CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net loss attributable to BlackLine, Inc.	$ (12,843)	$ (8,781)
Net loss and adjustment attributable to redeemable non-controlling interest (Note 3)	1,873	(250)
Net loss	(10,970)	(9,031)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	4,570	5,689
Change in fair value of contingent consideration	145	(9)
Amortization of debt discount and issuance costs	5,532
Stock-based compensation	9,456	6,452
Noncash lease expense	1,230	1,245
Accretion amortization of purchase discounts on marketable securities, net	(523)	(409)
Net foreign currency losses	826	128
Deferred income taxes	13	320
Provision for doubtful accounts receivable	69	25
Changes in operating assets and liabilities:
Accounts receivable	12,147	2,333
Prepaid expenses and other current assets	(1,499)	1,789
Other assets	(1,167)	(2,499)
Accounts payable	1,253	826
Accrued expenses and other current liabilities	(10,014)	(6,362)
Deferred revenue	(1,298)	3,869
Operating lease liabilities	(1,253)	(1,340)
Net cash provided by operating activities	8,517	3,026
Cash flows from investing activities
Purchases of marketable securities	(116,400)	(29,975)
Proceeds from maturities of marketable securities	289,149	31,795
Proceeds from sales of marketable securities	12,000
Capitalized software development costs	(2,289)	(1,232)
Purchases of property and equipment	(1,152)	(1,103)
Net cash provided by (used in) investing activities	181,308	(515)
Cash flows from financing activities
Proceeds from exercises of stock options	4,656	2,764
Acquisition of common stock for tax withholding obligations	(3,562)	(1,729)
Financed purchases of property and equipment	(169)
Net cash provided by financing activities	925	1,035
Effect of foreign currency exchange rate changes on cash, cash equivalents, and restricted cash		(56)
Net increase in cash, cash equivalents, and restricted cash	190,750	3,490
Cash, cash equivalents, and restricted cash, beginning of period	120,502	46,455
Cash, cash equivalents, and restricted cash, end of period	311,252	49,945
Reconciliation of cash, cash equivalents, and restricted cash to the consolidated balance sheets
Cash and cash equivalents at end of period	310,989	49,676
Restricted cash included within prepaid expenses and other current assets at end of period	19
Restricted cash included within other assets at end of period	244	269
Total cash, cash equivalents, and restricted cash at end of period shown in the consolidated statements of cash flows	311,252	49,945
Non-cash financing and investing activities
Stock-based compensation capitalized for software development	180	63
Capitalized software development costs included in accounts payable and accrued expenses and other current liabilities at end of period	388	140
Purchases of property and equipment included in accounts payable and accrued expenses and other current liabilities at end of period	1,386	796
Purchases of prepaid expenses and other current assets included in accounts payable at end of period	2,333
Leased assets obtained in exchange for new operating lease liabilities	$ 130	$ 37