Accumulated Other Comprehensive Income (Loss) (Schedule Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2021		Jun. 30, 2020		Jun. 30, 2021		Jun. 30, 2020		Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Investment securities, Balance at beginning of period, net of tax						$ 211		$ 65
Net unrealized holding (losses) gains arising during the period						(184)		286
Investment securities, Less: (Benefit) provision for income taxes						(43)		68
Investment securities, Change in net unrealized gains on investment securities, net of tax						(141)		218
Investment securities, Balance at end of period, net of tax		$ 70		$ 283		70		283
Cash flow hedges, Balance at beginning of period, net of tax						155		34
Cash flow hedges, Net (losses) gains arising during the period						(16)		233
Cash flow hedges, Less: (Benefit) provision for income tax						(4)		56
Change in net cash flow hedge gains arising during the period, net of tax						(12)		177
Net cash flow hedge gains included in interest and fees on loans		24		19		48		22
Cash flow hedges, Less: Provision for income taxes						11		7
Cash flow hedges, reclassification adjustment for net cash flow hedge gains included in net income, net of tax						37		15
Change in net cash flow hedge gains, net of tax						(49)		162
Cash flow hedges, Balance at end of period, net of tax	[1]	106		196		106		196
Benefit plans, Balance at beginning of period, net of tax	[2]					(302)		(415)
Benefit plans, Actuarial loss arising during the period	[2]					0		(6)
Benefit plans, Less: Benefit for income taxes	[2]					0		(1)
Benefit plans, Net defined benefit pension and other postretirement adjustment arising during the period, net of tax	[2]					0		(5)
Benefit plans, Amortization of actuarial net loss	[2]					20		23
Benefit plans, Amortization of prior service credit						(12)		(14)
Benefit plans, Amounts recognized in other noninterest expenses	[2]					8		9
Benefit plans, Less: Provision for income taxes	[2]					2		2
Benefit plans, Adjustment for amounts recognized as components of net periodic benefit cost during the period, net of tax	[2]					6		7
Benefit plans, Change in defined benefit pension and other postretirement plans adjustment, net of tax	[2]					6		2
Benefit plans, Balance at end of period, net of tax	[2]	(296)		(413)		(296)		(413)
Total accumulated other comprehensive (loss) income at end of period, net of tax		$ (120)	[2]	$ 66	[2]	$ (120)	[2]	$ 66	[2]	$ 64

[1] The Corporation expects to reclassify $64 million of gains, net of tax, from accumulated other comprehensive loss to earnings over the next twelve months if interest yield curves and notional amounts remain at June 30, 2021 levels.

[2] Balances at beginning of period, net of tax, and changes for the six months ended June 30, 2021 have been recast to reflect the retrospective application of the Corporation's election to change the accounting method for certain components of the qualified defined benefit pension plan as of January 1, 2021. Refer to Note 1 for further information.