Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Components of income (loss) before income taxes
Domestic	$ (34,276)	$ (25,337)	$ (13,294)
Foreign	(28)	1,138	883
Loss before income taxes	(34,304)	(24,199)	(12,411)
Current expense (benefit):
Federal			(22)
State	(15)	40	57
Foreign	566	353	311
Deferred tax expense (benefit):
Federal	(1,494)
State	(53)
Total income tax expense (benefit)	(996)	393	346
Reconciliation of income tax expense (benefit) and the amount computed by applying the statutory federal income tax rate
Federal tax at statutory rate	(12,006)	(8,470)	(4,344)
Stock-based compensation	782	789	1,149
Non-deductible meals and entertainment	558	531	507
Net operating losses not used (used)	10,499	7,478	2,999
Tax benefit on available-for-sale securities	(1,494)
State tax, net of federal benefit	(63)	26	37
Other	728	39	(2)
Total income tax expense (benefit)	(996)	393	346
Deferred tax assets:
Net operating loss carryforwards	43,870	35,060
Stock-based compensation	10,850	10,210
Research tax credits	15,220	12,500
Fixed assets	3,440	3,520
Capitalized costs	420	3,590
Other	8,080	6,890
Total deferred tax assets	81,880	71,770
Valuation allowance	(81,880)	(71,770)
Increase (decrease) in net valuation allowance	$ 10,100	$ 9,900	$ 7,200