Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net income	$ 5,489	$ 6,592	$ 7,989	$ 9,587
Other comprehensive income, net of tax:
Auction-rate securities valuation adjustments, net of $0 tax for the three and six months ended June 30, 2013 and 2012	(17)	9	(32)	99
Unrealized gain (loss) on available-for-sale securities, net of $0 tax for the three and six months ended June 30, 2013 and 2012	(15)	10	(22)	(6)
Foreign currency translation adjustments, net of $0 tax for the three and six months ended June 30, 2013 and 2012	862	(2)	1,164	396
Total other comprehensive income, net of tax	830	17	1,110	489
Comprehensive income	$ 6,319	$ 6,609	$ 9,099	$ 10,076