Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities:
Net loss	$ (35,878)	$ (33,340)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	6,438	4,322
Amortization of intangible assets	2,112	330
Amortization of deferred financing costs	15	24
Change in fair value of mark-to-market liabilities	(1,266)	98
Stock-based compensation	16,102	11,707
Other	(757)	(42)
Changes in assets and liabilities:
Accounts receivable, net	(14,011)	(17,270)
Prepaid expenses and other assets	(168)	(1,868)
Deferred commissions	(1,172)	(3,833)
Accounts payable and accrued liabilities	10,241	8,197
Deferred revenue	37,011	35,692
Deferred rent	1,603	(63)
Other liabilities		(32)
Net cash provided by operating activities	20,270	3,922
Investing activities:
Purchases of property and equipment	(8,888)	(10,830)
Purchases of intangible assets		(301)
Proceeds from sale of property and equipment	78	50
Purchases of marketable securities	(92,170)	(8,088)
Maturities of marketable securities	37,850	23,900
Net cash (used in) provided by investing activities	(63,130)	4,731
Financing activities:
Proceeds from common stock offerings, net of offering costs	109,789
Proceeds from issuance of common stock from employee equity plans	8,760	5,769
Shares repurchased for tax withholdings on vesting of restricted stock	(333)	(214)
Payments for financing costs	(18)	(31)
Net cash provided by financing activities	118,198	5,524
Net increase in cash and cash equivalents	75,338	14,177
Cash and cash equivalents, beginning of period	35,693	44,539
Cash and cash equivalents, end of period	111,031	58,716
Supplemental cash flow disclosure:
Cash paid for taxes	131	247
Non-cash investing and financing activities:
Capital expenditures incurred but not yet paid	$ 192	$ 24