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Securities, Held to Maturity (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Held-to-maturity securities, fair value to amortized cost [Abstract] |  |  |
Amortized cost | $ 733,210 | $ 616,560 |
Unrealized gains | 10,040 | 21,942 |
Unrealized losses | 7,990 | 1,675 |
Estimated fair value | 735,260 | 636,827 |
Allowance for credit losses on HTM securities | 0 | 0 |
Transactions of HTM securities [Abstract] |  |  |
Gains from calls on HTM securities | 29 | 24 | $ 12
Held-to-maturity securities sold, amortized cost | 0 | 1,000 | $ 0
Held-to-maturity securities sold, realized loss |  | 1 |
Federal Agency [Member] |  |  |
Held-to-maturity securities, fair value to amortized cost [Abstract] |  |  |
Amortized cost | 100,000 | 100,000 |
Unrealized gains | 0 | 0 |
Unrealized losses | 4,365 | 1,658 |
Estimated fair value | 95,635 | 98,342 |
Mortgage-backed Securities, Government-Sponsored Enterprises [Member] |  |  |
Held-to-maturity securities, fair value to amortized cost [Abstract] |  |  |
Amortized cost | 161,462 | 107,914 |
Unrealized gains | 2,232 | 4,583 |
Unrealized losses | 1,319 | 0 |
Estimated fair value | 162,375 | 112,497 |
Mortgage-Backed, U.S. Government Agency Securities [Member] |  |  |
Held-to-maturity securities, fair value to amortized cost [Abstract] |  |  |
Amortized cost | 9,112 | 11,533 |
Unrealized gains | 514 | 979 |
Unrealized losses | 0 | 0 |
Estimated fair value | 9,626 | 12,512 |
Collateralized Mortgage Obligations, Government-Sponsored Enterprises [Member] |  |  |
Held-to-maturity securities, fair value to amortized cost [Abstract] |  |  |
Amortized cost | 94,342 | 103,105 |
Unrealized gains | 1,932 | 4,477 |
Unrealized losses | 129 | 0 |
Estimated fair value | 96,145 | 107,582 |
Collateralized Mortgage Obligations, U.S. Government Agency Securities [Member] |  |  |
Held-to-maturity securities, fair value to amortized cost [Abstract] |  |  |
Amortized cost | 44,473 | 79,145 |
Unrealized gains | 336 | 3,950 |
Unrealized losses | 674 | 0 |
Estimated fair value | 44,135 | 83,095 |
State & Municipal [Member] |  |  |
Held-to-maturity securities, fair value to amortized cost [Abstract] |  |  |
Amortized cost | 323,821 | 214,863 |
Unrealized gains | 5,026 | 7,953 |
Unrealized losses | 1,503 | 17 |
Estimated fair value | 327,344 | 222,799 |
Public Deposits and Other Purposes [Member] |  |  |
Securities pledged [Abstract] |  |  |
Amortized costs of securities available for sale and held to maturity pledged | 1,600,000 | 1,400,000 |
Securities Sold under Repurchase Agreements [Member] |  |  |
Securities pledged [Abstract] |  |  |
Amortized costs of securities available for sale and held to maturity pledged | $ 162,100 | $ 305,200 |

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