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Loans (Narrative) (Details) $ in Thousands, loan in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($) contract | Dec. 31, 2018 USD ($) loan contract | Dec. 31, 2017 USD ($) contract
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Financing Receivable, Nonaccrual | $ 33,060 |  |
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans | 2,000 | $ 3,600 | $ 2,400
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing, Number of Loans | 0 |  |
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing, Number of Loans | loan |  | 0.0 |
Loans and Leases Receivable, Nonaccrual of Interest, Commitments of Additional Funds | 2,000 | $ 2,100 |
Financing Receivable Modifications Additional Commitment To Lend | $ 1,100 | $ 2,100 |
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contract | 1 | 0 | 0
Loans Receivable [Member] |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans pledged to collateralize Federal Home Loan Bank Advances | $ 3,240,000 | $ 3,220,000 |
Commercial Loan [Member] |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans pledged to collateralize Federal Reserve Bank Borrowings | $ 151,300 | $ 82,000 |

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