Other Comprehensive Income (Components of Other Comprehensive Income) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Other Comprehensive Income
Net income	$ 3,416	$ 21,109	$ 34,814	$ 44,849
Unrealized gains on available-for-sale securities, net of tax	5,445	4,047	6,638	6,955
Unrealized losses in cash flow hedging instruments, net of tax	(4,398)	(3,027)	(1,592)	(6,397)
Foreign currency translation adjustment, net of tax	472	0	1,006	0
Other comprehensive income (loss)	1,519	1,020	6,052	558
Comprehensive income	$ 4,935	$ 22,129	$ 40,866	$ 45,407