Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (29,260)	$ (9,639)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	6,328	5,228
Amortization of deferred costs	2,513	2,808
Loss on disposal of assets	84
Deferred income taxes	101	41
Accretion of interest on convertible senior notes	2,274
Non-cash investment income	(228)	(8)
Provision for doubtful accounts and sales reserve	24	369
Change in fair value of contingent consideration	(250)
Stock-based compensation	16,512	2,044
Increase (decrease) in operating assets and liabilities:
Accounts receivable	5,627	(2,973)
Prepaid expenses	(2,011)	(1,044)
Deferred costs	(4,198)	(2,427)
Other assets	(1,005)	(352)
Accounts payable	93	(430)
Accrued payroll and employee related liabilities	305	500
Accrued expenses	566	293
Deferred revenue	1,061	2,868
Other liabilities	12	363
Net cash used in operating activities	(1,452)	(2,359)
Cash flows from investing activities:
Capital expenditures	(414)	(505)
Proceeds from sale leaseback		395
Payments for acquisition of business, net of acquired cash	(35,857)	(21,529)
Purchase of short-term investments	(30,932)	(12,427)
Maturities of short-term investments	70,645
Additions to intangibles	(168)
Additions to capitalized software development costs	(4,038)	(3,044)
Net cash used in investing activities	(764)	(37,110)
Cash flows from financing activities:
Restricted stock units withheld to settle employee tax withholding liability	(3,772)
Payment of contingent consideration	(431)
Proceeds from follow on offering, net		10,444
Payments of public offering costs		(729)
Payments of debt issuance costs	(84)
Proceeds from employee stock purchase plan	881	854
Proceeds from stock option exercises	5,835	1,115
Net cash provided by financing activities	2,429	11,684
Effect of exchange rates on cash and cash equivalents	(665)	(147)
Net decrease in cash, cash equivalents and restricted cash	(452)	(27,932)
Cash, cash equivalents and restricted cash—beginning of period	103,051	60,765
Cash, cash equivalents and restricted cash—end of period	102,599	32,833
Supplemental disclosures of cash flow information:
Interest	771
Taxes, net of refunds received	41	3
Supplemental disclosure of non-cash activities:
Capitalized assets included in accounts payable and accrued expenses	85	1,335
Deferred offering costs in accounts payable and accrued expenses		143
Stock-based compensation capitalized for software development	$ 204	$ 25