Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Statement of Other Comprehensive Income [Abstract]
Net income	$ 34,773	$ 31,398
Unrealized gains on available-for-sale securities, net of tax	4,850	1,193
Unrealized gains on cash flow hedging instruments, net of tax	2,364	2,806
Foreign currency translation adjustment, net of tax	535	534
Total other comprehensive income	7,749	4,533
Comprehensive income	$ 42,522	$ 35,931