Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Components of income (loss) before income taxes
Domestic	$ 8,018	$ 7,778	$ 4,019
Foreign	653	497	133
Income before income taxes	8,671	8,275	4,152
Current expense (benefit):
Federal	111	21	(128)
State	99	264	(49)
Foreign	212	144	41
Total income tax expense (benefit)	422	429	(136)
Reconciliation of income tax expense (benefit) and the amount computed by applying the statutory federal income tax rate
Federal tax at statutory rate	3,035	2,896	1,453
Stock-based compensation	1,659	1,914	2,427
Non-deductible meals and entertainment	492	465	450
Net operating losses used	(4,973)	(5,067)	(4,301)
Federal alternative minimum tax	120	21	(123)
State tax, net of federal benefit	64	172	(32)
Other	25	28	(10)
Total income tax expense (benefit)	422	429	(136)
Deferred tax assets:
Net operating loss carryforwards	35,400	41,200
Stock-based compensation	6,600	5,140
Research tax credits	6,080	5,570
Fixed assets	2,550	3,310
Capitalized costs	720	820
Other	3,330	2,470
Total deferred tax assets	54,680	58,510
Valuation allowance	$ (54,680)	$ (58,510)