Investment Securities (Details 1) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Changes in credit losses associated with debt securities for which other than temporary impairment losses
Beginning balance	$ 322,719	$ 308,017	$ 327,912	$ 284,513
Additions for credit losses not previously recognized	26,530	10,387	42,571	37,189
Reductions for increases in cash flows	(4,881)	(173)	(5,020)	(342)
Reductions for realized losses	(46,227)	(3,968)	(67,322)	(7,097)
Ending balance	$ 298,141	$ 314,263	$ 298,141	$ 314,263