Loans and Related Allowance for Credit Losses (Analysis of Loan Portfolio) (Details) - USD ($) $ in Millions		Dec. 31, 2023	Dec. 31, 2022
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans	[1]	$ 321,508	$ 326,025
Percentage of total loans, past due		100.00%	100.00%
Accrued interest on loan portfolio		$ 1,500	$ 1,200
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]		Other	Other
Unearned income, unamortized deferred fees and costs on originated loans, and premiums or discounts on purchased loans		$ 1,000	$ 900
Collateral Pledged
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		1,400	1,300
Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		$ 1,384	$ 1,490
Percentage of total loans, past due		0.43%	0.46%
Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		$ 317,359	$ 321,904
Percentage of total loans, past due		98.71%	98.73%
30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		$ 685	$ 747
Percentage of total loans, past due		0.21%	0.23%
60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		$ 270	$ 261
Percentage of total loans, past due		0.08%	0.08%
90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		$ 429	$ 482
Percentage of total loans, past due		0.13%	0.15%
Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		$ 2,180	$ 1,985
Percentage of total loans, past due		0.68%	0.61%
Fair Value Option Nonaccrual Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Nonaccrual loans		$ 585	$ 646
Percentage of total loans, nonaccrual, past due		0.18%	0.20%
Residential real estate
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		$ 47,544	$ 45,889
Residential real estate | Government insured or guaranteed loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		653	693
Home equity
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		26,150	25,983
Education
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		1,945	2,173
Other consumer
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		4,271	5,026
Commercial
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		219,558	225,049
Commercial | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		290	380
Commercial | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		217,961	223,811
Commercial | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		152	208
Commercial | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		53	35
Commercial | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		85	137
Commercial | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		1,307	858
Commercial | Commercial and industrial
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		177,580	182,219
Commercial | Commercial and industrial | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		225	333
Commercial | Commercial and industrial | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		176,796	181,223
Commercial | Commercial and industrial | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		104	169
Commercial | Commercial and industrial | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		45	27
Commercial | Commercial and industrial | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		76	137
Commercial | Commercial and industrial | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		559	663
Commercial | Commercial real estate
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		35,436	36,316
Commercial | Commercial real estate | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		16	23
Commercial | Commercial real estate | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		34,685	36,104
Commercial | Commercial real estate | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		7	19
Commercial | Commercial real estate | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans			4
Commercial | Commercial real estate | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		9
Commercial | Commercial real estate | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		735	189
Commercial | Equipment lease financing
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		6,542	6,514
Commercial | Equipment lease financing | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		49	24
Commercial | Equipment lease financing | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		6,480	6,484
Commercial | Equipment lease financing | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		41	20
Commercial | Equipment lease financing | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		8	4
Commercial | Equipment lease financing | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans
Commercial | Equipment lease financing | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		13	6
Consumer
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		101,950	100,976
Consumer | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		1,094	1,110
Consumer | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		99,398	98,093
Consumer | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		533	539
Consumer | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		217	226
Consumer | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		344	345
Consumer | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		873	1,127
Consumer | Fair Value Option Nonaccrual Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Nonaccrual loans		585	646
Consumer | Residential real estate
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		47,544	45,889
Consumer | Residential real estate | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		575	592
Consumer | Residential real estate | Total Past Due | Government insured or guaranteed loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		300	300
Consumer | Residential real estate | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		46,159	44,306
Consumer | Residential real estate | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		282	281
Consumer | Residential real estate | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		101	112
Consumer | Residential real estate | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		192	199
Consumer | Residential real estate | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		294	424
Consumer | Residential real estate | Fair Value Option Nonaccrual Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Nonaccrual loans		516	567
Consumer | Home equity
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		26,150	25,983
Consumer | Home equity | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		90	73
Consumer | Home equity | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		25,533	25,305
Consumer | Home equity | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		63	53
Consumer | Home equity | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		27	20
Consumer | Home equity | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans
Consumer | Home equity | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		458	526
Consumer | Home equity | Fair Value Option Nonaccrual Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Nonaccrual loans		69	79
Consumer | Automobile
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		14,860	14,836
Consumer | Automobile | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		118	138
Consumer | Automobile | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		14,638	14,543
Consumer | Automobile | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		91	106
Consumer | Automobile | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		20	25
Consumer | Automobile | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		7	7
Consumer | Automobile | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		104	155
Consumer | Credit card
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		7,180	7,069
Consumer | Credit card | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		179	155
Consumer | Credit card | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		6,991	6,906
Consumer | Credit card | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		54	50
Consumer | Credit card | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		39	35
Consumer | Credit card | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		86	70
Consumer | Credit card | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		10	8
Consumer | Education
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		1,945	2,173
Consumer | Education | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		95	115
Consumer | Education | Total Past Due | Government insured or guaranteed loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		100	100
Consumer | Education | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		1,850	2,058
Consumer | Education | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		27	34
Consumer | Education | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		19	22
Consumer | Education | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		49	59
Consumer | Education | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans
Consumer | Other consumer
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		4,271	5,026
Consumer | Other consumer | Total Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		37	37
Consumer | Other consumer | Current or Less Than 30 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		4,227	4,975
Consumer | Other consumer | 30-59 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		16	15
Consumer | Other consumer | 60-89 Days Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		11	12
Consumer | Other consumer | 90 Days or More Past Due
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		10	10
Consumer | Other consumer | Nonperforming Loans
Financing Receivable. Recorded Investment, Past Due [Line Items]
Total loans		$ 7	$ 14

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $0.7 billion, Loans of $1.2 billion and Other assets of $0.1 billion at December 31, 2023. Comparable amounts at December 31, 2022 were $0.9 billion, $1.3 billion and $0.1 billion, respectively.