Loans and Related Allowance for Credit Losses (Analysis of Loan Portfolio) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Total Loans	$ 258,236	$ 239,843
% of Loans	100.00%	100.00%
Financing receivable, deferred income	$ 1,600	$ 1,100
Collateral Dependent [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	1,100
Other Assets [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, accrued interest	700
Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	$ 254,525	$ 234,819
% of Loans	98.56%	97.90%
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	$ 590	$ 661
% of Loans	0.23%	0.28%
60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	$ 264	$ 258
% of Loans	0.10%	0.11%
90 Days or More Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	$ 456	$ 585
% of Loans	0.18%	0.24%
Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	$ 1,310	$ 1,504
% of Loans	0.51%	0.63%
Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	$ 1,876	$ 1,635
% of Loans	0.73%	0.68%
Fair Value Option Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	$ 525	$ 166
% of Loans	0.20%	0.07%
Purchased Impaired Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans		$ 1,719
% of Loans		0.72%
Total commercial
Financing Receivable, Past Due [Line Items]
Total Loans	$ 180,195	$ 160,602
Total commercial | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	179,254	159,825
Total commercial | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	108	155
Total commercial | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	41	36
Total commercial | 90 Days or More Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	34	85
Total commercial | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	183	276
Total commercial | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	758	501
Total consumer
Financing Receivable, Past Due [Line Items]
Total Loans	78,041	79,241
Total consumer | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	75,271	74,994
Total consumer | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	482	506
Total consumer | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	223	222
Total consumer | 90 Days or More Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	422	500
Total consumer | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	1,127	1,228
Total consumer | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	1,118	1,134
Total consumer | Fair Value Option Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	525	166
Total consumer | Purchased Impaired Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans		1,719
Commercial and industrial [Member] | Total commercial
Financing Receivable, Past Due [Line Items]
Total Loans	144,335	125,337
Commercial and industrial [Member] | Total commercial | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	143,531	124,695
Commercial and industrial [Member] | Total commercial | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	49	102
Commercial and industrial [Member] | Total commercial | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	28	30
Commercial and industrial [Member] | Total commercial | 90 Days or More Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	34	85
Commercial and industrial [Member] | Total commercial | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	111	217
Commercial and industrial [Member] | Total commercial | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	693	425
Commercial Real Estate [Member] | Total commercial
Financing Receivable, Past Due [Line Items]
Total Loans	28,763	28,110
Commercial Real Estate [Member] | Total commercial | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	28,665	28,061
Commercial Real Estate [Member] | Total commercial | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	51	4
Commercial Real Estate [Member] | Total commercial | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	4	1
Commercial Real Estate [Member] | Total commercial | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	55	5
Commercial Real Estate [Member] | Total commercial | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	43	44
Equipment Lease Financing [Member] | Total commercial
Financing Receivable, Past Due [Line Items]
Total Loans	7,097	7,155
Equipment Lease Financing [Member] | Total commercial | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	7,058	7,069
Equipment Lease Financing [Member] | Total commercial | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	8	49
Equipment Lease Financing [Member] | Total commercial | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	9	5
Equipment Lease Financing [Member] | Total commercial | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	17	54
Equipment Lease Financing [Member] | Total commercial | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	22	32
Home Equity [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	24,879	25,085
Home Equity [Member] | Total consumer
Financing Receivable, Past Due [Line Items]
Total Loans	24,879	25,085
Home Equity [Member] | Total consumer | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	24,089	23,791
Home Equity [Member] | Total consumer | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	70	58
Home Equity [Member] | Total consumer | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	27	24
Home Equity [Member] | Total consumer | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	97	82
Home Equity [Member] | Total consumer | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	636	669
Home Equity [Member] | Total consumer | Fair Value Option Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	57
Home Equity [Member] | Total consumer | Purchased Impaired Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans		543
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	22,469	21,821
Residential Real Estate [Member] | Government Insured or Guaranteed Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	579	584
Residential Real Estate [Member] | Total consumer
Financing Receivable, Past Due [Line Items]
Total Loans	22,469	21,821
Residential Real Estate [Member] | Total consumer | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	21,141	19,640
Residential Real Estate [Member] | Total consumer | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	198	140
Residential Real Estate [Member] | Total consumer | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	93	69
Residential Real Estate [Member] | Total consumer | 90 Days or More Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	264	315
Residential Real Estate [Member] | Total consumer | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	555	524
Residential Real Estate [Member] | Total consumer | Total Past Due [Member] | Government Insured or Guaranteed Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	400	400
Residential Real Estate [Member] | Total consumer | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	305	315
Residential Real Estate [Member] | Total consumer | Fair Value Option Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	468	166
Residential Real Estate [Member] | Total consumer | Purchased Impaired Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans		1,176
Automobile [Member] | Total consumer
Financing Receivable, Past Due [Line Items]
Total Loans	16,157	16,754
Automobile [Member] | Total consumer | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	15,843	16,376
Automobile [Member] | Total consumer | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	105	178
Automobile [Member] | Total consumer | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	34	47
Automobile [Member] | Total consumer | 90 Days or More Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	19	18
Automobile [Member] | Total consumer | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	158	243
Automobile [Member] | Total consumer | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	156	135
Credit Card [Member]
Financing Receivable, Past Due [Line Items]
Total Loans		7,308
Credit Card [Member] | Total consumer
Financing Receivable, Past Due [Line Items]
Total Loans	6,575	7,308
Credit Card [Member] | Total consumer | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	6,408	7,133
Credit Card [Member] | Total consumer | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	53	60
Credit Card [Member] | Total consumer | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	38	37
Credit Card [Member] | Total consumer | 90 Days or More Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	61	67
Credit Card [Member] | Total consumer | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	152	164
Credit Card [Member] | Total consumer | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	15	11
Education [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	3,132	3,336
Education [Member] | Total consumer
Financing Receivable, Past Due [Line Items]
Total Loans	3,132	3,336
Education [Member] | Total consumer | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	3,004	3,156
Education [Member] | Total consumer | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	39	55
Education [Member] | Total consumer | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	23	34
Education [Member] | Total consumer | 90 Days or More Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	66	91
Education [Member] | Total consumer | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	128	180
Education [Member] | Total consumer | Total Past Due [Member] | Government Insured or Guaranteed Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	100	200
Other Consumer [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	4,829	4,937
Other Consumer [Member] | Total consumer
Financing Receivable, Past Due [Line Items]
Total Loans	4,829	4,937
Other Consumer [Member] | Total consumer | Current or Less Than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	4,786	4,898
Other Consumer [Member] | Total consumer | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	17	15
Other Consumer [Member] | Total consumer | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	8	11
Other Consumer [Member] | Total consumer | 90 Days or More Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	12	9
Other Consumer [Member] | Total consumer | Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	37	35
Other Consumer [Member] | Total consumer | Nonperforming Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans	$ 6	$ 4