Loans and Related Allowance for Credit Losses (Commercial Lending Asset Quality Indicators) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 237,013	$ 241,928
Total commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	15,477	37,554
Financing receivable, originated in year one	25,128	22,152
Financing receivable, originated in year two	21,041	13,389
Financing receivable, originated in year three	12,451	10,331
Financing receivable, originated in year four	9,750	7,634
Prior	23,313	16,824
Revolving Loans	57,275	59,247
Revolving Loans Converted to Term	71	72
Total Loans	164,506	167,203
Total commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	13,954	32,019
Financing receivable, originated in year one	20,299	14,042
Financing receivable, originated in year two	13,129	8,787
Financing receivable, originated in year three	8,143	6,290
Financing receivable, originated in year four	5,876	4,466
Prior	11,309	7,492
Revolving Loans	57,017	58,905
Revolving Loans Converted to Term	71	72
Total Loans	129,798	132,073
Total commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	1,173	4,028
Financing receivable, originated in year one	3,398	6,816
Financing receivable, originated in year two	6,697	3,574
Financing receivable, originated in year three	3,361	3,264
Financing receivable, originated in year four	3,162	2,741
Prior	10,270	7,951
Revolving Loans	258	342
Revolving Loans Converted to Term
Total Loans	28,319	28,716
Total commercial | Equipment lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	350	1,507
Financing receivable, originated in year one	1,431	1,294
Financing receivable, originated in year two	1,215	1,028
Financing receivable, originated in year three	947	777
Financing receivable, originated in year four	712	427
Prior	1,734	1,381
Total Loans	6,389	6,414
Pass Rated | Total commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	13,796	31,680
Financing receivable, originated in year one	19,870	13,340
Financing receivable, originated in year two	12,404	8,209
Financing receivable, originated in year three	7,540	5,956
Financing receivable, originated in year four	5,559	4,242
Prior	10,715	7,141
Revolving Loans	53,161	54,775
Revolving Loans Converted to Term	51	53
Total Loans	123,096	125,396
Pass Rated | Total commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	1,041	3,709
Financing receivable, originated in year one	3,261	6,268
Financing receivable, originated in year two	6,034	3,426
Financing receivable, originated in year three	3,195	2,841
Financing receivable, originated in year four	2,675	2,341
Prior	8,673	6,792
Revolving Loans	239	218
Total Loans	25,118	25,595
Pass Rated | Total commercial | Equipment lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	339	1,429
Financing receivable, originated in year one	1,360	1,202
Financing receivable, originated in year two	1,142	942
Financing receivable, originated in year three	868	738
Financing receivable, originated in year four	678	405
Prior	1,711	1,350
Total Loans	6,098	6,066
Criticized | Total commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	158	339
Financing receivable, originated in year one	429	702
Financing receivable, originated in year two	725	578
Financing receivable, originated in year three	603	334
Financing receivable, originated in year four	317	224
Prior	594	351
Revolving Loans	3,856	4,130
Revolving Loans Converted to Term	20	19
Total Loans	6,702	6,677
Criticized | Total commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	132	319
Financing receivable, originated in year one	137	548
Financing receivable, originated in year two	663	148
Financing receivable, originated in year three	166	423
Financing receivable, originated in year four	487	400
Prior	1,597	1,159
Revolving Loans	19	124
Total Loans	3,201	3,121
Criticized | Total commercial | Equipment lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current year	11	78
Financing receivable, originated in year one	71	92
Financing receivable, originated in year two	73	86
Financing receivable, originated in year three	79	39
Financing receivable, originated in year four	34	22
Prior	23	31
Total Loans	$ 291	$ 348