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Investment Securities (Narrative) (Details) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2019 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions |  |  | 461 |
Loan interest receivable |  |  | $ 23 | $ 18
Repositioning lower-yielding treasury securities |  | $ 1,000 |  |
Investment securities available-for-sale, Amortized Cost |  |  | 17,116 | 14,752
Investment Securities, Available-for-sale |  |  | 16,986 | 15,028
Carrying value of securities pledged |  |  | 2,700 |
Pledged to the FHLB as collateral for potential future borrowings |  |  | 1,700 |
Debt Instrument, Unused Borrowing Capacity, Amount |  |  | 1,600 |
Securities Borrowed, Liability |  |  | 1,000 |
Liabilities secured by pledged collateral |  |  | $ 946 |
U.S. Treasury and other U.S. government agency securities |  |  |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions |  |  | 20 |
Investment securities available-for-sale, Amortized Cost |  |  | $ 3,010 | 4,583
Investment Securities, Available-for-sale |  |  | $ 2,993 | 4,658
Residential mortgage-backed securities |  |  |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions |  |  | 406 |
Debt Securities |  |  | $ 13,300 |
Investment securities available-for-sale, Amortized Cost | [1] |  | 13,397 | 10,169
Investment Securities, Available-for-sale | [1] |  | 13,288 | $ 10,370
Residential mortgage-backed securities | Prepayment options |  |  |  |
Debt Securities |  |  | $ 13,400 |
Commercial Mortgage Backed Securities |  |  |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions |  |  | 35 |
Investment securities available-for-sale, Amortized Cost | [1] |  | $ 709 |
Investment Securities, Available-for-sale | [1] |  | $ 705 |
[1] | Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

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