Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income	$ 84,050	$ 78,982	$ 242,498	$ 213,749
Other comprehensive income:
Net unrealized gains on securities available for sale	222,946	85,953	295,018	182,904
Net unrealized losses on derivative instruments	(1,382)	(116,032)	(33,116)	(171,600)
Other comprehensive income	221,564	(30,079)	261,902	11,304
Comprehensive income	$ 305,614	$ 48,903	$ 504,400	$ 225,053