Loans and Related Allowance for Credit Losses (Commercial Lending Asset Quality Indicators) (Details) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	[1]	$ 290,230	$ 241,928
Total commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		27,982	37,554
Financing receivable, originated in year one		20,114	22,152
Financing receivable, originated in year two		23,174	13,389
Financing receivable, originated in year three		14,994	10,331
Financing receivable, originated in year four		11,917	7,634
Prior		25,806	16,824
Revolving Loans		71,080	59,247
Revolving Loans Converted to Term		120	72
Total Loans		195,187	167,203
Total commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		24,207	32,019
Financing receivable, originated in year one		13,980	14,042
Financing receivable, originated in year two		13,559	8,787
Financing receivable, originated in year three		8,518	6,290
Financing receivable, originated in year four		7,661	4,466
Prior		14,062	7,492
Revolving Loans		70,628	58,905
Revolving Loans Converted to Term		120	72
Total Loans		152,735	132,073
Total commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		2,864	4,028
Financing receivable, originated in year one		4,818	6,816
Financing receivable, originated in year two		8,545	3,574
Financing receivable, originated in year three		5,666	3,264
Financing receivable, originated in year four		3,663	2,741
Prior		10,187	7,951
Revolving Loans		452	342
Total Loans		36,195	28,716
Total commercial | Equipment lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		911	1,507
Financing receivable, originated in year one		1,316	1,294
Financing receivable, originated in year two		1,070	1,028
Financing receivable, originated in year three		810	777
Financing receivable, originated in year four		593	427
Prior		1,557	1,381
Total Loans		6,257	6,414
Pass Rated | Total commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		23,953	31,680
Financing receivable, originated in year one		13,493	13,340
Financing receivable, originated in year two		12,681	8,209
Financing receivable, originated in year three		7,612	5,956
Financing receivable, originated in year four		7,144	4,242
Prior		13,065	7,141
Revolving Loans		66,452	54,775
Revolving Loans Converted to Term		93	53
Total Loans		144,493	125,396
Pass Rated | Total commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		2,704	3,709
Financing receivable, originated in year one		4,531	6,268
Financing receivable, originated in year two		7,545	3,426
Financing receivable, originated in year three		4,956	2,841
Financing receivable, originated in year four		3,006	2,341
Prior		8,375	6,792
Revolving Loans		429	218
Total Loans		31,546	25,595
Pass Rated | Total commercial | Equipment lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		885	1,429
Financing receivable, originated in year one		1,257	1,202
Financing receivable, originated in year two		1,026	942
Financing receivable, originated in year three		777	738
Financing receivable, originated in year four		570	405
Prior		1,551	1,350
Total Loans		6,066	6,066
Criticized | Total commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		254	339
Financing receivable, originated in year one		487	702
Financing receivable, originated in year two		878	578
Financing receivable, originated in year three		906	334
Financing receivable, originated in year four		517	224
Prior		997	351
Revolving Loans		4,176	4,130
Revolving Loans Converted to Term		27	19
Total Loans		8,242	6,677
Criticized | Total commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		160	319
Financing receivable, originated in year one		287	548
Financing receivable, originated in year two		1,000	148
Financing receivable, originated in year three		710	423
Financing receivable, originated in year four		657	400
Prior		1,812	1,159
Revolving Loans		23	124
Total Loans		4,649	3,121
Criticized | Total commercial | Equipment lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year		26	78
Financing receivable, originated in year one		59	92
Financing receivable, originated in year two		44	86
Financing receivable, originated in year three		33	39
Financing receivable, originated in year four		23	22
Prior		6	31
Total Loans		$ 191	$ 348

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $2.0 billion, Loans held for investment of $1.6 billion and Other assets of $0.1 billion at September 30, 2021. Comparable amounts at December 31, 2020 were $1.2 billion, $1.4 billion and $0.1 billion, respectively.