Investment Securities Summary of Gains and Losses from Equity and Debt Securities, and Losses from Other-than-Temporary Impairment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Gross Realized Gains	$ 7,490	$ 15,429	$ 15,298
Gross Realized Losses	(19)	(777)	(818)
Other-than-temporary Impairment Losses	(2,910)	(13,951)	(13,401)
Net Gains (Losses)	4,561	701	1,079
Equity Securities [Member]
Gross Realized Gains	835	2,424	666
Gross Realized Losses	0	(706)	(689)
Other-than-temporary Impairment Losses	(1,212)	(1,982)	(3,931)
Net Gains (Losses)	(377)	(264)	(3,954)
Debt Securities [Member]
Gross Realized Gains	6,655	13,005	14,632
Gross Realized Losses	(19)	(71)	(129)
Other-than-temporary Impairment Losses	(1,698)	(11,969)	(9,470)
Net Gains (Losses)	$ 4,938	$ 965	$ 5,033