Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of income (loss) before income taxes
Domestic	$ (14,676)	$ (34,276)	$ (25,337)
Foreign	2,138	(28)	1,138
Loss before income taxes	(12,538)	(34,304)	(24,199)
Current expense (benefit):
Federal	18
State	67	(15)	40
Foreign	569	566	353
Deferred tax expense (benefit):
Federal	702	(1,494)
State	25	(53)
Total income tax expense (benefit)	1,381	(996)	393
Reconciliation of income tax expense (benefit) and the amount computed by applying the statutory federal income tax rate
Federal tax at statutory rate	(4,388)	(12,006)	(8,470)
Stock-based compensation	867	782	789
Non-deductible meals and entertainment	530	558	531
Net operating losses not used	3,705	10,499	7,478
Tax benefit on available-for-sale securities	702	(1,494)
State tax, net of federal benefit	68	(63)	26
Other	(103)	728	39
Total income tax expense (benefit)	1,381	(996)	393
Deferred tax assets:
Net operating loss carryforwards	42,550	43,870
Stock-based compensation	12,290	10,850
Research tax credits	17,620	15,220
Fixed assets	1,960	3,440
Capitalized costs	1,310	420
Accrued compensation	6,080	3,580
Other	6,180	4,500
Total deferred tax assets	87,990	81,880
Valuation allowance	(87,990)	(81,880)
Increase (decrease) in net valuation allowance	$ 6,100	$ 10,100	$ 9,900