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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Other noninterest income									$ 109	$ 96	$ 108
Provision for income taxes	$ 82	$ 80	$ 87	$ 85	$ 90	$ 63	$ 54	$ 93	334	300	491
Variable Interest Entity
Variable Interest Entity [Line Items]
Other noninterest income									2	5	2
Provision for income taxes									(10)	(11)	(20)
Low income housing tax credits | Variable Interest Entity
Variable Interest Entity [Line Items]
Provision for income taxes, amortization of LIHTC investments									65	65	67
Provision for income taxes, affordable housing tax credits and other tax benefits									(62)	(62)	(63)
Other tax benefits related to tax credit entities | Variable Interest Entity
Variable Interest Entity [Line Items]
Provision for income taxes, affordable housing tax credits and other tax benefits									$ (13)	$ (14)	$ (24)