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Investment Securities - Summary of Unrealized Loss Positions on Investment Securities (Details) $ in Millions | Sep. 30, 2025 USD ($) security | Dec. 31, 2024 USD ($) security
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security | 607 | 609
Fair Value |  |
Less than Twelve Months | $ 913 | $ 1,674
Twelve Months or Longer | 5,625 | 5,592
Total | 6,538 | 7,266
Unrealized Loss |  |
Less than Twelve Months | 1 | 3
Twelve Months or Longer | 731 | 929
Total | $ 732 | $ 932
Debt Securities | GSE CMOs |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security | 230 | 223
Fair Value |  |
Less than Twelve Months | $ 899 | $ 1,636
Twelve Months or Longer | 3,037 | 2,822
Total | 3,936 | 4,458
Unrealized Loss |  |
Less than Twelve Months | 1 | 3
Twelve Months or Longer | 370 | 444
Total | $ 371 | $ 447
Debt Securities | U.S. Government agency and GSE obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security | 33 | 33
Fair Value |  |
Less than Twelve Months | $ 0 | $ 0
Twelve Months or Longer | 1,287 | 1,203
Total | 1,287 | 1,203
Unrealized Loss |  |
Less than Twelve Months | 0 | 0
Twelve Months or Longer | 216 | 299
Total | $ 216 | $ 299
Debt Securities | GSE certificates |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security | 326 | 328
Fair Value |  |
Less than Twelve Months | $ 0 | $ 38
Twelve Months or Longer | 948 | 1,040
Total | 948 | 1,078
Unrealized Loss |  |
Less than Twelve Months | 0 | 0
Twelve Months or Longer | 126 | 167
Total | $ 126 | $ 167
Debt Securities | Corporate bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security | 6 | 11
Fair Value |  |
Less than Twelve Months | $ 0 | $ 0
Twelve Months or Longer | 157 | 308
Total | 157 | 308
Unrealized Loss |  |
Less than Twelve Months | 0 | 0
Twelve Months or Longer | 7 | 6
Total | $ 7 | $ 6
Debt Securities | Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security | 5 | 5
Fair Value |  |
Less than Twelve Months | $ 14 | $ 0
Twelve Months or Longer | 142 | 154
Total | 156 | 154
Unrealized Loss |  |
Less than Twelve Months | 0 | 0
Twelve Months or Longer | 4 | 2
Total | $ 4 | $ 2
Debt Securities | Capital trust notes |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security | 5 | 5
Fair Value |  |
Less than Twelve Months | $ 0 | $ 0
Twelve Months or Longer | 35 | 33
Total | 35 | 33
Unrealized Loss |  |
Less than Twelve Months | 0 | 0
Twelve Months or Longer | 8 | 10
Total | $ 8 | $ 10
Debt Securities | Private Label CMOs |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security | 1 | 2
Fair Value |  |
Less than Twelve Months | $ 0 | $ 0
Twelve Months or Longer | 14 | 17
Total | 14 | 17
Unrealized Loss |  |
Less than Twelve Months | 0 | 0
Twelve Months or Longer | 0 | 1
Total | $ 0 | $ 1
Debt Securities | Foreign notes |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security |  | 1
Fair Value |  |
Less than Twelve Months |  | $ 0
Twelve Months or Longer |  | 10
Total |  | 10
Unrealized Loss |  |
Less than Twelve Months |  | 0
Twelve Months or Longer |  | 0
Total |  | $ 0
Debt Securities | Municipal bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Debt Securities | security | 1 | 1
Fair Value |  |
Less than Twelve Months | $ 0 | $ 0
Twelve Months or Longer | 5 | 5
Total | 5 | 5
Unrealized Loss |  |
Less than Twelve Months | 0 | 0
Twelve Months or Longer | 0 | 0
Total | $ 0 | $ 0

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