Other Comprehensive Income - Changes in the Components of Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	$ 17,168	$ 33,434	$ 55,366	$ 33,675
Total other comprehensive income (loss), tax expense (benefit)	4,297	8,412	13,928	8,513
Other comprehensive income, net of tax	12,871	25,022	41,438	25,162
Securities available for sale:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized holding gains (losses) on securities, pre-tax	15,440	31,313	51,167	25,769
Unrealized holding gains (losses) on securities, tax expense (benefit)	3,855	7,872	12,854	6,494
Unrealized holding gains (losses) on securities, net of tax	11,585	23,441	38,313	19,275
Amortization of unrealized holding losses on securities transferred to held to maturity category, pre tax	3,005	3,131	8,889	9,658
Amortization of unrealized holding losses on securities transferred to the held to maturity category	768	800	2,274	2,468
Amortization of unrealized holding losses on securities transferred to held to maturity category, net of tax	2,237	2,331	6,615	7,190
Total other comprehensive income (loss), pre-tax	18,445	34,444	60,056	35,427
Total other comprehensive income (loss), tax expense (benefit)	4,623	8,672	15,128	8,962
Other comprehensive income, net of tax	13,822	25,772	44,928	26,465
Derivative instruments:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized holding gains (losses) on securities, pre-tax	(1,376)	(1,116)	(4,988)	(2,069)
Unrealized holding gains (losses) on securities, tax expense (benefit)	(350)	(288)	(1,275)	(530)
Unrealized holding gains (losses) on securities, net of tax	(1,026)	(828)	(3,713)	(1,539)
Total other comprehensive income (loss), pre-tax	(1,376)	(1,116)	(4,988)	(2,069)
Total other comprehensive income (loss), tax expense (benefit)	(350)	(288)	(1,275)	(530)
Other comprehensive income, net of tax	(1,026)	(828)	(3,713)	(1,539)
Total defined benefit pension and post-retirement benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of unrealized holding losses on securities transferred to held to maturity category, pre tax	99	106	298	317
Amortization of unrealized holding losses on securities transferred to the held to maturity category	24	28	75	81
Amortization of unrealized holding losses on securities transferred to held to maturity category, net of tax	75	78	223	236
Total other comprehensive income (loss), pre-tax	99	106	298	317
Total other comprehensive income (loss), tax expense (benefit)	24	28	75	81
Other comprehensive income, net of tax	$ 75	$ 78	$ 223	$ 236