Investment Securities Summary of Cumulative Other-than-Temporary Impairment Charges Recognized as Components of Earnings (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance of cumulative credit losses on debt securities, beginning of period	$ (20,607)	$ (22,692)	$ (23,079)	$ (22,781)
Reductions for securities sold during the period	0	0	2,468	0
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, Additional Credit Losses	(97)	(19)	(97)	(19)
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	0	66	4	155
Balance of cumulative credit losses on debt securities, end of period	$ (20,704)	$ (22,645)	$ (20,704)	$ (22,645)