Shareholders' Equity - Net Change in Components of Accumulated Other Comprehensive Income (Loss) and the Related Tax Effects (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax amount	$ 323,790	$ (42,013)	$ 30,068
Other comprehensive income (loss), tax (expense) benefit	(80,947)	10,504	(7,519)
Other comprehensive income (loss), before reclassifications, net of tax amount	244,088	(32,971)	21,502
Reclassification from accumulated other comprehensive income, current period, net of tax amount	1,245	1,462	1,047
Other comprehensive income (loss), net of tax amount	242,843	(31,509)	22,549
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	229,524	(49,454)	30,622
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, before tax amount	86,033	2,647	3,177
Other comprehensive income (loss), before tax amount	315,557	(46,807)	33,799
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	(57,381)	12,364	(7,657)
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, tax (expense) benefit	(21,508)	(662)	(794)
Other comprehensive income (loss), tax (expense) benefit	(78,889)	11,702	(8,451)
Other comprehensive income (loss), before reclassifications, net of tax amount	(172,143)	(37,090)	22,965
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, net of tax amount	(64,525)	1,985	2,383
Other comprehensive income (loss), net of tax amount	(236,668)	(35,105)	25,348
Change in Net Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(10,792)	2,845	(5,128)
Reclassification from accumulated other comprehensive income, current period, before tax amount	(1,089)	1,655	1,128
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	2,698	(711)	1,282
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(272)	(414)	(282)
Other comprehensive income (loss), before reclassifications, net of tax amount	(8,094)	2,134	(3,846)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	817	1,241	846
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	111	111	150
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(28)	(27)	(38)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	83	84	112
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	183	119
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	0	(46)	(30)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	0	137	89
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	11,992	4,794	(3,731)
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(2,998)	(1,198)	932
Reclassification from accumulated other comprehensive income, current period, net of tax amount	8,994	$ 3,596	$ (2,799)
Cash Flow Hedge Derivatives {Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(20,685)
Reclassification from accumulated other comprehensive income, current period, before tax amount	(460)
Other comprehensive income (loss), before tax amount	(20,225)
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	5,171
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	115
Other comprehensive income (loss), tax (expense) benefit	5,056
Other comprehensive income (loss), before reclassifications, net of tax amount	(15,514)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	(345)
Other comprehensive income (loss), net of tax amount	$ (15,169)