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Investment Securities - Securities in Gross Unrealized Loss Position (Details) $ in Millions | Dec. 31, 2024 USD ($) security | Dec. 31, 2023 USD ($) security
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Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | $ 15,189 | $ 5,068
Gross Unrealized Loss - Less than 12 Months | (194) | (50)
Fair Value - 12 Months or Longer | 55,326 | 62,711
Gross Unrealized Loss - 12 Months or Longer | (9,927) | (9,102)
Fair Value - Total | 70,515 | 67,779
Gross Unrealized Loss - Total | $ (10,121) | $ (9,152)
Number of securities in gross unrealized loss positions | security | 2,740 | 2,740
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | $ 1,724 | $ 733
Gross Unrealized Loss - Less than 12 Months | (6) | 0
Fair Value - 12 Months or Longer | 931 | 2,242
Gross Unrealized Loss - 12 Months or Longer | (3) | (49)
Fair Value - Total | 2,655 | 2,975
Gross Unrealized Loss - Total | (9) | (49)
RMBS, Agency |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 11,324 | 3,511
Gross Unrealized Loss - Less than 12 Months | (178) | (43)
Fair Value - 12 Months or Longer | 48,707 | 53,987
Gross Unrealized Loss - 12 Months or Longer | (9,349) | (8,407)
Fair Value - Total | 60,031 | 57,498
Gross Unrealized Loss - Total | (9,527) | (8,450)
RMBS, Non-agency |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 3 | 1
Gross Unrealized Loss - Less than 12 Months | 0 | 0
Fair Value - 12 Months or Longer | 11 | 13
Gross Unrealized Loss - 12 Months or Longer | (1) | (1)
Fair Value - Total | 14 | 14
Gross Unrealized Loss - Total | (1) | (1)
Total RMBS |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 11,327 | 3,512
Gross Unrealized Loss - Less than 12 Months | (178) | (43)
Fair Value - 12 Months or Longer | 48,718 | 54,000
Gross Unrealized Loss - 12 Months or Longer | (9,350) | (8,408)
Fair Value - Total | 60,045 | 57,512
Gross Unrealized Loss - Total | (9,528) | (8,451)
Agency CMBS |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 700 | 547
Gross Unrealized Loss - Less than 12 Months | (7) | (7)
Fair Value - 12 Months or Longer | 5,677 | 6,465
Gross Unrealized Loss - 12 Months or Longer | (574) | (645)
Fair Value - Total | 6,377 | 7,012
Gross Unrealized Loss - Total | (581) | (652)
Other securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 1,438 | 276
Gross Unrealized Loss - Less than 12 Months | (3) | 0
Fair Value - 12 Months or Longer | 0 | 4
Gross Unrealized Loss - 12 Months or Longer | 0 | 0
Fair Value - Total | 1,438 | 280
Gross Unrealized Loss - Total | $ (3) | $ 0

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