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Fair Value Measurements and Fair Value of Financial Instruments, Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Financial assets [Abstract] |  |
HTM securities | $ 642,325 | $ 641,262
Carrying Amount [Member] | Level 2 [Member] |  |
Financial assets [Abstract] |  |
HTM securities | 621,359 | 630,074
Financial liabilities [Abstract] |  |
Time deposits | 843,279 | 861,193
Long-term debt | 64,183 | 64,211
Junior subordinated debt | 101,196 | 101,196
Carrying Amount [Member] | Level 3 [Member] |  |
Financial assets [Abstract] |  |
Net loans | 7,153,858 | 7,074,864
Estimated Fair Value [Member] | Level 2 [Member] |  |
Financial assets [Abstract] |  |
HTM securities | 642,325 | 641,262
Financial liabilities [Abstract] |  |
Time deposits | 847,284 | 858,085
Long-term debt | 64,815 | 64,373
Junior subordinated debt | 89,368 | 105,694
Estimated Fair Value [Member] | Level 3 [Member] |  |
Financial assets [Abstract] |  |
Net loans | $ 7,210,148 | $ 6,999,690

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