Variable Interest Entities (VIEs) (Impact Of VIEs On The Consolidated Statements Of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Other noninterest income									$ 118	$ 109	$ 96
Provision (benefit) for income taxes	$ 63	$ 48	$ 27	$ (21)	$ 82	$ 80	$ 87	$ 85	117	334	300
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Other noninterest income									1	2	5
Provision (benefit) for income taxes									(12)	(10)	(11)
Low income housing tax credits | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Provision for income taxes, amortization of LIHTC investments									67	65	65
Provision for income taxes, affordable housing tax credits and other tax benefits									(63)	(62)	(62)
Other tax benefits related to tax credit entities | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Provision for income taxes, affordable housing tax credits and other tax benefits									$ (16)	$ (13)	$ (14)