Accumulated Other Comprehensive Income (Loss) (Schedule Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Investment securities, Balance at beginning of period, net of tax	$ 37	$ (68)	$ 150
Investment securities, Net unrealized holding (losses) gains arising during the period	(55)	166	(343)
Investment securities, Less: (Benefit) provision for income taxes	(21)	60	(126)
Investment securities, Net unrealized holding (losses) gains arising during period, net of tax	(34)	106	(217)
Investment securities, Net realized (losses) gains included in net securities gains	(2)	1	1
Investment securities, Less: Benefit for income taxes	(1)	0	0
Investment securities, Reclassification adjustment for net securities (losses) gains included in net income, net of tax	(1)	1	1
Investment securities, Net losses realized as a yield adjustment in interest on investment securities	(8)	0	0
Investment securities, Less: Benefit for income taxes	(3)	0	0
Investment securities, Reclassification adjustment for net losses realized as a yield adjustment included in net income, net of tax	(5)	0	0
Investment securities, Change in net unrealized (losses) gains on investment securities available-for-sale, net of tax	(28)	105	(218)
Investment securities, Balance at end of period, net of tax	9	37	(68)
Benefit plans, Balance at beginning of period, net of tax	(449)	(323)	(563)
Benefit plans, Actuarial (loss) gain arising during the period	(57)	(240)	286
Benefit plans, Prior service credit arising during the period	3	0	0
Benefit plans, Net defined benefit pension and other postretirement adjustment arising during the period	(54)	(240)	286
Benefit plans, Less: (Benefit) provision for income taxes	(19)	(87)	103
Benefit plans, Net defined benefit pension and other postretirement adjustment arising during the period, net of tax	(35)	(153)	183
Benefit plans, Amortization of actuarial net loss	70	39	89
Benefit plans, Amortization of prior service cost	1	3	2
Benefit plans, Total amounts recognized in employee benefits expense	71	42	91
Benefit plans, Less: Benefit for income taxes	25	15	34
Benefit plans, Adjustment for amounts recognized as components of net periodic benefit cost during the period, net of tax	46	27	57
Benefit plans, Change in defined benefit pension and other postretirement plans adjustment, net of tax	11	(126)	240
Benefit plans, Balance at end of period, net of tax	(438)	(449)	(323)
Total accumulated other comprehensive loss at end of period, net of tax	$ (429)	$ (412)	$ (391)