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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance of cumulative credit losses on debt securities, beginning of period	$ (11,510)	$ (12,302)	$ (11,510)	$ (16,242)
Reductions for securities sold during the period	0	792	0	4,730
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	0	0	0	2
Balance of cumulative credit losses on debt securities, end of period	$ (11,510)	$ (11,510)	$ (11,510)	$ (11,510)