Loans and Related Allowance for Credit Losses (Analysis of Loan Portfolio) (Details) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Total loans	[1]	$ 318,416	$ 326,025
Percentage of total loans, past due		100.00%	100.00%
Accrued interest on loan portfolio		$ 1,400	$ 1,200
Unearned income, unamortized deferred fees and costs on originated loans, and premiums or discounts on purchased loans		800	900
Collateral Dependent
Financing Receivable, Past Due [Line Items]
Total loans		1,100	1,300
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 1,287	$ 1,490
Percentage of total loans, past due		0.40%	0.46%
Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 314,407	$ 321,904
Percentage of total loans, past due		98.74%	98.73%
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 607	$ 747
Percentage of total loans, past due		0.19%	0.23%
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 253	$ 261
Percentage of total loans, past due		0.08%	0.08%
90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 427	$ 482
Percentage of total loans, past due		0.13%	0.15%
Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		$ 2,123	$ 1,985
Percentage of total loans, past due		0.67%	0.61%
Fair Value Option Nonaccrual Loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans		$ 599	$ 646
Percentage of total loans, nonaccrual, past due		0.19%	0.20%
Total commercial
Financing Receivable, Past Due [Line Items]
Total loans		$ 216,432	$ 225,049
Total commercial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		253	380
Total commercial | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		214,968	223,811
Total commercial | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		111	208
Total commercial | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		40	35
Total commercial | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans		102	137
Total commercial | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		1,211	858
Total consumer
Financing Receivable, Past Due [Line Items]
Total loans		101,984	100,976
Total consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		1,034	1,110
Total consumer | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		99,439	98,093
Total consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		496	539
Total consumer | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		213	226
Total consumer | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans		325	345
Total consumer | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		912	1,127
Total consumer | Fair Value Option Nonaccrual Loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans		599	646
Commercial and industrial | Total commercial
Financing Receivable, Past Due [Line Items]
Total loans		174,163	182,219
Commercial and industrial | Total commercial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		218	333
Commercial and industrial | Total commercial | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		173,487	181,223
Commercial and industrial | Total commercial | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		84	169
Commercial and industrial | Total commercial | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		32	27
Commercial and industrial | Total commercial | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans		102	137
Commercial and industrial | Total commercial | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		458	663
Commercial real estate | Total commercial
Financing Receivable, Past Due [Line Items]
Total loans		35,776	36,316
Commercial real estate | Total commercial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		4	23
Commercial real estate | Total commercial | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		35,049	36,104
Commercial real estate | Total commercial | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		2	19
Commercial real estate | Total commercial | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		2	4
Commercial real estate | Total commercial | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans
Commercial real estate | Total commercial | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		723	189
Equipment lease financing | Total commercial
Financing Receivable, Past Due [Line Items]
Total loans		6,493	6,514
Equipment lease financing | Total commercial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		31	24
Equipment lease financing | Total commercial | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		6,432	6,484
Equipment lease financing | Total commercial | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		25	20
Equipment lease financing | Total commercial | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		6	4
Equipment lease financing | Total commercial | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		30	6
Residential real estate
Financing Receivable, Past Due [Line Items]
Total loans		47,359	45,889
Residential real estate | Government insured or guaranteed loans
Financing Receivable, Past Due [Line Items]
Total loans		652	693
Residential real estate | Total consumer
Financing Receivable, Past Due [Line Items]
Total loans		47,359	45,889
Residential real estate | Total consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		542	592
Residential real estate | Total consumer | Financial Asset, Past Due | Government insured or guaranteed loans
Financing Receivable, Past Due [Line Items]
Total loans		300	300
Residential real estate | Total consumer | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		45,958	44,306
Residential real estate | Total consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		257	281
Residential real estate | Total consumer | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		103	112
Residential real estate | Total consumer | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans		182	199
Residential real estate | Total consumer | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		330	424
Residential real estate | Total consumer | Fair Value Option Nonaccrual Loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans		529	567
Home equity
Financing Receivable, Past Due [Line Items]
Total loans		26,159	25,983
Home equity | Total consumer
Financing Receivable, Past Due [Line Items]
Total loans		26,159	25,983
Home equity | Total consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		81	73
Home equity | Total consumer | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		25,562	25,305
Home equity | Total consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		59	53
Home equity | Total consumer | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		22	20
Home equity | Total consumer | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		446	526
Home equity | Total consumer | Fair Value Option Nonaccrual Loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans		70	79
Automobile | Total consumer
Financing Receivable, Past Due [Line Items]
Total loans		14,940	14,836
Automobile | Total consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		108	138
Automobile | Total consumer | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		14,718	14,543
Automobile | Total consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		83	106
Automobile | Total consumer | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		19	25
Automobile | Total consumer | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans		6	7
Automobile | Total consumer | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		114	155
Credit card | Total consumer
Financing Receivable, Past Due [Line Items]
Total loans		7,060	7,069
Credit card | Total consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		168	155
Credit card | Total consumer | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		6,881	6,906
Credit card | Total consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		50	50
Credit card | Total consumer | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		38	35
Credit card | Total consumer | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans		80	70
Credit card | Total consumer | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		11	8
Education
Financing Receivable, Past Due [Line Items]
Total loans		2,020	2,173
Education | Total consumer
Financing Receivable, Past Due [Line Items]
Total loans		2,020	2,173
Education | Total consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		102	115
Education | Total consumer | Financial Asset, Past Due | Government insured or guaranteed loans
Financing Receivable, Past Due [Line Items]
Total loans		100	100
Education | Total consumer | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		1,918	2,058
Education | Total consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		32	34
Education | Total consumer | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		22	22
Education | Total consumer | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans		48	59
Other consumer
Financing Receivable, Past Due [Line Items]
Total loans		4,446	5,026
Other consumer | Total consumer
Financing Receivable, Past Due [Line Items]
Total loans		4,446	5,026
Other consumer | Total consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		33	37
Other consumer | Total consumer | Current or Less Than 30 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		4,402	4,975
Other consumer | Total consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		15	15
Other consumer | Total consumer | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans		9	12
Other consumer | Total consumer | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total loans		9	10
Other consumer | Total consumer | Nonperforming Loans
Financing Receivable, Past Due [Line Items]
Total loans		$ 11	$ 14

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $0.9 billion, Loans held for investment of $1.2 billion and Other assets of $0.1 billion at September 30, 2023. Comparable amounts at December 31, 2022 were $0.9 billion, $1.3 billion and $0.1 billion, respectively.