Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income	$ 22,898	$ 15,756	$ 13,301
Other comprehensive income, net of tax:
Change in unrealized losses on securities, net of tax	130	140
Foreign currency translation adjustments	1,988	408	1,381
Total other comprehensive income, net of tax	2,085	582	1,614
Comprehensive income	24,983	16,338	14,915
Auction Rate Securities [Member]
Other comprehensive income, net of tax:
Change in unrealized losses on securities, net of tax	130	140	270
Available-for-sale Securities [Member]
Other comprehensive income, net of tax:
Change in unrealized losses on securities, net of tax	$ (33)	$ 34	$ (37)