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Loans and allowance for loan losses - Loan and Leases Considered Nonaccrual and Interest Income Recognized on Loans (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2026 | Jun. 30, 2025 | Jun. 30, 2026 | Jun. 30, 2025 | Mar. 31, 2026 | Jan. 01, 2026 | Dec. 31, 2025 | Mar. 31, 2025 | Jan. 01, 2025
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | $ 890 | $ 1,152 | $ 890 | $ 1,152 |  |  |  |  |
Amortized Cost without Allowance | 318 | 421 | 318 | 421 |  |  |  |  |
Total | 1,208 | 1,573 | 1,208 | 1,573 | $ 1,240 | $ 1,252 | $ 1,252 | $ 1,540 | $ 1,690
Amortized Cost | 1,208 | 1,573 | 1,208 | 1,573 | 1,240 | 1,252 | 1,252 | 1,540 | 1,690
Interest Income Recognized | 22 | 22 | 34 | 40 |  |  |  |  |
Commercial and industrial |  |  |  |  |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | 520 | 663 | 520 | 663 |  |  |  |  |
Amortized Cost without Allowance | 50 | 124 | 50 | 124 |  |  |  |  |
Total | 570 | 787 | 570 | 787 | 535 | 527 | 527 | 662 | 696
Amortized Cost | 570 | 787 | 570 | 787 | 535 | 527 | 527 | 662 | 696
Interest Income Recognized | 8 | 6 | 15 | 12 |  |  |  |  |
Commercial real estate | Commercial |  |  |  |  |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | 162 | 289 | 162 | 289 |  |  |  |  |
Amortized Cost without Allowance | 54 | 87 | 54 | 87 |  |  |  |  |
Total | 216 | 376 | 216 | 376 | 294 | 320 | 320 | 394 | 468
Amortized Cost | 216 | 376 | 216 | 376 | 294 | 320 | 320 | 394 | 468
Interest Income Recognized | 8 | 10 | 9 | 17 |  |  |  |  |
Commercial real estate | Residential builder and developer |  |  |  |  |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | 0 | 1 | 0 | 1 |  |  |  |  |
Amortized Cost without Allowance | 0 | 0 | 0 | 0 |  |  |  |  |
Total | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 1 | 2
Amortized Cost | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 1 | 2
Interest Income Recognized | 0 | 0 | 0 | 0 |  |  |  |  |
Commercial real estate | Other commercial construction |  |  |  |  |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | 29 | 23 | 29 | 23 |  |  |  |  |
Amortized Cost without Allowance | 7 | 0 | 7 | 0 |  |  |  |  |
Total | 36 | 23 | 36 | 23 | 10 | 13 | 13 | 28 | 66
Amortized Cost | 36 | 23 | 36 | 23 | 10 | 13 | 13 | 28 | 66
Interest Income Recognized | 0 | 0 | 0 | 0 |  |  |  |  |
Residential real estate | Residential |  |  |  |  |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | 111 | 115 | 111 | 115 |  |  |  |  |
Amortized Cost without Allowance | 151 | 150 | 151 | 150 |  |  |  |  |
Total | 262 | 265 | 262 | 265 | 272 | 264 | 264 | 284 | 279
Amortized Cost | 262 | 265 | 262 | 265 | 272 | 264 | 264 | 284 | 279
Interest Income Recognized | 4 | 4 | 6 | 7 |  |  |  |  |
Consumer | Home equity lines and loans (e) |  |  |  |  |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | 37 | 34 | 37 | 34 |  |  |  |  |
Amortized Cost without Allowance | 40 | 41 | 40 | 41 |  |  |  |  |
Total | 77 | 75 | 77 | 75 | 84 | 82 | 82 | 78 | 81
Amortized Cost | 77 | 75 | 77 | 75 | 84 | 82 | 82 | 78 | 81
Interest Income Recognized | 1 | 2 | 3 | 4 |  |  |  |  |
Consumer | Recreational finance |  |  |  |  |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | 19 | 15 | 19 | 15 |  |  |  |  |
Amortized Cost without Allowance | 14 | 10 | 14 | 10 |  |  |  |  |
Total | 33 | 25 | 33 | 25 | 32 | 30 | 30 | 26 | 31
Amortized Cost | 33 | 25 | 33 | 25 | 32 | 30 | 30 | 26 | 31
Interest Income Recognized | 1 | 0 | 1 | 0 |  |  |  |  |
Consumer | Automobile |  |  |  |  |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | 8 | 7 | 8 | 7 |  |  |  |  |
Amortized Cost without Allowance | 2 | 2 | 2 | 2 |  |  |  |  |
Total | 10 | 9 | 10 | 9 | 9 | 11 | 11 | 11 | 12
Amortized Cost | 10 | 9 | 10 | 9 | 9 | 11 | 11 | 11 | 12
Interest Income Recognized | 0 | 0 | 0 | 0 |  |  |  |  |
Consumer | Other |  |  |  |  |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |  |  |  |  |
Amortized Cost with Allowance | 4 | 5 | 4 | 5 |  |  |  |  |
Amortized Cost without Allowance | 0 | 7 | 0 | 7 |  |  |  |  |
Total | 4 | 12 | 4 | 12 | 4 | 5 | 5 | 56 | 55
Amortized Cost | 4 | 12 | 4 | 12 | $ 4 | $ 5 | $ 5 | $ 56 | $ 55
Interest Income Recognized | $ 0 | $ 0 | $ 0 | $ 0 |  |  |  |  |

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