Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net loss	$ (18,731)	$ (23,636)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities
Depreciation and amortization	4,657	4,487
Amortization of premiums on investments	59	20
Loss on disposal of property and equipment	7	26
Stock-based compensation	11,667	6,902
Accretion of capitalized loan fees	18	127
Loss on extinguishment of debt		722
Remeasurement of preferred stock warrant liability		202
Foreign exchange gain	(173)
Change in operating assets and liabilities
Accounts receivable	12,026	10,302
Prepaid expenses and other assets	3,260	(660)
Accounts payable	635	1,648
Accrued expenses	(2,025)	(2,442)
Deferred revenue	72	535
Deferred rent	(596)	(421)
Net cash provided by (used in) operating activities	10,876	(2,188)
Cash flows from investing activities
Purchases of property and equipment	(2,837)	(3,518)
Proceeds from sales of equipment	11
Proceeds from maturities of investments	35,075	6,245
Purchases of investments	(66,196)	(10,826)
Payments for security deposits	(23)	(43)
Net cash used in investing activities	(33,970)	(8,142)
Cash flows from financing activities
Proceeds from exercises of common stock options	8,948	1,000
Proceeds from purchases of stock under employee stock purchase plan	2,251
Proceeds from initial public offering, net of underwriting discounts		102,672
Payment of initial public offering costs	(243)	(574)
Proceeds from long-term debt		20,000
Principal payments on long-term debt		(20,000)
Payment of debt prepayment fees		(200)
Principal payments on capital lease obligations	(32)	(33)
Payment of capitalized loan fees		(248)
Net cash provided by financing activities	10,924	102,617
Foreign currency effect on cash, cash equivalents and restricted cash	(558)	(331)
Net (decrease) increase in cash, cash equivalents and restricted cash	(12,728)	91,956
Cash, cash equivalents and restricted cash
Beginning of period	42,007	19,756
End of period	$ 29,279	$ 111,712