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Securities - Amortized Cost and Estimated Fair Value of Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Available for sale:
Available for sale, amortized cost	$ 1,349,979	$ 1,407,675
Available for sale, gross unrealized gains	404	297
Available for sale, gross unrealized losses	(159,461)	(154,341)
Available for sale, fair value	1,190,922	1,253,631
Available for sale, allowance for credit losses	0	0
Available-for-sale, net carrying amount	1,190,922	1,253,631
Held to maturity:
Held to maturity, amortized cost	11,675
Held to maturity, fair value	10,956	10,848
Held to maturity, allowance for credit losses	(24)	(63)	$ (981)	$ (899)
Held to maturity, net carrying amount	11,651	11,615
Securities carried at fair value through income:
Securities carried at fair value through income, fair value	6,755	6,808
State and municipal securities
Available for sale:
Available for sale, amortized cost	320,999	323,356
Available for sale, gross unrealized gains	213	210
Available for sale, gross unrealized losses	(43,615)	(41,440)
Available for sale, fair value	277,597	282,126
Available for sale, allowance for credit losses	0	0
Available-for-sale, net carrying amount	277,597	282,126
Held to maturity:
Held to maturity, amortized cost	11,675	11,678
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	(719)	(830)
Held to maturity, fair value	10,956	10,848
Held to maturity, allowance for credit losses	(24)	(63)
Held to maturity, net carrying amount	11,651	11,615
Securities carried at fair value through income:
Securities carried at fair value through income, amortized cost	6,815	6,815
Securities carried at fair value through income, fair value	6,755	6,808
Securities carried at fair value through income, net carrying amount	6,755	6,808
Corporate bonds
Available for sale:
Available for sale, amortized cost	91,251	92,244
Available for sale, gross unrealized gains	166	80
Available for sale, gross unrealized losses	(8,170)	(8,689)
Available for sale, fair value	83,247	83,635
Available for sale, allowance for credit losses	0	0
Available-for-sale, net carrying amount	83,247	83,635
U.S. treasury and government agency securities
Available for sale:
Available for sale, amortized cost	67,172	84,377
Available for sale, gross unrealized gains	2	3
Available for sale, gross unrealized losses	(4,736)	(4,740)
Available for sale, fair value	62,438	79,640
Available for sale, allowance for credit losses	0	0
Available-for-sale, net carrying amount	62,438	79,640
Commercial mortgage-backed securities
Available for sale:
Available for sale, amortized cost	104,150	104,459
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(11,410)	(11,063)
Available for sale, fair value	92,740	93,396
Available for sale, allowance for credit losses	0	0
Available-for-sale, net carrying amount	92,740	93,396
Residential mortgage-backed securities
Available for sale:
Available for sale, amortized cost	552,647	569,622
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(66,024)	(63,120)
Available for sale, fair value	486,623	506,502
Available for sale, allowance for credit losses	0	0
Available-for-sale, net carrying amount	486,623	506,502
Commercial collateralized mortgage obligations
Available for sale:
Available for sale, amortized cost	45,874	39,386
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(4,448)	(4,203)
Available for sale, fair value	41,426	35,183
Available for sale, allowance for credit losses	0	0
Available-for-sale, net carrying amount	41,426	35,183
Residential collateralized mortgage obligations
Available for sale:
Available for sale, amortized cost	147,310	150,710
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(20,977)	(20,566)
Available for sale, fair value	126,333	130,144
Available for sale, allowance for credit losses	0	0
Available-for-sale, net carrying amount	126,333	130,144
Asset-backed securities
Available for sale:
Available for sale, amortized cost	20,576	43,521
Available for sale, gross unrealized gains	23	4
Available for sale, gross unrealized losses	(81)	(520)
Available for sale, fair value	20,518	43,005
Available for sale, allowance for credit losses	0	0
Available-for-sale, net carrying amount	$ 20,518	$ 43,005

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