 Non-executive Bonus Plan and in April 2018, the Compensation Committee of our board of directors approved the 2018 Executive Bonus Plan, or collectively, the 2018 Bonus Plans. The 2018 Bonus Plans provide for the issuance of shares of unrestricted common stock to employees based on the achievement of certain 2018 Company metrics. Shares issued under the aforementioned Bonus Plans are issued from our 2014 Plan and reduce the 2014 Plan shares available for issuance. We record stock-based compensation expense related to the Bonus Plans over the service period of eligible employees based on forecasted performance relative to the Company metrics. To the extent that updated estimates of bonus expense differ from original estimates, the cumulative effect on current and prior periods of those changes is recorded in the period those estimates are revised. In 2016 we recorded $6.6 million of stock-based compensation expense under the 2016 Bonus Plans and $923,000 under the 2015 Non-Executive Bonus Plan. In 2017, we recorded $7.7 million of stock-based compensation expense under the 2017 Bonus Plans and $1.7 million under the 2016 Bonus Plans. In 2018, we recorded $9.4 million of stock-based compensation expense under the 2018 Bonus Plans and $1.9 million under the 2017 Bonus Plans. Stock Options Stock option activity under the 2008 Plan, 2014 Plan and the 2015 Inducement Plan in 2016, 2017 and 2018 was as follows: Options Outstanding Weighted- Number of Average Aggregate Shares Weighted- Remaining Intrinsic Available Number of Average Contractual Value for Issuance Shares Exercise Price Term (Years) (In thousands) Balance—December 31, 2015 6,672,236 11,498,747 $ 4.51 6.86 $ 6,256 Authorized 4,436,933 — Stock options granted (1,316,200) 1,316,200 3.36 Issuance of shares under 2015 Bonus Plans (1,653,371) — Restricted stock units granted (9,070,854) — Exercised — (1,040,902) 2.37 Stock options canceled 1,938,053 (1,938,053) 5.46 Restricted stock units canceled 3,192,618 — Balance—December 31, 2016 4,199,415 9,835,992 $ 4.39 6.23 $ 5,734 Authorized 4,453,425 — Stock options granted (300,000) 300,000 4.20 Issuance of shares under 2016 Bonus Plans (1,688,097) — Shares withheld from net settlement of restricted stock units 677,547 — Restricted stock units granted (9,329,181) — Exercised — (1,172,409) 2.80 Stock options canceled 1,225,087 (1,225,087) 6.24 Restricted stock units canceled 2,621,801 — Balance—December 31, 2017 1,859,997 7,738,496 $ 4.34 3.96 $ 4,897 Authorized 4,860,197 — Stock options granted (400,000) 400,000 4.71 Issuance of shares under 2017 Bonus Plans (1,974,771) — Shares withheld from net settlement of restricted stock units 1,294,360 — Restricted stock units granted (8,250,061) — Exercised — (2,488,544) 2.62 Stock options canceled 1,153,395 (1,153,395) 5.49 Restricted stock units canceled 3,794,428 — Balance—December 31, 2018 2,337,545 4,496,557 $ 5.02 4.98 $ 2,446 Vested and exercisable—December 31, 2018 3,869,458 $ 5.12 4.33 $ 2,257 Vested and expected to vest(1)—December 31, 2018 4,386,003 $ 5.04 $ 2,420 (1) Options expected to vest are net of an estimated forfeiture rate. Additional information regarding options outstanding at December 31, 2018 is as follows : Options Outstanding Options Exercisable Weighted- Average Remaining Weighted- Weighted- Number of Contractual Average Number of Average Range of exercises Shares Term (Years) Exercise Price Shares Exercise Price $0.04 — $3.70 $ 2.58 $ 2.55 $3.76 — $4.55 4.26 4.33 $4.66— $5.77 5.44 5.77 $6.20 — $9.00 7.05 7.07 $9.18 — $12.05 9.87 9.87 Outstanding at December 31, 2018 $ 5.02 $ 5.12 The aggregate pretax intrinsic value of vested options exercised in 2018, 2017 and 2016 was $5.7 million, $2.3 million and $1.4 million, respectively. The intrinsic value is the difference between the estimated fair value of the Company’s common stock at the date of exercise and the exercise price for in-the-money options. The weighted-average grant-date fair value of options granted in 2018, 2017 and 2016 was $2.43, $1.74 and $1.42 per share, respectively. Our stock-based compensation expense was recorded in the following cost and expense categories (in thousands): Year ended December 31, 2018 2017 2016 Cost of revenue $ 5,006 $ 3,772 $ 3,043 Research and development 15,981 14,520 11,728 Sales and marketing 9,464 8,659 10,474 General and administrative 7,985 6,780 9,144 Total $ 38,436 $ 33,731 $ 34,389 Determining Fair Value of Stock Options and ESPP The fair value of each grant of stock options was determined by us using the methods and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment to determine. Expected Term— The expected term of stock options represents the weighted-average period the stock options are expected to be outstanding. For option grants that are considered to be “plain vanilla”, we have opted to use the simplified method for estimating the expected term as provided by the Securities and Exchange Commission. The simplified method calculates the expected term as the average of time-to-vesting and the contractual life of the options. For ESPP, the expected term is based on the offering period and purchase periods within the offering period. Expected Volatility— When we did not have a sufficient trading history for our common stock, the expected stock price volatility assumption was determined by examining the historical volatilities of a group of industry peers. As more historical data for our common stock became available, we began to use our own historical stock price volatility to determine expected stock price volatility. Risk-Free Interest Rate— The risk free rate assumption was based on the U.S. Treasury instruments with terms that were consistent with the expected term of our stock options and ESPP. Expected Dividend— The expected dividend assumption was based on our history and expectation of dividend payouts. Forfeiture Rate— Forfeitures were estimated based on historical experience. Fair Value of Common Stock— Since our IPO, the fair value of our common stock has been determined based on the closing price of our common stock on the Nasdaq Global Select Market. We used the Black-Scholes Model to estimate the fair value of our stock options granted to employees with the following weighted-average assumptions: Year ended December 31, 2018 2017 2016 Expected dividend yield — — — Risk-free interest rate 2.7% 2.1% 1.4% Expected volatility 51% 40% 42% Expected life (in years) 6.1 6.1 6.1 We used the Black-Scholes model to estimate the fair value of our Employee Stock Purchase Plan awards with the following assumptions: Year ended December 31, 2018 2017 2016 Expected dividend yield — — — Risk-free interest rate 1.8% - 2.6% 0.9% - 1.3% 0.5% - 0.7% Expected volatility 34% - 54% 34% - 54% 34% - 41% Expected life (in years) 0.5 - 2.0 0.5 - 2.0 0.5 - 2.0 As required by Topic 718 Compensation—Stock Compensation, we estimate expected forfeitures and recognize compensation costs only for those equity awards expected to vest. Our stock options granted are typically granted with vesting terms of 48 months. The following table summarizes our unrecognized stock-based compensation expense as of December 31, 2018 net of estimated forfeitures: Unrecognized Remaining Stock-based Weighted-Average Compensation Recognition Expense Period (in millions) (in years) Stock options $ 1.0 3.0 Restricted stock units 41.9 2.8 ESPP 1.6 1.6 Total $ 44.5

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2018
Employee Benefit Plan
Employee Benefit Plan	11. Employee Benefit Plan We maintain a defined contribution 401(k) plan. The plan covers all full-time U.S. employees over the age of 21. Each employee can contribute up to $18,500 annually (with a $6,000 catch up contribution limit for employees aged 50 or older). We have the option to provide matching contributions, but have not done so to date.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies
Commitments and Contingencies	12. Commitments and Contingencies Operating Leases We lease our office facilities under noncancelable agreements expiring between 2019 and 2023. Rent expense in 2018, 2017 and 2016 was $6.8 million, $7.2 million and $6.7 million, respectively. The aggregate future minimum lease payments under the agreements as of December 31, 2018 are as follows (in thousands): Year 2019 $ 7,144 2020 5,553 2021 4,083 2022 3,074 2023 1,163 Total $ 21,017 Litigation We continually evaluate uncertainties associated with litigation and record a charge equal to at least the minimum estimated liability for a loss contingency when both of the following conditions are met: (i) information available prior to issuance of the financial statements indicates that it is probable that a liability has been incurred at the date of the financial statements and (ii) the loss or range of loss can be reasonably estimated. If we determine that a loss is possible and a range of the loss can be reasonably estimated, we disclose the range of the possible loss in the Notes to the Consolidated Financial Statements. We evaluate, on a quarterly basis, developments in our legal matters that could affect the amount of liability that has been previously accrued, if any, and the matters and related ranges of possible losses disclosed, and make adjustments and changes to our disclosures as appropriate. Significant judgment is required to determine both likelihood of there being and the estimated amount of a loss related to such matters. Until the final resolution of such matters, there may be an exposure to loss, and such amounts could be material. For legal proceedings for which there is a reasonable possibility of loss (meaning those losses for which the likelihood is more than remote but less than probable), we have determined we do not have material exposure on an aggregate basis . Indemnification Under the indemnification provisions of our standard sales related contracts, we agree to defend and/or settle claims brought by third parties against our customers and channel partners alleging that our software or the customer’s use thereof infringes the third party’s intellectual property right, such as a patent right. These indemnification obligations are typically not subject to limitation; however if we believe such a claim is reasonably likely to occur and if it is commercially impractical for us to either procure the right for the customer to continue to use our software or modify our software so that it’s not infringing, we can terminate the customer agreement and refund the customer a portion of the license fees paid (prorated over the three year period from initial delivery for software licensed on a perpetual basis). We also on occasion indemnify our customers for other types of third party claims. In addition, we indemnify our officers, directors, and certain key employees while they are serving in such capacities in good faith. Through December 31, 2018, we have not received any material written claim for indemnification.

Unearned Revenue

Unearned Revenue	12 Months Ended
	Dec. 31, 2018
Unearned Revenue
Unearned Revenue	13. Unearned Revenue Changes in unearned revenue were as follows for years ended December 31, 2018 and 2017 : Year ended December 31, (in thousands) 2018 2017 Balance, beginning of period $ 77,022 $ 60,588 Billings, excluding billings for customer arrangements with termination rights 205,816 179,294 Additions to unearned revenue upon expiration of termination rights 17,651 16,273 Recognition of revenue, net of change in unbilled accounts receivable* (194,652) (179,133) Balance, end of period $ 105,837 $ 77,022 * Reconciliation to Revenue Reported per Condensed Consolidated Statement of Operations: Year ended December 31, (in thousands) 2018 2017 Revenue billed as of the end of period $ 194,652 $ 179,133 Increase (decrease) in total unbilled accounts receivable (1,460) 625 Revenue Reported in Condensed Consolidated Statement of Operations $ 193,192 $ 179,758 Revenue allocated to remaining performance obligations includes unearned revenue plus contractually committed amounts that will be invoiced and recognized as revenue in future periods, but excludes amounts invoiced and not recognized as revenue under customer arrangements that contain termination rights. Remaining performance obligations were $112.7 million as of December 31, 2018, of which we expect to recognize approximately 70% as revenue over the next 12 months and the remainder thereafter. As of December 31, 2018 and 2017, the balance of customer arrangements that contain termination rights was $19.4 million and $19.5 million, respectively.

Segment and Disaggregated Reven

Segment and Disaggregated Revenue Information	12 Months Ended
	Dec. 31, 2018
Segment and Disaggregated Revenue Information [Abstract]
Segment Information	14. Segment and Disaggregated Revenue Information We conduct business globally. Our chief operating decision maker (Chief Executive Officer) reviews financial information presented on a consolidated basis accompanied by information about revenue by geographic region for purposes of allocating resources and evaluating financial performance. We have one business activity, software and services to manage and secure mobile devices, applications and content, and there are no segment managers who are held accountable for operations, operating results and plans for levels, components or types of products or services below the consolidated unit level. Accordingly, we are considered to be in a single reportable segment and operating unit structure. Revenue by geographic region based on the billing address was as follows: Year ended December 31, (in thousands) 2018 2017 2016 Revenue United States $ 82,033 $ 83,625 $ 76,217 International 111,159 96,133 89,965 Total $ 193,192 $ 179,758 $ 166,182 We recognized $30.7 million, or 16% of total revenue, $22.6 million, or 13% of total revenue, and $22.0 million, or 13% of total revenue, from customers with a billing address in Germany in 2018, 2017 and 2016, respectively. No other country, outside of the United States, exceeded 10% of the total revenue in 2018, 2017 or 2016. Revenue from recurring and nonrecurring contractual arrangements was as follows: Year ended December 31, (in thousands) 2018 2017 2016 Perpetual license - point-in-time $ 38,390 $ 48,041 $ 50,733 Professional services - point-in-time 3,654 3,140 3,069 Non-recurring revenue 42,044 51,181 53,802 On-premise subscriptions - point-in-time 20,948 15,994 15,614 On-premise subscriptions - ratable 16,275 14,779 14,300 Cloud subscriptions - ratable 50,714 38,728 31,093 Software support on perpetual licenses - ratable 63,211 59,076 51,373 Recurring revenue 151,148 128,577 112,380 Total revenue $ 193,192 $ 179,758 $ 166,182 As of December 31, 2018 and 2017, $2.5 million and $2.7 million, or 35% and 30%, respectively, of our net Property and Equipment was attributable to our operations located in India. Substantially all other long-lived assets were attributable to operations in the United States.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2018
Net Loss per Share
Net Loss per Share	15. Net Loss per Share The following table sets forth the computation of basic and diluted net loss per share for 2018, 2017 and 2016 (in thousands, except per share data): Year ended December 31, 2018 2017 2016 Numerator: Net loss $ (43,084) $ (53,362) $ (65,494) Denominator: Weighted–average shares outstanding 102,527 93,771 85,853 Less: weighted average shares subject to repurchase — (1) (8) Weighted–average shares used to compute basic and diluted net loss per share 102,527 93,770 85,845 Basic and diluted net loss per share $ (0.42) $ (0.57) $ (0.76) Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period. Because we have reported a net loss for 2018, 2017 and 2016, the number of shares used to calculate diluted net loss per common share is the same as the number of shares used to calculate basic net loss per common share for those periods presented because the potentially dilutive shares would have been anti-dilutive if included in the calculation. The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares): December 31, 2018 2017 2016 Stock options outstanding, net of unvested exercised stock options 4,496,557 7,738,496 9,838,463 Unvested restricted stock units 12,303,913 12,906,030 10,474,975 ESPP shares 478,026 726,643 676,196 Stock-settled bonus shares 1,234,474 1,185,373 1,057,093 Total potentially dilutive securities 18,512,970 22,556,542 22,046,727 For December 31, 2016, we have corrected the previously reported amount to include 1.7 million of additional shares related to our ESPP and stock-settled bonus plans that were excluded from the computation of the weighted-average diluted shares because such securities have an antidilutive impact due to losses reported. We do not consider this correction to be material, and there was no impact to our consolidated financial statements.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	16. Income Taxes Loss before income taxes consisted of the following (in thousands): Year ended December 31, 2018 2017 2016 United States $ $ $ International Total $ $ $ A significant portion of our international income is earned by foreign branches of our United States parent corporation and thus is already subject to United States taxation. The income of our foreign branches has been included as part of the United States jurisdiction in the table above. Income tax expense for 2018, 2017 and 2016, was composed of the following (in thousands): Year ended December 31, 2018 2017 2016 Current: Federal $ — $ — $ — State 26 36 22 Foreign 1,454 1,196 960 Total current income tax expense 1,480 1,232 982 Foreign (133) (90) — Total deferred income tax benefit (133) (90) — Total income tax expense $ 1,347 $ 1,142 $ 982 For 2018, 2017 and 2016, our effective tax rate differs from the amount computed by applying the statutory federal and state income tax rates to net loss before income tax, primarily as the result of changes in our valuation allowance. Year ended December 31, 2018 2017 2016 Federal tax benefit at statutory rate 21.0 % 34.0 % 34.0 % State tax benefit net of federal effect 6.3 8.8 4.4 Foreign taxes (1.7) (0.7) (0.4) Change in valuation allowance (29.8) 42.8 (33.0) Change in federal tax rate — (86.1) — Credits 3.7 3.4 1.8 Stock-based compensation (2.3) (3.9) (8.0) Non-deductible expenses and other (0.4) (0.4) (0.3) Effective tax rate (3.2) % (2.1) % (1.5) % Income tax expense for 2018, 2017 and 2016 relates to state minimum income tax, income tax on our earnings in foreign jurisdictions and withholding taxes on sales to customers in certain jurisdictions. A significant portion of our international income is earned by foreign branches of our United States parent corporation and thus is already subject to United States taxation. The income of our foreign branches has been included as part of the United States jurisdiction in the table above. The components of net deferred tax assets at December 31, 2018 and 2017 consisted of the following (in thousands): As of December 31, 2018 2017 Deferred tax assets: Accruals and allowances $ 6,037 $ 7,440 Gains on foreign exchange (72) (18) Net operating loss carryforwards 76,648 67,980 Depreciation and amortization 2,345 3,512 R&D tax credits 17,536 14,560 Stock-based compensation 5,755 6,333 Capitalized commissions (3,915) — Valuation allowance (104,201) (99,716) Net deferred tax assets $ 133 $ 91 Our accounting for deferred taxes involves the evaluation of a number of factors concerning the realizability of our net deferred tax assets. We primarily considered such factors as our history of operating losses, the nature of our deferred tax assets and the timing, likelihood and amount, if any, of future taxable income during the periods in which those temporary differences and carryforwards become deductible. At present, we do not believe that it is more likely than not that the deferred tax assets will be realized; accordingly, a full valuation allowance has been established and no deferred tax asset is shown in the accompanying consolidated balance sheets. On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system, and a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. We calculated our estimate of the impact of the Tax Act in our December 31, 2017 income tax provision in accordance with our understanding of the Tax Act and guidance available as of the date of that filing. The amount related to the remeasurement of certain deferred tax assets and liabilities based on the updated tax rate was approximately $44.7 million with a corresponding and fully offsetting adjustment to our valuation allowance for the year ended December 31, 2017. During the fourth quarter of the year ending December 31, 2018 we finalized our accounting for the Tax Act and there was no material change from the estimate. There was not a material impact related to the one-time transition tax on the mandatory deemed repatriation of foreign earnings. As of December 31, 2018, we had net operating loss carryforwards of approximately $321.3 million and $152.2 million available to reduce future taxable income, if any, for both federal and state income tax purposes, respectively. The federal and state net operating loss carryforwards will expire at various dates beginning 2027 and 2028, respectively. As of December 31, 2018, we had federal and California R&D tax credit carryforwards of approximately $13.3 million and $14.6 million, respectively. If not utilized, the federal R&D tax credit carryforward will expire in various portions beginning 2027. The California R&D tax credit can be carried forward indefinitely. A limitation may apply to the use of the net operating loss and credit carryforwards, under provisions of the Internal Revenue Code that are applicable if we experience an “ownership change”. That may occur, for example, as a result of trading in our stock by significant investors as well as issuance of new equity. Should these limitations apply, the carryforwards would be subject to an annual limitation, resulting in a substantial reduction in the gross deferred tax assets before considering the valuation allowance. Further, a portion of the carryforwards may expire before being applied to reduce future earnings. We follow the provisions of ASC 740-10, Accounting for Uncertainty in Income Taxes. ASC 740-10 prescribes a comprehensive model for the recognition, measurement, presentation and disclosure in financial statements of uncertain tax positions that have been taken or expected to be taken on a tax return. No non-current liability related to uncertain tax positions is recorded in the financial statements as the deferred tax assets have been presented net of these unrecognized tax benefits. At December 31, 2018 and 2017, our reserve for unrecognized tax benefits was approximately $8.3 million and $6.8 million, respectively. Due to the full valuation allowance at December 31, 2018, current adjustments to the unrecognized tax benefit will have no impact on our effective income tax rate; any adjustments made after the valuation allowance is released will have an impact on the tax rate. We do not anticipate any significant change in our uncertain tax positions within 12 months of this reporting date. We include penalties and interest expense related to income taxes as a component of other expense and interest expense, respectively, as necessary. A reconciliation of the gross unrealized tax benefits is as follows (in thousands): Year ended December 31, 2018 2017 2016 Unrecognized tax benefits, beginning of year $ 6,839 $ 5,306 $ 4,052 Gross increases—tax positions from prior periods (31) 34 43 Gross increases—tax positions from current period 1,532 1,499 1,211 Unrecognized tax benefits, end of year $ 8,340 $ 6,839 $ 5,306 We are subject to taxation in the United States and various states and foreign jurisdictions. As of December 31, 2018, the statute of limitations is open for all tax years from inception, that is, for the period from July 23, 2007 (date of inception) to December 31, 2018 and forward for federal and state purposes. The foreign statutes of limitation are generally two to four years.

Description of Business and S_2

Description of Business and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Description of Business and Significant Accounting Policies
Description of Business	Description of Business MobileIron, Inc. and its wholly owned subsidiaries, collectively, the “Company”, “we”, “us” or “our”, provides a purpose-built mobile IT platform that enables enterprises to manage and secure mobile applications, content and devices while providing their employees with device choice, privacy and a native user experience. We were incorporated in Delaware in July 2007 and are headquartered in Mountain View, California, with additional sales and support presence in North America, Europe, the Middle East, Asia and Australia and employees in India primarily focused on research and development.
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying audited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, and include the accounts of our wholly owned subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation.
Foreign Currency Translation	Foreign Currency Translation Our reporting currency is the U.S. dollar. The functional currency of all our international operations is the U.S. dollar. All monetary asset and liability accounts are translated into U.S. dollars at the period-end rate, nonmonetary assets and liabilities are translated at historical exchange rates, and revenue and expenses are translated at the weighted-average exchange rates in effect during the period. Translation adjustments arising are recorded as foreign currency gains (losses) in the consolidated statements of operations. We recognized a foreign currency loss of $471,000 in 2018, a foreign currency gain of $242,000 in 2017, and a foreign currency loss of $339,000 in 2016, in other income (expense)—net in our consolidated statements of operations.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. These estimates include, but are not limited to, revenue recognition, stock-based compensation, commissions, goodwill and accounting for income taxes. Actual results could differ from those estimates.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject us to a concentration of credit risk consist of cash, money market funds and fixed income investments. Although we deposit our cash with multiple financial institutions, our deposits, at times, exceed federally insured limits. We invest in fixed income securities that are of high-credit quality. Substantially all of our money market funds, or $36.6 million, are held in five funds that are rated “AAA.” We generally do not require collateral or other security in support of accounts receivable. Allowances are provided for individual accounts receivable when we become aware of a customer’s inability to meet its financial obligations, such as in the case of bankruptcy, deterioration in the customer’s operating results, or change in financial position. If circumstances related to customers change, estimates of the recoverability of receivables would be further adjusted. We also consider broader factors in evaluating the sufficiency of our allowances for doubtful accounts, including the length of time receivables are past due, significant one-time events and historical experience. Activity in our allowance for doubtful accounts was as follow (in thousands): Balance at Bad Write-offs, Balance at Beginning Debt Net of End of Period Expense Recoveries of Period Balance as of December 31, 2018 $ 475 199 (249) $ 425 Balance as of December 31, 2017 $ 433 149 (107) $ 475 Balance as of December 31, 2016 $ 628 77 (272) $ 433 One reseller accounted for 11% (1% as an end customer), 14% (1% as an end customer) and 15% (1% as an end customer) of total revenue in 2018, 2017 and 2016, respectively. The same reseller accounted for 7% and 16% of net accounts receivable as of December 31, 2018 and 2017, respectively. There were no other resellers or end-user customers that accounted for 10% or more as a percentage of our revenue or net accounts receivable for any period presented.
Segments	Segments We have one reportable segment.
Revenue Recognition	Revenue Recognition Revenue Presentation License revenue includes sales of perpetual software licenses, software licenses sold as part of on-premises term subscriptions, and appliances. Cloud services include sales of cloud-based solutions that allow customers to use hosted software over a contract period without taking possession of our software and are typically provided on a subscription or usage basis. Software support and services revenue includes sales of software support sold as part of on-premises term subscriptions, software support for perpetual licenses, and professional services. Revenue Recognition Revenue is recognized upon transfer of control of promised products or services to customers in an amount that reflects the consideration we expect to receive in exchange for those products or services. We enter into contracts that can include various combinations of products and services, which are generally capable of being distinct and accounted for as separate performance obligations. Revenue is recognized net of allowances for returns and any taxes collected from customers, which are subsequently remitted to governmental authorities. Nature of Products and Services Licenses for on-premises software provide the customer with a right to use the software as it exists when made available to the customer. Customers may purchase on-premises software licenses as perpetual licenses or as part of subscriptions. On-premises licenses are considered distinct performance obligations and revenue from the licenses is recognized upfront when the software is made available to the customer. Software support and services convey rights to the upgrades released over the contract period and provide support and tools to help customers deploy and use our products more efficiently. Revenue allocated to software support and services is generally recognized ratably over the contract period as customers simultaneously consume and receive benefits, given that the software support and services comprises a distinct performance obligation that is satisfied over time. On-premises subscriptions and software support and services occasionally contain termination rights. We recognize revenue from those arrangements, including the distinct licenses contained therein, as the termination rights for the performance obligation expire. See also Unearned Revenue and Customer Arrangements with Termination Rights below. Cloud services, which allow customers to use hosted software over a contract period without taking possession of our software, are provided on a subscription or usage basis. Revenue related to cloud services provided on a subscription basis is recognized ratably over the contract period and revenue related to cloud services based on usage is generally recognized as the usage occurs. Professional services include consulting, deployment and training services. Our professional services represent distinct performance obligations as our customers benefit from the services separately or together with other readily available resources. Professional services revenue is recognized as services are delivered. Appliance revenue was less than 5% of total revenue for all periods presented and is included as a component of license revenue within the consolidated statements of operations. Refer to Note 14 – Segment and Disaggregated Revenue Information for further information. Significant Judgments Our contracts with customers often include promises to transfer multiple products and services to a customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment. Judgment is required to determine whether a software license is considered distinct and accounted for separately, or not distinct and accounted for together with the software support and services and recognized over time. Judgment is required to determine the standalone selling price (“SSP”) for each distinct performance obligation. We use a range of amounts to estimate the SSP for items that are not sold separately, including on-premises licenses sold with software support and services. In instances where SSP is not directly observable, such as when we do not sell the product or service separately, we determine the SSP using information that may include other observable inputs. We typically have more than one SSP for individual products and services due to the stratification of those products and services by customer classes and circumstances. In these instances, we may use information such as the size and type of customer in determining the SSP. Contract Balances Timing of revenue recognition may differ from the timing of invoicing customers. We record a receivable when revenue is recognized prior to invoicing, or unearned revenue when revenue will be recognized after invoicing. For multi-year agreements, we either invoice our customer in full at the inception of the contract or annually at the beginning of each annual period. We record an unbilled receivable related to revenue recognized for multi-year on-premises licenses invoiced annually when we have an unconditional right to invoice and receive payment in the future for those licenses or when we have the right to invoice future monthly periods under committed monthly recurring charge (“MRC”) agreements. The majority of our MRC agreements are for a month to month term (“non-committed”) or usage-based. Payment terms and conditions vary by contract type, although terms generally include a requirement to pay within 30 to 60 days. In instances where the timing of revenue recognition differs from the timing of invoicing, we have determined our contracts generally do not include a significant financing component. The primary purpose of our invoicing terms is to provide customers with simplified and predictable ways of purchasing our products and services, not to receive financing from our customers or to provide customers with financing. This includes invoicing at the beginning of a subscription term with revenue recognized ratably over the contract period or multi-year on-premises licenses that are invoiced annually with a portion of the revenue recognized upfront. As of December 31, 2018 and 2017, the balance of accounts receivable, net of the allowance for doubtful accounts, included $1.4 million and $2.5 million, respectively, of unbilled receivables from upfront recognition of revenue for certain multi-period on-premises software subscriptions that include both distinct software licenses and software support and services. As of December 31, 2018 and 2017, unbilled receivables included in other long-term assets on our consolidated balance sheets were $592,000 and $977,000, respectively. Unearned Revenue and Customer Arrangements with Termination Rights We generally invoice our customers upfront for subscriptions and software support and services associated with perpetual licenses. Unearned revenue from those upfront billings is comprised of unearned revenue from cloud-based subscriptions, software support and services for on-premises subscriptions, software support and services associated with perpetual licenses, and professional services to be performed in the future. Because some of our arrangements with customers contain termination rights, the arrangements do not meet the definition of a contract under Accounting Standard Codification, or ASC, Topic 606, Revenue Recognition from Contracts with Customers, or ASC 606, and are not recorded as unearned revenue and instead are recorded as “customer arrangements with termination rights” on our consolidated balance sheets. Refer to Note 13 – Unearned Revenue for further information on unearned revenue, changes in unearned revenue during the period, and customer arrangements with termination rights. Deferred Commissions We recognize an asset for the incremental costs of obtaining a contract with a customer. We have determined that certain sales incentive programs meet the requirements to be capitalized and we include those costs in current and non-current deferred commissions on our consolidated balance sheets. Deferred commissions are amortized over the period commensurate with revenue recognition. Changes in deferred commissions were as follows (in thousands): Year ended December 31, 2018 2017 Balance, beginning of the period $ 18,408 $ 18,738 Deferral of commissions earned 15,312 17,470 Recognition of commission expense (16,240) (17,621) Impairment of deferred commissions (149) (179) Balance, end of the period $ 17,331 $ 18,408
Cash Equivalents	Cash Equivalents We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents. As of December 31, 2018 and 2017, cash and cash equivalents consisted of cash deposited with banks, money market funds and investments that mature within three months of their purchase.
Held-To-Maturity Investments	Held-To-Maturity Investments We determine the appropriate classification of our fixed income investments at the time of purchase and reevaluate their classifications each reporting period. Investments are classified as held-to-maturity since the Company has positive intent and the ability to hold the securities to maturity. Held-to-maturity securities are stated at amortized cost.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes all changes in equity (net assets) during a period from non-owner sources. In 2018, 2017 and 2016, there were no differences between net loss and comprehensive loss. Therefore, the consolidated statements of comprehensive loss have been omitted.
Net Loss per Share of Common Stock	Net Loss per Share of Common Stock Basic net loss per common share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and potentially dilutive securities outstanding for the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, convertible preferred stock, unvested restricted stock, restricted stock units and stock options are considered to be potentially dilutive securities. Because we have reported a net loss for 2018, 2017 and 2016, the number of shares used to calculate diluted net loss per common share is the same as the number of shares used to calculate basic net loss per common share for those periods presented because the potentially dilutive shares would have been anti-dilutive if included in the calculation.
Software Development Costs Incurred in Connection with Software to be Sold or Marketed	Software Development Costs Incurred in Connection with Software to be Sold or Marketed The costs to develop new software products and enhancements to existing software products are expensed as incurred until technological feasibility has been established. We consider technological feasibility to have occurred when all planning, designing, coding and testing have been completed according to design specifications. Once technological feasibility is established, any additional costs would be capitalized. We believe our current process for developing software is essentially completed concurrent with the establishment of technological feasibility, and accordingly, no costs have been capitalized.
Internal Use Software	Internal Use Software We capitalize costs incurred during the application development stage related to our internally used software. Such costs are primarily incurred by third-party vendors and consultants. Costs related to preliminary project activities and post-implementation activities are expensed as incurred. Amounts capitalized in all periods presented were not significant. All software development costs incurred in connection with our cloud offering, or SaaS, are also sold or marketed to partners or end customers, therefore we start capitalizing costs when technological feasibility is achieved. No costs were capitalized in any periods presented as we believe that our current process for developing software is essentially completed concurrent with the establishment of technological feasibility.
Property and Equipment	Property and Equipment Property and equipment are stated at cost. Depreciation is computed using the straight-line method over the estimated useful life of the property and equipment, determined to be three years for computers and equipment and software, five years for furniture and fixtures, and the lesser of the remaining lease term or estimated useful life for leasehold improvements. Expenditures for repairs and software support are charged to expense as incurred. Upon disposition, the cost and related accumulated depreciation are removed from the accounts and the resulting gain or loss is reflected as operating expenses in the consolidated statements of operations.
Goodwill	Goodwill and Intangible Assets We record the excess of the acquisition purchase price over the fair value of the tangible and identifiable intangible assets acquired as goodwill. We perform an impairment test of our goodwill in the third quarter of our fiscal year, or more frequently if indicators of potential impairment arise. We have a single reporting unit and consequently evaluate goodwill for impairment based on an evaluation of the fair value of the Company as a whole. We record purchased intangible assets at their respective estimated fair values at the date of acquisition. Purchased intangible assets were amortized using the straight-line method over their remaining estimated useful lives, which ranged from three to five years. We have determined that our intangible assets were not impaired during the years ended December 31, 2018, 2017 and 2016.
Long-Lived Assets with Finite Lives	Long-Lived Assets with Finite Lives Long-lived assets are reviewed for possible impairment whenever events or circumstances indicate that the carrying amount of these assets may not be recoverable. We evaluate the recoverability of each of our long-lived assets, including property and equipment, by comparison of its carrying amount to the future discounted cash flows we expect the asset to generate. If we consider the asset to be impaired, we measure the amount of any impairment as the difference between the carrying amount and the fair value of the impaired asset.
Stock-Based Compensation	Stock-Based Compensation We use the estimated grant-date fair value method of accounting in accordance with ASC Topic 718 Compensation—Stock Compensation . Fair value is determined using the Black-Scholes Model using various inputs, including our estimates of expected volatility, term and future dividends. We estimated the forfeiture rate in 2018, 2017 and 2016 based on our historical experience for annual grant years where the majority of the vesting terms have been satisfied. We recognize compensation costs for awards with service and performance vesting conditions and for our Employee Stock Purchase Plan, or ESPP, on an accelerated method over the requisite service period of the award. For stock options or restricted stock grants with no performance condition, we recognize compensation costs on a straight-line basis over the requisite service period of the award, which is generally the vesting term of four years.
Research and Development	Research and Development Research and development, or R&D, costs are charged to expense as incurred.
Advertising	Advertising Advertising costs are expensed and included in sales and marketing expense when incurred. Advertising expense in 2018, 2017 and 2016 was $204,000, $102,000 and $305,000, respectively.
Income Taxes	Income Taxes We account for income taxes in accordance with ASC Topic 740, Income Taxes , under which deferred tax liabilities and assets are recognized for the expected future tax consequences of temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities and net operating loss and tax credit carryforwards. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. We use a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. A tax position is recognized when it is more likely than not that the tax position will be sustained upon examination, including resolution of any related appeals or litigation processes. A tax position that meets the more-likely-than-not recognition threshold is measured at the largest amount of benefit that is greater than 50% likely of being realized upon ultimate settlement with a taxing authority. The standard also provides guidance on derecognition of tax benefits, classification on the balance sheet, interest and penalties, accounting in interim periods, disclosure and transition.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board, or FASB, or other standard setting bodies and adopted by us as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on our financial position or results of operations upon adoption. Guidance Not Yet Adopted Financial Instruments – Credit Losses In June 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses – Measurement of Credit Losses on Financial Instruments, which introduces a model based on expected losses to estimate credit losses for most financial assets and certain other instruments. In addition, for available-for-sale debt securities with unrealized losses, the losses will be recognized as allowances rather than reductions in the amortized cost of the securities. The standard is effective for annual reporting periods beginning after December 15, 2019, with early adoption permitted for annual reporting periods beginning after December 15, 2018. Entities will apply the standard’s provisions by recording a cumulative-effect adjustment to retained earnings. We are evaluating the impact of the adoption on our consolidated balance sheet, results of operations, cash flows and disclosures . We intend to adopt ASU No. 2016-13 effective January 1, 2020. Leases In February 2016, the FASB finalized ASU 2016-02, Leases. ASU 2016-02 requires lessees to recognize the assets and liabilities on the balance sheet for the rights and obligations created by most leases and continue to recognize expenses on the income statements over the lease term. It will also require disclosure designed to give financial statement users information on the amount, timing, and uncertainly of cash flows arising from leases. The guidance is effective for annual reporting periods beginning after December 15, 2018 and interim periods within those fiscal years. We adopted ASU 2016-02 effective January 1, 2019 and, as permitted by ASU 2018-11, we do not plan to recast our prior periods. As a result of this new standard, we expect to record a lease commitment liability of approximately $18.0 million and corresponding right-of-use asset of approximately $16.5 million at March 31, 2019 for our leases designated as operating leases in Note 12, “Commitments and Contingencies,” upon adoption . We do not expect the new standard to materially impact our results of operations. Recently Adopted Guidance Revenue from Contracts with Customers In May 2014, the FASB, jointly with the International Accounting Standards Board, issued a comprehensive new standard, ASC 606. The standard’s core principle is that a reporting entity will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In addition, the standard requires disclosure of the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The guidance permitted two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (modified retrospective method). We adopted the standard using the full retrospective method and restated each prior reporting period presented. The standard was effective for us beginning January 1, 2018. In preparation for adoption of the standard, we implemented internal controls and key system functionality to enable the preparation of financial information and reached conclusions on key accounting assessments related to the standard, including our assessment of the impact of accounting for costs incurred to obtain a contract. The most significant impact of the standard relates to the elimination of the requirement to have vendor specific objective evidence, or VSOE, of fair value to separate and recognize revenue for products and services in a contract. The elimination of the VSOE requirement causes a significant change to the timing of revenue recognition for on-premises software term license revenue and other multiple-element arrangements with products or services that lacked VSOE of fair value. Our on-premises term license agreements include distinct software licenses and software support and services. Under ASC 606, we recognize the software license revenue at the time of delivery and recognize the software support and services revenue ratably over the term of the subscription agreements. Under Accounting Standard Codification Topic 605, Revenue Recognition, or ASC 605, we recognized all revenue from those arrangements ratably over the term of the subscription agreements. Due to the complexity of certain of our revenue contracts, the actual revenue recognition treatment required under the new standard depends on contract-specific terms and in some instances may vary from recognition at the time of delivery. The timing of revenue recognized from our cloud offerings, perpetual licenses, professional services and appliances remain substantially unchanged. In addition, Accounting Standards Codification Subtopic 340-40, Other Assets and Deferred Costs - Contracts with Customers, or ASC 340, requires us to recognize an asset for the incremental costs of obtaining a contract with a customer if our sales incentive programs meet the requirements for capitalization. Previously we recorded these incremental costs of obtaining a contract as commission expense when we booked a sales transaction; whereas under ASC 340, we record an asset for the incremental cost to obtain a contract and recognize the cost over the period commensurate with revenue recognition. In connection with our adoption of ASC 606 on January 1, 2018, there was a decrease to our deferred income tax liabilities and an offsetting increase in the valuation allowance recorded against deferred tax assets. No income tax impact was recorded to retained earnings upon adoption as a result of the full valuation allowance on United States deferred tax assets. In 2018, we recorded no income tax expense or benefit as a result of the adoption of the ASC 606. Adoption of the standard resulted in the recognition of additional revenue of $3.3 million and $2.3 million in 2017 and 2016, respectively, primarily due to an increase in revenue recognized from on-premises software subscriptions delivered and recognized in 2017 and 2016 and earlier recognition from other arrangements that lacked VSOE of fair value under ASC 605, partially offset by lower on-premises software subscription revenue from amounts billed prior to 2016. The new standard for accounting for costs to obtain a contract resulted in an increase in sales and marketing expense of $330,000 and $570,000 in 2017 and 2016, respectively, primarily due to the net impact of the capitalization of commissions earned in 2017 and 2016 and the amortization expense from commissions capitalized prior to 2016. The new standard did not have a material impact on net cash provided by (used in) operating, financing, or investing activities in our consolidated cash flow statements. Adoption of the standard resulted in an increase in accounts receivable and other assets of $3.4 million as of December 31, 2017, driven primarily by unbilled receivables from upfront recognition of revenue for certain multi-period on-premises software subscriptions that include both distinct software licenses and software update and support services. Unearned revenue was reduced by $35.5 million as of December 31, 2017 due to (a) cumulative changes to revenue and (b) a reclassification of approximately $19.5 million as of December 31, 2017 for arrangements with customers which contain termination rights. Because of the termination rights, the arrangements did not meet the definition of a contract under ASC 606 and were not recorded as unearned revenue but they were instead recorded as “customer arrangements with termination rights” on our consolidated balance sheets. Total capitalized costs to obtain a contract included in current and non-current prepaid and other current assets on our consolidated balance sheets were $9.3 million and $9.1 million, respectively, as of December 31, 2017. The following tables show the impact of adoption of the standards related to revenue recognition on our reported results (in thousands except per share information): Year ended December 31, 2017 New Revenue Standard As Statement of Operations: As Reported Adjustment Adjusted Revenue $ 176,491 $ 3,267 $ 179,758 Total operating expenses 202,099 330 202,429 Net loss (56,299) 2,937 (53,362) Net loss per share, basic and diluted (0.60) 0.03 (0.57) Year ended December 31, 2016 New Revenue Standard As Statement of Operations: As Reported Adjustment Adjusted Revenue $ 163,926 $ 2,256 $ 166,182 Total operating expenses 199,721 570 200,291 Net loss (67,180) 1,686 (65,494) Net loss per share, basic and diluted (0.78) 0.02 (0.76) December 31, 2017 New Revenue Standard As Balance Sheets: As Reported Adjustment Adjusted Assets Accounts receivable, net $ 48,171 $ 2,458 $ 50,629 Deferred commissions-current — 9,285 9,285 Deferred commissions-noncurrent — 9,123 9,123 Other assets 1,999 977 2,976 Liabilities and stockholders' equity Accrued expenses 24,995 75 25,070 Unearned revenue-current 84,467 (29,362) 55,105 Unearned revenue-noncurrent 28,034 (6,117) 21,917 Customer arrangements with termination rights — 19,546 19,546 Total stockholders' equity 21,851 37,701 59,552

Description of Business and S_3

Description of Business and Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Description of Business and Significant Accounting Policies
Schedule of allowance for doubtful accounts	Activity in our allowance for doubtful accounts was as follow (in thousands): Balance at Bad Write-offs, Balance at Beginning Debt Net of End of Period Expense Recoveries of Period Balance as of December 31, 2018 $ 475 199 (249) $ 425 Balance as of December 31, 2017 $ 433 149 (107) $ 475 Balance as of December 31, 2016 $ 628 77 (272) $ 433
Schedule of changes in deferred commissions	Changes in deferred commissions were as follows (in thousands): Year ended December 31, 2018 2017 Balance, beginning of the period $ 18,408 $ 18,738 Deferral of commissions earned 15,312 17,470 Recognition of commission expense (16,240) (17,621) Impairment of deferred commissions (149) (179) Balance, end of the period $ 17,331 $ 18,408
Schedule of adoption of the expected impact of adoption of the standards related to revenue recognition	The following tables show the impact of adoption of the standards related to revenue recognition on our reported results (in thousands except per share information): Year ended December 31, 2017 New Revenue Standard As Statement of Operations: As Reported Adjustment Adjusted Revenue $ 176,491 $ 3,267 $ 179,758 Total operating expenses 202,099 330 202,429 Net loss (56,299) 2,937 (53,362) Net loss per share, basic and diluted (0.60) 0.03 (0.57) Year ended December 31, 2016 New Revenue Standard As Statement of Operations: As Reported Adjustment Adjusted Revenue $ 163,926 $ 2,256 $ 166,182 Total operating expenses 199,721 570 200,291 Net loss (67,180) 1,686 (65,494) Net loss per share, basic and diluted (0.78) 0.02 (0.76) December 31, 2017 New Revenue Standard As Balance Sheets: As Reported Adjustment Adjusted Assets Accounts receivable, net $ 48,171 $ 2,458 $ 50,629 Deferred commissions-current — 9,285 9,285 Deferred commissions-noncurrent — 9,123 9,123 Other assets 1,999 977 2,976 Liabilities and stockholders' equity Accrued expenses 24,995 75 25,070 Unearned revenue-current 84,467 (29,362) 55,105 Unearned revenue-noncurrent 28,034 (6,117) 21,917 Customer arrangements with termination rights — 19,546 19,546 Total stockholders' equity 21,851 37,701 59,552

Significant Balance Sheet Com_2

Significant Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2018
Significant Balance Sheet Components
Schedule of accounts receivable, net	Accounts receivable, net at December 31, 2018 and 2017 consisted of the following (in thousands): December 31, 2018 December 31, 2017 Accounts receivable - billed $ 60,037 $ 48,646 Accounts receivable - unbilled 1,382 2,458 Allowance for doubtful accounts (425) (475) Accounts receivable, net $ 60,994 $ 50,629
Schedule of property and equipment	Property and equipment at December 31, 2018 and 2017 consisted of the following (in thousands): As of December 31, 2018 2017 Computers and appliances $ 13,517 $ 13,178 Purchased software 4,711 4,063 Furniture and fixtures 1,695 1,734 Leasehold improvements 3,503 3,226 Total property and equipment 23,426 22,201 Accumulated depreciation and amortization (16,380) (13,389) Total property and equipment—net $ 7,046 $ 8,812
Schedule of accrued expenses	Accrued expenses at December 31, 2018 and 2017 consisted of the following (in thousands): As of December 31, 2018 2017 Accrued commissions $ 4,398 $ 3,989 Accrued stock-settled bonus 9,355 7,705 Employee Stock Purchase Plan liability 1,923 2,047 Other accrued payroll-related expenses 3,630 4,285 Accrued royalties 3,596 733 Other accrued liabilities 4,445 6,311 Total accrued expenses $ 27,347 $ 25,070

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Measurement
Schedule of financial instruments measured at fair market value	Our financial instruments measured at fair market value as of December 31, 2018 and 2017 were as follows: As of December 31, 2018 (in thousands) Level 1 Level 2 Level 3 Total Money market funds $ 36,617 $ — $ — $ 36,617 Corporate debt securities — 6,555 — 6,555 Commercial paper — 53,598 — 53,598 Total $ 36,617 $ 60,153 $ — $ 96,770 As of December 31, 2017 (in thousands) Level 1 Level 2 Level 3 Total Money market funds $ 10,583 $ — $ — $ 10,583 Corporate debt securities — 7,076 — 7,076 Commercial paper — 51,796 — 51,796 Total $ 10,583 $ 58,872 $ — $ 69,455

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Investments
Schedule of investments in fixed income securities	Our investments in fixed income securities as of December 31, 2018 and 2017 were as follows: As of December 31, 2018 Amortized Fair (in thousands) cost Gains Losses Value Corporate debt securities $ 6,556 $ — $ (1) $ 6,555 Commercial paper 53,600 1 (3) 53,598 Total $ 60,156 $ 1 $ (4) $ 60,153 As of December 31, 2017 Amortized Fair (in thousands) cost Gains Losses Value Corporate debt securities $ 7,078 $ — $ (2) $ 7,076 Commercial paper 51,805 — (9) 51,796 Total $ 58,883 $ — $ (11) $ 58,872
Summary of balance sheet classification of investments	As of December 31, (in thousands) 2018 2017 Cash equivalents $ 59,156 $ 52,086 Short-term investments 1,000 6,797 Total investments $ 60,156 $ 58,883
Schedule of held-to-maturity investments by contractual maturity	As of December 31, 2018 2017 Gross Gross Amortized Fair Amortized Fair (in thousands) Cost Value Cost Value Due in one year or less $ 60,156 60,153 $ 58,883 $ 58,872 Due after one year through five years — — — — Total $ 60,156 $ 60,153 $ 58,883 $ 58,872

Goodwill and Intangibles (Table

Goodwill and Intangibles (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of intangible assets subject to amortization	The following table reflects intangible assets subject to amortization as of December 31, 2017 (in thousands): December 31, 2017 Gross Carrying Accumulated Net Book Amount Amortization Impairment Value Technology $ 3,080 $ (2,980) — $ 100 Total $ 3,080 $ (2,980) $ — $ 100

Restructuring Charges (Tables)

Restructuring Charges (Tables)	12 Months Ended
	Dec. 31, 2018
Restructuring Charges
Summary of restructuring activities	The following table sets forth a summary of restructuring activities which took place during the years ended December 31, 2018, 2017 and 2016 (in thousands): Severance and Related Costs Balance, December 31, 2015 $ — Provision for restructuring charges 1,052 Cash payments (1,037) Balance, December 31, 2016 $ 15 Provision for restructuring charges 1,349 Cash payments (867) Balance, December 31, 2017 $ 497 Provision for restructuring charges — Cash payments (497) Balance, December 31, 2018 $ —

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2018
Common Stock
Schedule of reserved shares of common stock for issuance	As of December 31, 2018 and 2017, we reserved shares of common stock for issuance as follows: As of December 31, 2018 2017 Options outstanding 4,496,557 7,738,496 Unvested restricted stock units outstanding 12,303,913 12,906,030 Shares available for grant under the 2014 equity plan and 2015 inducement plan 2,337,545 1,859,997 Shares available for purchase under the Employee Stock Purchase Plan 364,762 990,501 Total 19,502,777 23,495,024

Share Based Awards (Tables)

Share Based Awards (Tables)	12 Months Ended
	Dec. 31, 2018
Schedule of stock option activity under the 2008 Plan, 2014 Plan and 2015 Inducement Plan	Options Outstanding Weighted- Number of Average Aggregate Shares Weighted- Remaining Intrinsic Available Number of Average Contractual Value for Issuance Shares Exercise Price Term (Years) (In thousands) Balance—December 31, 2015 6,672,236 11,498,747 $ 4.51 6.86 $ 6,256 Authorized 4,436,933 — Stock options granted (1,316,200) 1,316,200 3.36 Issuance of shares under 2015 Bonus Plans (1,653,371) — Restricted stock units granted (9,070,854) — Exercised — (1,040,902) 2.37 Stock options canceled 1,938,053 (1,938,053) 5.46 Restricted stock units canceled 3,192,618 — Balance—December 31, 2016 4,199,415 9,835,992 $ 4.39 6.23 $ 5,734 Authorized 4,453,425 — Stock options granted (300,000) 300,000 4.20 Issuance of shares under 2016 Bonus Plans (1,688,097) — Shares withheld from net settlement of restricted stock units 677,547 — Restricted stock units granted (9,329,181) — Exercised — (1,172,409) 2.80 Stock options canceled 1,225,087 (1,225,087) 6.24 Restricted stock units canceled 2,621,801 — Balance—December 31, 2017 1,859,997 7,738,496 $ 4.34 3.96 $ 4,897 Authorized 4,860,197 — Stock options granted (400,000) 400,000 4.71 Issuance of shares under 2017 Bonus Plans (1,974,771) — Shares withheld from net settlement of restricted stock units 1,294,360 — Restricted stock units granted (8,250,061) — Exercised — (2,488,544) 2.62 Stock options canceled 1,153,395 (1,153,395) 5.49 Restricted stock units canceled 3,794,428 — Balance—December 31, 2018 2,337,545 4,496,557 $ 5.02 4.98 $ 2,446 Vested and exercisable—December 31, 2018 3,869,458 $ 5.12 4.33 $ 2,257 Vested and expected to vest(1)—December 31, 2018 4,386,003 $ 5.04 $ 2,420 (1) Options expected to vest are net of an estimated forfeiture rate.
Schedule of additional information regarding options outstanding	Options Outstanding Options Exercisable Weighted- Average Remaining Weighted- Weighted- Number of Contractual Average Number of Average Range of exercises Shares Term (Years) Exercise Price Shares Exercise Price $0.04 — $3.70 $ 2.58 $ 2.55 $3.76 — $4.55 4.26 4.33 $4.66— $5.77 5.44 5.77 $6.20 — $9.00 7.05 7.07 $9.18 — $12.05 9.87 9.87 Outstanding at December 31, 2018 $ 5.02 $ 5.12
Schedule of stock-based compensation expense recognized	Our stock-based compensation expense was recorded in the following cost and expense categories (in thousands): Year ended December 31, 2018 2017 2016 Cost of revenue $ 5,006 $ 3,772 $ 3,043 Research and development 15,981 14,520 11,728 Sales and marketing 9,464 8,659 10,474 General and administrative 7,985 6,780 9,144 Total $ 38,436 $ 33,731 $ 34,389
Schedule of weighted-average assumptions to estimate fair value of stock options granted to employees	Year ended December 31, 2018 2017 2016 Expected dividend yield — — — Risk-free interest rate 2.7% 2.1% 1.4% Expected volatility 51% 40% 42% Expected life (in years) 6.1 6.1 6.1
Schedule of assumptions used to calculate the fair value of Employee Stock Purchase Plan awards	Year ended December 31, 2018 2017 2016 Expected dividend yield — — — Risk-free interest rate 1.8% - 2.6% 0.9% - 1.3% 0.5% - 0.7% Expected volatility 34% - 54% 34% - 54% 34% - 41% Expected life (in years) 0.5 - 2.0 0.5 - 2.0 0.5 - 2.0
Schedule of unrecognized stock-based compensation expense and its remaining weighted-average recognition period	Unrecognized Remaining Stock-based Weighted-Average Compensation Recognition Expense Period (in millions) (in years) Stock options $ 1.0 3.0 Restricted stock units 41.9 2.8 ESPP 1.6 1.6 Total $ 44.5
Restricted stock units
Schedule of restricted stock unit activity	Restricted Stock Units Weighted- Average Number of Grant Date Shares Fair Value Unvested, December 31, 2015 7,832,962 $ 6.66 Granted 10,724,225 3.36 Vested (4,889,594) 4.99 Cancelled/Forfeited (3,192,618) 5.39 Unvested, December 31, 2016 10,474,975 $ 4.45 Granted 11,017,278 5.04 Vested (5,964,422) 4.70 Cancelled/Forfeitures (2,621,801) 5.01 Unvested, December 31, 2017 12,906,030 $ 4.72 Granted 10,224,832 4.63 Vested (7,032,521) 4.88 Cancelled/Forfeitures (3,794,428) 4.48 Unvested, December 31, 2018 12,303,913 $ 4.63

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies
Schedule of aggregate future minimum lease payments	The aggregate future minimum lease payments under the agreements as of December 31, 2018 are as follows (in thousands): Year 2019 $ 7,144 2020 5,553 2021 4,083 2022 3,074 2023 1,163 Total $ 21,017

Unearned Revenue (Tables)

Unearned Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Unearned Revenue
Schedule of changes in unearned revenue	Year ended December 31, (in thousands) 2018 2017 Balance, beginning of period $ 77,022 $ 60,588 Billings, excluding billings for customer arrangements with termination rights 205,816 179,294 Additions to unearned revenue upon expiration of termination rights 17,651 16,273 Recognition of revenue, net of change in unbilled accounts receivable* (194,652) (179,133) Balance, end of period $ 105,837 $ 77,022 * Reconciliation to Revenue Reported per Condensed Consolidated Statement of Operations: Year ended December 31, (in thousands) 2018 2017 Revenue billed as of the end of period $ 194,652 $ 179,133 Increase (decrease) in total unbilled accounts receivable (1,460) 625 Revenue Reported in Condensed Consolidated Statement of Operations $ 193,192 $ 179,758

Segment and Disaggregated Rev_2

Segment and Disaggregated Revenue Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment and Disaggregated Revenue Information [Abstract]
Schedule of revenue by geographic region	Year ended December 31, (in thousands) 2018 2017 2016 Revenue United States $ 82,033 $ 83,625 $ 76,217 International 111,159 96,133 89,965 Total $ 193,192 $ 179,758 $ 166,182
Revenue from recurring and nonrecurring billing models	Year ended December 31, (in thousands) 2018 2017 2016 Perpetual license - point-in-time $ 38,390 $ 48,041 $ 50,733 Professional services - point-in-time 3,654 3,140 3,069 Non-recurring revenue 42,044 51,181 53,802 On-premise subscriptions - point-in-time 20,948 15,994 15,614 On-premise subscriptions - ratable 16,275 14,779 14,300 Cloud subscriptions - ratable 50,714 38,728 31,093 Software support on perpetual licenses - ratable 63,211 59,076 51,373 Recurring revenue 151,148 128,577 112,380 Total revenue $ 193,192 $ 179,758 $ 166,182

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Net Loss per Share
Computation of basic and diluted net loss per share	The following table sets forth the computation of basic and diluted net loss per share for 2018, 2017 and 2016 (in thousands, except per share data): Year ended December 31, 2018 2017 2016 Numerator: Net loss $ (43,084) $ (53,362) $ (65,494) Denominator: Weighted–average shares outstanding 102,527 93,771 85,853 Less: weighted average shares subject to repurchase — (1) (8) Weighted–average shares used to compute basic and diluted net loss per share 102,527 93,770 85,845 Basic and diluted net loss per share $ (0.42) $ (0.57) $ (0.76)
Schedule of antidilutive securities excluded from computation of diluted weighted-average shares outstanding	The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares): December 31, 2018 2017 2016 Stock options outstanding, net of unvested exercised stock options 4,496,557 7,738,496 9,838,463 Unvested restricted stock units 12,303,913 12,906,030 10,474,975 ESPP shares 478,026 726,643 676,196 Stock-settled bonus shares 1,234,474 1,185,373 1,057,093 Total potentially dilutive securities 18,512,970 22,556,542 22,046,727

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of loss before income taxes	Loss before income taxes consisted of the following (in thousands): Year ended December 31, 2018 2017 2016 United States $ $ $ International Total $ $ $
Schedule of income tax expense	Income tax expense for 2018, 2017 and 2016, was composed of the following (in thousands): Year ended December 31, 2018 2017 2016 Current: Federal $ — $ — $ — State 26 36 22 Foreign 1,454 1,196 960 Total current income tax expense 1,480 1,232 982 Foreign (133) (90) — Total deferred income tax benefit (133) (90) — Total income tax expense $ 1,347 $ 1,142 $ 982
Schedule of reconciliation of effective tax rate	Year ended December 31, 2018 2017 2016 Federal tax benefit at statutory rate 21.0 % 34.0 % 34.0 % State tax benefit net of federal effect 6.3 8.8 4.4 Foreign taxes (1.7) (0.7) (0.4) Change in valuation allowance (29.8) 42.8 (33.0) Change in federal tax rate — (86.1) — Credits 3.7 3.4 1.8 Stock-based compensation (2.3) (3.9) (8.0) Non-deductible expenses and other (0.4) (0.4) (0.3) Effective tax rate (3.2) % (2.1) % (1.5) %
Schedule of components of net deferred tax assets	The components of net deferred tax assets at December 31, 2018 and 2017 consisted of the following (in thousands): As of December 31, 2018 2017 Deferred tax assets: Accruals and allowances $ 6,037 $ 7,440 Gains on foreign exchange (72) (18) Net operating loss carryforwards 76,648 67,980 Depreciation and amortization 2,345 3,512 R&D tax credits 17,536 14,560 Stock-based compensation 5,755 6,333 Capitalized commissions (3,915) — Valuation allowance (104,201) (99,716) Net deferred tax assets $ 133 $ 91
Schedule of reconciliation of gross unrealized tax benefits	A reconciliation of the gross unrealized tax benefits is as follows (in thousands): Year ended December 31, 2018 2017 2016 Unrecognized tax benefits, beginning of year $ 6,839 $ 5,306 $ 4,052 Gross increases—tax positions from prior periods (31) 34 43 Gross increases—tax positions from current period 1,532 1,499 1,211 Unrecognized tax benefits, end of year $ 8,340 $ 6,839 $ 5,306

Description of Business and S_4

Description of Business and Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2018USD ($)segmentitem	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Description Of Business And Significant Accounting Policies [Line Items]
AAA-rated money market funds	$ 36,600,000
Number of Money Market Funds | item	5
Balance at Beginning of Period	$ 475,000	$ 433,000	$ 628,000
Bad Debt Expense	199,000	149,000	77,000
Write-offs, Net of Recoveries	(249,000)	(107,000)	(272,000)
Balance at End of Period	$ 425,000	475,000	433,000
Number of reportable segments | segment	1
Other income (expense)—net
Description Of Business And Significant Accounting Policies [Line Items]
Foreign currency (loss)/gain	$ (471,000)	$ 242,000	$ (339,000)
As reseller | Total revenue
Description Of Business And Significant Accounting Policies [Line Items]
Concentration risk, percentage	11.00%	14.00%	15.00%
As reseller | Net accounts receivable
Description Of Business And Significant Accounting Policies [Line Items]
Concentration risk, percentage	7.00%	16.00%
As an end customer | Total revenue
Description Of Business And Significant Accounting Policies [Line Items]
Concentration risk, percentage	1.00%	1.00%	1.00%

Description of Business and S_5

Description of Business and Significant Accounting Policies - Revenue Recognition (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Description Of Business And Significant Accounting Policies [Line Items]
Accounts receivable, net	$ 60,994,000	$ 50,629,000
Deferred commissions balance, beginning of period	18,408,000	18,738,000
Deferral of commissions earned	15,312,000	17,470,000
Recognition of commission expense	(16,240,000)	(17,621,000)
Impairment of deferred commissions	(149,000)	(179,000)
Deferred commissions balance, end of period	17,331,000	18,408,000
Other long-term assets
Description Of Business And Significant Accounting Policies [Line Items]
Unbilled receivables, noncurrent	592,000	977,000
Unbilled
Description Of Business And Significant Accounting Policies [Line Items]
Accounts receivable, net	$ 1,400,000	$ 2,500,000
Minimum
Description Of Business And Significant Accounting Policies [Line Items]
Payment terms	30 days
Maximum
Description Of Business And Significant Accounting Policies [Line Items]
Payment terms	60 days
Total revenue | Product | Appliance | Maximum
Description Of Business And Significant Accounting Policies [Line Items]
Concentration risk, percentage	5.00%

Description of Business and S_6

Description of Business and Significant Accounting Policies - Software Development Costs Incurred to Advertising (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Description Of Business And Significant Accounting Policies [Line Items]
Capitalized development costs of software to be sold or marketed	$ 0
Capitalized development costs of software for internal use	$ 0
Stock-based compensation, vesting term (in years)	4 years
Advertising costs	$ 204,000	$ 102,000	$ 305,000
Minimum
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life, purchased intangible assets	3 years
Maximum
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life, purchased intangible assets	5 years
Computers and appliances
Description Of Business And Significant Accounting Policies [Line Items]
Property plant and equipment useful life	3 years
Furniture and fixtures
Description Of Business And Significant Accounting Policies [Line Items]
Property plant and equipment useful life	5 years

Description of Business and S_7

Description of Business and Significant Accounting Policies – Recent Accounting Pronouncements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense or benefit	$ 1,347,000	$ 1,142,000	$ 982,000
Recognition of additional revenue	193,192,000	179,758,000	166,182,000
Increase in sales and marketing expense	94,204,000	96,807,000	102,327,000
Unearned revenue	(105,837,000)	(77,022,000)	(60,588,000)
Capitalized costs to obtain a contract - current	8,265,000	9,285,000
Capitalized costs to obtain a contract - non-current	9,066,000	9,123,000
ASU 2016-02 | Forecast adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease commitment liability				$ 18,000,000
Right-of-use asset				$ 16,500,000
ASC 606 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense or benefit	$ 0
Recognition of additional revenue		3,267,000	2,256,000
Increase in sales and marketing expense		330,000	$ 570,000
Increase in accounts receivable and other assets		3,400,000
Unearned revenue		35,500,000
Capitalized costs to obtain a contract - current		9,285,000
Capitalized costs to obtain a contract - non-current		$ 9,123,000

Description of Business and S_8

Description of Business and Significant Accounting Policies – Revenue from Contracts with Customers: Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	$ 193,192	$ 179,758	$ 166,182
Total operating expenses	201,131	202,429	200,291
Net loss	$ (43,084)	$ (53,362)	$ (65,494)
Net loss per share, basic and diluted (in dollars per share)	$ (0.42)	$ (0.57)	$ (0.76)
ASC 606 | As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		$ 176,491	$ 163,926
Total operating expenses		202,099	199,721
Net loss		$ (56,299)	$ (67,180)
Net loss per share, basic and diluted (in dollars per share)		$ (0.60)	$ (0.78)
ASC 606 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		$ 3,267	$ 2,256
Total operating expenses		330	570
Net loss		$ 2,937	$ 1,686
Net loss per share, basic and diluted (in dollars per share)		$ 0.03	$ 0.02

Description of Business and S_9

Description of Business and Significant Accounting Policies – Revenue from Contracts with Customers: Balance sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Accounts receivable, net	$ 60,994	$ 50,629
Deferred commissions-current	8,265	9,285
Deferred commissions-noncurrent	9,066	9,123
Other assets	5,561	2,976
Liabilities and stockholders' equity
Accrued expenses	27,347	25,070
Unearned revenue - current	74,177	55,105
Unearned revenue - noncurrent	31,660	21,917
Customer arrangements with termination rights	19,367	19,546
Customer arrangements with termination rights		19,546
Total stockholders' equity	$ 54,117	59,552	$ 75,581	$ 101,217
ASC 606 | As Reported
Assets
Accounts receivable, net		48,171
Other assets		1,999
Liabilities and stockholders' equity
Accrued expenses		24,995
Unearned revenue - current		84,467
Unearned revenue - noncurrent		28,034
Total stockholders' equity		21,851
ASC 606 | Adjustment
Assets
Accounts receivable, net		2,458
Deferred commissions-current		9,285
Deferred commissions-noncurrent		9,123
Other assets		977
Liabilities and stockholders' equity
Accrued expenses		75
Unearned revenue - current		(29,362)
Unearned revenue - noncurrent		(6,117)
Customer arrangements with termination rights		19,546
Total stockholders' equity		$ 37,701

Significant Balance Sheet Com_3

Significant Balance Sheet Components - Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts Receivable, Net
Allowance for doubtful accounts	$ (425)	$ (475)
Accounts receivable, net	60,994	50,629
Billed
Accounts Receivable, Net
Accounts receivable	60,037	48,646
Unbilled
Accounts Receivable, Net
Accounts receivable	1,382	2,458
Accounts receivable, net	$ 1,400	$ 2,500

Significant Balance Sheet Com_4

Significant Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Total property and equipment	$ 23,426	$ 22,201
Accumulated depreciation and amortization	(16,380)	(13,389)
Total property and equipment-net	7,046	8,812
Computers and appliances
Property Plant And Equipment [Line Items]
Total property and equipment	13,517	13,178
Purchased software
Property Plant And Equipment [Line Items]
Total property and equipment	4,711	4,063
Furniture and fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	1,695	1,734
Leasehold improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 3,503	$ 3,226

Significant Balance Sheet Com_5

Significant Balance Sheet Components - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Expenses [Abstract]
Accrued commissions	$ 4,398	$ 3,989
Accrued stock-settled bonus	9,355	7,705
Employee Stock Purchase Plan liability	1,923	2,047
Other accrued payroll-related expenses	3,630	4,285
Accrued royalties	3,596	733
Other accrued liabilities	4,445	6,311
Total accrued expenses	$ 27,347	$ 25,070

Fair Value Measurement (Details

Fair Value Measurement (Details) - Recurring basis - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Financial and nonfinancial liabilities measured at fair value	$ 0	$ 0
Nonfinancial assets measured at fair value	0	0
Total	96,770	69,455
Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total	36,617	10,583
Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total	60,153	58,872
Money market funds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total	36,617	10,583
Money market funds | Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total	36,617	10,583
Corporate debt securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total	6,555	7,076
Corporate debt securities | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total	6,555	7,076
Commercial paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total	53,598	51,796
Commercial paper | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total	$ 53,598	$ 51,796

Investments - Investments in fi

Investments - Investments in fixed income securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 60,156	$ 58,883
Gains	1
Losses	(4)	(11)
Fair Value	60,153	58,872
Corporate debt securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	6,556	7,078
Losses	(1)	(2)
Fair Value	6,555	7,076
Commercial paper
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	53,600	51,805
Gains	1
Losses	(3)	(9)
Fair Value	$ 53,598	$ 51,796

Investments - Balance sheet cla

Investments - Balance sheet classification of investments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investments
Cash equivalents	$ 59,156	$ 52,086
Short-term investments	1,000	6,797
Total	$ 60,156	$ 58,883

Investments - Gross amortized c

Investments - Gross amortized cost and estimated fair value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Gross Amortized Cost
Due in one year or less	$ 60,156	$ 58,883
Total	60,156	58,883
Fair Value
Due in one year or less	60,153	58,872
Total	$ 60,153	$ 58,872

Goodwill and Intangibles (Detai

Goodwill and Intangibles (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 3,080,000
Accumulated Amortization		(2,980,000)
Net Book Value	$ 0	100,000
Goodwill	5,475,000	5,475,000
Technology
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		3,080,000
Accumulated Amortization		(2,980,000)
Net Book Value		100,000
Cost of revenue | Technology
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 100,000	$ 545,000	$ 616,000

Restructuring Charges (Details)

Restructuring Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 497	$ 15
Provision for restructuring charges		1,349	$ 1,052
Cash payments	$ (497)	(867)	(1,037)
Ending Balance		$ 497	$ 15

Line of Credit (Details)

Line of Credit (Details) $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2015USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Nov. 30, 2017USD ($)
Line Of Credit Facility [Line Items]
Revolving line of credit, maximum borrowing capacity		$ 20
Adjusted quick ratio		1.25
Line of Credit Facility, Remaining Borrowing Capacity				$ 15.5
Revolving line of credit amount outstanding		$ 0	$ 0
Prime rate
Line Of Credit Facility [Line Items]
Revolving line of credit, basis spread over variable rate		5.00%
Revolving line of credit
Line Of Credit Facility [Line Items]
Bank guarantee to customer				$ 3
Letter of credit
Line Of Credit Facility [Line Items]
Amount drawn from revolving line of credit	$ 1.5

Preferred Stock (Details)

Preferred Stock (Details) - Convertible preferred stock - shares	Dec. 31, 2018	Dec. 31, 2017
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized	10,000,000	10,000,000
Convertible preferred stock, shares issued	0	0
Convertible preferred stock, shares outstanding	0	0

Common Stock (Details)

Common Stock (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Common Stock
Common stock, shares authorized	300,000,000	300,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, voting rights	one	one

Common Stock - Shares of common

Common Stock - Shares of common stock reserved for issuance (Details) - shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Options outstanding	4,496,557	7,738,496	9,835,992	11,498,747
Shares available for grant	2,337,545	1,859,997	4,199,415	6,672,236
Shares available for purchase/reserved for issuance	19,502,777	23,495,024
Restricted stock units
Unvested restricted stock units outstanding	12,303,913	12,906,030	10,474,975	7,832,962
2014 equity plan and 2015 inducement plan
Shares available for grant	2,337,545	1,859,997

Common Stock - Repurchase Progr

Common Stock - Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Oct. 31, 2018
Common Stock
Common stock authorized to repurchase		$ 25,000
Common stock repurchased (in shares)	821,888
Average price (in dollars per share)	$ 4.66
Total cost of common stock repurchased	$ 3,831

Share Based Awards (Details)

Share Based Awards (Details) - shares	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 05, 2016	Dec. 20, 2015
Share Based Compensation Arrangement By Share Based Payment Award
Options granted, exercisable term		4 years 3 months 29 days
Shares of common stock available for issuance		19,502,777	23,495,024
Additional shares authorized		4,860,197	4,453,425	4,436,933
ESPP
Share Based Compensation Arrangement By Share Based Payment Award
Maximum annual percentage increase in shares issuable		1.00%
Maximum percentage of employee base compensation that may be utilized to purchase common stock under the ESPP		15.00%
Percentage of purchase price of common stock at fair market value		85.00%
Maximum increase in shares issuable		2,142,857
2008 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award
Expiry term of exercisable options		10 years
2014 Equity Incentive Plan | Incentive Stock Options
Share Based Compensation Arrangement By Share Based Payment Award
Shares of common stock, authorized for issuance		8,142,857
Shares of common stock available for issuance	5,310,327
Maximum annual percentage increase in shares issuable		5.00%
Additional shares authorized as a percentage of capital stock outstanding	5.00%
Total shares issuable assuming annual increases		16,312,202
2015 Inducement Plan
Share Based Compensation Arrangement By Share Based Payment Award
Shares of common stock, authorized for issuance						1,600,000
Shares of common stock available for issuance					1,970,000
2015 Inducement Plan | Options and restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award
Shares outstanding under the 2015 Inducement Plan		1,000,000
2014 Employee Stock Purchase Plan/ESPP
Share Based Compensation Arrangement By Share Based Payment Award
Additional shares authorized	1,062,065
Additional shares authorized as a percentage of capital stock outstanding	1.00%
2014 Employee Stock Purchase Plan/ESPP | ESPP
Share Based Compensation Arrangement By Share Based Payment Award
Shares of common stock available for issuance		364,762	990,501
Minimum | 2008 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award
Options granted, exercisable term		3 years
Maximum | 2008 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award
Options granted, exercisable term		4 years

Share Based Awards - RSUs and B

Share Based Awards - RSUs and Bonus Plans (Details) - USD ($)	3 Months Ended			12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share withholding				(1,294,360)
Stock-based compensation expense				$ 38,436,000	$ 33,731,000	$ 34,389,000
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, Beginning Balance	12,906,030	10,474,975	7,832,962	12,906,030	10,474,975	7,832,962
Granted				10,224,832	11,017,278	10,724,225
Vested				(7,032,521)	(5,964,422)	(4,889,594)
Cancelled/Forfeited				(3,794,428)	(2,621,801)	(3,192,618)
Unvested, Ending Balance				12,303,913	12,906,030	10,474,975
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Unvested, Beginning Balance	$ 4.72	$ 4.45	$ 6.66	$ 4.72	$ 4.45	$ 6.66
Granted (in dollars per share)				4.63	5.04	3.36
Vested (in dollars per share)				4.88	4.70	4.99
Cancelled/Forfeited (in dollars per share)				4.48	5.01	5.39
Unvested, Ending Balance				$ 4.63	$ 4.72	$ 4.45
Non-Executive Bonus Plan 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted						1,653,371
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Common stock issued (in shares)			1,653,371
Share withholding					(677,547)
Stock-based compensation expense						$ 923,000
Executive Bonus Plan 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Common stock issued (in shares)				0
2016 Bonus Plans
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted					1,688,097
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Common stock issued (in shares)		1,010,550
Stock-based compensation expense					$ 1,700,000	$ 6,600,000
2016 Bonus Plans | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share withholding				677,547
2017 Bonus Plans
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted				1,974,771
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Common stock issued (in shares)	1,220,822
Stock-based compensation expense				$ 1,900,000	$ 7,700,000
2017 Bonus Plans | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share withholding				752,564
2018 Bonus Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Stock-based compensation expense				$ 9,400,000

Share Based Awards - Options ac

Share Based Awards - Options activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Options Activity Rollforward
Number of Shares Available for Issuance, Beginning Balance	1,859,997	4,199,415	6,672,236
Options Outstanding, Number, Beginning Balance	7,738,496	9,835,992	11,498,747
Number of Shares Available for Issuance, Authorized	4,860,197	4,453,425	4,436,933
Number of Shares Available for Issuance, Granted	(400,000)	(300,000)	(1,316,200)
Options Outstanding, Shares Granted	400,000	300,000	1,316,200
Share withheld from net settlement of restricted stock units and options	1,294,360
Options exercised	(2,488,544)	(1,172,409)	(1,040,902)
Number of Shares Available for Issuance, Cancelled	1,153,395	1,225,087	1,938,053
Number of Shares Available for Issuance, Ending Balance	2,337,545	1,859,997	4,199,415	6,672,236
Options Outstanding, Number, Ending Balance	4,496,557	7,738,496	9,835,992	11,498,747
Vested and exercisable- end of the period	3,869,458
Vested and expected to vest - end of the period	4,386,003
Options Activity, Weighted Average Exercise Price Rollforward
Options Outstanding, Weighted-Average Exercise Price, Beginning Balance	$ 4.34	$ 4.39	$ 4.51
Options Outstanding, Weighted Average Exercise Price Granted	4.71	4.20	3.36
Options Outstanding, Weighted Average Exercise Price Exercised	2.62	2.80	2.37
Options Outstanding, Weighted Average Exercise Price Cancelled	5.49	6.24	5.46
Options Outstanding, Weighted-Average Exercise Price, Ending Balance	5.02	$ 4.34	$ 4.39	$ 4.51
Options Outstanding, Weighted-Average Exercise Price, Vested and exercisable	5.12
Options Outstanding, Weighted-Average Exercise Price, Vested and expected to vest	$ 5.04
Options Outstanding, Weighted-Average Remaining Contractual Term (Years)	4 years 11 months 23 days	3 years 11 months 16 days	6 years 2 months 23 days	6 years 10 months 10 days
Options Outstanding, Weighted-Average Remaining Contractual Term Vested and exercisable (Years)	4 years 3 months 29 days
Options Outstanding, Weighted-Average Remaining Contractual Term Vested and expected to vest (Years)	4 years 10 months 17 days
Options Outstanding, Aggregate Intrinsic Value	$ 2,446	$ 4,897	$ 5,734	$ 6,256
Options Outstanding, Vested and exercisable, Aggregate Intrinsic Value	2,257
Options Outstanding, Vested and expected to vest, Aggregate Intrinsic Value	$ 2,420
RSUs, excluding Bonus Plans
Options Activity Rollforward
Number of Shares Available for Issuance, other than Options granted	(8,250,061)	(9,329,181)	(9,070,854)
Restricted stock units
Options Activity Rollforward
Number of Shares Available for Issuance, other than Options granted	(10,224,832)	(11,017,278)	(10,724,225)
Number of Shares Available for Issuance, Restricted stock units cancelled	3,794,428	2,621,801	3,192,618
Non-Executive Bonus Plan 2015
Options Activity Rollforward
Number of Shares Available for Issuance, other than Options granted			(1,653,371)
Share withheld from net settlement of restricted stock units and options		677,547
2017 Bonus Plans
Options Activity Rollforward
Number of Shares Available for Issuance, other than Options granted	(1,974,771)
2017 Bonus Plans | Common Stock
Options Activity Rollforward
Share withheld from net settlement of restricted stock units and options	(752,564)
2016 Bonus Plans
Options Activity Rollforward
Number of Shares Available for Issuance, other than Options granted		(1,688,097)
2016 Bonus Plans | Common Stock
Options Activity Rollforward
Share withheld from net settlement of restricted stock units and options	(677,547)

Share Based Awards - Options by

Share Based Awards - Options by price (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of shares outstanding	4,496,557
Weighted average remaining contractual term, outstanding	4 years 11 months 23 days
Weighted average exercise price, outstanding	$ 5.02
Number of shares exercisable	3,869,458
Weighted average exercise price, exercisable	$ 5.12
Vested options exercised, intrinsic value	$ 5.7	$ 2.3	$ 1.4
Options granted, grant date fair value per share	$ 2.43	$ 1.74	$ 1.42
$0.04 - $3.70
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit	0.04
Exercise price, upper limit	$ 3.70
Number of shares outstanding	1,048,382
Weighted average remaining contractual term, outstanding	3 years 6 months 15 days
Weighted average exercise price, outstanding	$ 2.58
Number of shares exercisable	995,257
Weighted average exercise price, exercisable	$ 2.55
$3.76 - $4.55
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit	3.76
Exercise price, upper limit	$ 4.55
Number of shares outstanding	1,015,058
Weighted average remaining contractual term, outstanding	4 years 11 months 27 days
Weighted average exercise price, outstanding	$ 4.26
Number of shares exercisable	865,056
Weighted average exercise price, exercisable	$ 4.33
$4.66 - $5.77
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit	4.66
Exercise price, upper limit	$ 5.77
Number of shares outstanding	1,285,265
Weighted average remaining contractual term, outstanding	6 years 1 month 10 days
Weighted average exercise price, outstanding	$ 5.44
Number of shares exercisable	885,265
Weighted average exercise price, exercisable	$ 5.77
$6.20 - $9.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit	6.20
Exercise price, upper limit	$ 9
Number of shares outstanding	978,615
Weighted average remaining contractual term, outstanding	5 years 7 days
Weighted average exercise price, outstanding	$ 7.05
Number of shares exercisable	954,643
Weighted average exercise price, exercisable	$ 7.07
$9.18 - $12.05
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit	9.18
Exercise price, upper limit	$ 12.05
Number of shares outstanding	169,237
Weighted average remaining contractual term, outstanding	5 years 1 month 17 days
Weighted average exercise price, outstanding	$ 9.87
Number of shares exercisable	169,237
Weighted average exercise price, exercisable	$ 9.87

Share Based Awards - Compensati

Share Based Awards - Compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	$ 38,436	$ 33,731	$ 34,389
Cost of revenue
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	5,006	3,772	3,043
Research and development
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	15,981	14,520	11,728
Sales and marketing
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	9,464	8,659	10,474
General and administrative
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	$ 7,985	$ 6,780	$ 9,144

Share Based Awards - Options as

Share Based Awards - Options assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award
Vesting period (in months)	4 years
Incentive Stock Options
Share Based Compensation Arrangement By Share Based Payment Award
Risk-free interest rate (as a percent)	2.70%	2.10%	1.40%
Expected volatility (as a percent)	51.00%	40.00%	42.00%
Expected life (in years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days
Vesting period (in months)			48 months
Minimum | ESPP
Share Based Compensation Arrangement By Share Based Payment Award
Risk-free interest rate (as a percent)	1.80%	0.90%	0.50%
Expected volatility (as a percent)	34.00%	34.00%	34.00%
Expected life (in years)	6 months	6 months	6 months
Maximum | ESPP
Share Based Compensation Arrangement By Share Based Payment Award
Risk-free interest rate (as a percent)	2.60%	1.30%	0.70%
Expected volatility (as a percent)	54.00%	54.00%	41.00%
Expected life (in years)	2 years	2 years	2 years

Share Based Awards - Unrecogniz

Share Based Awards - Unrecognized expense (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Share Based Compensation Arrangement By Share Based Payment Award
Total, Unrecognized Stock-based Compensation Expense	$ 44.5
Incentive Stock Options
Share Based Compensation Arrangement By Share Based Payment Award
Total, Unrecognized Stock-based Compensation Expense	$ 1
Unrecognized stock-based compensation expense, Remaining Weighted-Average Recognition Period (in years)	3 years
Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award
Total, Unrecognized Stock-based Compensation Expense	$ 41.9
Unrecognized stock-based compensation expense, Remaining Weighted-Average Recognition Period (in years)	2 years 9 months 18 days
ESPP
Share Based Compensation Arrangement By Share Based Payment Award
Total, Unrecognized Stock-based Compensation Expense	$ 1.6
Unrecognized stock-based compensation expense, Remaining Weighted-Average Recognition Period (in years)	1 year 7 months 6 days

Employee Benefit Plan (Details)

Employee Benefit Plan (Details)	12 Months Ended
	Dec. 31, 2018USD ($)
Employee Benefit Plan
Age restriction of employees	21 years
Employee's contribution to plan 401(k) plan	$ 18,500
Catch up contribution limit for employees age 50 or older	$ 6,000
Minimum age of employees with catch up contribution limit	50 years

Commitments and Contingencies -

Commitments and Contingencies - Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leased Assets [Line Items]
Rent expense	$ 6,800	$ 7,200	$ 6,700
Aggregate future minimum lease payments
2,019	7,144
2,020	5,553
2,021	4,083
2,022	3,074
2,023	1,163
Total	$ 21,017
Minimum | Operating Leases
Operating Leased Assets [Line Items]
Lease agreement expiration year	2,019
Maximum | Operating Leases
Operating Leased Assets [Line Items]
Lease agreement expiration year	2,023

Commitments and Contingencies_2

Commitments and Contingencies - Litigation (Details)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies
Refund term	3 years

Unearned Revenue - Changes in U

Unearned Revenue - Changes in Unearned Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unearned Revenue
Balance, beginning of period	$ 77,022	$ 60,588
Billings, excluding billings for customer arrangements with termination rights	205,816	179,294
Additions to unearned revenue upon expiration of termination rights	17,651	16,273
Recognition of revenue, net of change in unbilled accounts receivable	(194,652)	(179,133)
Revenue billed as of the end of period	105,837	77,022	$ 60,588
Increase (decrease) in total unbilled accounts receivable	(1,460)	625
Revenue Reported in Condensed Consolidated Statement of Operations	$ 193,192	$ 179,758	$ 166,182

Unearned Revenue - Narratives (

Unearned Revenue - Narratives (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Unearned Revenue
Remaining performance obligations	$ 112,700
Customer arrangements with termination rights	$ 19,367	$ 19,546
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Percentage of remaining performance obligation expected to be recognized in period	70.00%
Period of remaining performance obligation expected to be recognized	12 months

Segment and Disaggregated Rev_3

Segment and Disaggregated Revenue Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment-net	$ 7,046	$ 8,812
Revenue	193,192	179,758	$ 166,182
Non-recurring revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	42,044	51,181	53,802
Perpetual license - point-in-time
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	38,390	48,041	50,733
Professional services - point-in-time
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	3,654	3,140	3,069
Recurring revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	151,148	128,577	112,380
On-premise subscriptions - point-in-time
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	20,948	15,994	15,614
On-premise subscriptions - ratable
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	16,275	14,779	14,300
Cloud services
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	50,714	38,728	31,093
Software support on perpetual licenses- ratable
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	63,211	59,076	51,373
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	82,033	83,625	76,217
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 111,159	$ 96,133	$ 89,965
Germany | Total revenue | Geographic
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	16.00%	13.00%	13.00%
Revenue	$ 30,700	$ 22,600	$ 22,000
India | Net Property and Equipment | Geographic
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment-net	$ 2,500	$ 2,700
Concentration risk, percentage	35.00%	30.00%

Net Loss per Share (Details)

Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net loss	$ (43,084)	$ (53,362)	$ (65,494)
Denominator:
Weighted-average shares outstanding	102,527	93,771	85,853
Less: weighted average shares subject to repurchase		(1)	(8)
Weighted-average shares used to compute basic and diluted net loss per share	102,527	93,770	85,845
Basic and diluted net loss per share	$ (0.42)	$ (0.57)	$ (0.76)

Net Loss Per Share - Antidiluti

Net Loss Per Share - Antidilutive (Details) - shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (shares)	18,512,970	22,556,542	22,046,727
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (shares)	4,496,557	7,738,496	9,838,463
Restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (shares)	12,303,913	12,906,030	10,474,975
ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (shares)	478,026	726,643	676,196
Stock-settled bonus shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (shares)	1,234,474	1,185,373	1,057,093
ESPP and stock-settled bonus plans | Adjustment
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (shares)			(1,700,000)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loss before Income Taxes
United States	$ (44,137)	$ (56,852)	$ (67,402)
International	2,400	1,695	1,204
Total	(41,737)	(55,157)	(66,198)
Income tax expense, current:
State	26	36	22
Foreign	1,454	1,196	960
Total current income tax expense	1,480	1,232	982
Foreign	(133)	(90)
Total deferred income tax benefit	(133)	(90)
Total income tax expense	$ 1,347	$ 1,142	$ 982

Income Taxes - Rate reconciliat

Income Taxes - Rate reconciliation (Details)	Dec. 22, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal tax benefit at statutory rate	35.00%	21.00%	34.00%	34.00%
State tax benefit net of federal effect		6.30%	8.80%	4.40%
Foreign taxes		(1.70%)	(0.70%)	(0.40%)
Change in valuation allowance		(29.80%)	42.80%	(33.00%)
Change in federal tax rate			(86.10%)
Credits		3.70%	3.40%	1.80%
Stock-based compensation		(2.30%)	(3.90%)	(8.00%)
Non-deductible expenses and other		(0.40%)	(0.40%)	(0.30%)
Effective tax rate		(3.20%)	(2.10%)	(1.50%)

Income Taxes - Deferred tax ass

Income Taxes - Deferred tax assets (Details) - USD ($) $ in Thousands	Dec. 22, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of Deferred Tax Assets [Abstract]
Accruals and allowances		$ 6,037	$ 7,440
Gains on foreign exchange		(72)	(18)
Net operating loss carryforwards		76,648	67,980
Depreciation and amortization		2,345	3,512
R&D tax credits		17,536	14,560
Stock-based compensation		5,755	6,333
Capitalized commissions		(3,915)
Valuation allowance		(104,201)	(99,716)
Net deferred tax assets		$ 133	$ 91	$ 0
Federal tax benefit at statutory rate	35.00%	21.00%	34.00%	34.00%
Tax cuts and jobs act of 2017 change in tax rate decrease in valuation allowance			$ 44,700

Income Taxes - Loss CF (Details

Income Taxes - Loss CF (Details) $ in Millions	Dec. 31, 2018USD ($)
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 321.3
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 152.2

Income Taxes - Credit CF (Detai

Income Taxes - Credit CF (Details) - R&D $ in Millions	Dec. 31, 2018USD ($)
California Tax Authority
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 14.6
Federal
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 13.3

Income Taxes - Unrealized benef

Income Taxes - Unrealized benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Non-current liability related to uncertain tax positions	$ 0
Reconciliation of the gross unrealized tax benefits
Unrecognized tax benefits, beginning of year	6,839	$ 5,306	$ 4,052
Gross increases—tax positions from prior periods	(31)	34	43
Gross increases - tax positions from current period	1,532	1,499	1,211
Unrecognized tax benefits, end of year	$ 8,340	$ 6,839	$ 5,306
Minimum
Reconciliation of the gross unrealized tax benefits
Foreign statutes of limitation	2 years
Maximum
Reconciliation of the gross unrealized tax benefits
Foreign statutes of limitation	4 years