Investment Securities (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Credit loss portion of other than temporary impairment
Credit-related other-than-temporary impairment	$ (28,393)	$ (27,575)	$ (24,499)
Credit losses on newly identified impairment	(818)	(3,076)
Non-agency Mortgage-Related Securities
Credit loss portion of other than temporary impairment
Credit-related other-than-temporary impairment	(17,558)	(17,556)	(17,472)
Credit losses on newly identified impairment	(2)	(84)
Trust Preferred Debt Securities
Credit loss portion of other than temporary impairment
Credit-related other-than-temporary impairment	(10,835)	(10,019)	(7,027)
Credit losses on newly identified impairment	$ (816)	$ (2,992)