Statement Of Other Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net income	$ 43,335	$ 42,541	$ 88,505	$ 77,233
Amounts related to available-for-sale securities:
Change in net unrealized gains	27,061	29,439	67,673	30,447
Amounts related to cash flow hedges:
Change in net unrealized losses	(15,334)	(16,883)	(17,085)	(17,561)
Reclassification adjustment for amounts included in net income	4,830	7,467	9,795	13,579
Other comprehensive income	16,557	20,023	60,383	26,465
Comprehensive income	$ 59,892	$ 62,564	$ 148,888	$ 103,698