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Borrowings (Short-Term Borrowings) (Details) - Federal Funds Purchased And Repurchase Agreements [Member] - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Short-term Debt [Line Items] |  |  |
Year End Weighted Rate | 0.04% | 0.80% | 0.90%
Average Weighted Rate | 0.30% | 1.60% | 1.30%
Average Balance Outstanding | $ 1,966,479 | $ 1,822,098 | $ 1,514,144
Maximum Outstanding at any Month End | 2,314,756 | 2,394,294 | 1,981,761
Balance at December 31 | $ 2,098,383 | $ 1,850,772 | $ 1,956,389

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- Definition For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period. + References No definition available. + Details
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