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Securities - Amortized Cost and Estimated Fair Value of Securities (Details) - USD ($) $ in Thousands | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | --- | --- | ---
Available for sale: |  |  |  |
Available for sale, amortized cost | $ 1,407,675 | $ 1,844,975 |  |
Available for sale, gross unrealized gains | 297 | 1,000 |  |
Available for sale, gross unrealized losses | (154,341) | (204,491) |  |
Available for sale, fair value | 1,253,631 | 1,641,484 |  |
Available for sale, allowance for credit losses | 0 | 0 |  |
Available-for-sale, net carrying amount | 1,253,631 | 1,641,484 |  |
Held to maturity: |  |  |  |
Held to maturity, amortized cost | 11,678 |  |  |
Held to maturity, fair value | 10,848 | 11,970 |  |
Held to maturity, allowance for credit losses | (63) | (899) | $ (167) | $ (66)
Held to maturity, net carrying amount | 11,615 | 11,275 |  |
Securities carried at fair value through income: |  |  |  |
Securities carried at fair value through income, fair value | 6,808 | 6,368 |  |
State and municipal securities |  |  |  |
Available for sale: |  |  |  |
Available for sale, amortized cost | 323,356 | 447,086 |  |
Available for sale, gross unrealized gains | 210 | 996 |  |
Available for sale, gross unrealized losses | (41,440) | (58,605) |  |
Available for sale, fair value | 282,126 | 389,477 |  |
Available for sale, allowance for credit losses | 0 | 0 |  |
Available-for-sale, net carrying amount | 282,126 | 389,477 |  |
Held to maturity: |  |  |  |
Held to maturity, amortized cost | 11,678 | 12,174 |  |
Held to maturity, gross unrealized gains | 0 | 278 |  |
Held to maturity, gross unrealized losses | (830) | (482) |  |
Held to maturity, fair value | 10,848 | 11,970 |  |
Held to maturity, allowance for credit losses | (63) | (899) |  |
Held to maturity, net carrying amount | 11,615 | 11,275 |  |
Securities carried at fair value through income: |  |  |  |
Securities carried at fair value through income, amortized cost | 6,815 | 7,100 |  |
Securities carried at fair value through income, fair value | 6,808 | 6,368 |  |
Securities carried at fair value through income, net carrying amount | 6,808 | 6,368 |  |
Corporate bonds |  |  |  |
Available for sale: |  |  |  |
Available for sale, amortized cost | 92,244 | 89,449 |  |
Available for sale, gross unrealized gains | 80 | 0 |  |
Available for sale, gross unrealized losses | (8,689) | (7,191) |  |
Available for sale, fair value | 83,635 | 82,258 |  |
Available for sale, allowance for credit losses | 0 | 0 |  |
Available-for-sale, net carrying amount | 83,635 | 82,258 |  |
U.S. government and agency securities |  |  |  |
Available for sale: |  |  |  |
Available for sale, amortized cost | 84,377 | 264,755 |  |
Available for sale, gross unrealized gains | 3 | 4 |  |
Available for sale, gross unrealized losses | (4,740) | (16,339) |  |
Available for sale, fair value | 79,640 | 248,420 |  |
Available for sale, allowance for credit losses | 0 | 0 |  |
Available-for-sale, net carrying amount | 79,640 | 248,420 |  |
Commercial mortgage-backed securities |  |  |  |
Available for sale: |  |  |  |
Available for sale, amortized cost | 104,459 | 105,536 |  |
Available for sale, gross unrealized gains | 0 | 0 |  |
Available for sale, gross unrealized losses | (11,063) | (13,593) |  |
Available for sale, fair value | 93,396 | 91,943 |  |
Available for sale, allowance for credit losses | 0 | 0 |  |
Available-for-sale, net carrying amount | 93,396 | 91,943 |  |
Residential mortgage-backed securities |  |  |  |
Available for sale: |  |  |  |
Available for sale, amortized cost | 569,622 | 649,765 |  |
Available for sale, gross unrealized gains | 0 | 0 |  |
Available for sale, gross unrealized losses | (63,120) | (77,462) |  |
Available for sale, fair value | 506,502 | 572,303 |  |
Available for sale, allowance for credit losses | 0 | 0 |  |
Available-for-sale, net carrying amount | 506,502 | 572,303 |  |
Commercial collateralized mortgage obligations |  |  |  |
Available for sale: |  |  |  |
Available for sale, amortized cost | 39,386 | 44,330 |  |
Available for sale, gross unrealized gains | 0 | 0 |  |
Available for sale, gross unrealized losses | (4,203) | (5,517) |  |
Available for sale, fair value | 35,183 | 38,813 |  |
Available for sale, allowance for credit losses | 0 | 0 |  |
Available-for-sale, net carrying amount | 35,183 | 38,813 |  |
Residential collateralized mortgage obligations |  |  |  |
Available for sale: |  |  |  |
Available for sale, amortized cost | 150,710 | 170,136 |  |
Available for sale, gross unrealized gains | 0 | 0 |  |
Available for sale, gross unrealized losses | (20,566) | (23,766) |  |
Available for sale, fair value | 130,144 | 146,370 |  |
Available for sale, allowance for credit losses | 0 | 0 |  |
Available-for-sale, net carrying amount | 130,144 | 146,370 |  |
Asset-backed securities |  |  |  |
Available for sale: |  |  |  |
Available for sale, amortized cost | 43,521 | 73,918 |  |
Available for sale, gross unrealized gains | 4 | 0 |  |
Available for sale, gross unrealized losses | (520) | (2,018) |  |
Available for sale, fair value | 43,005 | 71,900 |  |
Available for sale, allowance for credit losses | 0 | 0 |  |
Available-for-sale, net carrying amount | $ 43,005 | $ 71,900 |  |

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