Shareholders' Equity - Net Change in Components of Accumulated Other Comprehensive Income (Loss) and the Related Tax Effects (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax amount	$ 180,796	$ (31,100)	$ 170,888	$ 12,623
Other Comprehensive Income (Loss), Tax, Total	(45,199)	7,777	(42,722)	(2,924)
Other comprehensive income (loss), before reclassifications, net of tax amount			(16,361)	4,333
Reclassification from accumulated other comprehensive income, current period, net of tax amount			144,527	5,366
Other comprehensive income (loss), net of tax amount	135,597	(23,323)	128,166	9,699
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(5,761)	(19,633)	(8,313)	10,901
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, before tax amount	3,671	3,940	7,332	7,799
Reclassification from accumulated other comprehensive income, current period, before tax amount	182,792	0	182,792	0
Other comprehensive income (loss), before tax amount	180,702	(15,693)	181,811	18,700
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	1,440	4,910	2,078	(2,494)
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(45,698)	0	(45,698)	0
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, tax (expense) benefit	(918)	(985)	(1,833)	(1,950)
Other Comprehensive Income (Loss), Tax, Total	(45,176)	3,925	(45,453)	(4,444)
Other comprehensive income (loss), before reclassifications, net of tax amount	(4,321)	(14,723)	(6,235)	8,407
Reclassification from accumulated other comprehensive income, current period, net of tax amount	137,094	0	137,094	0
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, net of tax amount	2,753	2,955	5,499	5,849
Other comprehensive income (loss), net of tax amount	135,526	(11,768)	136,358	14,256
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	27	27	55	55
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(7)	(7)	(14)	(14)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	20	20	41	41
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	(13)	0	(13)	25
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	3	0	3	(6)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	(10)	0	(10)	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	84	69	179	146
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(20)	(17)	(44)	(36)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	64	52	135	110
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	98	96	221	226
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(24)	(24)	(55)	(56)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	74	72	166	170
Cash Flow Hedge Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(4,873)	(19,500)	(20,833)	(13,231)
Reclassification from accumulated other comprehensive income, current period, before tax amount	4,869	3,997	9,689	6,928
Other comprehensive income (loss), before tax amount	(4)	(15,503)	(11,144)	(6,303)
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	1,218	4,875	5,208	3,308
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(1,217)	(999)	(2,422)	(1,732)
Other Comprehensive Income (Loss), Tax, Total	1	3,876	2,786	1,576
Other comprehensive income (loss), before reclassifications, net of tax amount	(3,655)	(14,625)	(15,625)	(9,923)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	3,652	2,998	7,267	5,196
Other comprehensive income (loss), net of tax amount	$ (3)	$ (11,627)	$ (8,358)	$ (4,727)