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Loans and Allowance for Credit Losses, Loans by Portfolio Type (Details) - USD ($) $ in Thousands | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest | $ 6,129,401 | $ 6,134,362
Loans, variable rate of interest | 16,171,397 | 15,435,674
Loans, non-accrual | 163,172 | 180,951
Total | 22,463,970 | 21,750,987
Past Due 90 Days or More and Accruing | 100,686 | 7,680
Credit Commitments [Abstract] |  |
Outstanding commitments to extend credit | 10,000,000 |
Outstanding standby letters of credit | 684,000 |
Commercial [Member] |  |
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest | 3,205,558 | 3,231,485
Loans, variable rate of interest | 11,471,793 | 10,684,749
Loans, non-accrual | 118,624 | 115,416
Total | 14,795,975 | 14,031,650
Past Due 90 Days or More and Accruing | 788 |
Commercial real estate [Member] |  |
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest | 1,045,825 | 1,056,321
Loans, variable rate of interest | 3,395,715 | 3,349,836
Loans, non-accrual | 8,545 | 27,626
Total | 4,450,085 | 4,433,783
Past Due 90 Days or More and Accruing | 2,796 |
Loans to individuals [Member] |  |
Loan receivables disclosure [Abstract] |  |
Loans, fixed rate of interest | 1,878,018 |
Loans, variable rate of interest | 1,303,889 |
Loans, non-accrual | 36,003 |
Total | 3,217,910 | 2,084,172
Past Due 90 Days or More and Accruing | 97,102 |
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 | 1,844,555 | 2,084,172
Past Due 90 Days or More and Accruing | 119 |
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 | 1,175,466 | $ 1,201,382
Past Due 90 Days or More and Accruing | $ 3 |

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