Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities
Net loss	$ (13,560)	$ (14,881)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities
Depreciation and amortization	3,082	2,985
Amortization of premiums on investments	54	15
(Gain) loss on disposal of property and equipment	(4)	25
Stock-based compensation	7,310	4,415
Accretion of capitalized loan fees	18	72
Remeasurement of preferred stock warrant liability		(8)
Foreign exchange gain	(68)
Change in operating assets and liabilities
Accounts receivable	7,330	8,543
Prepaid expenses and other assets	1,481	(761)
Accounts payable	1,037	1,475
Accrued expenses	(1,727)	(1,942)
Deferred revenue	(2,820)	(1,041)
Deferred rent	(398)	(306)
Net cash provided by (used in) operating activities	1,735	(1,409)
Cash flows from investing activities
Purchases of property and equipment	(2,236)	(2,320)
Proceeds from sales of equipment	9
Proceeds from maturities of investments	19,700	6,245
Purchases of investments	(28,898)
Payments for security deposits	(29)	(52)
Net cash (used in) provided by investing activities	(11,454)	3,873
Cash flows from financing activities
Proceeds from exercises of common stock options	5,495	511
Proceeds from purchases of stock under employee stock purchase plan	2,251
Payment of initial public offering costs	(243)	(218)
Proceeds from long-term debt		20,000
Principal payments on capital lease obligations	(21)	(23)
Payment of capitalized loan fees		(236)
Net cash provided by financing activities	7,482	20,034
Foreign currency effect on cash, cash equivalents and restricted cash	64	(202)
Net (decrease) increase in cash, cash equivalents and restricted cash	(2,173)	22,296
Cash, cash equivalents and restricted cash
Beginning of period	42,007	19,756
End of period	$ 39,834	$ 42,052