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Investment Securities - Securities in Gross Unrealized Loss Position (Details) $ in Millions | Jun. 30, 2024 USD ($) security | Dec. 31, 2023 USD ($) security
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | $ 7,702 | $ 5,068
Gross Unrealized Loss - Less than 12 Months | (52) | (50)
Fair Value - 12 Months or Longer | 61,421 | 62,711
Gross Unrealized Loss - 12 Months or Longer | (10,406) | (9,102)
Fair Value - Total | 69,123 | 67,779
Gross Unrealized Loss - Total | $ (10,458) | $ (9,152)
Number of securities in gross unrealized loss positions | security | 2,790 | 2,740
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | $ 1,329 | $ 733
Gross Unrealized Loss - Less than 12 Months | (3) | 0
Fair Value - 12 Months or Longer | 2,014 | 2,242
Gross Unrealized Loss - 12 Months or Longer | (23) | (49)
Fair Value - Total | 3,343 | 2,975
Gross Unrealized Loss - Total | (26) | (49)
RMBS, Agency |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 5,024 | 3,511
Gross Unrealized Loss - Less than 12 Months | (42) | (43)
Fair Value - 12 Months or Longer | 53,037 | 53,987
Gross Unrealized Loss - 12 Months or Longer | (9,714) | (8,407)
Fair Value - Total | 58,061 | 57,498
Gross Unrealized Loss - Total | (9,756) | (8,450)
RMBS, Non-agency |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 4 | 1
Gross Unrealized Loss - Less than 12 Months | 0 | 0
Fair Value - 12 Months or Longer | 12 | 13
Gross Unrealized Loss - 12 Months or Longer | (1) | (1)
Fair Value - Total | 16 | 14
Gross Unrealized Loss - Total | (1) | (1)
Total RMBS |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 5,028 | 3,512
Gross Unrealized Loss - Less than 12 Months | (42) | (43)
Fair Value - 12 Months or Longer | 53,049 | 54,000
Gross Unrealized Loss - 12 Months or Longer | (9,715) | (8,408)
Fair Value - Total | 58,077 | 57,512
Gross Unrealized Loss - Total | (9,757) | (8,451)
Agency CMBS |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 632 | 547
Gross Unrealized Loss - Less than 12 Months | (7) | (7)
Fair Value - 12 Months or Longer | 6,262 | 6,465
Gross Unrealized Loss - 12 Months or Longer | (668) | (645)
Fair Value - Total | 6,894 | 7,012
Gross Unrealized Loss - Total | (675) | (652)
Other securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 713 | 276
Gross Unrealized Loss - Less than 12 Months | 0 | 0
Fair Value - 12 Months or Longer | 96 | 4
Gross Unrealized Loss - 12 Months or Longer | 0 | 0
Fair Value - Total | 809 | 280
Gross Unrealized Loss - Total | $ 0 | $ 0

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