Outstanding Loans and Leases and Allowance for Credit Losses - Modifications to Borrowers in Financial Difficulty and Financial Effect of Modified Loans (Details)

Outstanding Loans and Leases and Allowance for Credit Losses - Modifications to Borrowers in Financial Difficulty and Financial Effect of Modified Loans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Consumer real estate
Financing Receivable, Modified [Line Items]
Total	$ 176	$ 73	$ 239	$ 127
Consumer real estate \| Forbearance and Other Payment Plans
Financing Receivable, Modified [Line Items]
Total	115	10	138	17
Consumer real estate \| Permanent Modification
Financing Receivable, Modified [Line Items]
Total	61	63	101	110
Consumer real estate \| Residential Mortgage
Financing Receivable, Modified [Line Items]
Total	172	68	229	115
Consumer real estate \| Residential Mortgage \| Forbearance and Other Payment Plans
Financing Receivable, Modified [Line Items]
Total	$ 115	$ 10	$ 135	$ 17
Weighted-average duration	5 months	6 months	11 months	6 months
Consumer real estate \| Residential Mortgage \| Permanent Modification
Financing Receivable, Modified [Line Items]
Total	$ 57	$ 58	$ 94	$ 98
Weighted-average duration	10 years 1 month 6 days	9 years 2 months 12 days	10 years 2 months 12 days	9 years 4 months 24 days
Weighted-average Interest Rate Reduction	1.45%	1.06%	1.52%	1.19%
Consumer real estate \| Home equity
Financing Receivable, Modified [Line Items]
Total	$ 4	$ 5	$ 10	$ 12
Consumer real estate \| Home equity \| Forbearance and Other Payment Plans
Financing Receivable, Modified [Line Items]
Total	0	0	3	0
Consumer real estate \| Home equity \| Permanent Modification
Financing Receivable, Modified [Line Items]
Total	$ 4	$ 5	$ 7	$ 12
Weighted-average duration	5 years 4 months 24 days	14 years 8 months 12 days	6 years	16 years 7 months 6 days
Weighted-average Interest Rate Reduction	2.29%	2.27%	2.93%	2.23%
Commercial
Financing Receivable, Modified [Line Items]
Total	$ 1,373	$ 1,709	$ 2,284	$ 2,740
Commercial \| United States
Financing Receivable, Modified [Line Items]
Total	985	501	1,545	744
Commercial \| Non United States
Financing Receivable, Modified [Line Items]
Total	81	0	88	42
Commercial \| Term Extension
Financing Receivable, Modified [Line Items]
Total	964	1,166	1,574	2,046
Commercial \| Term Extension \| United States
Financing Receivable, Modified [Line Items]
Total	586	397	1,133	610
Commercial \| Term Extension \| Non United States
Financing Receivable, Modified [Line Items]
Total	71	0	78	33
Commercial \| Forbearances
Financing Receivable, Modified [Line Items]
Total	409	543	710	694
Commercial \| Forbearances \| United States
Financing Receivable, Modified [Line Items]
Total	399	104	412	134
Commercial \| Forbearances \| Non United States
Financing Receivable, Modified [Line Items]
Total	10	0	10	9
Commercial \| Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Total	0	0	0	0
Commercial \| Interest Rate Reduction \| United States
Financing Receivable, Modified [Line Items]
Total	0	0	0	0
Commercial \| Interest Rate Reduction \| Non United States
Financing Receivable, Modified [Line Items]
Total	0	0	0	0
Commercial \| Commercial real estate
Financing Receivable, Modified [Line Items]
Total	307	1,208	651	1,954
Commercial \| Commercial real estate \| Term Extension
Financing Receivable, Modified [Line Items]
Total	307	769	363	1,403
Commercial \| Commercial real estate \| Forbearances
Financing Receivable, Modified [Line Items]
Total	0	439	288	551
Commercial \| Commercial real estate \| Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0	$ 0	$ 0

Quarterly report [Sections 13 or 15(d)]

Outstanding Loans and Leases and Allowance for Credit Losses - Modifications to Borrowers in Financial Difficulty and Financial Effect of Modified Loans (Details)