BlackLine (BL) 10-K 28 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. 22, 2019	Jun. 29, 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
Trading Symbol	BL
Entity Registrant Name	BLACKLINE, INC.
Entity Central Index Key	1,666,134
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		54,956,059
Entity Public Float			$ 1,565

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 46,181	$ 31,104	[1]
Marketable securities	86,396	81,476
Accounts receivable, net of allowances for doubtful accounts of $46 and $695 at December 31, 2018 and 2017, respectively	74,902	61,918
Prepaid expenses and other current assets	14,042	13,956
Total current assets	221,521	188,454
Capitalized software development costs, net	9,023	6,824
Property and equipment, net	13,536	12,769
Intangible assets, net	27,785	40,808
Goodwill	185,138	185,138
Other assets	36,865	26,820
Total assets	493,868	460,813
Current liabilities:
Accounts payable	3,442	7,254
Accrued expenses and other current liabilities	24,705	20,874
Deferred revenue	129,074	104,184
Short-term portion of contingent consideration	2,008	2,008
Total current liabilities	159,229	134,320
Contingent consideration	4,308	3,858
Deferred tax liabilities, net	1,116	1,743
Deferred revenue, noncurrent	277	468
Other long-term liabilities	2,982	3,119
Total liabilities	167,912	143,508
Commitments and contingencies (Note 14)
Redeemable non-controlling interest (Note 4)	4,387
Stockholders' equity:
Preferred stock, $0.01 par value, 50,000,000 shares authorized, no shares issued and outstanding at December 31, 2018 and 2017
Common stock, $0.01 par value, 500,000,000 shares authorized, 54,682,647 issued and outstanding at December 31, 2018 and 52,982,976 issued and outstanding at December 31, 2017	547	530
Additional paid-in capital	451,571	419,628
Accumulated other comprehensive income (loss)	45	(63)
Accumulated deficit	(130,594)	(102,790)
Total stockholders' equity	321,569	317,305
Total liabilities, redeemable non-controlling interest, and stockholders' equity	$ 493,868	$ 460,813
[1]	See Note 3 for a summary of adjustments.

CONSOLIDATED BALANCE SHEETS (PA

CONSOLIDATED BALANCE SHEETS (PARENTHETICAL) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Allowances for doubtful accounts	$ 46	$ 695
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares Issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	54,682,647	52,982,976
Common stock, shares outstanding	54,682,647	52,982,976

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Revenues
Total revenues		$ 227,788	$ 175,603	[1]	$ 128,034	[1]
Cost of revenues
Total cost of revenues		50,874	41,385	[1]	30,211	[1]
Gross profit		176,914	134,218	[1]	97,823	[1]
Operating expenses
Sales and marketing		128,808	103,967	[1]	71,970	[1]
Research and development		30,754	23,874	[1]	21,125	[1]
General and administrative		47,188	36,786	[1]	27,911	[1]
Total operating expenses		206,750	164,627	[1]	121,006	[1]
Loss from operations		(29,836)	(30,409)	[1]	(23,183)	[1]
Other income (expense)
Interest income		2,136	1,069	[1]	4	[1]
Interest expense		(4)	(13)	[1]	(5,936)	[1]
Change in fair value of the common stock warrant liability	[1]		(3,490)		(5,880)
Other income (expense), net		2,132	(2,434)	[1]	(11,812)	[1]
Loss before income taxes		(27,704)	(32,843)	[1]	(34,995)	[1]
Provision for (benefit from) income taxes		162	208	[1]	(8,658)	[1]
Net loss		(27,866)	(33,051)	[1]	(26,337)	[1]
Net loss attributable to non-controlling interest (Note 4)		(62)
Net loss attributable to BlackLine, Inc.		$ (27,804)	$ (33,051)	[1]	$ (26,337)	[1]
Basic net loss per share attributable to BlackLine, Inc.		$ (0.52)	$ (0.63)	[1]	$ (0.62)	[1]
Shares used to calculate basic net loss per share		53,912	52,161	[1]	42,497	[1]
Diluted net loss per share attributable to BlackLine, Inc.		$ (0.52)	$ (0.63)	[1]	$ (0.62)	[1]
Shares used to calculate diluted net loss per share		53,912	52,161	[1]	42,497	[1]
Subscription and Support
Revenues
Total revenues		$ 217,406	$ 167,081	[1]	$ 122,441	[1]
Cost of revenues
Total cost of revenues		41,428	33,530	[1]	25,900	[1]
Professional Services
Revenues
Total revenues		10,382	8,522	[1]	5,593	[1]
Cost of revenues
Total cost of revenues		$ 9,446	$ 7,855	[1]	$ 4,311	[1]
[1]	See Note 3 for a summary of adjustments.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	[1]	Dec. 31, 2016	[1]
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (27,866)	$ (33,051)		$ (26,337)
Other comprehensive income (loss):
Net change in unrealized gain on marketable securities, net of tax of $0 for the years ended December 31, 2018, 2017, and 2016	(26)	(22)		(41)
Foreign currency translation	266
Other comprehensive income (loss)	240	(22)		(41)
Comprehensive loss	(27,626)	(33,073)		(26,378)
Less: Other comprehensive income attributable to redeemable non-controlling interest	70
Comprehensive loss attributable to BlackLine, Inc.	$ (27,696)	$ (33,073)		$ (26,378)
[1]	See Note 3 for a summary of adjustments.

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (PARENTHETICAL) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net change in unrealized gain on marketable securities, tax	$ 0	$ 0	$ 0

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands		Total	Initial Public Offering	Common Stock	Common StockInitial Public Offering	Treasury Stock, at cost	Additional Paid-in Capital	Additional Paid-in CapitalInitial Public Offering	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2015		$ 171,013		$ 407		$ (254)	$ 214,171			$ (43,311)	[1]
Beginning Balance, shares at Dec. 31, 2015				40,673
Stock option exercises		2,860		$ 5			2,855
Stock option exercises, shares				523
Common stock issuance		3,075	$ 151,879	$ 2	$ 99		3,073	$ 151,780
Common Stock Issuance, shares				192	9,890
Retirement of treasury stock						$ 254	(235)			(19)	[1]
Stock-based compensation		6,628					6,628
Other comprehensive income (loss)		(41)							$ (41)
Net loss attributable to BlackLine, Inc.	[1]	(26,337)								(26,337)
Ending Balance at Dec. 31, 2016		309,077		$ 513			378,272		(41)	(69,667)	[1]
Ending Balance, shares at Dec. 31, 2016				51,278
Adjustment for change in accounting policy for stock option forfeitures							72			(72)	[1]
Adjusted Balance		309,077		$ 513			378,344		(41)	(69,739)	[1]
Net exercise of stock warrants		14,870		$ 4			14,866
Net exercise of stock warrants, shares				428
Stock option exercises		10,252		$ 13			10,239
Stock option exercises, shares				1,277
Stock-based compensation		16,179					16,179
Other comprehensive income (loss)		(22)							(22)
Net loss attributable to BlackLine, Inc.	[1]	(33,051)								(33,051)
Ending Balance at Dec. 31, 2017		317,305		$ 530			419,628		(63)	(102,790)	[1]
Ending Balance, shares at Dec. 31, 2017				52,983
Stock option exercises		14,004		$ 17			13,987
Stock option exercises, shares				1,698
Vesting of restricted stock units, shares				2
Acquisition of common stock for tax		(3,356)					(3,356)
Stock-based compensation		21,312					21,312
Other comprehensive income (loss)		108							108
Net loss attributable to BlackLine, Inc.		(27,804)								(27,804)	[1]
Ending Balance at Dec. 31, 2018		$ 321,569		$ 547			$ 451,571		$ 45	$ (130,594)	[1]
Ending Balance, shares at Dec. 31, 2018				54,683
[1]	See Note 3 for a summary of adjustments.

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)		Dec. 31, 2017USD ($)		Dec. 31, 2016USD ($)
Cash flows from operating activities
Net loss attributable to BlackLine, Inc.	$ (27,804)		$ (33,051)	[1]	$ (26,337)	[1]
Net loss attributable to redeemable non-controlling interest (Note 4)	(62)
Net loss	(27,866)		(33,051)	[1]	(26,337)	[1]
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	22,336		19,971	[1]	17,424	[1]
Change in fair value of common stock warrant liability			3,490	[1]	5,880	[1]
Change in fair value of contingent consideration	450		628	[1]	371	[1]
Stock-based compensation	20,895		16,044	[1]	6,526	[1]
(Accretion) amortization of purchase discounts/premiums on marketable securities, net	(928)		37	[1]
Net foreign currency losses	420
Deferred income taxes	(923)		(272)	[1]	(9,467)	[1]
Provision for (benefit from) doubtful accounts receivable	(84)		565	[1]
Accretion of debt discount and accrual of paid-in-kind interest					4,557	[1]
Payment of paid-in-kind interest					(6,418)	[1]
Changes in operating assets and liabilities:
Accounts receivable	(13,207)		(20,189)	[1]	(15,541)	[1]
Prepaid expenses and other current assets	(449)		(2,035)	[1]	(5,214)	[1]
Other assets	(9,475)		(7,176)	[1]	(7,434)	[1]
Accounts payable	(4,008)		(25)	[1]	3,544	[1]
Accrued expenses and other current liabilities	4,417		2,120	[1]	3,864	[1]
Deferred revenue	24,699		26,504	[1]	24,626	[1]
Other long-term liabilities	(137)		(187)	[1]	(1,189)	[1]
Net cash provided by (used in) operating activities	16,140		6,424	[1]	(4,808)	[1]
Cash flows from investing activities
Purchases of marketable securities	(122,530)		(76,610)	[1]	(83,192)	[1]
Proceeds from maturities of marketable securities	111,394		78,205	[1]
Proceeds from sales of marketable securities	7,118
Capitalized software development costs	(5,675)		(4,624)	[1]	(3,270)	[1]
Purchases of property and equipment	(6,284)		(4,002)	[1]	(1,724)	[1]
Acquisition, net of cash acquired					(31,488)	[1]
Net cash used in investing activities	(15,977)		(7,031)	[1]	(119,674)	[1]
Cash flows from financing activities
Investment from redeemable non-controlling interest	4,317
Principal payments on capital lease obligations	(443)		(549)	[1]	(124)	[1]
Proceeds from exercises of stock options	14,004		10,252	[1]	2,860	[1]
Acquisition of common stock for tax withholding obligations	(3,356)
Payments of initial public offering costs			(110)	[1]	(4,372)	[1]
Proceeds from term loan, net of issuance costs					34,300	[1]
Principal payments on term loan and prepayment penalties					(60,706)	[1]
Proceeds from issuance of common stock					3,075	[1]
Proceeds from initial public offering, net of underwriting discounts and commissions					156,362	[1]
Net cash provided by financing activities	14,522		9,593	[1]	131,395	[1]
Effect of foreign currency exchange rate changes on cash, cash equivalents, and restricted cash	266
Net increase in cash, cash equivalents, and restricted cash	14,951		8,986	[1]	6,913	[1]
Cash, cash equivalents, and restricted cash, beginning of period	31,504	[1]	22,518	[1]	15,605	[1]
Cash, cash equivalents, and restricted cash, end of period	46,455		31,504	[1]	22,518	[1]
Reconciliation of cash, cash equivalents, and restricted cash to the consolidated balance sheets
Cash and cash equivalents at end of period	46,181		31,104	[1]	22,118	[1]
Restricted cash included within prepaid expenses and other current assets at end of period			400	[1]
Restricted cash included within other assets at end of period	274				400	[1]
Total cash, cash equivalents, and restricted cash at end of period shown in the consolidated statements of cash flows	46,455		31,504	[1]	22,518	[1]
Supplemental disclosures of cash flow information
Cash paid for interest			8		8,646
Cash paid for income taxes	591		868		176
Non-cash financing and investing activities
Stock-based compensation capitalized for software development	417		135		102
Net exercise of stock warrants			14,870
Capitalized software development costs included in accounts payable and accrued expenses and other current liabilities at end of period	359		331		153
Purchases of property and equipment included in accounts payable and accrued expenses and other current liabilities at end of period	$ 168		293		63
Leasehold improvements paid directly by landlord			$ 1,176
Deferred offering costs included in accounts payable and accrued expenses and other current liabilities at end of period					$ 110
[1]	See Note 3 for a summary of adjustments.

The Company

The Company	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
The Company	Note 1—The Company BlackLine, Inc. and its subsidiaries (the “Company” or “BlackLine”) provide financial accounting close solutions delivered primarily as Software as a Service (“SaaS”). The Company’s solutions enable its customers to address various aspects of their financial close process including account reconciliations, variance analysis of account balances, journal entry capabilities, and certain types of data matching capabilities. The Company is a holding company and conducts its operations through its wholly-owned subsidiary, BlackLine Systems, Inc. (“BlackLine Systems”). BlackLine Systems funded its business with investments from its founder and cash flows from operations until September 3, 2013, when the Company acquired BlackLine Systems, and Silver Lake Sumeru and Iconiq acquired a controlling interest in the Company, which is referred to as the “2013 Acquisition.” On August 31, 2016 the Company acquired Runbook Company B.V. (“Runbook”), which is referred to as the “Runbook Acquisition.” The Company is headquartered in Los Angeles, California and has offices in New York, Vancouver, London, Paris, Frankfurt, Sydney, Melbourne, Kuala Lumpur, Netherlands, Poland, Romania, Singapore, and South Africa.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	Note 2—Significant Accounting Policies Principles of consolidation and basis of presentation The Company’s consolidated financial statements are presented in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and include the operating results of its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. Reverse stock split On October 12, 2016, the Company effected a 1-for-5 reverse stock split of its outstanding common stock. All share and per share amounts for all periods presented in these consolidated financial statements and notes thereto have been adjusted retrospectively, where applicable, to reflect this reverse stock split. Redeemable non-controlling interest The Company's Japanese subsidiary (“BlackLine K.K.”) is not wholly owned. The agreements with the minority investors of BlackLine K.K. contain redemption features whereby the interest held by the minority investors are redeemable either (i) at the option of the minority investors or (ii) at the option of the Company, both beginning on the seventh anniversary of the initial capital contribution. If the interest of the minority investors were to be redeemed under these agreements, the Company would be required to redeem the interest based on a prescribed formula derived from the relative revenue of BlackLine K.K. and the Company. The balance of the redeemable non-controlling interest is reported at the greater of the initial carrying amount adjusted for the redeemable non-controlling interest's share of earnings or losses and other comprehensive income or loss, or its estimated redemption value. The resulting changes in the estimated redemption amount (increases or decreases) are recorded with corresponding adjustments against retained earnings or, in the absence of retained earnings, additional paid-in-capital. These interests are presented on the consolidated balance sheets outside of equity under the caption "Redeemable non-controlling interest." Use of estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the dates of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its estimates, primarily those related to determining the stand alone selling price (“SSP”) for separate deliverables in the Company’s subscription revenue arrangements, allowance for doubtful accounts, fair value of assets and liabilities assumed in a business combination, recoverability of goodwill and long-lived assets, useful lives associated with long-lived assets, income taxes, contingencies, fair value of contingent consideration, and the valuation and assumptions underlying stock-based compensation and common stock warrants. These estimates are based on historical data and experience, as well as various other factors that management believes to be reasonable under the circumstances. Actual results could differ from those estimates. Reclassifications Certain prior-period amounts have been reclassified to conform to the current-period presentation. These reclassifications had no impact on the previously-reported consolidated results of operations or stockholders' equity. Segments Management has determined that the Company has one operating segment. The Company’s chief executive officer, who is the Company’s chief operating decision maker, reviews financial information on a consolidated and aggregate basis, together with certain operating metrics principally to make decisions about how to allocate resources and to measure the Company’s performance. Cash and cash equivalents The Company considers all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents. Cash includes cash held in checking and savings accounts. Cash equivalents are comprised of investments in money market mutual funds. The carrying value of cash and cash equivalents approximates fair value. Restricted cash Included in other assets at December 31, 2018 and in prepaid expenses and other current assets at 2017 was cash totaling $0.3 million and $0.4 million, respectively, which was required to be restricted as to use by the Company’s office leaseholder to collateralize a standby letter of credit. Investments in Marketable Securities The Company’s marketable securities consist of commercial paper, corporate bonds, U.S. treasury securities, and asset-backed securities. The Company classifies its marketable securities as available-for-sale at the time of purchase, and the Company reevaluates such classification as of each balance sheet date. All marketable securities are recorded at their estimated fair value, with any unrealized gains and losses reported as a component of stockholders’ equity until realized or until a determination is made that an other-than-temporary decline in market value has occurred. Impairments are considered to be other than temporary if they are related to deterioration in credit risk or if it is likely the Company will sell the securities before the recovery of their cost basis. Realized gains and losses and declines in value deemed to be other than temporary are determined based on the specific identification method and are reported in other income (expense), net in the consolidated statements of operations. The Company classifies its investments in marketable securities in current assets as the investments are available for use, if needed, in current operations. Accounts receivable and allowance for doubtful accounts Accounts receivable are recorded at the invoiced amount, do not require collateral and do not bear interest. The Company estimates its allowance for doubtful accounts by evaluating specific accounts where information indicates the Company’s customers may have an inability to meet financial obligations, such as bankruptcy and significantly aged receivables outstanding. Concentration of credit risk and significant customers Financial instruments that potentially subject the Company to a significant concentration of credit risk consist of cash and cash equivalents, investments in marketable securities and accounts receivable. The Company maintains the majority of its cash balances with one major commercial bank in non-interest bearing accounts, which exceeds the Federal Deposit Insurance Corporation, or FDIC, federally insured limits. The Company invests its excess cash in money market mutual funds, commercial paper, corporate bonds, U.S. treasury securities, and asset-backed securities. To date, the Company has not experienced any impairment losses on its investments. For the years ended December 31, 2018, 2017, and 2016, no single customer comprised 10% or more of the Company’s total revenues. No single customer had an accounts receivable balance of 10% or greater of total accounts receivable at December 31, 2018 or 2017. Property and equipment Property and equipment is stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which is generally three to five years for machinery and equipment and purchased software and five years for furniture and fixtures. Leasehold improvements, which are included in furniture and fixtures, are amortized using the straight-line method over the shorter of the lease term or seven years. Expenditures for repairs and maintenance are expensed as incurred, while renewals and betterments are capitalized. Depreciation expense is charged to operations on a straight-line basis over the estimated useful lives of the assets. Assets acquired under capital leases are capitalized at the present value of the related lease payments and are amortized over the shorter of the lease term or useful life of the asset. Capitalized internal-use software costs The Company accounts for the costs of computer software obtained or developed for internal use in accordance with ASC 350, Intangibles—Goodwill and Other During the years ended December 31, 2018, 2017, and 2016, the Company amortized $3.9 million, $2.7 million, and $1.8 million, respectively, of internal-use software development costs to subscription and support cost of revenue. At December 31, 2018 and 2017, the accumulated amortization of capitalized internal-use software development costs was $9.5 million and $5.6 million, respectively. Business combinations The results of businesses acquired in a business combination are included in the Company’s consolidated financial statements from the date of the acquisition. Purchase accounting results in assets and liabilities of an acquired business generally being recorded at their estimated fair values on the acquisition date. Any excess consideration over the fair value of assets acquired and liabilities assumed is recognized as goodwill. Transaction costs associated with business combinations are expensed as incurred and are included in general and administrative expenses in the consolidated statements of operations. The Company performs valuations of assets acquired and liabilities assumed and allocates the purchase price to its respective assets and liabilities. Determining the fair value of assets acquired and liabilities assumed requires management to use significant judgment and estimates, including the selection of valuation methodologies, estimates of future revenue, costs and cash flows, discount rates, and selection of comparable companies. The Company engages the assistance of valuation specialists in concluding on fair value measurements in connection with determining fair values of assets acquired and liabilities assumed in a business combination. Intangible assets Intangible assets primarily consist of acquired developed technology, customer relationships, trade names and non-compete agreements, which were acquired as part of the 2013 Acquisition and the Runbook Acquisition. The Company determines the appropriate useful life of its intangible assets by performing an analysis of expected cash flows of the acquired assets. Intangible assets are amortized on a straight-line basis over their estimated useful lives, ranging from one to ten years. Impairment of long-lived assets Management evaluates the recoverability of the Company’s property and equipment, finite-lived intangible assets and capitalized internal-software costs when events or changes in circumstances indicate a potential impairment exists. Events and changes in circumstances considered by the Company in determining whether the carrying value of long-lived assets may not be recoverable include, but are not limited to, significant changes in performance relative to expected operating results, significant changes in the use of the assets, significant negative industry or economic trends, and changes in the Company’s business strategy. Impairment testing is performed at an asset level that represents the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities (an “asset group”). In determining if impairment exists, the Company estimates the undiscounted cash flows to be generated from the use and ultimate disposition of the asset group. If impairment is indicated based on a comparison of the assets’ carrying values and the undiscounted cash flows, the impairment loss is measured as the amount by which the carrying amount of the assets exceeds the fair value of the assets. The Company determined that there were no events or changes in circumstances that potentially indicated that the Company’s long-lived assets were impaired during the years ended December 31, 2018, 2017, and 2016. Goodwill Goodwill represents the excess of the purchase price over the fair value of net assets acquired in a business combination. The Company tests goodwill for impairment in accordance with the provisions of Accounting Standards Codification (“ASC”) 350, Intangibles—Goodwill and Other ASC 350 provides that an entity has the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events or circumstances, an entity determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then additional impairment testing is not required. However, if an entity concludes otherwise, then it is required to perform the first of a two-step impairment test. The first step involves comparing the estimated fair value of a reporting unit with its book value, including goodwill. If the estimated fair value exceeds book value, goodwill is considered not to be impaired and no additional steps are necessary. If, however, the fair value of the reporting unit is less than book value, then, under the second step, the carrying amount of the goodwill is compared with its implied fair value. The estimate of implied fair value of goodwill may require valuations of certain internally-generated and unrecognized intangible assets. If the carrying amount of goodwill exceeds the implied fair value of that goodwill, an impairment loss is recognized in an amount equal to the excess. The Company has one reporting unit and it tests its goodwill for impairment annually, during the fourth quarter of the calendar year. At December 31, 2018 and 2017, the Company used the quantitative approach to perform its annual goodwill impairment test. The Company’s fair value significantly exceeded the carrying value of its net assets and, accordingly, goodwill was not impaired. Deferred rent Rent expense is recorded on a straight-line basis over the term of the lease. The difference between rent expense and the cash paid under the lease agreement is recorded as deferred rent. Lease incentives, including tenant improvement allowances, are also recorded as deferred rent and amortized on a straight-line basis over the lease term. Debt issued with warrants to purchase common stock The Company issued warrants to purchase common stock in connection with its former credit facility. These warrants were a liability classified under ASC 815-40, Contracts in Entity’s Own Equity In May 2017, warrants to purchase 499,999 shares of common stock were net exercised resulting in the issuance of 428,033 shares of common stock and, accordingly, there will be no further changes in the fair value The initial carrying value of the debt was reduced by the fair value of the warrants. The resulting debt discount was amortized to interest expense over the life of the debt on a straight-line basis, which approximated the effective interest method. In November 2016, the Company repaid all outstanding debt and expensed the then-remaining unamortized debt discount to interest expense in the consolidated statements of operations. Fair value of financial instruments ASC 820, Fair Value Measurements Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. ASC 820 describes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value, which are the following: Level 1: Quoted prices in active markets for identical or similar assets and liabilities. Level 2: Quoted prices for identical or similar assets and liabilities in markets that are not active or observable inputs other than quoted prices in active markets for identical or similar assets or liabilities. Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. At December 31, 2018 and 2017, the carrying values of cash equivalents, accounts receivable, accounts payable, and accrued expenses, approximate fair values due to the short-term nature of such instruments. Contingent consideration relating to the 2013 Acquisition (see Note 13) is recorded as a liability and is measured at fair value each period, based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The valuation of contingent consideration uses assumptions management believes would be made by a market participant. Management assesses these estimates on an ongoing basis as additional data impacting the assumptions becomes available. Changes in the fair value of contingent consideration related to updated assumptions and estimates are recognized within general and administrative expenses in the consolidated statements of operations. The Company determined the fair value of the contingent consideration by discounting estimated future taxable income. The significant inputs used in the fair value measurement of contingent consideration are the timing and amount of taxable income in any given period and determining an appropriate discount rate, which considers the risk associated with the forecasted taxable income. Significant changes in the estimated future taxable income and the periods in which they are generated would significantly impact the fair value of the contingent consideration liability. Warrants to purchase common stock were liability classified and were measured at fair value each period. The fair value was determined using a binomial lattice valuation model. The fair value included significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy. The valuation of common stock warrants used assumptions management believed would be made by a market participant. Management assessed these estimates on an ongoing basis as additional data impacting the assumptions became available. Changes in the fair value of the common stock warrant liability related to updated assumptions and estimates were recognized within other income (expense), net in the consolidated statements of operations. The significant inputs used in the fair value measurement of the common stock warrants were the estimated fair value of the Company’s common stock and, to a lesser extent, the expected stock volatility, the probability of a change in control and future stock issuances, which impacted the term of the warrants. Certain assets, including goodwill and long-lived assets, are also subject to measurement at fair value on a non-recurring basis if they are deemed to be impaired a result of an impairment review. For the years ended December 31, 2018, 2017, and 2016, no impairments were identified on those assets required to be measured at fair value on a non-recurring basis. Revenue recognition Revenue is recognized upon transfer of control of promised products or services to customers in an amount that reflects the consideration the Company expects to receive in exchange for those products or services. The Company enters into contracts that can include various combinations of subscription and support services and professional services, which are generally capable of being distinct and accounted for as separate performance obligations. The Company’s agreements do not contain any refund provisions other than in the event of the Company’s non-performance or breach. The Company determines revenue recognition through the following steps: • Identification of the contract, or contracts, with a customer • Identification of the performance obligations in the contract • Determination of the transaction price • Allocation of the transaction price to the performance obligations in the contract • Recognition of revenue when, or as, the Company satisfies a performance obligation Subscription and support revenue – Customers pay subscription and support fees for access to the Company’s SaaS platform generally for a one-year period. In more limited cases, customers may pay for up to three years in advance. Fees are based on a number of factors, including the solutions subscribed for by the customer and the number of users having access to the solutions. Subscription services, which allow customers to use hosted software over the contract period without taking possession of the software, are considered distinct performance obligations and are recognized ratably as the Company transfers control evenly over the contract period. Subscription and support revenue also includes software and related maintenance and support fees on legacy BlackLine solutions and Runbook Company B.V. (“Runbook”) software. Software licenses for legacy BlackLine solutions and Runbook software provide the customer with a right to use the software as it exists when made available to the customer. Customers may have purchased perpetual licenses or term based licenses, which provide customers with the same functionality and differ mainly in the duration over which the customer benefits from the software. Software licenses are bundled with software maintenance and support, and the transaction price of the contract is allocated between the software licenses and the software maintenance and support. Maintenance and support convey rights to new software and upgrades released over the contract period and provide support, tools, and training to help customers deploy and use products more efficiently. Software licenses are considered distinct performance obligations and revenue is recognized at a point in time when control of the license has transferred and the license period commences. Maintenance and support are distinct performance obligations that are satisfied over time, and revenue is recognized ratably over the contract period as customers simultaneously consume and receive benefits. Professional services revenue – Professional services consist of implementation and consulting services to assist the Company’s customers as they deploy its solutions. These services are considered distinct performance obligations. Professional services do not result in significant customization of the subscription service. The Company applies the practical expedient to recognize professional services revenue when it has the right to invoice based on time and materials incurred. Significant judgments – The Company’s contracts with customers often include promises to transfer multiple products and services. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment. Judgment is also required to determine the stand alone selling price (“SSP”) for each distinct performance obligation. The Company typically has more than one SSP for its SaaS solutions and professional services. Additionally, management has determined that there are no third-party offerings reasonably comparable to the Company’s solutions. Therefore, the Company determines the SSPs of subscriptions to the SaaS solutions and professional services based on numerous factors including the Company’s overall pricing objectives, geography, customer size and number of users, and discounting practices . The Company uses historical maintenance renewal fees to estimate SSP for maintenance and support fees bundled with software licenses. The Company uses the residual method to estimate SSP of software licenses, because license pricing is highly variable and not sold separately from maintenance and support. Contract balances – Timing of revenue recognition may differ from the timing of invoicing to customers. The Company records an unbilled receivable when revenue is recognized prior to invoicing, and deferred revenue when revenue is recognized subsequent to invoicing. The Company generally invoices customers annually at the beginning of each annual contract period. The Company records a receivable related to revenue recognized for multi-year agreements as it has an unconditional right to invoice and receive payment in the future related to those services. Deferred revenue is comprised mainly of billings related to the Company’s SaaS solutions in advance of revenue being recognized. Deferred revenue also includes payments for: professional services to be performed in the future; legacy BlackLine maintenance and support; Runbook maintenance, support, license, and implementation; and other offerings for which the Company has been paid in advance and earns the revenue when the Company transfers control of the product or service. Changes in deferred revenue for the years ended December 31, 2018, 2017, and 2016 were primarily due to additional billings in the periods, partially offset by revenue recognized of $104.2 million, $78.2 million, and $52.9 million, respectively, that was previously included in the deferred revenue balance at December 31, 2017, 2016, and 2015, respectively. The transaction price is generally determined by the stated fixed fees in the contract, excluding any related sales taxes. Transaction price allocated to remaining performance obligations represents contracted revenue that has not yet been recognized (“contracted not recognized”), which includes deferred revenue and amounts that will be invoiced and recognized as revenue in future periods. Contracted not recognized revenue was $285.0 million at December 31, 2018, of which the Company expects to recognize approximately 62% over the next 12 months and the remainder thereafter. Fees are generally due and payable upon receipt of invoice or within 30 days. None of the Company’s contracts includes a significant financing component. Assets recognized from the costs to obtain a contract with a customer – The Company recognizes an asset for the incremental and recoverable costs of obtaining a contract with a customer if the Company expects the benefit of those costs to be one year or longer. The Company has determined that certain sales incentive programs to the Company’s employees ("deferred customer contract acquisition costs") and its partners ("partner referral fees") meet the requirements to be capitalized. Deferred customer acquisition costs related to new revenue contracts and upsells are deferred and then amortized straight line over the expected period of benefit, which the Company has determined to be five years, based upon both the product turnover rate and estimated customer life. Partner referral fees are deferred and then amortized on a straight-line basis over the related contractual period, as the fees for renewals are commensurate with fees incurred for the initial contract. Deferred customer acquisition costs and partner referral fees are included within other assets and prepaid expenses and other current assets, respectively, on the consolidated balance sheets. There were no impairment losses in relation to the costs capitalized for the periods presented. Amortization expense related to the asset recognized from the costs to obtain a contract with a customer is included in sales and marketing expenses in the consolidated statements of operations and was $23.6 million, $15.6 million, and $9.8 million for the years ended December 31, 2018, 2017, and 2016, respectively. Cost of revenues Cost of revenues primarily consists of costs related to hosting the Company’s cloud-based application suite, salaries and benefits of operations and support personnel, including stock-based compensation, and amortization of capitalized internal-use software costs. The Company allocates a portion of overhead, such as rent, information technology costs and depreciation and amortization to cost of revenues. Costs associated with providing professional services are expensed as incurred when the services are performed. In addition, subscription and support cost of revenues includes amortization of acquired developed technology. Sales and marketing Sales and marketing expenses consist primarily of compensation and employee benefits, including stock-based compensation, of sales and marketing personnel and related sales support teams, sales and partner commissions, marketing events, advertising costs, travel, trade shows, other marketing materials, and allocated overhead. Sales and marketing expenses also include amortization of customer relationship intangible assets. Advertising costs are expensed as incurred and totaled $8.0 million, $7.7 million, and $4.2 million for the years ended December 31, 2018, 2017, and 2016, respectively. Research and development Research and development expenses are comprised primarily of salaries, benefits and stock-based compensation associated with the Company’s engineering, product and quality assurance personnel. Research and development expenses also include third-party contractors and supplies and allocated overhead. Other than software development costs that qualify for capitalization, as discussed above, research and development costs are expensed as incurred. General and administrative General and administrative expenses consist primarily of personnel costs associated with the Company’s executive, finance, legal, human resources, compliance, and other administrative personnel, as well as accounting and legal professional services fees, other corporate-related expenses and allocated overhead. General and administrative expenses also include amortization of covenant not to compete and tradename intangible assets, the change in value of the contingent consideration, acquisition-related costs of business combinations, costs associated with the secondary offering, and costs associated with the shelf offerings. Stock-based compensation The Company accounts for stock-based compensation awards granted to employees and directors based on the awards’ estimated grant date fair value. The Company estimates the fair value of its stock options using the Black-Scholes option-pricing model. For awards that vest solely based on continued service (“service-only vesting conditions”), the resulting fair value is recognized on a straight-line basis over the period during which an employee is required to provide service in exchange for the award, usually the vesting period, which is generally four years. The Company recognizes the fair value of stock options which contain performance conditions based upon the probability of the performance conditions being met, using the graded vesting method. On January 1, 2017, the Company changed its accounting policy to account for forfeitures when they occur rather than estimate a forfeiture rate. Determining the grant date fair value of options using the Black-Scholes option-pricing model requires management to make assumptions and judgments. These estimates involve inherent uncertainties and, if different assumptions had been used, stock-based compensation expense could have been materially different from the amounts recorded. The assumptions and estimates are as follows: Value per share of the Company’s common stock . Prior to the Company’s initial public offering in October 2016, because there was no public market for the Company’s common stock, the Company’s management, with the assistance of a third-party valuation specialist, determined the fair value of the Company’s common stock at the time of the grant of stock options by considering a number of objective and subjective factors, including the Company’s actual operating and financial performance, market conditions and performance of comparable publicly-traded companies, developments and milestones in the Company, the likelihood of achieving a liquidity event and transactions involving the Company’s common stock, among other factors. The fair value of the underlying common stock was determined by the Company’s board of directors through the date of the initial public offering. The fair value of the Company’s common stock was determined in accordance with applicable elements of the practice aid issued by the American Institute of Certified Public Accountants, Valuation of Privately Held Company Equity Securities Issued as Compensation . For awards granted subsequent to the Company’s initial public offering, the fair value of common stock is based on the closing price of the Company’s common stock, as reported on the NASDAQ, on the date of grant. Expected volatility. The Company determines the expected volatility based on historical average volatilities of similar publicly-traded companies corresponding to the expected term of the awards. The Company determines

Revenues

Revenues	12 Months Ended
	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Revenues	Note 3—Revenues The Company adopted the new revenue standard effective January 1, 2018 using the full retrospective method to restate each prior reporting period presented. Impacts to previously reported results The following table presents the effect of the adoption of ASC 606 on the Company’s consolidated balance sheet: December 31, 2017 As Reported Adjustments As Adjusted (in thousands) Accounts receivable, net $ 61,589 $ 329 $ 61,918 Prepaid expenses and other current assets $ 19,785 $ (5,829 ) $ 13,956 Total current assets $ 193,954 $ (5,500 ) $ 188,454 Other assets $ 1,391 $ 25,429 $ 26,820 Total assets $ 440,884 $ 19,929 $ 460,813 Deferred revenue $ 106,903 $ (2,719 ) $ 104,184 Total current liabilities $ 137,039 $ (2,719 ) $ 134,320 Deferred tax liabilities, net $ 1,328 $ 415 $ 1,743 Deferred revenue, noncurrent $ 912 $ (444 ) $ 468 Total liabilities $ 146,256 $ (2,748 ) $ 143,508 Accumulated deficit $ (125,467 ) $ 22,677 $ (102,790 ) Total stockholders' equity $ 294,628 $ 22,677 $ 317,305 Total liabilities and stockholders' equity $ 440,884 $ 19,929 $ 460,813 The following table presents the effect of the adoption of ASC 606 on the Company’s consolidated statement of operations: Year Ended December 31, 2017 Year Ended December 31, 2016 As Reported Adjustments As Adjusted As Reported Adjustments As Adjusted (in thousands, except per share data) (in thousands, except per share data) Revenues Subscription and support $ 168,542 $ (1,461 ) $ 167,081 $ 117,524 $ 4,917 $ 122,441 Professional services 8,489 33 8,522 5,599 (6 ) 5,593 Total revenues $ 177,031 $ (1,428 ) $ 175,603 $ 123,123 $ 4,911 $ 128,034 Cost of revenues Subscription and support $ 33,631 $ (101 ) $ 33,530 $ 25,900 $ — $ 25,900 Total cost of revenues $ 41,486 $ (101 ) $ 41,385 $ 30,211 $ — $ 30,211 Gross profit $ 135,545 $ (1,327 ) $ 134,218 $ 92,912 $ 4,911 $ 97,823 Operating expenses Sales and marketing $ 109,775 $ (5,808 ) $ 103,967 $ 77,810 $ (5,840 ) $ 71,970 General and administrative $ 36,956 $ (170 ) $ 36,786 $ 27,911 $ — $ 27,911 Total operating expenses $ 170,605 $ (5,978 ) $ 164,627 $ 126,846 $ (5,840 ) $ 121,006 Loss from operations $ (35,060 ) $ 4,651 $ (30,409 ) $ (33,934 ) $ 10,751 $ (23,183 ) Loss before income taxes $ (37,494 ) $ 4,651 $ (32,843 ) $ (45,746 ) $ 10,751 $ (34,995 ) Provision for (benefit from) income taxes $ 567 $ (359 ) $ 208 $ (6,587 ) $ (2,071 ) $ (8,658 ) Net loss $ (38,061 ) $ 5,010 $ (33,051 ) $ (39,159 ) $ 12,822 $ (26,337 ) Basic net loss per share $ (0.73 ) $ 0.10 $ (0.63 ) $ (0.92 ) $ 0.30 $ (0.62 ) Diluted net loss per share $ (0.73 ) $ 0.10 $ (0.63 ) $ (0.92 ) $ 0.30 $ (0.62 ) The following table presents the effect of the adoption of ASC 606 on the Company’s consolidated statement of cash flows: Year Ended December 31, 2017 Year Ended December 31, 2016 As Reported Adjustments As Adjusted As Reported Adjustments As Adjusted (in thousands) (in thousands) Net loss attributable to BlackLine, Inc. $ (38,061 ) $ 5,010 $ (33,051 ) $ (39,159 ) $ 12,822 $ (26,337 ) Deferred income taxes $ 66 $ (338 ) $ (272 ) $ (7,432 ) $ (2,035 ) $ (9,467 ) Accounts receivable $ (19,860 ) $ (329 ) $ (20,189 ) $ (15,541 ) $ — $ (15,541 ) Prepaid expenses and other current assets $ (3,104 ) $ 1,069 $ (2,035 ) $ (6,516 ) $ 1,302 $ (5,214 ) Other assets $ (342 ) $ (6,834 ) $ (7,176 ) $ (201 ) $ (7,233 ) $ (7,434 ) Deferred revenue $ 25,082 $ 1,422 $ 26,504 $ 29,482 $ (4,856 ) $ 24,626 There was no effect to net cash provided by (used in) operating, investing, or financing activities. Disaggregation of Revenues The Company disaggregates its revenue from contracts with customers by geographic location, as it believes it best depicts how the nature, amount, timing, and uncertainty of its revenues and cash flows are affected by economic factors. The following table sets forth the Company’s revenues by geographic region (in thousands): Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted United States $ 180,152 $ 141,499 $ 106,421 International 47,636 34,104 21,613 $ 227,788 $ 175,603 $ 128,034 No countries outside the United States represented 10% or more of total revenues.

Redeemable Non-Controlling Inte

Redeemable Non-Controlling Interest	12 Months Ended
	Dec. 31, 2018
Equity Method Investments And Joint Ventures [Abstract]
Redeemable Non-Controlling Interest	Note 4—Redeemable Non-Controlling Interest In September 2018, the Company entered into an agreement with Japanese Cloud Computing and M30 LLC (the “Investors”) to engage in the investment, organization, management, and operation of a Japanese subsidiary (“BlackLine K.K.”) of the Company that is focused on the sale of the Company's products in Japan. In October 2018, the Company initially contributed approximately $4.5 million in cash in exchange for 51% of the outstanding common stock of BlackLine K.K. As the Company controls a majority stake in BlackLine K.K., the entity will be consolidated. All of the common stock held by the Investors may be callable by the Company or puttable by the Investors upon certain contingent events. Should the call or put option be exercised, the redemption value would be determined based on a prescribed formula derived from the discrete revenues of BlackLine K.K. and the Company and may be settled, at the Company’s discretion, with Company stock or cash. As a result of the put right available to the redeemable non-controlling interest holders in the future, the redeemable non-controlling interests in BlackLine K.K. are classified outside of permanent equity in the Company’s consolidated balance sheet at December 31, 2018, and the balance is reported at the greater of the initial carrying amount adjusted for the redeemable non-controlling interests’ share of earnings, or its estimated redemption value. The resulting changes in the estimated redemption amount are recorded within retained earnings or, in the absence of retained earnings, additional paid-in-capital. The estimated redemption value of the call/put option embedded in the redeemable non-controlling interests was $0 at December 31, 2018. The following table summarizes the activity in the redeemable non-controlling interests for the period indicated below: Balance at December 31, 2017 $ — Investment by redeemable non-controlling interest 4,317 Net loss attributable to redeemable non-controlling interest (62 ) Foreign currency translation 132 Balance at December 31, 2018 $ 4,387

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	Note 5—Balance Sheet Components Investments in Marketable Securities Investments in marketable securities presented within current assets on the consolidated balance sheet consisted of the following: December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Marketable securities U.S. treasury securities $ 25,856 $ — $ (29 ) $ 25,827 Corporate bonds 32,030 — (60 ) 31,970 Commercial paper 28,599 — — 28,599 $ 86,485 $ — $ (89 ) $ 86,396 December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Marketable securities U.S. treasury securities $ 21,454 $ — $ (19 ) $ 21,435 Corporate bonds 32,437 — (43 ) 32,394 Commercial paper 25,048 — — 25,048 Asset-backed securities 2,600 — (1 ) 2,599 $ 81,539 $ — $ (63 ) $ 81,476 During the years ended December 31, 2018, 2017, and 2016 there were no material realized gains or losses related to sales of marketable securities recognized in the Company’s consolidated statements of operations. Net gains and losses related to maturities of marketable securities that were reclassified from accumulated other comprehensive loss to earnings in the consolidated statements of operations were $1.0 million for the year ended December 31, 2018. Net gains and losses related to maturities of marketable securities that were reclassified from accumulated other comprehensive loss to earnings in the consolidated statements of operations were not material for the years ended December 31, 2017 and 2016. The Company’s marketable securities have a contractual maturity of less than 1 year. The amortized cost and fair values of marketable securities, by remaining contractual maturity, were as follows: December 31, 2018 Amortized Cost Fair Value (in thousands) Maturing within 1 year $ 86,485 $ 86,396 $ 86,485 $ 86,396 Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following (in thousands): December 31, December 31, 2018 2017 Partner referral fees $ 5,219 $ 7,945 Restricted cash — 400 Other prepaid expenses and other current assets 8,823 5,611 $ 14,042 $ 13,956 Other Assets Other assets consisted of the following (in thousands): December 31, December 31, 2018 2017 Deferred customer contract acquisition costs $ 34,172 $ 25,338 Restricted cash 274 — Other assets 2,419 1,482 $ 36,865 $ 26,820 Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, December 31, 2018 2017 Accrued salaries and employee benefits $ 17,054 $ 11,945 Accrued income and other taxes payable 4,547 1,798 Short-term tenant improvement allowance 475 475 Partner referral fees — 2,991 Short-term portion of capital lease — 443 Other accrued expenses and current liabilities 2,629 3,222 $ 24,705 $ 20,874

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 6 – Fair Value Measurements The following table summarizes the Company’s financial assets and liabilities measured at fair value on a recurring basis by level, within the fair value hierarchy. Financial assets and financial liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement (in thousands): December 31, 2018 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 32,021 $ — $ — $ 32,021 Marketable securities U.S. treasury securities 25,827 — — 25,827 Corporate bonds — 31,970 — 31,970 Commercial paper — 28,599 — 28,599 Total assets $ 57,848 $ 60,569 $ — $ 118,417 Liabilities Contingent consideration $ — $ — $ 6,316 $ 6,316 Total liabilities $ — $ — $ 6,316 $ 6,316 December 31, 2017 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 21,247 $ — $ — $ 21,247 Marketable securities U.S. treasury securities 21,435 — — 21,435 Corporate bonds — 32,394 — 32,394 Commercial paper — 25,048 — 25,048 Asset-backed securities — 2,599 — 2,599 Total assets $ 42,682 $ 60,041 $ — $ 102,723 Liabilities Contingent consideration $ — $ — $ 5,866 $ 5,866 Total liabilities $ — $ — $ 5,866 $ 5,866 The following table summarizes the changes in the common stock warrant liability (in thousands): Year Ended December 31, 2017 2016 Beginning fair value $ 11,380 $ 5,500 Change in fair value 3,490 5,880 Exercise of stock warrants (14,870 ) — Ending fair value $ — $ 11,380 In May 2017, warrants to purchase 499,999 shares of common stock were net exercised resulting in the issuance of 428,033 shares of common stock and, accordingly, there will be no further changes in the fair value. The following table summarizes the changes in the contingent consideration liability (in thousands): Year Ended December 31, 2018 2017 2016 Beginning fair value $ 5,866 $ 5,238 $ 4,867 Change in fair value 450 628 371 Ending fair value $ 6,316 $ 5,866 $ 5,238

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Property and Equipment	Note 7—Property and Equipment Property and equipment consisted of the following (in thousands): December 31, 2018 2017 Computers and equipment $ 6,598 $ 4,919 Purchased software 7,356 4,934 Furniture and fixtures 2,571 2,204 Leasehold improvements 10,077 9,075 Construction in progress — 180 26,602 21,312 Less: accumulated depreciation and amortization (13,066 ) (8,543 ) $ 13,536 $ 12,769 Depreciation and amortization expense related to property and equipment was $5.4 million, $4.0 million, and $3.1 million for the years ended December 31, 2018, 2017, and 2016, respectively. Software and construction in progress included assets held under capital lease of $1.6 million at December 31, 2018 and 2017, reduced by related accumulated amortization thereon of $1.5 million and $1.0 million, respectively.

Business Combination

Business Combination	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Business Combination	Note 8 – Business Combination On August 31, 2016, the Company acquired all the issued and outstanding capital stock of Runbook, a Netherlands-based provider of financial close automation software and integration solutions for SAP. The purpose of the acquisition was to enhance the Company’s position as a leading provider of software solutions to automate the financial close process for SAP customers and supports the Company’s European expansion strategy. The acquisition has been accounted for as a business combination. The total purchase consideration was approximately $34.1 million which was paid in cash. The purchase consideration is subject to a final working capital adjustment, which has not yet been finalized. Any adjustment will be recorded in the consolidated statement of operations in the period of settlement. A portion of the purchase price totaling $3.1 million was paid into escrow for indemnification obligations relating to potential breach of representations and warranties of the sellers. Any amounts remaining in escrow after satisfaction of any resolved claims will be released from escrow. For the year ended December 31, 2016, acquisition-related costs incurred by the Company of approximately $1.6 million were expensed as incurred and are included in general and administrative expenses in the consolidated statements of operations.

Intangible Assets and Goodwill

Intangible Assets and Goodwill	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	Note 9—Intangible Assets and Goodwill The carrying value of intangible assets was as follows (in thousands): December 31, 2018 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Trade name $ 15,977 $ (8,528 ) $ 7,449 Developed technology 42,558 (34,472 ) 8,086 Customer relationships 31,783 (19,533 ) 12,250 $ 90,318 $ (62,533 ) $ 27,785 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Trade name $ 15,977 $ (6,930 ) $ 9,047 Developed technology 42,558 (27,577 ) 14,981 Non-compete agreements 4,520 (3,882 ) 638 Customer relationships 31,783 (15,641 ) 16,142 $ 94,838 $ (54,030 ) $ 40,808 The Company removed approximately $4.5 million of fully amortized non-compete agreements that were no longer in effect at December 31, 2018. These assets were fully amortized and, accordingly, there was no impact to the Company’s consolidated financial statements. Amortization expense is included in the following functional statements of operations expense categories. Amortization expense was as follows (in thousands): Year Ended December 31, 2018 2017 2016 Cost of revenues $ 6,863 $ 6,847 $ 6,368 Sales and marketing 3,887 3,872 3,605 General and administrative 2,273 2,591 2,532 $ 13,023 $ 13,310 $ 12,505 The following table presents the Company’s estimate of remaining amortization expense for each of the five succeeding fiscal years and thereafter for finite-lived intangible assets at December 31, 2018 (in thousands): 2019 $ 10,266 2020 6,173 2021 5,010 2022 2,686 2023 2,154 Thereafter 1,496 $ 27,785 There were no changes in the carrying amount of goodwill for the years ended December 31, 2018, 2017, and 2016.

Term Loan

Term Loan	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Term Loan	Note 10—Term Loan In September 2013, the Company entered into a $25 million term loan agreement (the “Term Loan”). In March 2016 and August 2016, the Company amended its credit facility to add an additional $5.0 million term loan (the “2016 Incremental Term Loan”) and to add an additional $30 million term loan (the “2016 Acquisition Term Loan”), respectively. Both the 2016 Incremental Term Loan and the 2016 Acquisition Term Loan had similar terms and conditions to the original Term Loan, and both were subject to prepayment penalties if the Company elected to repay the loans before the expiration date. In November 2016, the Company repaid in full all outstanding debt under the Company’s credit facility and terminated the agreement, as amended. In connection with the termination of the agreement, the Company paid a total of approximately $67.7 million, which included principal, accrued interest, paid in kind interest, and prepayment penalties. For the year ended December 31, 2016, upon the termination of the credit facility, accumulated paid in kind interest of $6.4 million was repaid and has been classified in cash flows from operating activities. In conjunction with Term Loan, the Company issued warrants to purchase 499,999 shares of common stock at an exercise price per share of $5.00. The warrants were exercisable at any time by the holder and expired upon the earlier of ten years from the issuance date or the sale of the Company. In May 2017, warrants to purchase 499,999 shares of common stock were net exercised, resulting in the issuance of 428,033 shares of common stock and, accordingly, there will be no further changes in the fair value.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 11—Income Taxes The components of income (loss) before income taxes were as follows (in thousands): Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted United States $ (27,289 ) $ (30,690 ) $ (38,355 ) International (415 ) (2,153 ) 3,360 $ (27,704 ) $ (32,843 ) $ (34,995 ) The components of the total provision for (benefit from) income taxes were as follows (in thousands): Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted Current Federal $ — $ — $ — State 24 51 5 Foreign 1,061 450 840 Total current tax expense 1,085 501 845 Deferred Federal — — (8,680 ) State — — (395 ) Foreign (923 ) (293 ) (428 ) Total deferred tax provision (benefit) (923 ) (293 ) (9,503 ) Total provision for (benefit from) income taxes $ 162 $ 208 $ (8,658 ) A reconciliation of the statutory U.S. federal income tax rate to the Company’s effective tax rate for the years ended December 31, 2018, 2017, and 2016 was as follows: Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted Federal statutory income tax rate 21.0 % 34.0 % 34.0 % State tax, net of federal benefit (0.1 %) (0.1 %) 0.7 % Federal tax credits 7.1 % 3.3 % 1.6 % Change in valuation allowance (63.1 %) (13.6 %) (5.0 %) Common stock warrants — (3.7 %) (5.8 %) Foreign tax differential (2.3 %) (2.4 %) — Windfall tax benefits, net related to stock-based compensation 40.2 % 15.3 % — Effect of rate and other changes on federal deferred taxes, net due to enactment of Tax Cuts and Jobs Act — (30.0 %) — Nondeductible officer compensation (1.8 %) — — Nondeductible meals and entertainment (1.7 %) — — Other 0.1 % (3.4 %) (0.8 %) (0.6 %) (0.6 %) 24.7 % In December 2017, the U.S. Congress passed, and the President signed, legislation commonly referred to as the Tax Cuts and Jobs Act (“the Tax Act”), which contains many significant changes to the U.S. tax laws, including reducing the U.S. federal corporate tax rate from 34% to 21% and creating a territorial tax system with a one-time mandatory tax on previously-deferred foreign earnings of U.S. subsidiaries. As the Company has a full valuation allowance against its U.S. deferred tax assets, the revaluation of its net deferred tax assets resulting from the reduction in the U.S federal corporate income tax rate did not impact the Company’s effective tax rate. In addition, due to cumulative foreign deficits, no liability for foreign earnings and profits has been established. At December 31, 2018, the Company completed its analysis of the Tax Act with no impact to its consolidated financial statements. Significant components of the Company’s deferred tax assets and liabilities were as follows (in thousands): December 31, December 31, 2018 2017 *As Adjusted Deferred tax assets Net operating loss carryforwards $ 43,106 $ 29,607 Business credits 8,487 5,197 Stock-based compensation 6,321 3,961 Accrued expenses and other current liabilities 2,910 1,462 Other 1,963 1,389 Total deferred tax assets 62,787 41,616 Less: valuation allowance (45,579 ) (23,904 ) Deferred tax assets, net of valuation allowance 17,208 17,712 Deferred tax liabilities Intangible assets (8,735 ) (11,287 ) Prepaid expenses (8,400 ) (6,376 ) Property and equipment (802 ) (1,589 ) Other — (112 ) Total deferred tax liabilities (17,937 ) (19,364 ) Net deferred taxes $ (729 ) $ (1,652 ) ASC 740 requires that the tax benefit of net operating losses, temporary differences, and credit carryforwards be recorded as an asset to the extent that management assesses that realization is "more likely than not." A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized. Realization of future tax benefits is dependent on the Company’s ability to generate sufficient taxable income within the carryforward period. For financial reporting purposes, the Company has incurred losses for each of the past three years. Based on available objective evidence, including the Company’s history of losses, management believes it is more likely than not that the net deferred tax assets will not be fully realizable. Accordingly, the Company provided a valuation allowance against certain deferred tax assets. The net deferred tax liability position at December 31, 2018 was related to a foreign tax jurisdiction of the Company. The changes in the valuation allowance were as follows (in thousands). Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted Valuation allowance, at beginning of year $ 23,904 $ 2,674 $ 887 Increase in valuation allowance recorded through earnings 21,675 7,332 1,787 Increase in valuation allowance as result of adoption of ASU 2016-09 — 13,898 — Valuation allowance, at end of year $ 45,579 $ 23,904 $ 2,674 The Company did not provide for U.S. income taxes on the undistributed earnings and other outside temporary differences of foreign subsidiaries as they are considered indefinitely reinvested outside the United States. At December 31, 2018 and 2017, the amount of temporary differences related to undistributed earnings and other outside temporary differences upon which U.S. income taxes have not been provided is immaterial to these consolidated financial statements. At December 31, 2018, the Company had consolidated federal and state net operating loss carryforwards available to offset future taxable income of approximately $172.7 million and $94.1 million, respectively. The federal losses will begin to expire in 2033, and the state losses will begin to expire between 2023 and 2033, depending on the jurisdiction. The Company has federal research and development credits and foreign tax credits of $3.3 million and $2.0 million, respectively, which begin to expire in 2033 and 2023, respectively. The Company has state research and development credits and enterprise zone credits of $3.5 million and $0.6 million, respectively, which are indefinite in expiration and begin to expire in 2023, respectively. Pursuant to Internal Revenue Code Section 382, use of the Company’s net operating loss carryforwards may be limited if the Company experiences a cumulative change in ownership of more than 50% over a three-year period. The following is a rollforward of the Company’s total gross unrecognized tax benefits (in thousands): Year Ended December 31, 2018 2017 2016 Beginning gross unrecognized tax benefits $ 672 $ 382 $ 278 Increases related to prior year tax positions 130 38 — Increases related to current year tax positions 421 252 104 Ending gross unrecognized tax benefits $ 1,223 $ 672 $ 382 At December 31, 2018, the realization of unrecognized tax benefits were not expected to impact the effective rate due to a full valuation allowance on federal and state deferred taxes. The Company has not recorded any interest or penalties in its provision for (benefit from) income taxes for the years ended December 31, 2018, 2017, and 2016 and no such amounts have been accrued at December 31, 2018 and 2017. The Company files U.S. federal, various state, and foreign income tax returns. In the normal course of business, the Company is subject to examination by taxing authorities. The tax years 2016 and 2017 remain subject to examination for federal purposes. Generally, state and foreign tax authorities may examine the Company’s tax returns for four years and five years, respectively, from the date an income tax return is filed. However, the taxing authorities may continue to examine the Company’s federal and state net operating loss carryforwards until the statute of limitations closes on the tax years in which the federal and state net operating losses are utilized. The Company does not anticipate material changes in the total amount or composition of its unrecognized tax benefits within 12 months of the reporting date.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss per Share	Note 12—Net Loss per Share The following table sets forth the computation of basic and diluted net loss per share (in thousands, except per share amounts): Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted Numerator: Net loss attributable to BlackLine, Inc. $ (27,804 ) $ (33,051 ) $ (26,337 ) Denominator: Weighted average shares 53,912 52,161 42,497 Add: Dilutive effect of securities — — — Shares used to calculate diluted net loss per share 53,912 52,161 42,497 Basic net loss per share attributable to BlackLine, Inc. $ (0.52 ) $ (0.63 ) $ (0.62 ) Diluted net loss per share attributable to BlackLine, Inc. $ (0.52 ) $ (0.63 ) $ (0.62 ) The following potentially dilutive shares were excluded from the calculation of diluted net loss per share attributable to common stockholders because they were anti-dilutive: Year Ended December 31, 2018 2017 2016 Stock options with service-only vesting conditions 3,820 5,019 5,874 Stock options with performance conditions 683 683 683 Restricted stock units 1,300 2 — Common stock warrants — — 500 Total shares excluded from net loss per share 5,803 5,704 7,057

Contingent Consideration

Contingent Consideration	12 Months Ended
	Dec. 31, 2018
Business Combination Contingent Consideration Arrangements [Abstract]
Contingent Consideration	Note 13—Contingent Consideration On September 3, 2013, the Company acquired BlackLine Systems, Inc. Under the terms of the acquisition agreement, BlackLine Systems, Inc.’s option holders were allowed to cancel their stock option rights and receive a cash payment equal to the amount of calculated gain (less applicable expense and other items) had they exercised their stock options and then sold their common shares as part of the acquisition. As a condition of the acquisition, the Company is required to pay additional cash consideration to certain equity holders if the Company realizes a tax benefit from the use of net operating losses generated from the stock option exercises concurrent with the acquisition. The maximum contingent cash consideration to be distributed is $8.0 million. The fair value of the contingent consideration was $6.3 million and $5.9 million at December 31, 2018 and 2017, respectively. See Note 2 for additional information regarding the valuation of the contingent consideration.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 14—Commitments and Contingencies Operating leases —The Company has various non-cancelable operating leases for its corporate and international offices, as well as non-cancelable data center and equipment leases. These leases expire at various times through 2024. Certain lease agreements contain renewal options, rent abatement and escalation clauses. The Company recognizes rent expense on a straight-line basis over the lease term, commencing when the Company takes possession of the property. Certain of the Company’s office leases entitle the Company to receive a tenant allowance from the landlord. The Company records tenant allowances as a deferred rent credit, which the Company amortizes on a straight-line basis, as a reduction of rent expense, over the term of the underlying lease. Total rent expense under the operating leases related to offices was approximately $4.2 million, $3.4 million, and $2.9 million for the years ended December 31, 2018, 2017, and 2016, respectively. Total rent expense under the operating leases related to data center and equipment leases was approximately $3.7 million, $3.2 million, and $1.5 million for the years ended December 31, 2018, 2017, and 2016, respectively. Future minimum lease payments under non-cancelable operating leases at December 31, 2018 was (in thousands): 2019 $ 7,059 2020 5,307 2021 3,786 2022 2,586 2023 2,638 Thereafter 237 $ 21,613 Purchase obligations — At December 31, 2018, the Company had $5.2 million of non-cancelable purchase obligations primarily related to future sales and user conferences and software agreements. Litigation —From time to time, the Company may become subject to legal proceedings, claims and litigation arising in the ordinary course of business. The Company is not currently a party to any legal proceedings, nor is it aware of any pending or threatened litigation, that would have a material adverse effect on the Company’s business, operating results, cash flows, or financial condition should such litigation be resolved unfavorably. Indemnification —In the ordinary course of business, the Company may provide indemnification of varying scope and terms to customers, vendors, investors, directors, and officers with respect to certain matters, including, but not limited to, losses arising out of our breach of such agreements, services to be provided by the Company, or from intellectual property infringement claims made by third parties. These indemnification provisions may survive termination of the underlying agreement and the maximum potential amount of future payments the Company could be required to make under these indemnification provisions may not be subject to maximum loss clauses. The maximum potential amount of future payments the Company could be required to make under these indemnification provisions is indeterminable. The Company has never paid a material claim, nor has it been sued in connection with these indemnification arrangements. At December 31, 2018 and 2017, the Company has not accrued a liability for these indemnification arrangements because the likelihood of incurring a payment obligation, if any, in connection with these indemnification arrangements was not probable or reasonably estimable.

Capitalization

Capitalization	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Capitalization	Note 15—Capitalization At December 31, 2018, the authorized capital stock of the Company consisted of 500 million shares of common stock and 50 million shares of preferred stock. No shares of preferred stock were issued and outstanding at December 31, 2018. The board of directors can determine the voting rights, dividend rights, conversion rights, redemption privileges and liquidation preferences of the preferred stock. On January 14, 2016, the board of directors approved the retirement of 47,000 shares of treasury stock. In September 2016, the Company raised gross proceeds of $3.1 million from the sale of 192,187 shares of common stock to former Runbook employees. On November 2, 2016, the Company completed its initial public offering in which it issued and sold 9,890,000 shares of its common stock, which included the exercise in full of the underwriters’ option to purchase an additional 1,290,000 shares at an initial offering price of $17.00 per share. The Company received proceeds from the offering of approximately $151.9 million after deducting underwriting discounts and commissions and other offering expenses.

Equity Awards

Equity Awards	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Awards	Note 16—Equity Awards 2014 and 2016 Plans On March 3, 2014, the Company adopted the 2014 Stock Incentive Plan (the “2014 Plan”). In November 2016, upon the completion of the Company’s initial public offering, the Company adopted the 2016 Equity Incentive Plan (the “2016 Plan”) and determined that it will no longer grant any additional awards under the 2014 Plan. However, the 2014 Plan continues to govern the terms and conditions of the outstanding awards previously granted under the 2014 plan. Upon the adoption of the 2016 Plan, the maximum number of shares issuable was 6.2 million, plus a number of shares equal to the number of shares subject to outstanding awards granted under the 2014 Plan after the date the 2014 Plan is terminated without having been exercised in full. The Company’s board of directors may grant stock options and restricted stock units to employees, directors and consultants under the 2016 Plan. The aggregate number of shares available under the 2016 Plan and the number of shares subject to outstanding options automatically adjusts for any changes in the Company’s outstanding common stock by reason of any recapitalization, spin-off, reorganization, reclassification, stock dividend, stock split, reverse stock split, or similar transaction. Stock options and restricted stock units generally vest over four years and have contractual terms of ten years. At December 31, 2018, 9.1 million shares were available for issuance under the 2016 Plan. Stock options with service-only vesting conditions A summary of the Company’s stock option activity and related information for awards that contain service-only vesting conditions was as follows: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (in thousands) (in years) (in thousands) Outstanding at December 31, 2017 5,019 $ 13.90 7.5 $ 95,353 Granted 845 $ 42.06 Exercised (1,788 ) $ 8.39 Forfeited/canceled (256 ) $ 26.64 Outstanding at December 31, 2018 3,820 $ 21.85 7.5 $ 75,287 Exercisable at December 31, 2018 1,729 $ 13.11 6.4 $ 48,136 The weighted average grant date fair value per share of options granted during the years ended December 31, 2018, 2017, and 2016 that contain service only vesting conditions were $20.15, $15.20, and $6.78, respectively. The aggregate intrinsic value of options exercised that contain service only vesting conditions during the years ended December 31, 2018, 2017, and 2016 were $66.7 million, $31.4 million, and $4.8 million, respectively. Cash received from the exercise of stock options for the years ended December 31, 2018, 2017, and 2016 was $14.0 million, $10.4 million, and $2.9 million, respectively. Unrecognized compensation expense relating to stock options that contain service only vesting conditions was $23.1 million at December 31, 2018, which is expected to be recognized over a weighted-average period of 2.8 years. Stock options with performance conditions In October 2016, the Company granted options to purchase 682,800 shares of common stock at an exercise price of $14.00 per share to two executive officers that vest upon meeting certain performance conditions and continued service. The performance conditions include meeting yearly cash flow targets and cumulative annual recurring revenue targets through 2019. If each yearly cash flow target is met through 2019, but the full cumulative annual recurring target through 2019 is not met, the executive officers are still able to vest in the award if an additional cash flow target for 2020 and a cumulative annual recurring revenue target through 2020 are achieved. The cash flow performance targets for each year are determined concurrently with the annual budget process and because each yearly target has not yet been set, no grant date for the options has been established. At December 31, 2018, the Company has determined that the achievement of the performance targets is not probable and, accordingly, no stock-based compensation expense has been recorded for these awards. To the extent that the awards become probable of vesting prior to the grant date, the amount of compensation cost to be recognized will be based on the then fair value of the options. The fair value of the options will be remeasured each period until a grant date has been established. Accordingly, stock-based compensation cost, if any, to be recognized will depend on the value of the stock options when all performance conditions have been set and whether the performance conditions are probable of being achieved. Restricted stock units The following table summarizes activity for restricted stock units: Weighted-Average Restricted Grant Date Stock Units Fair Value (in thousands) Nonvested at December 31, 2017 2 $ 34.12 Granted 1,372 $ 42.38 Vested (2 ) $ 34.46 Forfeited/canceled (72 ) $ 44.09 Nonvested at December 31, 2018 1,300 $ 42.29 At December 31, 2018, the intrinsic value of nonvested restricted stock units was $53.2 million. At December 31, 2018, total unrecognized compensation cost related to nonvested restricted stock units was $44.9 million and was expected to be recognized over a weighted-average period of 3.3 years. Employee Stock Purchase Plan Under the Company’s 2018 Employee Stock Purchase Plan (“ESPP”) eligible employees are granted the right to purchase shares at the lower of 85% of the fair value of the stock at the time of grant or 85% of the fair value at the time of exercise. The right to purchase shares is granted twice yearly for six month offering periods in May and November and exercisable on or about the succeeding November and May, respectively, of each year. Under the ESPP, 1.5 million shares remained available for issuance, at December 31, 2018. The Company recognized stock-based compensation expense related to the ESPP of $0.2 million for the year ended December 31, 2018. The fair value of employee stock purchase plan shares granted was estimated using the Black-Scholes option pricing model with the following weighted-average assumptions: Year Ended December 31, 2018 Risk-free interest rate 2.6 % Expected term (in years) 0.7 Volatility 42.9 % At December 31, 2018, total unrecognized compensation cost related to the 2018 Employee Stock Purchase Plan was $1.6 million and was expected to be recognized over a weighted-average period of 0.7 years. Stock-based compensation expense Stock-based compensation expense recorded in the Company’s consolidated statements of operations was as follows (in thousands): Year Ended December 31, 2018 2017 2016 Cost of revenues $ 3,265 $ 1,149 $ 715 Sales and marketing 8,674 10,811 2,490 Research and development 2,570 767 809 General and administrative 6,386 3,317 2,512 $ 20,895 $ 16,044 $ 6,526 Stock-based compensation capitalized as an asset was $0.4 million, $0.1 million, and $0.1 million in the years ended December 31, 2018, 2017, and 2016, respectively. T he Company recorded $0.2 million of foreign tax benefits attributable to equity awards for the year ended December 31, 2018. For the years ended December 31, 2017 and 2016, no additional tax benefit attributable to equity awards was recorded due to the full valuation allowance provided on the Company’s U.S. net deferred tax assets. On July 21, 2017, the Company modified the vesting terms of options to purchase 219,000 shares of common stock to a time-based vesting schedule, for eight employees. Prior to the modification, the options vested solely upon a change in control of the Company. The Company recorded $6.6 million of stock-based compensation in the year ended December 31, 2017 related to the modification.

Defined Contribution Plan

Defined Contribution Plan	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Defined Contribution Plan	Note 17—Defined Contribution Plan The Company sponsors a defined contribution retirement plan (the “Plan”) that covers substantially all domestic employees. The Company makes matching contributions of 100% of each $1 of the employee’s contribution up to the first 3% of the employee’s bi-weekly compensation and 50% of each $1 of the employee’s contribution up to the next 2% of the employee’s bi-weekly compensation. Matching contributions to the Plan recorded in the Company’s consolidated statements of operations totaled $2.9 million, $2.2 million, and $2.3 million for the years ended December 31, 2018, 2017, and 2016, respectively.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Note 18—Related-Party Transactions The Company had no material related-party transactions during the years ended December 31, 2018, 2017, and 2016.

Geographic Information

Geographic Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Geographic Information	Note 19—Geographic Information The following table sets forth the Company’s long-lived assets, which consist of property and equipment, net by geographic region (in thousands): Year Ended December 31, 2018 2017 United States $ 12,407 $ 12,210 International 1,129 559 $ 13,536 $ 12,769

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Note 20—Subsequent Events On February 2 5 0.1 On February 2 5 0.2 The vast majority of the

Unaudited Quarterly Data

Unaudited Quarterly Data	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Unaudited Quarterly Data	Note 21—Unaudited Quarterly Data The following table sets forth unaudited quarterly consolidated statements of operations data for each of the quarters in the years ended December 31, 2018 and 2017. The Company has prepared the unaudited quarterly consolidated statements of operations data on a basis consistent with the audited annual consolidated financial statements. In the opinion of management, the financial information in this table reflects all adjustments, consisting of normal and recurring adjustments, necessary for the fair statement of this data. Quarter Ended 2018 2017 December 31, September 30, June 30, March 31, December 31, September 30, June 30, March 31, *As Adjusted *As Adjusted *As Adjusted *As Adjusted Revenues $ 62,316 $ 58,734 $ 55,454 $ 51,284 $ 50,017 $ 45,424 $ 41,981 $ 38,181 Gross profit $ 48,431 $ 45,217 $ 43,588 $ 39,678 $ 39,070 $ 34,553 $ 31,624 $ 28,971 Net loss $ (7,794 ) $ (4,460 ) $ (8,457 ) $ (7,155 ) $ (4,166 ) $ (12,074 ) $ (9,126 ) $ (7,685 ) Net loss attributable to redeemable non-controlling interest $ (62 ) $ — $ — $ — $ — $ — $ — $ — Net loss attributable to BlackLine, Inc. $ (7,732 ) $ (4,460 ) $ (8,457 ) $ (7,155 ) $ (4,166 ) $ (12,074 ) $ (9,126 ) $ (7,685 ) Basic net loss per share attributable to BlackLine, Inc. $ (0.14 ) $ (0.08 ) $ (0.16 ) $ (0.13 ) $ (0.08 ) $ (0.23 ) $ (0.18 ) $ (0.15 ) Diluted net loss per share attributable to BlackLine, Inc. $ (0.14 ) $ (0.08 ) $ (0.16 ) $ (0.13 ) $ (0.08 ) $ (0.23 ) $ (0.18 ) $ (0.15 )

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Principles of Consolidation and Basis of Presentation	Principles of consolidation and basis of presentation The Company’s consolidated financial statements are presented in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and include the operating results of its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.
Reserve Stock Split	Reverse stock split On October 12, 2016, the Company effected a 1-for-5 reverse stock split of its outstanding common stock. All share and per share amounts for all periods presented in these consolidated financial statements and notes thereto have been adjusted retrospectively, where applicable, to reflect this reverse stock split.
Redeemable Non-controlling Interest	Redeemable non-controlling interest The Company's Japanese subsidiary (“BlackLine K.K.”) is not wholly owned. The agreements with the minority investors of BlackLine K.K. contain redemption features whereby the interest held by the minority investors are redeemable either (i) at the option of the minority investors or (ii) at the option of the Company, both beginning on the seventh anniversary of the initial capital contribution. If the interest of the minority investors were to be redeemed under these agreements, the Company would be required to redeem the interest based on a prescribed formula derived from the relative revenue of BlackLine K.K. and the Company. The balance of the redeemable non-controlling interest is reported at the greater of the initial carrying amount adjusted for the redeemable non-controlling interest's share of earnings or losses and other comprehensive income or loss, or its estimated redemption value. The resulting changes in the estimated redemption amount (increases or decreases) are recorded with corresponding adjustments against retained earnings or, in the absence of retained earnings, additional paid-in-capital. These interests are presented on the consolidated balance sheets outside of equity under the caption "Redeemable non-controlling interest."
Use of Estimates	Use of estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the dates of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its estimates, primarily those related to determining the stand alone selling price (“SSP”) for separate deliverables in the Company’s subscription revenue arrangements, allowance for doubtful accounts, fair value of assets and liabilities assumed in a business combination, recoverability of goodwill and long-lived assets, useful lives associated with long-lived assets, income taxes, contingencies, fair value of contingent consideration, and the valuation and assumptions underlying stock-based compensation and common stock warrants. These estimates are based on historical data and experience, as well as various other factors that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Reclassifications	Reclassifications Certain prior-period amounts have been reclassified to conform to the current-period presentation. These reclassifications had no impact on the previously-reported consolidated results of operations or stockholders' equity.
Segments	Segments Management has determined that the Company has one operating segment. The Company’s chief executive officer, who is the Company’s chief operating decision maker, reviews financial information on a consolidated and aggregate basis, together with certain operating metrics principally to make decisions about how to allocate resources and to measure the Company’s performance.
Cash and Cash Equivalents	Cash and cash equivalents The Company considers all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents. Cash includes cash held in checking and savings accounts. Cash equivalents are comprised of investments in money market mutual funds. The carrying value of cash and cash equivalents approximates fair value.
Restricted Cash	Restricted cash Included in other assets at December 31, 2018 and in prepaid expenses and other current assets at 2017 was cash totaling $0.3 million and $0.4 million, respectively, which was required to be restricted as to use by the Company’s office leaseholder to collateralize a standby letter of credit.
Investments in Marketable Securities	Investments in Marketable Securities The Company’s marketable securities consist of commercial paper, corporate bonds, U.S. treasury securities, and asset-backed securities. The Company classifies its marketable securities as available-for-sale at the time of purchase, and the Company reevaluates such classification as of each balance sheet date. All marketable securities are recorded at their estimated fair value, with any unrealized gains and losses reported as a component of stockholders’ equity until realized or until a determination is made that an other-than-temporary decline in market value has occurred. Impairments are considered to be other than temporary if they are related to deterioration in credit risk or if it is likely the Company will sell the securities before the recovery of their cost basis. Realized gains and losses and declines in value deemed to be other than temporary are determined based on the specific identification method and are reported in other income (expense), net in the consolidated statements of operations. The Company classifies its investments in marketable securities in current assets as the investments are available for use, if needed, in current operations.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts receivable and allowance for doubtful accounts Accounts receivable are recorded at the invoiced amount, do not require collateral and do not bear interest. The Company estimates its allowance for doubtful accounts by evaluating specific accounts where information indicates the Company’s customers may have an inability to meet financial obligations, such as bankruptcy and significantly aged receivables outstanding.
Concentration of Credit Risk and Significant Customers	Concentration of credit risk and significant customers Financial instruments that potentially subject the Company to a significant concentration of credit risk consist of cash and cash equivalents, investments in marketable securities and accounts receivable. The Company maintains the majority of its cash balances with one major commercial bank in non-interest bearing accounts, which exceeds the Federal Deposit Insurance Corporation, or FDIC, federally insured limits. The Company invests its excess cash in money market mutual funds, commercial paper, corporate bonds, U.S. treasury securities, and asset-backed securities. To date, the Company has not experienced any impairment losses on its investments. For the years ended December 31, 2018, 2017, and 2016, no single customer comprised 10% or more of the Company’s total revenues. No single customer had an accounts receivable balance of 10% or greater of total accounts receivable at December 31, 2018 or 2017.
Property and Equipment	Property and equipment Property and equipment is stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which is generally three to five years for machinery and equipment and purchased software and five years for furniture and fixtures. Leasehold improvements, which are included in furniture and fixtures, are amortized using the straight-line method over the shorter of the lease term or seven years. Expenditures for repairs and maintenance are expensed as incurred, while renewals and betterments are capitalized. Depreciation expense is charged to operations on a straight-line basis over the estimated useful lives of the assets. Assets acquired under capital leases are capitalized at the present value of the related lease payments and are amortized over the shorter of the lease term or useful life of the asset.
Capitalized Internal-Use Software Costs	Capitalized internal-use software costs The Company accounts for the costs of computer software obtained or developed for internal use in accordance with ASC 350, Intangibles—Goodwill and Other During the years ended December 31, 2018, 2017, and 2016, the Company amortized $3.9 million, $2.7 million, and $1.8 million, respectively, of internal-use software development costs to subscription and support cost of revenue. At December 31, 2018 and 2017, the accumulated amortization of capitalized internal-use software development costs was $9.5 million and $5.6 million, respectively.
Business Combinations	Business combinations The results of businesses acquired in a business combination are included in the Company’s consolidated financial statements from the date of the acquisition. Purchase accounting results in assets and liabilities of an acquired business generally being recorded at their estimated fair values on the acquisition date. Any excess consideration over the fair value of assets acquired and liabilities assumed is recognized as goodwill. Transaction costs associated with business combinations are expensed as incurred and are included in general and administrative expenses in the consolidated statements of operations. The Company performs valuations of assets acquired and liabilities assumed and allocates the purchase price to its respective assets and liabilities. Determining the fair value of assets acquired and liabilities assumed requires management to use significant judgment and estimates, including the selection of valuation methodologies, estimates of future revenue, costs and cash flows, discount rates, and selection of comparable companies. The Company engages the assistance of valuation specialists in concluding on fair value measurements in connection with determining fair values of assets acquired and liabilities assumed in a business combination.
Intangible Assets	Intangible assets Intangible assets primarily consist of acquired developed technology, customer relationships, trade names and non-compete agreements, which were acquired as part of the 2013 Acquisition and the Runbook Acquisition. The Company determines the appropriate useful life of its intangible assets by performing an analysis of expected cash flows of the acquired assets. Intangible assets are amortized on a straight-line basis over their estimated useful lives, ranging from one to ten years.
Impairment of Long-Lived Assets	Impairment of long-lived assets Management evaluates the recoverability of the Company’s property and equipment, finite-lived intangible assets and capitalized internal-software costs when events or changes in circumstances indicate a potential impairment exists. Events and changes in circumstances considered by the Company in determining whether the carrying value of long-lived assets may not be recoverable include, but are not limited to, significant changes in performance relative to expected operating results, significant changes in the use of the assets, significant negative industry or economic trends, and changes in the Company’s business strategy. Impairment testing is performed at an asset level that represents the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities (an “asset group”). In determining if impairment exists, the Company estimates the undiscounted cash flows to be generated from the use and ultimate disposition of the asset group. If impairment is indicated based on a comparison of the assets’ carrying values and the undiscounted cash flows, the impairment loss is measured as the amount by which the carrying amount of the assets exceeds the fair value of the assets. The Company determined that there were no events or changes in circumstances that potentially indicated that the Company’s long-lived assets were impaired during the years ended December 31, 2018, 2017, and 2016.
Goodwill	Goodwill Goodwill represents the excess of the purchase price over the fair value of net assets acquired in a business combination. The Company tests goodwill for impairment in accordance with the provisions of Accounting Standards Codification (“ASC”) 350, Intangibles—Goodwill and Other ASC 350 provides that an entity has the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events or circumstances, an entity determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then additional impairment testing is not required. However, if an entity concludes otherwise, then it is required to perform the first of a two-step impairment test. The first step involves comparing the estimated fair value of a reporting unit with its book value, including goodwill. If the estimated fair value exceeds book value, goodwill is considered not to be impaired and no additional steps are necessary. If, however, the fair value of the reporting unit is less than book value, then, under the second step, the carrying amount of the goodwill is compared with its implied fair value. The estimate of implied fair value of goodwill may require valuations of certain internally-generated and unrecognized intangible assets. If the carrying amount of goodwill exceeds the implied fair value of that goodwill, an impairment loss is recognized in an amount equal to the excess. The Company has one reporting unit and it tests its goodwill for impairment annually, during the fourth quarter of the calendar year. At December 31, 2018 and 2017, the Company used the quantitative approach to perform its annual goodwill impairment test. The Company’s fair value significantly exceeded the carrying value of its net assets and, accordingly, goodwill was not impaired.
Deferred Rent	Deferred rent Rent expense is recorded on a straight-line basis over the term of the lease. The difference between rent expense and the cash paid under the lease agreement is recorded as deferred rent. Lease incentives, including tenant improvement allowances, are also recorded as deferred rent and amortized on a straight-line basis over the lease term.
Debt Issued with Warrants To Purchase Common Stock	Debt issued with warrants to purchase common stock The Company issued warrants to purchase common stock in connection with its former credit facility. These warrants were a liability classified under ASC 815-40, Contracts in Entity’s Own Equity In May 2017, warrants to purchase 499,999 shares of common stock were net exercised resulting in the issuance of 428,033 shares of common stock and, accordingly, there will be no further changes in the fair value The initial carrying value of the debt was reduced by the fair value of the warrants. The resulting debt discount was amortized to interest expense over the life of the debt on a straight-line basis, which approximated the effective interest method. In November 2016, the Company repaid all outstanding debt and expensed the then-remaining unamortized debt discount to interest expense in the consolidated statements of operations.
Fair Value of Financial Instruments	Fair value of financial instruments ASC 820, Fair Value Measurements Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. ASC 820 describes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value, which are the following: Level 1: Quoted prices in active markets for identical or similar assets and liabilities. Level 2: Quoted prices for identical or similar assets and liabilities in markets that are not active or observable inputs other than quoted prices in active markets for identical or similar assets or liabilities. Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. At December 31, 2018 and 2017, the carrying values of cash equivalents, accounts receivable, accounts payable, and accrued expenses, approximate fair values due to the short-term nature of such instruments. Contingent consideration relating to the 2013 Acquisition (see Note 13) is recorded as a liability and is measured at fair value each period, based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The valuation of contingent consideration uses assumptions management believes would be made by a market participant. Management assesses these estimates on an ongoing basis as additional data impacting the assumptions becomes available. Changes in the fair value of contingent consideration related to updated assumptions and estimates are recognized within general and administrative expenses in the consolidated statements of operations. The Company determined the fair value of the contingent consideration by discounting estimated future taxable income. The significant inputs used in the fair value measurement of contingent consideration are the timing and amount of taxable income in any given period and determining an appropriate discount rate, which considers the risk associated with the forecasted taxable income. Significant changes in the estimated future taxable income and the periods in which they are generated would significantly impact the fair value of the contingent consideration liability. Warrants to purchase common stock were liability classified and were measured at fair value each period. The fair value was determined using a binomial lattice valuation model. The fair value included significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy. The valuation of common stock warrants used assumptions management believed would be made by a market participant. Management assessed these estimates on an ongoing basis as additional data impacting the assumptions became available. Changes in the fair value of the common stock warrant liability related to updated assumptions and estimates were recognized within other income (expense), net in the consolidated statements of operations. The significant inputs used in the fair value measurement of the common stock warrants were the estimated fair value of the Company’s common stock and, to a lesser extent, the expected stock volatility, the probability of a change in control and future stock issuances, which impacted the term of the warrants. Certain assets, including goodwill and long-lived assets, are also subject to measurement at fair value on a non-recurring basis if they are deemed to be impaired a result of an impairment review. For the years ended December 31, 2018, 2017, and 2016, no impairments were identified on those assets required to be measured at fair value on a non-recurring basis.
Revenue Recognition	Revenue recognition Revenue is recognized upon transfer of control of promised products or services to customers in an amount that reflects the consideration the Company expects to receive in exchange for those products or services. The Company enters into contracts that can include various combinations of subscription and support services and professional services, which are generally capable of being distinct and accounted for as separate performance obligations. The Company’s agreements do not contain any refund provisions other than in the event of the Company’s non-performance or breach. The Company determines revenue recognition through the following steps: • Identification of the contract, or contracts, with a customer • Identification of the performance obligations in the contract • Determination of the transaction price • Allocation of the transaction price to the performance obligations in the contract • Recognition of revenue when, or as, the Company satisfies a performance obligation Subscription and support revenue – Customers pay subscription and support fees for access to the Company’s SaaS platform generally for a one-year period. In more limited cases, customers may pay for up to three years in advance. Fees are based on a number of factors, including the solutions subscribed for by the customer and the number of users having access to the solutions. Subscription services, which allow customers to use hosted software over the contract period without taking possession of the software, are considered distinct performance obligations and are recognized ratably as the Company transfers control evenly over the contract period. Subscription and support revenue also includes software and related maintenance and support fees on legacy BlackLine solutions and Runbook Company B.V. (“Runbook”) software. Software licenses for legacy BlackLine solutions and Runbook software provide the customer with a right to use the software as it exists when made available to the customer. Customers may have purchased perpetual licenses or term based licenses, which provide customers with the same functionality and differ mainly in the duration over which the customer benefits from the software. Software licenses are bundled with software maintenance and support, and the transaction price of the contract is allocated between the software licenses and the software maintenance and support. Maintenance and support convey rights to new software and upgrades released over the contract period and provide support, tools, and training to help customers deploy and use products more efficiently. Software licenses are considered distinct performance obligations and revenue is recognized at a point in time when control of the license has transferred and the license period commences. Maintenance and support are distinct performance obligations that are satisfied over time, and revenue is recognized ratably over the contract period as customers simultaneously consume and receive benefits. Professional services revenue – Professional services consist of implementation and consulting services to assist the Company’s customers as they deploy its solutions. These services are considered distinct performance obligations. Professional services do not result in significant customization of the subscription service. The Company applies the practical expedient to recognize professional services revenue when it has the right to invoice based on time and materials incurred. Significant judgments – The Company’s contracts with customers often include promises to transfer multiple products and services. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment. Judgment is also required to determine the stand alone selling price (“SSP”) for each distinct performance obligation. The Company typically has more than one SSP for its SaaS solutions and professional services. Additionally, management has determined that there are no third-party offerings reasonably comparable to the Company’s solutions. Therefore, the Company determines the SSPs of subscriptions to the SaaS solutions and professional services based on numerous factors including the Company’s overall pricing objectives, geography, customer size and number of users, and discounting practices . The Company uses historical maintenance renewal fees to estimate SSP for maintenance and support fees bundled with software licenses. The Company uses the residual method to estimate SSP of software licenses, because license pricing is highly variable and not sold separately from maintenance and support. Contract balances – Timing of revenue recognition may differ from the timing of invoicing to customers. The Company records an unbilled receivable when revenue is recognized prior to invoicing, and deferred revenue when revenue is recognized subsequent to invoicing. The Company generally invoices customers annually at the beginning of each annual contract period. The Company records a receivable related to revenue recognized for multi-year agreements as it has an unconditional right to invoice and receive payment in the future related to those services. Deferred revenue is comprised mainly of billings related to the Company’s SaaS solutions in advance of revenue being recognized. Deferred revenue also includes payments for: professional services to be performed in the future; legacy BlackLine maintenance and support; Runbook maintenance, support, license, and implementation; and other offerings for which the Company has been paid in advance and earns the revenue when the Company transfers control of the product or service. Changes in deferred revenue for the years ended December 31, 2018, 2017, and 2016 were primarily due to additional billings in the periods, partially offset by revenue recognized of $104.2 million, $78.2 million, and $52.9 million, respectively, that was previously included in the deferred revenue balance at December 31, 2017, 2016, and 2015, respectively. The transaction price is generally determined by the stated fixed fees in the contract, excluding any related sales taxes. Transaction price allocated to remaining performance obligations represents contracted revenue that has not yet been recognized (“contracted not recognized”), which includes deferred revenue and amounts that will be invoiced and recognized as revenue in future periods. Contracted not recognized revenue was $285.0 million at December 31, 2018, of which the Company expects to recognize approximately 62% over the next 12 months and the remainder thereafter. Fees are generally due and payable upon receipt of invoice or within 30 days. None of the Company’s contracts includes a significant financing component. Assets recognized from the costs to obtain a contract with a customer – The Company recognizes an asset for the incremental and recoverable costs of obtaining a contract with a customer if the Company expects the benefit of those costs to be one year or longer. The Company has determined that certain sales incentive programs to the Company’s employees ("deferred customer contract acquisition costs") and its partners ("partner referral fees") meet the requirements to be capitalized. Deferred customer acquisition costs related to new revenue contracts and upsells are deferred and then amortized straight line over the expected period of benefit, which the Company has determined to be five years, based upon both the product turnover rate and estimated customer life. Partner referral fees are deferred and then amortized on a straight-line basis over the related contractual period, as the fees for renewals are commensurate with fees incurred for the initial contract. Deferred customer acquisition costs and partner referral fees are included within other assets and prepaid expenses and other current assets, respectively, on the consolidated balance sheets. There were no impairment losses in relation to the costs capitalized for the periods presented. Amortization expense related to the asset recognized from the costs to obtain a contract with a customer is included in sales and marketing expenses in the consolidated statements of operations and was $23.6 million, $15.6 million, and $9.8 million for the years ended December 31, 2018, 2017, and 2016, respectively.
Cost of revenues	Cost of revenues Cost of revenues primarily consists of costs related to hosting the Company’s cloud-based application suite, salaries and benefits of operations and support personnel, including stock-based compensation, and amortization of capitalized internal-use software costs. The Company allocates a portion of overhead, such as rent, information technology costs and depreciation and amortization to cost of revenues. Costs associated with providing professional services are expensed as incurred when the services are performed. In addition, subscription and support cost of revenues includes amortization of acquired developed technology.
Sales and Marketing	Sales and marketing Sales and marketing expenses consist primarily of compensation and employee benefits, including stock-based compensation, of sales and marketing personnel and related sales support teams, sales and partner commissions, marketing events, advertising costs, travel, trade shows, other marketing materials, and allocated overhead. Sales and marketing expenses also include amortization of customer relationship intangible assets. Advertising costs are expensed as incurred and totaled $8.0 million, $7.7 million, and $4.2 million for the years ended December 31, 2018, 2017, and 2016, respectively.
Research and Development	Research and development Research and development expenses are comprised primarily of salaries, benefits and stock-based compensation associated with the Company’s engineering, product and quality assurance personnel. Research and development expenses also include third-party contractors and supplies and allocated overhead. Other than software development costs that qualify for capitalization, as discussed above, research and development costs are expensed as incurred.
General and Administrative	General and administrative General and administrative expenses consist primarily of personnel costs associated with the Company’s executive, finance, legal, human resources, compliance, and other administrative personnel, as well as accounting and legal professional services fees, other corporate-related expenses and allocated overhead. General and administrative expenses also include amortization of covenant not to compete and tradename intangible assets, the change in value of the contingent consideration, acquisition-related costs of business combinations, costs associated with the secondary offering, and costs associated with the shelf offerings.
Stock-Based Compensation	Stock-based compensation The Company accounts for stock-based compensation awards granted to employees and directors based on the awards’ estimated grant date fair value. The Company estimates the fair value of its stock options using the Black-Scholes option-pricing model. For awards that vest solely based on continued service (“service-only vesting conditions”), the resulting fair value is recognized on a straight-line basis over the period during which an employee is required to provide service in exchange for the award, usually the vesting period, which is generally four years. The Company recognizes the fair value of stock options which contain performance conditions based upon the probability of the performance conditions being met, using the graded vesting method. On January 1, 2017, the Company changed its accounting policy to account for forfeitures when they occur rather than estimate a forfeiture rate. Determining the grant date fair value of options using the Black-Scholes option-pricing model requires management to make assumptions and judgments. These estimates involve inherent uncertainties and, if different assumptions had been used, stock-based compensation expense could have been materially different from the amounts recorded. The assumptions and estimates are as follows: Value per share of the Company’s common stock . Prior to the Company’s initial public offering in October 2016, because there was no public market for the Company’s common stock, the Company’s management, with the assistance of a third-party valuation specialist, determined the fair value of the Company’s common stock at the time of the grant of stock options by considering a number of objective and subjective factors, including the Company’s actual operating and financial performance, market conditions and performance of comparable publicly-traded companies, developments and milestones in the Company, the likelihood of achieving a liquidity event and transactions involving the Company’s common stock, among other factors. The fair value of the underlying common stock was determined by the Company’s board of directors through the date of the initial public offering. The fair value of the Company’s common stock was determined in accordance with applicable elements of the practice aid issued by the American Institute of Certified Public Accountants, Valuation of Privately Held Company Equity Securities Issued as Compensation . For awards granted subsequent to the Company’s initial public offering, the fair value of common stock is based on the closing price of the Company’s common stock, as reported on the NASDAQ, on the date of grant. Expected volatility. The Company determines the expected volatility based on historical average volatilities of similar publicly-traded companies corresponding to the expected term of the awards. The Company determines expected volatility for the Employee Stock Purchase Plan (“ESPP”) based on the historical volatility of its common stock. Expected term. The Company determines the expected term of awards which contain service-only vesting conditions using the simplified approach, in which the expected term of an award is presumed to be the mid-point between the vesting date and the expiration date of the award, as the Company does not have sufficient historical data relating to stock option exercises. The e xpected term for the Company’s ESPP represents the amount of time remaining in the 12-month offering period. Risk-free interest rate. The risk-free interest rate is based on the United States Treasury yield curve in effect during the period the options were granted corresponding to the expected term of the awards. Estimated dividend yield. The estimated dividend yield is zero, as the Company does not currently intend to declare dividends in the foreseeable future. The following information represents the weighted average of the assumptions used in the Black-Scholes option-pricing model for stock options granted: Year Ended December 31, 2018 2017 2016 Expected term (years) 6.1 6.2 6.3 Expected volatility 46.0 % 47.0 % 47.5 % Risk free interest rate 2.8 % 2.1 % 1.4 % Expected dividends — — —
Income Taxes	Income taxes The Company accounts for income taxes in accordance with ASC 740, Income Taxes The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such positions are then measured based on the largest benefit that has a greater than 50% likelihood of being realized. The Company recognizes interest and penalties accrued with respect to uncertain tax positions, if any, in the provision for income taxes in the consolidated statements of operations.
Net Loss Per Share	Net loss per share Basic and diluted loss per share is calculated by dividing net loss by the weighted average number of shares of common stock outstanding. As the Company has net losses for the periods presented, all potentially dilutive common stock, which are comprised of stock options and warrants, are antidilutive.
Foreign Currency	Foreign currency The Company’s functional currency for its foreign subsidiaries is the U.S. Dollar (“USD”), with the exception of its BlackLine K.K. subsidiary, for which the Japanese Yen is the functional currency. The foreign exchange impacts of remeasuring the local currency of the foreign subsidiaries to the functional currency is recorded in general and administrative expenses in the Company’s consolidated statements of operations. Monetary assets and liabilities of foreign operations are remeasured at balance sheet date exchange rates, non-monetary assets and liabilities and equity are remeasured at the historical exchange rates, while results of operations are remeasured at average exchange rates in effect for the period. Foreign currency transaction gains (losses) totaled $(0.1) million, $0.6 million, and $(28,000) for the years ended December 31, 2018, 2017, and 2016, respectively. The financial statements of BlackLine K.K. are translated to USD using balance sheet date exchange rates for monetary assets and liabilities, historical rates of exchange for non-monetary assets and liabilities and equity, and average exchange rates in the period for revenues and expenses. Translation gains and losses are recorded in accumulated other comprehensive income (loss) as a component of stockholders’ equity in the consolidated balance sheets.
Recent- Accounting Pronouncements	Recent accounting pronouncements Recently issued accounting pronouncements not yet adopted In February 2016, the Financial Accounting Standards Board (“FASB”) issued guidance that significantly changes the accounting for leases. The guidance requires that a lessee recognize in the balance sheet a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight-line basis over the lease term. For income statement purposes, the new guidance retained a dual model, requiring leases to be classified as either operating or financing. Operating leases will result in straight-line expense while finance leases will result in a front-loaded expense pattern similar to existing capital lease guidance. For statement of cash flow purposes, the new guidance also retained the existing dual method, where cash payments for operating leases are reflected in cash flows from operating activities and principal and interest payments for finance leases are reflected in cash flows from financing activities and cash flows from operating activities, respectively. The new guidance is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. Although the Company is evaluating the impact of adopting this guidance on its consolidated financial statements, the Company expects that most of its operating lease commitments will be recognized as operating lease liabilities and right-of-use assets upon adoption of the new guidance. The Company’s operating leases primarily include real estate (office space), equipment, and data centers. Capital leases are not material. The Company will elect a number of practical expedients allowed under the guidance, including not reassessing lease identification, lease classification or initial direct costs for existing leases as of the adoption date. The Company will adopt the guidance as of January 1, 2019, and comparative periods will not be adjusted. The Company is implementing changes to internal controls to enable the preparation of financial information. The Company expects the adoption of the new accounting guidance to have a material impact on its consolidated balance sheet. In June 2016, the FASB issued guidance which requires that financial assets measured at amortized cost be presented at the net amount expected to be collected. This guidance amends the accounting for credit losses for available-for-sale securities and purchased financial assets with credit deterioration. This guidance is effective for annual periods beginning after December 15, 2019, and interim periods within those annual periods. Early adoption is permitted for any interim or annual period after December 15, 2018. The Company has not determined the impact of this guidance on its consolidated financial statements. In February 2018, the FASB issued an Accounting Standard Update (“ASU”) that provides companies with an option to reclassify stranded tax effects resulting from enactment of the Tax Cuts and Jobs Act (the "Tax Act") from accumulated other comprehensive income to retained earnings. The guidance will be effective for the Company beginning in the first quarter of 2019 with early adoption permitted and would be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the tax rate as a result of the Tax Act is recognized. The Company does not expect the adoption of this ASU to have a material impact on its consolidated financial statements. In June 2018, the FASB issued guidance which expands the scope of Accounting Standards Codification Topic 718, Compensation—Stock Compensation In August 2018, the FASB issued guidance which aligns the accounting for implementation costs incurred in a hosting arrangement that is a service contract with the accounting for implementation costs incurred to develop or obtain internal-use software under ASC 350-40, in order to determine which costs to capitalize and recognize as an asset. The guidance will be effective for the Company for annual reporting periods, and interim periods within those years, beginning after December 15, 2019, and can be applied either prospectively to implementation costs incurred after the date of adoption or retrospectively to all arrangements. The Company does not expect the adoption of this ASU to have a material impact on its consolidated financial statements. In August 2018, the FASB issued guidance which modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement Conceptual Framework for Financial Reporting—Chapter 8: Notes to Financial Statements Recently adopted accounting pronouncements In May 2014, the FASB issued guidance related to revenue from contracts with customers. Under this guidance, revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received 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 Company adopted the new revenue guidance effective January 1, 2018 using the full retrospective method to restate each prior reporting period presented. The most significant impact of the standard relates to the Company’s accounting for the incremental costs of obtaining a contract, such as sales commissions. Under the new revenue standard, commissions are recognized over an estimated period of benefit of five years rather than over the non-cancelable contract term. The standard also impacted the Company’s accounting for on-premise solutions which includes software license, maintenance and support fees on Runbook solutions. Under the new guidance, the Company recognizes software license revenue at the time of delivery rather than over the maintenance term. Revenue recognition related to subscription, support, and professional services fees for access to the Company’s SaaS platform is substantially unchanged. Adoption of the standard using the full retrospective method required the Company to restate certain previously reported results; see Note 3 – “Revenues” for additional information regarding the impacts to previously reported results. In November 2016, the FASB issued guidance which requires that restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning and ending total amounts shown on the statement of cash flows. The Company adopted this guidance effective January 1, 2018, and all prior periods have been restated, as required by the new standard. In February 2017, the FASB issued guidance which simplifies the subsequent measurement of goodwill by no longer requiring an entity to determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination. Under this new guidance, an entity would perform its goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and would recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized would not exceed the total amount of goodwill allocated to that reporting unit. Additionally, an entity would consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. Under the new guidance, an entity continues to have the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. This guidance is effective for fiscal years beginning after December 15, 2019 and interim periods within those years. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company adopted this standard effective January 1, 2018, and the adoption of this standard did not have a material impact on the Company’s consolidated financial statements. In May 2017, the FASB issued guidance to clarify which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. Under this guidance an entity should account for the effects of a modification unless all the following are met: 1) The fair value of the modified award is the same as the fair value of the original award immediately before the original award is modified. If the modification does not affect any of the inputs to the valuation technique that the entity uses to value the award, the entity is not required to estimate the value immediately before and after the modification; 2) The vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified; and 3) The classification of the modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified. The Company adopted this standard effective January 1, 2018, and will apply this guidance to modifications of stock-based compensation arrangements, if any, after this date. T he adoption of this standard did not have a material impact on the Company’s consolidated financial statements.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Weighted Average Assumptions	The following information represents the weighted average of the assumptions used in the Black-Scholes option-pricing model for stock options granted: Year Ended December 31, 2018 2017 2016 Expected term (years) 6.1 6.2 6.3 Expected volatility 46.0 % 47.0 % 47.5 % Risk free interest rate 2.8 % 2.1 % 1.4 % Expected dividends — — — The fair value of employee stock purchase plan shares granted was estimated using the Black-Scholes option pricing model with the following weighted-average assumptions: Year Ended December 31, 2018 Risk-free interest rate 2.6 % Expected term (in years) 0.7 Volatility 42.9 %

Revenues (Tables)

Revenues (Tables)	12 Months Ended
	Dec. 31, 2018
Schedule of Disaggregation of Revenues by Geographic Region	The following table sets forth the Company’s revenues by geographic region (in thousands): Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted United States $ 180,152 $ 141,499 $ 106,421 International 47,636 34,104 21,613 $ 227,788 $ 175,603 $ 128,034
Adoption of ASC 606
Effect of Adoption of ASC 606 on Impacts to Previously Reported Results	The following table presents the effect of the adoption of ASC 606 on the Company’s consolidated balance sheet: December 31, 2017 As Reported Adjustments As Adjusted (in thousands) Accounts receivable, net $ 61,589 $ 329 $ 61,918 Prepaid expenses and other current assets $ 19,785 $ (5,829 ) $ 13,956 Total current assets $ 193,954 $ (5,500 ) $ 188,454 Other assets $ 1,391 $ 25,429 $ 26,820 Total assets $ 440,884 $ 19,929 $ 460,813 Deferred revenue $ 106,903 $ (2,719 ) $ 104,184 Total current liabilities $ 137,039 $ (2,719 ) $ 134,320 Deferred tax liabilities, net $ 1,328 $ 415 $ 1,743 Deferred revenue, noncurrent $ 912 $ (444 ) $ 468 Total liabilities $ 146,256 $ (2,748 ) $ 143,508 Accumulated deficit $ (125,467 ) $ 22,677 $ (102,790 ) Total stockholders' equity $ 294,628 $ 22,677 $ 317,305 Total liabilities and stockholders' equity $ 440,884 $ 19,929 $ 460,813 The following table presents the effect of the adoption of ASC 606 on the Company’s consolidated statement of operations: Year Ended December 31, 2017 Year Ended December 31, 2016 As Reported Adjustments As Adjusted As Reported Adjustments As Adjusted (in thousands, except per share data) (in thousands, except per share data) Revenues Subscription and support $ 168,542 $ (1,461 ) $ 167,081 $ 117,524 $ 4,917 $ 122,441 Professional services 8,489 33 8,522 5,599 (6 ) 5,593 Total revenues $ 177,031 $ (1,428 ) $ 175,603 $ 123,123 $ 4,911 $ 128,034 Cost of revenues Subscription and support $ 33,631 $ (101 ) $ 33,530 $ 25,900 $ — $ 25,900 Total cost of revenues $ 41,486 $ (101 ) $ 41,385 $ 30,211 $ — $ 30,211 Gross profit $ 135,545 $ (1,327 ) $ 134,218 $ 92,912 $ 4,911 $ 97,823 Operating expenses Sales and marketing $ 109,775 $ (5,808 ) $ 103,967 $ 77,810 $ (5,840 ) $ 71,970 General and administrative $ 36,956 $ (170 ) $ 36,786 $ 27,911 $ — $ 27,911 Total operating expenses $ 170,605 $ (5,978 ) $ 164,627 $ 126,846 $ (5,840 ) $ 121,006 Loss from operations $ (35,060 ) $ 4,651 $ (30,409 ) $ (33,934 ) $ 10,751 $ (23,183 ) Loss before income taxes $ (37,494 ) $ 4,651 $ (32,843 ) $ (45,746 ) $ 10,751 $ (34,995 ) Provision for (benefit from) income taxes $ 567 $ (359 ) $ 208 $ (6,587 ) $ (2,071 ) $ (8,658 ) Net loss $ (38,061 ) $ 5,010 $ (33,051 ) $ (39,159 ) $ 12,822 $ (26,337 ) Basic net loss per share $ (0.73 ) $ 0.10 $ (0.63 ) $ (0.92 ) $ 0.30 $ (0.62 ) Diluted net loss per share $ (0.73 ) $ 0.10 $ (0.63 ) $ (0.92 ) $ 0.30 $ (0.62 ) The following table presents the effect of the adoption of ASC 606 on the Company’s consolidated statement of cash flows: Year Ended December 31, 2017 Year Ended December 31, 2016 As Reported Adjustments As Adjusted As Reported Adjustments As Adjusted (in thousands) (in thousands) Net loss attributable to BlackLine, Inc. $ (38,061 ) $ 5,010 $ (33,051 ) $ (39,159 ) $ 12,822 $ (26,337 ) Deferred income taxes $ 66 $ (338 ) $ (272 ) $ (7,432 ) $ (2,035 ) $ (9,467 ) Accounts receivable $ (19,860 ) $ (329 ) $ (20,189 ) $ (15,541 ) $ — $ (15,541 ) Prepaid expenses and other current assets $ (3,104 ) $ 1,069 $ (2,035 ) $ (6,516 ) $ 1,302 $ (5,214 ) Other assets $ (342 ) $ (6,834 ) $ (7,176 ) $ (201 ) $ (7,233 ) $ (7,434 ) Deferred revenue $ 25,082 $ 1,422 $ 26,504 $ 29,482 $ (4,856 ) $ 24,626

Redeemable Non-Controlling In_2

Redeemable Non-Controlling Interest (Tables)	12 Months Ended
	Dec. 31, 2018
Equity Method Investments And Joint Ventures [Abstract]
Summary of Redeemable Non-Controlling Interests	The following table summarizes the activity in the redeemable non-controlling interests for the period indicated below: Balance at December 31, 2017 $ — Investment by redeemable non-controlling interest 4,317 Net loss attributable to redeemable non-controlling interest (62 ) Foreign currency translation 132 Balance at December 31, 2018 $ 4,387

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Schedule of Investments in Marketable Securities	Investments in marketable securities presented within current assets on the consolidated balance sheet consisted of the following: December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Marketable securities U.S. treasury securities $ 25,856 $ — $ (29 ) $ 25,827 Corporate bonds 32,030 — (60 ) 31,970 Commercial paper 28,599 — — 28,599 $ 86,485 $ — $ (89 ) $ 86,396 December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Marketable securities U.S. treasury securities $ 21,454 $ — $ (19 ) $ 21,435 Corporate bonds 32,437 — (43 ) 32,394 Commercial paper 25,048 — — 25,048 Asset-backed securities 2,600 — (1 ) 2,599 $ 81,539 $ — $ (63 ) $ 81,476
Summary of Amortized Cost and Fair Values of Marketable Securities, by Remaining Contractual Maturity	The amortized cost and fair values of marketable securities, by remaining contractual maturity, were as follows: December 31, 2018 Amortized Cost Fair Value (in thousands) Maturing within 1 year $ 86,485 $ 86,396 $ 86,485 $ 86,396
Summary of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): December 31, December 31, 2018 2017 Partner referral fees $ 5,219 $ 7,945 Restricted cash — 400 Other prepaid expenses and other current assets 8,823 5,611 $ 14,042 $ 13,956
Schedule of Other Assets	Other assets consisted of the following (in thousands): December 31, December 31, 2018 2017 Deferred customer contract acquisition costs $ 34,172 $ 25,338 Restricted cash 274 — Other assets 2,419 1,482 $ 36,865 $ 26,820
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, December 31, 2018 2017 Accrued salaries and employee benefits $ 17,054 $ 11,945 Accrued income and other taxes payable 4,547 1,798 Short-term tenant improvement allowance 475 475 Partner referral fees — 2,991 Short-term portion of capital lease — 443 Other accrued expenses and current liabilities 2,629 3,222 $ 24,705 $ 20,874

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table summarizes the Company’s financial assets and liabilities measured at fair value on a recurring basis by level, within the fair value hierarchy. Financial assets and financial liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement (in thousands): December 31, 2018 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 32,021 $ — $ — $ 32,021 Marketable securities U.S. treasury securities 25,827 — — 25,827 Corporate bonds — 31,970 — 31,970 Commercial paper — 28,599 — 28,599 Total assets $ 57,848 $ 60,569 $ — $ 118,417 Liabilities Contingent consideration $ — $ — $ 6,316 $ 6,316 Total liabilities $ — $ — $ 6,316 $ 6,316 December 31, 2017 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 21,247 $ — $ — $ 21,247 Marketable securities U.S. treasury securities 21,435 — — 21,435 Corporate bonds — 32,394 — 32,394 Commercial paper — 25,048 — 25,048 Asset-backed securities — 2,599 — 2,599 Total assets $ 42,682 $ 60,041 $ — $ 102,723 Liabilities Contingent consideration $ — $ — $ 5,866 $ 5,866 Total liabilities $ — $ — $ 5,866 $ 5,866
Common Stock Warrant Liability
Summary of Changes in Common Stock Warrant Liability and Contingent Consideration Liability	The following table summarizes the changes in the common stock warrant liability (in thousands): Year Ended December 31, 2017 2016 Beginning fair value $ 11,380 $ 5,500 Change in fair value 3,490 5,880 Exercise of stock warrants (14,870 ) — Ending fair value $ — $ 11,380
Contingent Consideration
Summary of Changes in Common Stock Warrant Liability and Contingent Consideration Liability	The following table summarizes the changes in the contingent consideration liability (in thousands): Year Ended December 31, 2018 2017 2016 Beginning fair value $ 5,866 $ 5,238 $ 4,867 Change in fair value 450 628 371 Ending fair value $ 6,316 $ 5,866 $ 5,238

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following (in thousands): December 31, 2018 2017 Computers and equipment $ 6,598 $ 4,919 Purchased software 7,356 4,934 Furniture and fixtures 2,571 2,204 Leasehold improvements 10,077 9,075 Construction in progress — 180 26,602 21,312 Less: accumulated depreciation and amortization (13,066 ) (8,543 ) $ 13,536 $ 12,769

Intangible Assets and Goodwill

Intangible Assets and Goodwill (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Carrying Value of Intangible Assets	The carrying value of intangible assets was as follows (in thousands): December 31, 2018 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Trade name $ 15,977 $ (8,528 ) $ 7,449 Developed technology 42,558 (34,472 ) 8,086 Customer relationships 31,783 (19,533 ) 12,250 $ 90,318 $ (62,533 ) $ 27,785 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Trade name $ 15,977 $ (6,930 ) $ 9,047 Developed technology 42,558 (27,577 ) 14,981 Non-compete agreements 4,520 (3,882 ) 638 Customer relationships 31,783 (15,641 ) 16,142 $ 94,838 $ (54,030 ) $ 40,808
Amortization Expense by Operation Expense Categories	Amortization expense is included in the following functional statements of operations expense categories. Amortization expense was as follows (in thousands): Year Ended December 31, 2018 2017 2016 Cost of revenues $ 6,863 $ 6,847 $ 6,368 Sales and marketing 3,887 3,872 3,605 General and administrative 2,273 2,591 2,532 $ 13,023 $ 13,310 $ 12,505
Summary of Estimated Amortization Expense	The following table presents the Company’s estimate of remaining amortization expense for each of the five succeeding fiscal years and thereafter for finite-lived intangible assets at December 31, 2018 (in thousands): 2019 $ 10,266 2020 6,173 2021 5,010 2022 2,686 2023 2,154 Thereafter 1,496 $ 27,785

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Components of Income (Loss) Before Income Taxes	The components of income (loss) before income taxes were as follows (in thousands): Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted United States $ (27,289 ) $ (30,690 ) $ (38,355 ) International (415 ) (2,153 ) 3,360 $ (27,704 ) $ (32,843 ) $ (34,995 )
Components of Total Provision for Benefit from Income Taxes	The components of the total provision for (benefit from) income taxes were as follows (in thousands): Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted Current Federal $ — $ — $ — State 24 51 5 Foreign 1,061 450 840 Total current tax expense 1,085 501 845 Deferred Federal — — (8,680 ) State — — (395 ) Foreign (923 ) (293 ) (428 ) Total deferred tax provision (benefit) (923 ) (293 ) (9,503 ) Total provision for (benefit from) income taxes $ 162 $ 208 $ (8,658 )
Reconciliation of Statutory U.S. Federal Tax Rate to Effective Tax Rate	A reconciliation of the statutory U.S. federal income tax rate to the Company’s effective tax rate for the years ended December 31, 2018, 2017, and 2016 was as follows: Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted Federal statutory income tax rate 21.0 % 34.0 % 34.0 % State tax, net of federal benefit (0.1 %) (0.1 %) 0.7 % Federal tax credits 7.1 % 3.3 % 1.6 % Change in valuation allowance (63.1 %) (13.6 %) (5.0 %) Common stock warrants — (3.7 %) (5.8 %) Foreign tax differential (2.3 %) (2.4 %) — Windfall tax benefits, net related to stock-based compensation 40.2 % 15.3 % — Effect of rate and other changes on federal deferred taxes, net due to enactment of Tax Cuts and Jobs Act — (30.0 %) — Nondeductible officer compensation (1.8 %) — — Nondeductible meals and entertainment (1.7 %) — — Other 0.1 % (3.4 %) (0.8 %) (0.6 %) (0.6 %) 24.7 %
Significant Components of Deferred Tax Assets and Liabilities	Significant components of the Company’s deferred tax assets and liabilities were as follows (in thousands): December 31, December 31, 2018 2017 *As Adjusted Deferred tax assets Net operating loss carryforwards $ 43,106 $ 29,607 Business credits 8,487 5,197 Stock-based compensation 6,321 3,961 Accrued expenses and other current liabilities 2,910 1,462 Other 1,963 1,389 Total deferred tax assets 62,787 41,616 Less: valuation allowance (45,579 ) (23,904 ) Deferred tax assets, net of valuation allowance 17,208 17,712 Deferred tax liabilities Intangible assets (8,735 ) (11,287 ) Prepaid expenses (8,400 ) (6,376 ) Property and equipment (802 ) (1,589 ) Other — (112 ) Total deferred tax liabilities (17,937 ) (19,364 ) Net deferred taxes $ (729 ) $ (1,652 )
Summary of Changes in Valuation Allowance	The changes in the valuation allowance were as follows (in thousands). Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted Valuation allowance, at beginning of year $ 23,904 $ 2,674 $ 887 Increase in valuation allowance recorded through earnings 21,675 7,332 1,787 Increase in valuation allowance as result of adoption of ASU 2016-09 — 13,898 — Valuation allowance, at end of year $ 45,579 $ 23,904 $ 2,674
Rollforward of Total Gross Unrecognized Tax Benefits	The following is a rollforward of the Company’s total gross unrecognized tax benefits (in thousands): Year Ended December 31, 2018 2017 2016 Beginning gross unrecognized tax benefits $ 672 $ 382 $ 278 Increases related to prior year tax positions 130 38 — Increases related to current year tax positions 421 252 104 Ending gross unrecognized tax benefits $ 1,223 $ 672 $ 382

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Loss per Share	The following table sets forth the computation of basic and diluted net loss per share (in thousands, except per share amounts): Year Ended December 31, 2018 2017 2016 *As Adjusted *As Adjusted Numerator: Net loss attributable to BlackLine, Inc. $ (27,804 ) $ (33,051 ) $ (26,337 ) Denominator: Weighted average shares 53,912 52,161 42,497 Add: Dilutive effect of securities — — — Shares used to calculate diluted net loss per share 53,912 52,161 42,497 Basic net loss per share attributable to BlackLine, Inc. $ (0.52 ) $ (0.63 ) $ (0.62 ) Diluted net loss per share attributable to BlackLine, Inc. $ (0.52 ) $ (0.63 ) $ (0.62 )
Schedule of Potentially Dilutive Shares Excluded From Calculation of Diluted Net Loss Per Share Attributable to Common Stockholders	The following potentially dilutive shares were excluded from the calculation of diluted net loss per share attributable to common stockholders because they were anti-dilutive: Year Ended December 31, 2018 2017 2016 Stock options with service-only vesting conditions 3,820 5,019 5,874 Stock options with performance conditions 683 683 683 Restricted stock units 1,300 2 — Common stock warrants — — 500 Total shares excluded from net loss per share 5,803 5,704 7,057

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Leases	Future minimum lease payments under non-cancelable operating leases at December 31, 2018 was (in thousands): 2019 $ 7,059 2020 5,307 2021 3,786 2022 2,586 2023 2,638 Thereafter 237 $ 21,613

Equity Awards (Tables)

Equity Awards (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	A summary of the Company’s stock option activity and related information for awards that contain service-only vesting conditions was as follows: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (in thousands) (in years) (in thousands) Outstanding at December 31, 2017 5,019 $ 13.90 7.5 $ 95,353 Granted 845 $ 42.06 Exercised (1,788 ) $ 8.39 Forfeited/canceled (256 ) $ 26.64 Outstanding at December 31, 2018 3,820 $ 21.85 7.5 $ 75,287 Exercisable at December 31, 2018 1,729 $ 13.11 6.4 $ 48,136
Summary of Restricted Stock Units Activity	The following table summarizes activity for restricted stock units: Weighted-Average Restricted Grant Date Stock Units Fair Value (in thousands) Nonvested at December 31, 2017 2 $ 34.12 Granted 1,372 $ 42.38 Vested (2 ) $ 34.46 Forfeited/canceled (72 ) $ 44.09 Nonvested at December 31, 2018 1,300 $ 42.29
Schedule of Weighted Average Assumptions	The following information represents the weighted average of the assumptions used in the Black-Scholes option-pricing model for stock options granted: Year Ended December 31, 2018 2017 2016 Expected term (years) 6.1 6.2 6.3 Expected volatility 46.0 % 47.0 % 47.5 % Risk free interest rate 2.8 % 2.1 % 1.4 % Expected dividends — — — The fair value of employee stock purchase plan shares granted was estimated using the Black-Scholes option pricing model with the following weighted-average assumptions: Year Ended December 31, 2018 Risk-free interest rate 2.6 % Expected term (in years) 0.7 Volatility 42.9 %
Summary of Stock-Based Compensation Expense	Stock-based compensation expense recorded in the Company’s consolidated statements of operations was as follows (in thousands): Year Ended December 31, 2018 2017 2016 Cost of revenues $ 3,265 $ 1,149 $ 715 Sales and marketing 8,674 10,811 2,490 Research and development 2,570 767 809 General and administrative 6,386 3,317 2,512 $ 20,895 $ 16,044 $ 6,526

Geographic Information (Tables)

Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Long-lived Assets Consist of Property and Equipment, Net by Geographic Region	The following table sets forth the Company’s long-lived assets, which consist of property and equipment, net by geographic region (in thousands): Year Ended December 31, 2018 2017 United States $ 12,407 $ 12,210 International 1,129 559 $ 13,536 $ 12,769

Unaudited Quarterly Data (Table

Unaudited Quarterly Data (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Summary of Unaudited Quarterly Consolidated Statements of Operations	The following table sets forth unaudited quarterly consolidated statements of operations data for each of the quarters in the years ended December 31, 2018 and 2017. The Company has prepared the unaudited quarterly consolidated statements of operations data on a basis consistent with the audited annual consolidated financial statements. In the opinion of management, the financial information in this table reflects all adjustments, consisting of normal and recurring adjustments, necessary for the fair statement of this data. Quarter Ended 2018 2017 December 31, September 30, June 30, March 31, December 31, September 30, June 30, March 31, *As Adjusted *As Adjusted *As Adjusted *As Adjusted Revenues $ 62,316 $ 58,734 $ 55,454 $ 51,284 $ 50,017 $ 45,424 $ 41,981 $ 38,181 Gross profit $ 48,431 $ 45,217 $ 43,588 $ 39,678 $ 39,070 $ 34,553 $ 31,624 $ 28,971 Net loss $ (7,794 ) $ (4,460 ) $ (8,457 ) $ (7,155 ) $ (4,166 ) $ (12,074 ) $ (9,126 ) $ (7,685 ) Net loss attributable to redeemable non-controlling interest $ (62 ) $ — $ — $ — $ — $ — $ — $ — Net loss attributable to BlackLine, Inc. $ (7,732 ) $ (4,460 ) $ (8,457 ) $ (7,155 ) $ (4,166 ) $ (12,074 ) $ (9,126 ) $ (7,685 ) Basic net loss per share attributable to BlackLine, Inc. $ (0.14 ) $ (0.08 ) $ (0.16 ) $ (0.13 ) $ (0.08 ) $ (0.23 ) $ (0.18 ) $ (0.15 ) Diluted net loss per share attributable to BlackLine, Inc. $ (0.14 ) $ (0.08 ) $ (0.16 ) $ (0.13 ) $ (0.08 ) $ (0.23 ) $ (0.18 ) $ (0.15 )

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details)		Oct. 12, 2016	May 31, 2017shares	Dec. 31, 2018USD ($)SegmentCustomerRepoting_unit	Dec. 31, 2017USD ($)Customershares	Dec. 31, 2016USD ($)Customer
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Reverse stock split description				1-for-5 reverse stock split
Reverse stock split ratio		0.2
Number of operating segments | Segment				1
Restricted cash included in prepaid expenses and other current assets	[1]				$ 400,000
Restricted cash included in other assets				$ 274,000		$ 400,000	[1]
Capitalized computer software, amortization				3,900,000	2,700,000	1,800,000
Capitalized computer software, accumulated amortization				$ 9,500,000	5,600,000
Number of Reporting Units | Repoting_unit				1
Asset impairment charges				$ 0	0	0
Subscription fees payable, description				Customers pay subscription and support fees for access to the Company’s SaaS platform generally for a one-year period. In more limited cases, customers may pay for up to three years in advance. Fees are based on a number of factors, including the solutions subscribed for by the customer and the number of users having access to the solutions.
SaaS platform subscription fee, period				1 year
SaaS platform subscription fee, maximum advance period				3 years
Deferred revenue recognized				$ 104,200,000	78,200,000	52,900,000
Contracted not recognized revenue				$ 285,000,000
Contracted not recognized revenue, expects to recognize revenue over next 12 months				62.00%
Contract capitalized cost, amortized method				straight line
Impairment losses in relation to costs capitalized				$ 0
Advertising cost expense				$ 8,000,000	7,700,000	4,200,000
Stock-based compensation award vesting period				4 years
Estimated dividend yield				0.00%
Foreign currency transaction gains (losses)				$ (100,000)	600,000	(28,000)
Sales and Marketing Expenses
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Amortization expense				$ 23,600,000	$ 15,600,000	$ 9,800,000
Common Stock
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Warrants to purchase of common stock | shares			499,999
Issuance of common stock | shares			428,033		428,000
Computer Software Development Costs
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Estimated useful life				3 years
Revenues
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Number of single customers comprising 10% or more | Customer				0	0	0
Accounts Receivable
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Number of single customers comprising 10% or more | Customer				0	0
Minimum
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Estimated useful life				1 year
Maximum
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Estimated useful life				10 years
Machinery and Equipment | Minimum
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life				3 years
Machinery and Equipment | Maximum
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life				5 years
Purchased Software | Minimum
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life				3 years
Purchased Software | Maximum
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life				5 years
Furniture and Fixtures
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life				5 years
Leasehold Improvements
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				lease term or seven years
[1]	See Note 3 for a summary of adjustments.

Significant Accounting Polici_5

Significant Accounting Policies - Schedule of Weighted Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Expected term (years)	6 years 1 month 6 days	6 years 2 months 12 days	6 years 3 months 18 days
Expected volatility	46.00%	47.00%	47.50%
Risk free interest rate	2.80%	2.10%	1.40%
Expected dividends	0.00%

Revenues - Effect of Adoption o

Revenues - Effect of Adoption of ASC 606 on Impacts to Previously Reported Results - Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Balance Sheet Statements Captions [Line Items]
Accounts receivable, net	$ 74,902	$ 61,918
Prepaid expenses and other current assets	14,042	13,956
Total current assets	221,521	188,454
Other assets	36,865	26,820
Total assets	493,868	460,813
Deferred revenue	129,074	104,184
Total current liabilities	159,229	134,320
Deferred tax liabilities, net	1,116	1,743
Deferred revenue, noncurrent	277	468
Total liabilities	167,912	143,508
Accumulated deficit	(130,594)	(102,790)
Total stockholders' equity	321,569	317,305	$ 309,077	$ 171,013
Total liabilities and stockholders' equity	$ 493,868	460,813
Adoption of ASC 606 | As Reported
Condensed Balance Sheet Statements Captions [Line Items]
Accounts receivable, net		61,589
Prepaid expenses and other current assets		19,785
Total current assets		193,954
Other assets		1,391
Total assets		440,884
Deferred revenue		106,903
Total current liabilities		137,039
Deferred tax liabilities, net		1,328
Deferred revenue, noncurrent		912
Total liabilities		146,256
Accumulated deficit		(125,467)
Total stockholders' equity		294,628
Total liabilities and stockholders' equity		440,884
Adoption of ASC 606 | Adjustments
Condensed Balance Sheet Statements Captions [Line Items]
Accounts receivable, net		329
Prepaid expenses and other current assets		(5,829)
Total current assets		(5,500)
Other assets		25,429
Total assets		19,929
Deferred revenue		(2,719)
Total current liabilities		(2,719)
Deferred tax liabilities, net		415
Deferred revenue, noncurrent		(444)
Total liabilities		(2,748)
Accumulated deficit		22,677
Total stockholders' equity		22,677
Total liabilities and stockholders' equity		$ 19,929

Revenues - Effect of Adoption_2

Revenues - Effect of Adoption of ASC 606 on Impacts to Previously Reported Results - Consolidated Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Revenues
Total revenues	$ 62,316	$ 58,734	$ 55,454	$ 51,284	$ 50,017	$ 45,424	$ 41,981	$ 38,181	$ 227,788	$ 175,603	[1]	$ 128,034	[1]
Cost of revenues
Total cost of revenues									50,874	41,385	[1]	30,211	[1]
Gross profit	48,431	45,217	43,588	39,678	39,070	34,553	31,624	28,971	176,914	134,218	[1]	97,823	[1]
Operating expenses
Sales and marketing									128,808	103,967	[1]	71,970	[1]
General and administrative									47,188	36,786	[1]	27,911	[1]
Total operating expenses									206,750	164,627	[1]	121,006	[1]
Loss from operations									(29,836)	(30,409)	[1]	(23,183)	[1]
Loss before income taxes									(27,704)	(32,843)	[1]	(34,995)	[1]
Provision for (benefit from) income taxes									162	208	[1]	(8,658)	[1]
Net loss	$ (7,794)	$ (4,460)	$ (8,457)	$ (7,155)	$ (4,166)	$ (12,074)	$ (9,126)	$ (7,685)	$ (27,866)	$ (33,051)	[1]	$ (26,337)	[1]
Basic net loss per share	$ (0.14)	$ (0.08)	$ (0.16)	$ (0.13)	$ (0.08)	$ (0.23)	$ (0.18)	$ (0.15)	$ (0.52)	$ (0.63)	[1]	$ (0.62)	[1]
Diluted net loss per share	$ (0.14)	$ (0.08)	$ (0.16)	$ (0.13)	$ (0.08)	$ (0.23)	$ (0.18)	$ (0.15)	$ (0.52)	$ (0.63)	[1]	$ (0.62)	[1]
Subscription and Support
Revenues
Total revenues									$ 217,406	$ 167,081	[1]	$ 122,441	[1]
Cost of revenues
Total cost of revenues									41,428	33,530	[1]	25,900	[1]
Professional Services
Revenues
Total revenues									10,382	8,522	[1]	5,593	[1]
Cost of revenues
Total cost of revenues									$ 9,446	7,855	[1]	4,311	[1]
Adoption of ASC 606 | As Reported
Revenues
Total revenues										177,031		123,123
Cost of revenues
Total cost of revenues										41,486		30,211
Gross profit										135,545		92,912
Operating expenses
Sales and marketing										109,775		77,810
General and administrative										36,956		27,911
Total operating expenses										170,605		126,846
Loss from operations										(35,060)		(33,934)
Loss before income taxes										(37,494)		(45,746)
Provision for (benefit from) income taxes										567		(6,587)
Net loss										$ (38,061)		$ (39,159)
Basic net loss per share										$ (0.73)		$ (0.92)
Diluted net loss per share										$ (0.73)		$ (0.92)
Adoption of ASC 606 | Adjustments
Revenues
Total revenues										$ (1,428)		$ 4,911
Cost of revenues
Total cost of revenues										(101)
Gross profit										(1,327)		4,911
Operating expenses
Sales and marketing										(5,808)		(5,840)
General and administrative										(170)
Total operating expenses										(5,978)		(5,840)
Loss from operations										4,651		10,751
Loss before income taxes										4,651		10,751
Provision for (benefit from) income taxes										(359)		(2,071)
Net loss										$ 5,010		$ 12,822
Basic net loss per share										$ 0.10		$ 0.30
Diluted net loss per share										$ 0.10		$ 0.30
Adoption of ASC 606 | Subscription and Support | As Reported
Revenues
Total revenues										$ 168,542		$ 117,524
Cost of revenues
Total cost of revenues										33,631		25,900
Adoption of ASC 606 | Subscription and Support | Adjustments
Revenues
Total revenues										(1,461)		4,917
Cost of revenues
Total cost of revenues										(101)
Adoption of ASC 606 | Professional Services | As Reported
Revenues
Total revenues										8,489		5,599
Adoption of ASC 606 | Professional Services | Adjustments
Revenues
Total revenues										$ 33		$ (6)
[1]	See Note 3 for a summary of adjustments.

Revenues - Effect of Adoption_3

Revenues - Effect of Adoption of ASC 606 on Impacts to Previously Reported Results - Consolidated Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Condensed Cash Flow Statements Captions [Line Items]
Net loss attributable to BlackLine, Inc.	$ (7,732)	$ (4,460)	$ (8,457)	$ (7,155)	$ (4,166)	$ (12,074)	$ (9,126)	$ (7,685)	$ (27,804)	$ (33,051)	[1]	$ (26,337)	[1]
Deferred income taxes									(923)	(272)	[1]	(9,467)	[1]
Accounts receivable									(13,207)	(20,189)	[1]	(15,541)	[1]
Prepaid expenses and other current assets									(449)	(2,035)	[1]	(5,214)	[1]
Other assets									(9,475)	(7,176)	[1]	(7,434)	[1]
Deferred revenue									$ 24,699	26,504	[1]	24,626	[1]
Adoption of ASC 606 | As Reported
Condensed Cash Flow Statements Captions [Line Items]
Net loss attributable to BlackLine, Inc.										(38,061)		(39,159)
Deferred income taxes										66		(7,432)
Accounts receivable										(19,860)		(15,541)
Prepaid expenses and other current assets										(3,104)		(6,516)
Other assets										(342)		(201)
Deferred revenue										25,082		29,482
Adoption of ASC 606 | Adjustments
Condensed Cash Flow Statements Captions [Line Items]
Net loss attributable to BlackLine, Inc.										5,010		12,822
Deferred income taxes										(338)		(2,035)
Accounts receivable										(329)
Prepaid expenses and other current assets										1,069		1,302
Other assets										(6,834)		(7,233)
Deferred revenue										$ 1,422		$ (4,856)
[1]	See Note 3 for a summary of adjustments.

Revenues - Schedule of Disaggre

Revenues - Schedule of Disaggregation of Revenues by Geographic Region (Details) - USD ($) $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Disaggregation Of Revenue [Line Items]

Total revenues

$ 62,316

$ 58,734

$ 55,454

$ 51,284

$ 50,017

$ 45,424

$ 41,981

$ 38,181

$ 227,788

$ 175,603

[1]

$ 128,034

[1]

United States

Disaggregation Of Revenue [Line Items]

Total revenues

180,152

141,499

106,421

International

Disaggregation Of Revenue [Line Items]

Total revenues

$ 47,636

$ 34,104

$ 21,613

[1]

See Note 3 for a summary of adjustments.

Redeemable Non-Controlling In_3

Redeemable Non-Controlling Interest - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018
Redeemable Noncontrolling Interest [Line Items]
Redeemable non-controlling interests		$ 0
BlackLine K.K.
Redeemable Noncontrolling Interest [Line Items]
Business combination, agreement date	Sep. 30, 2018
Business combination, contribution	$ 4,500
Business combination, outstanding common stock percentage	51.00%

Redeemable Non-Controlling In_4

Redeemable Non-Controlling Interest - Summary of Redeemable Non-Controlling Interests (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018
Equity Method Investments And Joint Ventures [Abstract]
Investment by redeemable non-controlling interest		$ 4,317
Net loss attributable to redeemable non-controlling interest (Note 4)	$ (62)	(62)
Foreign currency translation		132
Balance at December 31, 2018	$ 4,387	$ 4,387

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Investments in Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 86,485	$ 81,539
Gross Unrealized Losses	(89)	(63)
Fair Value	86,396	81,476
U.S. treasury securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	25,856	21,454
Gross Unrealized Losses	(29)	(19)
Fair Value	25,827	21,435
Corporate bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	32,030	32,437
Gross Unrealized Losses	(60)	(43)
Fair Value	31,970	32,394
Commercial paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	28,599	25,048
Fair Value	$ 28,599	25,048
Asset-backed securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		2,600
Gross Unrealized Losses		(1)
Fair Value		$ 2,599

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Realized gain and losses recognized	$ 0	$ 0	$ 0
Net gains and losses on maturities of marketable securities reclassified from accumulated other comprehensive loss to earnings	$ 1,000,000
Maximum
Schedule Of Available For Sale Securities [Line Items]
Marketable securities contractual maturity period	1 year

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Amortized Cost and Fair Values of Marketable Securities, by Remaining Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Maturing within 1 year	$ 86,485
Amortized Cost	86,485	$ 81,539
Maturing within 1 year	86,396
Total, Fair Value	$ 86,396

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Partner referral fees		$ 5,219	$ 7,945
Restricted cash	[1]		400
Other prepaid expenses and other current assets		8,823	5,611
Prepaid expenses and other current assets, Total		$ 14,042	$ 13,956
[1]	See Note 3 for a summary of adjustments.

Balance Sheet Components - Su_3

Balance Sheet Components - Summary of Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	[1]
Balance Sheet Related Disclosures [Abstract]
Deferred customer contract acquisition costs	$ 34,172	$ 25,338
Restricted cash	274		$ 400
Other assets	2,419	1,482
Other Assets Noncurrent	$ 36,865	$ 26,820
[1]	See Note 3 for a summary of adjustments.

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued salaries and employee benefits	$ 17,054	$ 11,945
Accrued income and other taxes payable	4,547	1,798
Short-term tenant improvement allowance	475	475
Partner referral fees		2,991
Short-term portion of capital lease		443
Other accrued expenses and current liabilities	2,629	3,222
Accrued expenses and other current liabilities	$ 24,705	$ 20,874

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	$ 118,417	$ 102,723
Liabilities
Contingent consideration	6,316	5,866
Total liabilities	6,316	5,866
Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	32,021	21,247
U.S. treasury securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	25,827	21,435
Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	31,970	32,394
Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	28,599	25,048
Asset-backed securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		2,599
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	57,848	42,682
Level 1 | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	32,021	21,247
Level 1 | U.S. treasury securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	25,827	21,435
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	60,569	60,041
Level 2 | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	31,970	32,394
Level 2 | Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	28,599	25,048
Level 2 | Asset-backed securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		2,599
Level 3
Liabilities
Contingent consideration	6,316	5,866
Total liabilities	$ 6,316	$ 5,866

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Changes in Common Stock Warrant Liability (Details) - Common Stock Warrant Liability - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Beginning fair value	$ 11,380	$ 5,500
Change in fair value	3,490	5,880
Exercise of stock warrants	$ (14,870)
Ending fair value		$ 11,380

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - Common Stock - shares	1 Months Ended	12 Months Ended
	May 31, 2017	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants to purchase of common stock	499,999
Issuance of common stock	428,033	428,000

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of Changes in Contingent Consideration Liability (Details) - Contingent Consideration - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Beginning fair value	$ 5,866	$ 5,238	$ 4,867
Change in fair value	450	628	371
Ending fair value	$ 6,316	$ 5,866	$ 5,238

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 26,602	$ 21,312
Less: accumulated depreciation and amortization	(13,066)	(8,543)
Property and equipment, net	13,536	12,769
Computers and equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,598	4,919
Purchased software
Property Plant And Equipment [Line Items]
Property and equipment, gross	7,356	4,934
Furniture and fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,571	2,204
Leasehold improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 10,077	9,075
Construction in progress
Property Plant And Equipment [Line Items]
Property and equipment, gross		$ 180

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Property Plant And Equipment [Line Items]
Depreciation and amortization expense related to property and equipment	$ 22,336	$ 19,971	[1]	$ 17,424	[1]
Software and Construction in Progress
Property Plant And Equipment [Line Items]
Assets held under capital lease	1,600	1,600
Assets held under capital lease, accumulated amortization	1,500	1,000
Property and Equipment
Property Plant And Equipment [Line Items]
Depreciation and amortization expense related to property and equipment	$ 5,400	$ 4,000		$ 3,100
[1]	See Note 3 for a summary of adjustments.

Business Combinations - Additio

Business Combinations - Additional Information (Details) - Runbook Company B.V. - USD ($) $ in Millions	Aug. 31, 2016	Dec. 31, 2018	Dec. 31, 2016
Business Acquisition [Line Items]
Date of acquisition		Aug. 31, 2016
Total purchase consideration	$ 34.1
Escrow amount	$ 3.1
Escrow deposit maturity, description		The purchase consideration is subject to a final working capital adjustment, which has not yet been finalized. Any adjustment will be recorded in the consolidated statement of operations in the period of settlement. A portion of the purchase price totaling $3.1 million was paid into escrow for indemnification obligations relating to potential breach of representations and warranties of the sellers. Any amounts remaining in escrow after satisfaction of any resolved claims will be released from escrow.
Acquisition related costs			$ 1.6

Intangible Assets and Goodwil_2

Intangible Assets and Goodwill - Summary of Carrying Value of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 90,318	$ 94,838
Accumulated Amortization	(62,533)	(54,030)
Net Carrying Amount	27,785	40,808
Trade name
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	15,977	15,977
Accumulated Amortization	(8,528)	(6,930)
Net Carrying Amount	7,449	9,047
Developed technology
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	42,558	42,558
Accumulated Amortization	(34,472)	(27,577)
Net Carrying Amount	8,086	14,981
Non-compete agreements
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		4,520
Accumulated Amortization		(3,882)
Net Carrying Amount		638
Customer relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	31,783	31,783
Accumulated Amortization	(19,533)	(15,641)
Net Carrying Amount	$ 12,250	$ 16,142

Intangible Assets and Goodwil_3

Intangible Assets and Goodwill - Additional Information (Details) - Non-compete Agreements - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Intangible assets write offs	$ 4,500,000
Changes in carrying amount of goodwill	$ 0	$ 0	$ 0

Intangible Assets and Goodwil_4

Intangible Assets and Goodwill - Amortization Expense by Operation Expense Categories (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Amortization expenses	$ 13,023	$ 13,310	$ 12,505
Cost of Revenue
Finite Lived Intangible Assets [Line Items]
Amortization expenses	6,863	6,847	6,368
Sales and Marketing
Finite Lived Intangible Assets [Line Items]
Amortization expenses	3,887	3,872	3,605
General and Administrative
Finite Lived Intangible Assets [Line Items]
Amortization expenses	$ 2,273	$ 2,591	$ 2,532

Intangible Assets and Goodwil_5

Intangible Assets and Goodwill - Summary of Estimated Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
2,019	$ 10,266
2,020	6,173
2,021	5,010
2,022	2,686
2,023	2,154
Thereafter	1,496
Net Carrying Amount	$ 27,785	$ 40,808

Term Loan - Additional Informat

Term Loan - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended			12 Months Ended
	May 31, 2017	Nov. 30, 2016	Sep. 30, 2013	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Aug. 31, 2016	Mar. 31, 2016
Debt Instrument [Line Items]
Repayments of debt		$ 67.7
Payment of paid in kind interest						$ 6.4
Common Stock
Debt Instrument [Line Items]
Warrants to purchase of common stock	499,999
Issuance of common stock	428,033				428,000
Term Loan
Debt Instrument [Line Items]
Term loan amount			$ 25
Term Loan | Common stock warrants
Debt Instrument [Line Items]
Warrants issued during period			499,999
Exercise price per share of warrants			$ 5
Expiry term of warrants exercise				ten years from the issuance date or the sale of the Company
Term Loan | Common stock warrants | Maximum
Debt Instrument [Line Items]
Warrants expiry period			10 years
2016 Incremental Term Loan
Debt Instrument [Line Items]
Credit facility additional amount to carrying value								$ 5
2016 Acquisition Term Loan
Debt Instrument [Line Items]
Credit facility additional amount to carrying value							$ 30

Income Taxes - Components of In

Income Taxes - Components of Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Income Tax Disclosure [Abstract]
United States	$ (27,289)	$ (30,690)		$ (38,355)
International	(415)	(2,153)		3,360
Loss before income taxes	$ (27,704)	$ (32,843)	[1]	$ (34,995)	[1]
[1]	See Note 3 for a summary of adjustments.

Income Taxes - Components of To

Income Taxes - Components of Total Provision for Benefit from Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Current
State	$ 24	$ 51		$ 5
Foreign	1,061	450		840
Total current tax expense	1,085	501		845
Deferred
Federal				(8,680)
State				(395)
Foreign	(923)	(293)		(428)
Total deferred tax provision (benefit)	(923)	(293)		(9,503)
Total provision for (benefit from) income taxes	$ 162	$ 208	[1]	$ (8,658)	[1]
[1]	See Note 3 for a summary of adjustments.

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Statutory U.S. Federal Tax Rate to Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Federal statutory income tax rate	21.00%	34.00%	34.00%
State tax, net of federal benefit	(0.10%)	(0.10%)	0.70%
Federal tax credits	7.10%	3.30%	1.60%
Change in valuation allowance	(63.10%)	(13.60%)	(5.00%)
Common stock warrants		(3.70%)	(5.80%)
Foreign tax differential	(2.30%)	(2.40%)
Windfall tax benefits, net related to stock-based compensation	40.20%	15.30%
Effect of rate and other changes on federal deferred taxes, net due to enactment of Tax Cuts and Jobs Act		(30.00%)
Nondeductible officer compensation	(1.80%)
Nondeductible meals and entertainment	(1.70%)
Other	0.10%	(3.40%)	(0.80%)
Effective tax rate	(0.60%)	(0.60%)	24.70%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Examination [Line Items]
Corporate tax rate	21.00%	34.00%	34.00%
Tax cuts and jobs act, liability for foreign earnings and profits		$ 0
Operating loss carryforwards, limitations on use	Pursuant to Internal Revenue Code Section 382, use of the Company’s net operating loss carryforwards may be limited if the Company experiences a cumulative change in ownership of more than 50% over a three-year period.
Unrecognized tax provision (benefits), interest or penalties expense	$ 0	0	$ 0
Unrecognized tax benefits, income tax penalties and interest accrued	0	$ 0
Enterprise Zone
Income Tax Examination [Line Items]
Tax credits	$ 600,000
Tax credits begin to expiration year	2,023
Federal
Income Tax Examination [Line Items]
Net operating loss carryforwards	$ 172,700,000
Operating loss carryforwards begin to expiration year	2,033
Federal | Research and Development
Income Tax Examination [Line Items]
Tax credits	$ 3,300,000
Tax credits begin to expiration year	2,033
State
Income Tax Examination [Line Items]
Net operating loss carryforwards	$ 94,100,000
Tax return period	4 years
State | Minimum
Income Tax Examination [Line Items]
Operating loss carryforwards begin to expiration year	2,023
State | Maximum
Income Tax Examination [Line Items]
Operating loss carryforwards begin to expiration year	2,033
State | Research and Development
Income Tax Examination [Line Items]
Tax credits	$ 3,500,000
Tax credits begin to expiration year	2,023
Foreign
Income Tax Examination [Line Items]
Tax credits	$ 2,000,000
Tax credits begin to expiration year	2,023
Tax return period	5 years

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets
Net operating loss carryforwards	$ 43,106	$ 29,607
Business credits	8,487	5,197
Stock-based compensation	6,321	3,961
Accrued expenses and other current liabilities	2,910	1,462
Other	1,963	1,389
Total deferred tax assets	62,787	41,616
Less: valuation allowance	(45,579)	(23,904)	$ (2,674)	$ (887)
Deferred tax assets, net of valuation allowance	17,208	17,712
Deferred tax liabilities
Intangible assets	(8,735)	(11,287)
Prepaid expenses	(8,400)	(6,376)
Property and equipment	(802)	(1,589)
Other		(112)
Total deferred tax liabilities	(17,937)	(19,364)
Net deferred taxes	$ (729)	$ (1,652)

Income taxes - Summary of Chang

Income taxes - Summary of Changes in Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Valuation Allowance [Line Items]
Valuation allowance, at beginning of year	$ 23,904	$ 2,674	$ 887
Increase in valuation allowance	21,675	7,332	1,787
Valuation allowance, at end of year	$ 45,579	23,904	$ 2,674
ASU 2016-09
Valuation Allowance [Line Items]
Increase in valuation allowance		$ 13,898

Income Taxes - Rollforward of T

Income Taxes - Rollforward of Total Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns Roll Forward
Beginning gross unrecognized tax benefits	$ 672	$ 382	$ 278
Increases related to prior year tax positions	130	38
Increases related to current year tax positions	421	252	104
Ending gross unrecognized tax benefits	$ 1,223	$ 672	$ 382

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Basic and Diluted Loss per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	[1]	Dec. 31, 2016	[1]
Numerator:
Net loss attributable to BlackLine, Inc.	$ (7,732)	$ (4,460)	$ (8,457)	$ (7,155)	$ (4,166)	$ (12,074)	$ (9,126)	$ (7,685)	$ (27,804)	$ (33,051)		$ (26,337)
Denominator:
Weighted average shares									53,912	52,161		42,497
Shares used to calculate diluted net loss per share									53,912	52,161		42,497
Basic net loss per share attributable to BlackLine, Inc.	$ (0.14)	$ (0.08)	$ (0.16)	$ (0.13)	$ (0.08)	$ (0.23)	$ (0.18)	$ (0.15)	$ (0.52)	$ (0.63)		$ (0.62)
Diluted net loss per share attributable to BlackLine, Inc.	$ (0.14)	$ (0.08)	$ (0.16)	$ (0.13)	$ (0.08)	$ (0.23)	$ (0.18)	$ (0.15)	$ (0.52)	$ (0.63)		$ (0.62)
[1]	See Note 3 for a summary of adjustments.

Net Loss per Share - Schedule_2

Net Loss per Share - Schedule of Potentially Dilutive Shares Excluded From Calculation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from net loss per share	5,803	5,704	7,057
Stock options with service-only vesting conditions
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from net loss per share	3,820	5,019	5,874
Stock options with performance conditions
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from net loss per share	683	683	683
Common stock warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from net loss per share			500
Restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from net loss per share	1,300	2

Contingent Consideration - Addi

Contingent Consideration - Additional Information (Details) - BlackLine Systems, Inc. - USD ($) $ in Millions	Sep. 03, 2013	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition Contingent Consideration [Line Items]
Maximum contingent cash consideration to be distributed	$ 8
Contingent Consideration
Business Acquisition Contingent Consideration [Line Items]
Fair value of contingent consideration		$ 6.3	$ 5.9

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition Contingent Consideration [Line Items]
Lease expiration year	2,024
Non-cancelable purchase obligations	$ 5.2
Offices
Business Acquisition Contingent Consideration [Line Items]
Rent expense under operating leases	4.2	$ 3.4	$ 2.9
Data Center and Equipment
Business Acquisition Contingent Consideration [Line Items]
Rent expense under operating leases	$ 3.7	$ 3.2	$ 1.5

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,019	$ 7,059
2,020	5,307
2,021	3,786
2,022	2,586
2,023	2,638
Thereafter	237
Total, Future minimum lease payments	$ 21,613

Capitalization - Additional Inf

Capitalization - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		Nov. 02, 2016	Jan. 14, 2016	Sep. 30, 2016	Dec. 31, 2016		Dec. 31, 2018	Dec. 31, 2017
Capitalization [Line Items]
Common stock, shares authorized							500,000,000	500,000,000
Preferred stock, shares authorized							50,000,000	50,000,000
Preferred stock, shares Issued							0	0
Preferred stock, shares outstanding							0	0
Treasury stock shares retired			47,000
Proceeds from issuance of common stock	[1]				$ 3,075
Proceeds from initial public offering, net of underwriting discounts and commissions and other offering expenses		$ 151,900			$ 156,362	[1]
Initial Public Offering
Capitalization [Line Items]
Common Stock Issuance, shares		9,890,000
Shares issued during period, exercise of underwriter option to purchase shares		1,290,000
Common stock, shares issued and sold price per share including shares issued upon exercise of underwriters overallotment		$ 17
Runbook Company B.V.
Capitalization [Line Items]
Proceeds from issuance of common stock				$ 3,100
Common Stock Issuance, shares				192,187
[1]	See Note 3 for a summary of adjustments.

Equity Awards - Additional Info

Equity Awards - Additional Information (Details)	Jul. 21, 2017Employeeshares	Nov. 30, 2016shares	Oct. 31, 2016ExecutiveOfficer$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / shares		Dec. 31, 2016USD ($)$ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation award vesting period				4 years
Cash received from exercise of stock options				$ 14,004,000	$ 10,252,000	[1]	$ 2,860,000	[1]
Stock options granted to purchase shares of common stock for employee | shares	219,000			845,000
Exercise price of options, granted | $ / shares				$ 42.38
Stock-based compensation, cost				$ 20,895,000	16,044,000		6,526,000
Stock-based compensation capitalized as an asset				400,000	100,000		100,000
Net operating losses related to foreign tax benefits for equity awards				$ 200,000	0		$ 0
Stock-based compensation					$ 6,600,000
Employee Stock Purchase Plan ("ESPP")
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for future issuance | shares				1,500,000
Weighted-average period to recognize unrecognized compensation expense				8 months 12 days
Stock-based compensation, cost				$ 200,000
Total unrecognized compensation cost				$ 1,600,000
Employee stock purchase plan, description				Under the Company’s 2018 Employee Stock Purchase Plan (“ESPP”) eligible employees are granted the right to purchase shares at the lower of 85% of the fair value of the stock at the time of grant or 85% of the fair value at the time of exercise. The right to purchase shares is granted twice yearly for six month offering periods in May and November and exercisable on or about the succeeding November and May, respectively, of each year.
Right to purchase shares at fair value of stock at the time of grant, percentage				85.00%
Right to purchase shares at fair value at the time of exercise, percentage				85.00%
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant date fair value per share, granted | $ / shares				$ 20.15	$ 15.20		$ 6.78
Aggregate intrinsic value, exercised				$ 66,700,000	$ 31,400,000		$ 4,800,000
Cash received from exercise of stock options				14,000,000	$ 10,400,000		$ 2,900,000
Unrecognized compensation expense				$ 23,100,000
Weighted-average period to recognize unrecognized compensation expense				2 years 9 months 18 days
Number of executive officers, options granted | ExecutiveOfficer			2
Number of employees impacted by modification | Employee	8
Stock Options | Executive Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted to purchase shares of common stock for employee | shares			682,800
Exercise price of options, granted | $ / shares			$ 14
Options vesting terms				The performance conditions include meeting yearly cash flow targets and cumulative annual recurring revenue targets through 2019.
Stock-based compensation, cost				$ 0
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period to recognize unrecognized compensation expense				3 years 3 months 18 days
Intrinsic value				$ 53,200,000
Total unrecognized compensation cost				$ 44,900,000
2016 Equity Incentive Plan | Stock Options and Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum number of shares Issuable | shares		6,200,000
Stock-based compensation award vesting period		4 years
Stock option, contractual terms		10 years
Common shares reserved for future issuance | shares				9,100,000
[1]	See Note 3 for a summary of adjustments.

Equity Awards - Summary of Stoc

Equity Awards - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 21, 2017	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Outstanding at Beginning balance		5,019,000
Shares, Granted	219,000	845,000
Shares, Exercised		(1,788,000)
Shares, Forfeited/canceled		(256,000)
Shares, Outstanding at Ending balance		3,820,000	5,019,000
Shares, Exercisable at December 31, 2018		1,729,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Outstanding at Beginning balance		$ 13.90
Weighted Average Exercise Price, Granted		42.06
Weighted Average Exercise Price, Exercised		8.39
Weighted Average Exercise Price, Forfeited/canceled		26.64
Weighted Average Exercise Price, Outstanding at Ending balance		21.85	$ 13.90
Weighted Average Exercise Price, Exercisable at December 31, 2018		$ 13.11
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Weighted Average Remaining Contractual Term (Years)		7 years 6 months	7 years 6 months
Weighted Average Remaining Contractual Term, Exercisable at December 31, 2018		6 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding at Beginning balance		$ 95,353
Aggregate Intrinsic Value, Outstanding at Ending balance		75,287	$ 95,353
Aggregate Intrinsic Value, Exercisable at December 31, 2018		$ 48,136

Equity Awards - Summary of Rest

Equity Awards - Summary of Restricted Stock Units Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Restricted stock units, Nonvested, Beginning balance | shares	2
Restricted stock units, Granted | shares	1,372
Restricted stock units, Vested | shares	(2)
Restricted stock units, Forfeited/canceled | shares	(72)
Restricted stock units, Nonvested, Ending balance | shares	1,300
Weighted Average Grant Date Fair Value, Nonvested at Beginning balance | $ / shares	$ 34.12
Exercise price of options, granted | $ / shares	42.38
Weighted Average Grant Date Fair Value, Vested | $ / shares	34.46
Weighted Average Grant Date Fair Value, Forfeited/canceled | $ / shares	44.09
Weighted Average Grant Date Fair Value, Nonvested at Ending balance | $ / shares	$ 42.29

Equity Awards - Schedule of Wei

Equity Awards - Schedule of Weighted Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk free interest rate	2.80%	2.10%	1.40%
Expected term (years)	6 years 1 month 6 days	6 years 2 months 12 days	6 years 3 months 18 days
Expected volatility	46.00%	47.00%	47.50%
Employee Stock Purchase Plan ("ESPP")
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk free interest rate	2.60%
Expected term (years)	8 months 12 days
Expected volatility	42.90%

Equity Awards - Summary of St_2

Equity Awards - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 20,895	$ 16,044	$ 6,526
Cost of Revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	3,265	1,149	715
Sales and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	8,674	10,811	2,490
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	2,570	767	809
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 6,386	$ 3,317	$ 2,512

Defined Contribution Plan - Add

Defined Contribution Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Defined contribution plan, description	The Company makes matching contributions of 100% of each $1 of the employee’s contribution up to the first 3% of the employee’s bi-weekly compensation and 50% of each $1 of the employee’s contribution up to the next 2% of the employee’s bi-weekly compensation.
Percentage of employer matching contribution	100.00%
Employer matching contribution, percent of employees' gross pay	3.00%
Percentage of employer matching contribution, second tier	50.00%
Employer matching contribution, percent of employees' gross pay, second tier	2.00%
Matching contributions to plan	$ 2.9	$ 2.2	$ 2.3

Geographic Information - Schedu

Geographic Information - Schedule of Long-lived Assets Consist of Property and Equipment, Net by Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	$ 13,536	$ 12,769
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	12,407	12,210
International
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	$ 1,129	$ 559

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - shares	Feb. 25, 2019	Feb. 20, 2019	Jul. 21, 2017	Dec. 31, 2018
Subsequent Event [Line Items]
Stock option grant to employee			219,000	845,000
Restricted stock unit grants to employees				1,372,000
Stock Options
Subsequent Event [Line Items]
Vesting term				The stock options will vest as to one-fourth of the total number of options awarded on the first anniversary of February 20, 2019 and quarterly thereafter for 12 consecutive quarters.
Restricted Stock Units
Subsequent Event [Line Items]
Vesting term				The vast majority of the restricted stock units will vest as to one-fourth of the total number of units awarded on the first anniversary of February 20, 2019 and quarterly thereafter for 12 consecutive quarters.
Subsequent Event | Stock Options
Subsequent Event [Line Items]
Stock option grant to employee	100,000
Number of common stock received by employees upon exercise of vested award and payment of exercise price	1
Vesting percentage		0.25%
Subsequent Event | Restricted Stock Units
Subsequent Event [Line Items]
Vesting percentage		0.25%
Restricted stock unit grants to employees	200,000
Number of common stock received by employees upon exercise of vested award	1

Unaudited Quarterly Data - Summ

Unaudited Quarterly Data - Summary of Unaudited Quarterly Consolidated Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	[1]	Dec. 31, 2016	[1]
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 62,316	$ 58,734	$ 55,454	$ 51,284	$ 50,017	$ 45,424	$ 41,981	$ 38,181	$ 227,788	$ 175,603		$ 128,034
Gross profit	48,431	45,217	43,588	39,678	39,070	34,553	31,624	28,971	176,914	134,218		97,823
Net loss	(7,794)	(4,460)	(8,457)	(7,155)	(4,166)	(12,074)	(9,126)	(7,685)	(27,866)	(33,051)		(26,337)
Net loss attributable to redeemable non-controlling interest (Note 4)	(62)								(62)
Net loss attributable to BlackLine, Inc.	$ (7,732)	$ (4,460)	$ (8,457)	$ (7,155)	$ (4,166)	$ (12,074)	$ (9,126)	$ (7,685)	$ (27,804)	$ (33,051)		$ (26,337)
Basic net loss per share attributable to BlackLine, Inc.	$ (0.14)	$ (0.08)	$ (0.16)	$ (0.13)	$ (0.08)	$ (0.23)	$ (0.18)	$ (0.15)	$ (0.52)	$ (0.63)		$ (0.62)
Diluted net loss per share attributable to BlackLine, Inc.	$ (0.14)	$ (0.08)	$ (0.16)	$ (0.13)	$ (0.08)	$ (0.23)	$ (0.18)	$ (0.15)	$ (0.52)	$ (0.63)		$ (0.62)
[1]	See Note 3 for a summary of adjustments.