Loans and Related Allowance for Credit Losses (Commercial Lending Asset Quality Indicators) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 241,928	$ 239,843	$ 226,245
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	37,554
2019	22,152
2018	13,389
2017	10,331
2016	7,634
Prior	16,824
Revolving Loans	59,247
Revolving Loans Converted to Term	72
Total Loans	167,203	160,602	$ 152,282
Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	32,019
2019	14,042
2018	8,787
2017	6,290
2016	4,466
Prior	7,492
Revolving Loans	58,905
Revolving Loans Converted to Term	72
Total Loans	132,073	125,337
Commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4,028
2019	6,816
2018	3,574
2017	3,264
2016	2,741
Prior	7,951
Revolving Loans	342
Revolving Loans Converted to Term
Total Loans	28,716	28,110
Commercial | Equipment lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,507
2019	1,294
2018	1,028
2017	777
2016	427
Prior	1,381
Total Loans	6,414	7,155
Pass Rated | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans		154,076
Pass Rated | Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	31,680
2019	13,340
2018	8,209
2017	5,956
2016	4,242
Prior	7,141
Revolving Loans	54,775
Revolving Loans Converted to Term	53
Total Loans	125,396	119,761
Pass Rated | Commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,709
2019	6,268
2018	3,426
2017	2,841
2016	2,341
Prior	6,792
Revolving Loans	218
Total Loans	25,595	27,424
Pass Rated | Commercial | Equipment lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,429
2019	1,202
2018	942
2017	738
2016	405
Prior	1,350
Total Loans	6,066	6,891
Criticized | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans		6,526
Criticized | Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	339
2019	702
2018	578
2017	334
2016	224
Prior	351
Revolving Loans	4,130
Revolving Loans Converted to Term	19
Total Loans	6,677	5,576
Criticized | Commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	319
2019	548
2018	148
2017	423
2016	400
Prior	1,159
Revolving Loans	124
Total Loans	3,121	686
Criticized | Commercial | Equipment lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	78
2019	92
2018	86
2017	39
2016	22
Prior	31
Total Loans	$ 348	$ 264