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Derivative Instruments and Hedging Activities - Derivative Assets and Liabilities at Fair Value (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | $ 367,924 | $ 325,778
Derivative assets, gross amount | 2,125 | 2,232
Derivative liabilities, gross amount | 1,971 | 2,032
Derivative Asset, netting adjustments | (481) | (1,056)
Derivative Liability, netting adjustments | (449) | (304)
Net Amounts as Recognized | 1,644 | 1,176
Net Amounts as Recognized | 1,522 | 1,728
Net valuation allowance on derivative assets and liabilities for non-performance risk | 6 | 1
Derivatives designated as accounting hedges: |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 188,430 | 171,725
Derivative assets, gross amount | 220 | 390
Derivative liabilities, gross amount | 112 | 138
Derivatives designated as accounting hedges: | Interest rate contracts: |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 179,774 | 163,800
Derivative assets, gross amount | 165 | 126
Derivative liabilities, gross amount | 10 | 37
Derivatives designated as accounting hedges: | Interest rate contracts: | Fair value hedges |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 62,024 | 61,250
Derivative assets, gross amount | 12 | 3
Derivative liabilities, gross amount | 2 | 13
Derivatives designated as accounting hedges: | Interest rate contracts: | Cash flow hedges |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 117,750 | 102,550
Derivative assets, gross amount | 153 | 123
Derivative liabilities, gross amount | 8 | 24
Derivatives designated as accounting hedges: | Foreign exchange and other contracts |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 8,656 | 7,925
Derivative assets, gross amount | 55 | 264
Derivative liabilities, gross amount | 102 | 101
Derivatives designated as accounting hedges: | Foreign exchange and other contracts | Fair value hedges |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 587 | 518
Derivative assets, gross amount | 0 | 0
Derivative liabilities, gross amount | 26 | 101
Derivatives designated as accounting hedges: | Foreign exchange and other contracts | Cash flow hedges |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 2,654 | 2,549
Derivative assets, gross amount | 21 | 74
Derivative liabilities, gross amount | 1 | 0
Derivatives designated as accounting hedges: | Foreign exchange and other contracts | Net investment hedges |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 5,415 | 4,858
Derivative assets, gross amount | 34 | 190
Derivative liabilities, gross amount | 75 | 0
Derivatives not designated as accounting hedges: |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 179,494 | 154,053
Derivative assets, gross amount | 1,905 | 1,842
Derivative liabilities, gross amount | 1,859 | 1,894
Derivatives not designated as accounting hedges: | Customer accommodation: |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 173,897 | 149,890
Derivative assets, gross amount | 1,853 | 1,803
Derivative liabilities, gross amount | 1,836 | 1,880
Derivatives not designated as accounting hedges: | Interest rate contracts: | Customer accommodation: |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 125,615 | 108,754
Derivative assets, gross amount | 723 | 865
Derivative liabilities, gross amount | 747 | 1,014
Derivatives not designated as accounting hedges: | Interest rate contracts: | Other interest rate exposures |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 2,198 | 909
Derivative assets, gross amount | 17 | 14
Derivative liabilities, gross amount | 10 | 9
Derivatives not designated as accounting hedges: | Foreign exchange and other contracts | Customer accommodation: |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 6,131 | 6,951
Derivative assets, gross amount | 73 | 80
Derivative liabilities, gross amount | 65 | 52
Derivatives not designated as accounting hedges: | Commodity contracts | Customer accommodation: |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 42,151 | 34,185
Derivative assets, gross amount | 1,057 | 858
Derivative liabilities, gross amount | 1,024 | 814
Derivatives not designated as accounting hedges: | Other contracts |  |
Derivatives, Fair Value [Line Items] |  |
Notional or Contractual Amount | 3,399 | 3,254
Derivative assets, gross amount | 35 | 25
Derivative liabilities, gross amount | $ 13 | $ 5

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