Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income	$ 7,410	$ 5,921	$ 15,399	$ 15,508
Other comprehensive income (loss), net of tax:
Auction-rate securities valuation adjustments, net of $0 tax for the three and nine months ended September 30, 2013 and 2012	149	42	117	141
Unrealized gains on available-for-sale securities, net of $0 tax for the three and nine months ended September 30, 2013 and 2012	34	42	12	36
Foreign currency translation adjustments, net of $0 tax for the three and nine months ended September 30, 2013 and 2012	431	(141)	1,595	255
Total other comprehensive income (loss), net of tax	614	(57)	1,724	432
Comprehensive income	$ 8,024	$ 5,864	$ 17,123	$ 15,940