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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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