Investment Securities (Rollforward Of Total Amount Of Credit-Related OTTI) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Investment [Line Items]
Balance of credit-related OTTI at beginning of period	$ 0	$ 104,551
Reductions for securities sold during the period	0	1,313
Balance of credit-related OTTI at end of period	0	(103,238)
Transfer of Securities from HTM to AFS	0	0
Held-to-maturity Securities [Member]
Investment [Line Items]
Balance of credit-related OTTI at beginning of period	0	9,079
Reductions for securities sold during the period	0	0
Balance of credit-related OTTI at end of period	0	0
Transfer of Securities from HTM to AFS	0	9,079
Available-for-sale Securities [Member]
Investment [Line Items]
Balance of credit-related OTTI at beginning of period	0	95,472
Reductions for securities sold during the period	0	1,313
Balance of credit-related OTTI at end of period	0	(103,238)
Transfer of Securities from HTM to AFS	$ 0	$ (9,079)