Shareholders' Equity - Net Change in Components of Accumulated Other Comprehensive Income (Loss) and the Related Tax Effects (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax amount	$ (9,908)	$ 43,723
Other Comprehensive Income (Loss), Tax, Total	2,477	(10,701)
Other comprehensive income (loss), before reclassifications, net of tax amount	(11,138)	30,726
Reclassification from accumulated other comprehensive income, current period, net of tax amount	(3,707)	(2,296)
Other comprehensive income (loss), net of tax amount	(7,431)	33,022
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(2,552)	30,534
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, before tax amount	3,661	3,859
Other comprehensive income (loss), before tax amount	1,109	34,393
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	638	(7,404)
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, tax (expense) benefit	(915)	(965)
Other Comprehensive Income (Loss), Tax, Total	(277)	(8,369)
Other comprehensive income (loss), before reclassifications, net of tax amount	(1,914)	23,130
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, net of tax amount	2,746	2,894
Other comprehensive income (loss), net of tax amount	832	26,024
Net Change in Prior Service Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	28	28
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(7)	(7)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	21	21
Recognized Net Loss Due to Lump Sum Settlements [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	0	25
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	0	(6)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	0	19
Change in Net Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	95	77
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(24)	(19)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	71	58
Pension and Other Postretirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	123	130
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(31)	(32)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	92	98
Cash Flow Hedge Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(15,960)	6,269
Reclassification from accumulated other comprehensive income, current period, before tax amount	4,820	2,931
Other comprehensive income (loss), before tax amount	(11,140)	9,200
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	3,990	(1,567)
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(1,205)	(733)
Other Comprehensive Income (Loss), Tax, Total	2,785	(2,300)
Other comprehensive income (loss), before reclassifications, net of tax amount	(11,970)	4,702
Reclassification from accumulated other comprehensive income, current period, net of tax amount	3,615	2,198
Other comprehensive income (loss), net of tax amount	$ (8,355)	$ 6,900