Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities:
Net loss	$ (11,868)	$ (11,601)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	2,013	1,237
Amortization of intangible assets	763	142
Amortization of deferred financing costs	7	6
Change in fair value of warrant liability	(122)	7
Stock-based compensation	4,744	3,373
Other	65	2
Changes in assets and liabilities:
Accounts receivable, net	8,720	5,297
Prepaid expenses and other assets	2,623	(5,518)
Deferred commissions	212	(759)
Accounts payable and accrued liabilities	2,068	(1,522)
Deferred revenue	(22,555)	(18,274)
Deferred rent	1,372	(139)
Other liabilities	(389)
Net cash used in operating activities	(12,347)	(27,749)
Investing Activities:
Purchases of property and equipment	(4,847)	(3,145)
Purchases of intangible assets		(290)
Proceeds from sale of property and equipment	26	15
Maturities of marketable securities	5,700	13,900
Net cash provided by investing activities	879	10,480
Financing Activities:
Proceeds from common stock offerings, net of offering costs	109,803
Proceeds from issuance of common stock from employee equity plans	2,832	1,038
Shares repurchased for tax withholdings on vesting of restricted stock	(127)	(42)
Net cash provided by financing activities	112,508	996
Net increase (decrease) in cash and cash equivalents	101,040	(16,273)
Cash and cash equivalents, beginning of period	35,693	44,539
Cash and cash equivalents, end of period	136,733	28,266
Supplemental cash flow disclosure:
Cash paid for taxes	61	127
Non-cash investing and financing activities:
Capital expenditures incurred but not yet paid	$ 275	$ 284