CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities
Net loss	$ (11,525)	$ (11,029)	$ (23,570)	$ (18,476)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	975	1,127	1,972	2,296
Stock-based compensation expense	3,502	2,620	6,892	4,794
Provision for doubtful accounts	48	52	170	126
Realized gain on sale of available-for-sale securities	(4)	0	(6)	0
Amortization (accretion) of premiums and discounts on marketable securities, net	36	0	75	0
Recognition of deferred government grant obligation	(230)	(206)	(663)	(272)
Deferred income tax	(12)	0	(12)	0
Changes in assets and liabilities:
Accounts receivable	(1,844)	(584)	(2,725)	(1,495)
Deferred commissions	(117)	(32)	(129)	113
Other receivables	142	(424)	(82)	(612)
Prepaid expenses and other	(1,327)	(65)	(1,513)	79
Other assets	(323)	38	(386)	94
Accounts payable	797	1,262	101	1,419
Deferred revenue	5,399	2,514	2,184	1,842
Accrued expenses and other liabilities	447	2,046	(5,422)	(1,846)
Change in restricted cash	0	73	0	101
Net cash used in operating activities	(4,036)	(2,608)	(23,114)	(11,837)
Cash flows from investing activities
Purchase of property and equipment	(597)	(159)	(1,009)	(1,030)
Purchase of marketable securities	(802)	0	(802)	0
Sale of marketable securities	2,404	0	7,197	0
Purchase of intangible assets	(59)	(195)	(114)	(278)
Net cash provided by (used in) investing activities	946	(354)	5,272	(1,308)
Cash flows from financing activities
Payment of equity issuance costs	0	(273)	0	(1,346)
Proceeds from option exercises	236	353	520	433
Taxes paid related to net share settlements of stock-based compensation awards	0	0	(761)	0
Changes in restricted cash	0	0	0	300
Repayment of other long-term debt	(18)	(42)	(18)	(67)
Principal payments on capital lease and financing obligations	(476)	(483)	(908)	(1,161)
Distributions to members	0	(35)	0	(35)
Proceeds from government grants	0	0	183	313
Payments of issuance costs on line of credit	(33)	0	(33)	0
Net cash used in financing activities	(291)	(480)	(1,017)	(1,563)
Effect of foreign exchange rates on cash	40	(19)	(6)	9
Net decrease in cash and cash equivalents	(3,341)	(3,461)	(18,865)	(14,699)
Cash and cash equivalents at beginning of period	43,226	89,893	58,750	101,131
Cash and cash equivalents at end of period	39,885	86,432	39,885	86,432
Supplemental cash flow disclosure
Cash paid for interest	470	496	792	919
Cash paid for income taxes, net of refunds	40	0	48	0
Supplemental disclosure of noncash investing and financing activities
Fixed assets acquired through capital lease arrangements	0	343	0	527
Allowance for tenant improvements	215	0	401	698
Accrued distributions to members	0	0	0	60
Purchases of property and equipment, accrued but not paid	$ 82	$ 0	$ 82	$ 0