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, 2012	Dec. 31, 2011	Dec. 31, 2010
Gross Realized Gains	$ 3,835	$ 7,490	$ 15,429
Gross Realized Losses	0	(19)	(777)
Other-than-temporary Impairment Losses	(809)	(2,910)	(13,951)
Net Gains (Losses)	3,026	4,561	701
Equity Securities [Member]
Gross Realized Gains	1,215	835	2,424
Gross Realized Losses	0	0	(706)
Other-than-temporary Impairment Losses	(356)	(1,212)	(1,982)
Net Gains (Losses)	859	(377)	(264)
Debt Securities [Member]
Gross Realized Gains	2,620	6,655	13,005
Gross Realized Losses	0	(19)	(71)
Other-than-temporary Impairment Losses	(453)	(1,698)	(11,969)
Net Gains (Losses)	$ 2,167	$ 4,938	$ 965