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Investment Securities - Additional Information (Details) - USD ($) $ in Millions |  |  | 3 Months Ended |  |
--- | --- | --- | --- | --- | ---
Mar. 31, 2020 | Dec. 31, 2019 | Mar. 31, 2020 | Mar. 31, 2019 | Jan. 01, 2020 | Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |
Decrease in AOCI | $ 3,679 | $ 1,156 | $ 3,679 | $ (660) |  | $ (1,263)
Increase in retained earnings | (36,552) | (40,340) | (36,552) |  |  |
Accrued interest receivable |  |  | 244 |  |  |
Proceeds from Sale of Available-for-sale Securities |  |  | 144 | 3,100 |  |
Debt Securities, Available-for-sale, Gain (Loss) |  |  | 1 | $ 24 |  |
Derivative, collateral, obligation to return securities | $ 1 | $ 1 | 1 |  |  |
Investment securities portfolio | US Treasury and Agency securities |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |
Percentage of portfolio | 97.00% | 96.00% |  |  |  |
Collateral pledged |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |
Debt securities, available-for-sale, restricted | $ 13,600 | $ 14,000 | $ 13,600 |  |  |
Adjustment amount |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |
Decrease in AOCI |  |  |  |  | $ (11) |
Increase in retained earnings |  |  |  |  | $ (11) |

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