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Investment Securities - Additional Information (Details) $ in Millions |  | 12 Months Ended
--- | --- | ---
Dec. 31, 2019 USD ($) Security | Dec. 31, 2019 USD ($) Security | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Transfer of securities held to maturity to available for sale | $ 33,200 | $ 33,187 | $ 0 | $ 0
AOCI, pre-tax | $ 1,200 | $ 1,200 |  |
Debt securities, available-for-sale, unrealized loss position, number of positions | Security | 900 | 900 |  |
Debt securities, available-for-sale, unrealized loss position, accumulated loss | $ 332 | $ 332 | 972 |
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, accumulated loss | 212 | 212 | 675 |
OTTI, credit losses recognized in earnings | 134 | 134 | 140 |
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 |  | 96.00% | 96.00% |
Collateral pledged |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Debt securities, available-for-sale, restricted | $ 14,000 | $ 14,000 | $ 16,300 |

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