Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Investment securities, Balance at beginning of period, net of tax	$ (138)	$ (101)
Cumulative effect of change in accounting principle	0	1
Investment securities, Net unrealized holding (losses) gains arising during the period	109	(142)
Investment securities, Less: (Benefit) provision for income taxes	25	(33)
Investment securities, Net unrealized holding (losses) gains arising during the period, net of tax	84	(109)
Investment securities, Net realized (losses) gains included in net securities (losses) gains	(8)	0
Investment securities, Less: Benefit for income taxes	(2)	0
Investment Securities, Reclassification adjustment for net securities (losses) gains included in net income, net of tax	(6)	0
Investment securities, Reclassification adjustment for net securities (losses) gains included in net income, net of tax	90	(109)
Investment securities, Balance at end of period, net of tax	(48)	(209)
Cash flow hedges, Balance at beginning of period, net of tax	0	0
Cash flow hedge: Net gains arising during the period	4	0
Cash flow hedges, Less: Provision for income tax	1	0
Cash flows hedges, Change in net gain on cash flow hedges	3	0
Cash flow hedges, Balance at end of period, net of tax	3	0
Benefit plans, Balance at beginning of period, net of tax	(471)	(350)
Benefit plans, Amortization of actuarial net loss	11	15
Benefit plans, Amortization of prior service credit	(7)	(7)
Benefit plans, Amounts recognized in other noninterest expense	4	8
Benefit plans, Less: Provision for income taxes	1	2
Benefit plans, Change in defined benefit pension and other postretirement plans adjustment, net of tax	3	6
Benefit plans, Balance at end of period, net of tax	(468)	(344)
Total accumulated other comprehensive loss at end of period, net of tax	$ (513)	$ (553)	$ (609)