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Investment Securities - Securities in Gross Unrealized Loss Position (Details) $ in Millions | Mar. 31, 2022 USD ($) security | Dec. 31, 2021 USD ($) security
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | $ 51,382 | $ 41,701
Fair Value - 12 Months or Longer | 18,531 | 9,410
Fair Value - Total | 69,913 | 51,111
Gross Unrealized Loss - Less than 12 Months | (2,508) | (670)
Gross Unrealized Loss - 12 Months or Longer | (1,836) | (326)
Gross Unrealized Loss - Total | $ (4,344) | $ (996)
Number of securities in gross unrealized loss positions | security | 1,790 | 740
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | $ 3,960 |
Fair Value - 12 Months or Longer | 0 |
Fair Value - Total | 3,960 |
Gross Unrealized Loss - Less than 12 Months | (29) |
Gross Unrealized Loss - 12 Months or Longer | 0 |
Gross Unrealized Loss - Total | (29) |
RMBS, Agency |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 40,778 | $ 37,492
Fair Value - 12 Months or Longer | 17,358 | 8,606
Fair Value - Total | 58,136 | 46,098
Gross Unrealized Loss - Less than 12 Months | (2,263) | (632)
Gross Unrealized Loss - 12 Months or Longer | (1,736) | (299)
Gross Unrealized Loss - Total | (3,999) | (931)
RMBS, Non-agency |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 14 | 3
Fair Value - 12 Months or Longer | 0 | 1
Fair Value - Total | 14 | 4
Gross Unrealized Loss - Less than 12 Months | 0 | 0
Gross Unrealized Loss - 12 Months or Longer | 0 | 0
Gross Unrealized Loss - Total | 0 | 0
RMBS |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 40,792 | 37,495
Fair Value - 12 Months or Longer | 17,358 | 8,607
Fair Value - Total | 58,150 | 46,102
Gross Unrealized Loss - Less than 12 Months | (2,263) | (632)
Gross Unrealized Loss - 12 Months or Longer | (1,736) | (299)
Gross Unrealized Loss - Total | (3,999) | (931)
CMBS, Agency |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 5,106 | 2,999
Fair Value - 12 Months or Longer | 1,173 | 803
Fair Value - Total | 6,279 | 3,802
Gross Unrealized Loss - Less than 12 Months | (204) | (36)
Gross Unrealized Loss - 12 Months or Longer | (100) | (27)
Gross Unrealized Loss - Total | (304) | (63)
Other securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value - Less than 12 Months | 1,524 | 1,207
Fair Value - 12 Months or Longer | 0 | 0
Fair Value - Total | 1,524 | 1,207
Gross Unrealized Loss - Less than 12 Months | (12) | (2)
Gross Unrealized Loss - 12 Months or Longer | 0 | 0
Gross Unrealized Loss - Total | $ (12) | $ (2)

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