Investment Securities Summary of Cumulative Other-than-Temporary Impairment Charges Recognized as Components of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance of cumulative credit losses on debt securities, beginning of period	$ (12,302)	$ (19,961)	$ (16,242)	$ (20,691)
Reductions for securities sold during the period	792	2,746	4,730	3,472
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	0	1	2	5
Balance of cumulative credit losses on debt securities, end of period	$ (11,510)	$ (17,214)	$ (11,510)	$ (17,214)