Business Segments - Impacts of Changes to Internal Management Reporting (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense		$ 47	$ 189	$ (951)	$ 393
Total Assets		260,376	215,763	260,376	215,763
Group Reporting Basis Total deposits		143,530	100,081	143,530	100,081
Group Reporting Basis Goodwill		358	1,260	358	1,260
Operating Segments [Member] | WPB [Member]
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense		(66)	(8)	(935)	(34)
Total Assets		61,326	50,886	61,326	50,886
Group Reporting Basis Total deposits		49,871	42,942	49,871	42,942
Group Reporting Basis Goodwill		0	902	0	902
Operating Segments [Member] | CMB [Member]
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense		(67)	114	(69)	236
Total Assets		41,511	35,568	41,511	35,568
Group Reporting Basis Total deposits		39,245	24,299	39,245	24,299
Group Reporting Basis Goodwill		358	358	358	358
Operating Segments [Member] | GB&M [Member]
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense		165	126	210	295
Total Assets		155,090	126,864	155,090	126,864
Group Reporting Basis Total deposits		54,414	32,840	54,414	32,840
Group Reporting Basis Goodwill		0	0	0	0
Operating Segments [Member] | CC [Member]
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense		15	(43)	(157)	(104)
Total Assets		2,449	2,445	2,449	2,445
Group Reporting Basis Total deposits		0	0	0	0
Group Reporting Basis Goodwill		$ 0	0	$ 0	0
As Previously Reported [Member] | Operating Segments [Member] | RBWM [Member]
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense			(26)		(72)
Total Assets	[1]		18,907		18,907
Group Reporting Basis Total deposits			33,606		33,606
Group Reporting Basis Goodwill			581		581
As Previously Reported [Member] | Operating Segments [Member] | CMB [Member]
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense			106		221
Total Assets			26,735		26,735
Group Reporting Basis Total deposits			23,554		23,554
As Previously Reported [Member] | Operating Segments [Member] | GB&M [Member]
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense			94		231
Total Assets			87,114		87,114
Group Reporting Basis Total deposits			29,674		29,674
As Previously Reported [Member] | Operating Segments [Member] | PB [Member]
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense			(4)		(3)
Total Assets	[1]		6,952		6,952
Group Reporting Basis Total deposits			7,226		7,226
Group Reporting Basis Goodwill			321		321
As Previously Reported [Member] | Operating Segments [Member] | CC [Member]
Segment Reporting Information [Line Items]
Profit (Loss) before Income Tax Expense			19		16
Total Assets			76,055		76,055
Group Reporting Basis Total deposits			$ 6,021		$ 6,021

[1] Segment total assets at June 30, 2019 included goodwill that was previously allocated to RBWM and PB of $581 million and $321 million, respectively.