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Short-Term Borrowings - Summary of Short-Term Borrowings (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Short-term Debt [Line Items] |  |  |
Short-term borrowings | $ 2,124 | $ 2,198 |
Trading Liabilities |  |  |
Short-term Debt [Line Items] |  |  |
Average balance | 540 | 457 | $ 503
Short-term borrowings | 426 | 353 | 506
Maximum month-end outstanding | $ 685 | $ 983 | $ 754
Average rate for the year | 1.11% | 1.24% | 2.48%
Average rate at year-end | 1.62% | 0.77% | 2.07%
Federal Funds Purchased |  |  |
Short-term Debt [Line Items] |  |  |
Average balance | $ 949 | $ 862 | $ 738
Short-term borrowings | 775 | 845 | 548
Maximum month-end outstanding | $ 1,037 | $ 1,487 | $ 1,282
Average rate for the year | 0.12% | 0.34% | 2.08%
Average rate at year-end | 0.10% | 0.10% | 1.55%
Securities Sold Under Agreements to Repurchase |  |  |
Short-term Debt [Line Items] |  |  |
Average balance | $ 1,235 | $ 1,109 | $ 701
Short-term borrowings | 1,247 | 1,187 | 717
Maximum month-end outstanding | $ 1,615 | $ 1,661 | $ 772
Average rate for the year | 0.30% | 0.50% | 2.07%
Average rate at year-end | 0.11% | 0.26% | 1.72%
Other Short-term Borrowings |  |  |
Short-term Debt [Line Items] |  |  |
Average balance | $ 124 | $ 626 | $ 538
Short-term borrowings | 102 | 166 | 2,253
Maximum month-end outstanding | $ 146 | $ 4,061 | $ 2,276
Average rate for the year | 0.09% | 0.84% | 2.10%
Average rate at year-end | 0.08% | 0.09% | 2.14%

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