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v3.21.1

Investment Securities - Additional Information (Details) - USD ($) $ in Millions |  |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Mar. 31, 2021 | Dec. 31, 2020 | Mar. 31, 2021 | Mar. 31, 2020 | Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |
Increase in retained earnings | $ 43,167 | $ 40,088 | $ 43,167 |  | $ 40,088
Accrued interest receivable |  |  | 237 |  | 230
Proceeds from sales |  |  | 595 | $ 144 |
Gross realized gains |  |  | 4 | $ 1 |
Derivative, collateral, obligation to return securities | $ 1 | $ 1 | 1 |  | 1
Investment securities portfolio | US Treasury and Agency securities |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |
Percentage of portfolio | 96.00% | 96.00% |  |  |
Collateral pledged |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |
Debt securities, available-for-sale, restricted | $ 16,800 | $ 16,500 | $ 16,800 |  | $ 16,500

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