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Loans and Allowance for Credit Losses, Loans by Portfolio Type (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest | $ 6,667,276 | $ 6,134,362
Loans, variable rate of interest | 16,914,871 | 15,435,674
Loans, non-accrual | 221,153 | 180,951
Total | 23,803,300 | 21,750,987
Past Due 90 Days or More and Accruing | 124,872 | 7,680
Credit Commitments [Abstract] |  |
Outstanding commitments to extend credit | 10,400,000 |
Outstanding standby letters of credit | 678,000 |
Commercial [Member] |  |
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest | 1,424,416 | 3,231,485
Loans, variable rate of interest | 11,971,337 | 10,684,749
Loans, non-accrual | 169,953 | 115,416
Total | 13,565,706 | 14,031,650
Past Due 90 Days or More and Accruing | 672 |
Commercial real estate [Member] |  |
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest | 1,012,882 | 1,056,321
Loans, variable rate of interest | 3,667,866 | 3,349,836
Loans, non-accrual | 12,952 | 27,626
Total | 4,693,700 | 4,433,783
Past Due 90 Days or More and Accruing | 4,771 |
Paycheck Protection Program |  |
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest | 2,097,325 |
Loans, variable rate of interest | 0 |
Loans, non-accrual | 0 |
Total | 2,097,325 |
Past Due 90 Days or More and Accruing | 0 |
Loans to individuals [Member] |  |
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest | 2,132,653 |
Loans, variable rate of interest | 1,275,668 |
Loans, non-accrual | 38,248 |
Total | 3,446,569 | 2,084,172
Past Due 90 Days or More and Accruing | 119,429 |
Loans to individuals [Member] | Residential mortgage [Member] |  |
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest |  | 1,652,653
Loans, variable rate of interest |  | 393,897
Loans, non-accrual |  | 37,622
Total | 1,849,144 | 2,084,172
Past Due 90 Days or More and Accruing | 2,241 |
Loans to individuals [Member] | Personal [Member] |  |
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest |  | 193,903
Loans, variable rate of interest |  | 1,007,192
Loans, non-accrual |  | 287
Total | 1,213,178 | $ 1,201,382
Past Due 90 Days or More and Accruing | $ 0 |

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