Shareholders' Equity - Net Change in Components of Accumulated Other Comprehensive Income (Loss) and the Related Tax Effects (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax amount	$ (132,361)	$ (11,252)	$ (365,138)	$ (24,039)
Other comprehensive income (loss), tax (expense) benefit	33,091	2,813	91,286	6,010
Other comprehensive income (loss), before reclassifications, net of tax amount			(274,118)	(19,236)
Reclassification from accumulated other comprehensive income, current period, net of tax amount			266	1,207
Other comprehensive income (loss), net of tax amount	(99,270)	(8,439)	(273,852)	(18,029)
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(114,317)	(12,543)	(314,517)	(27,731)
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, before tax amount	1,800	636	(31,451)	2,083
Other comprehensive income (loss), before tax amount	(112,517)	(11,907)	(345,968)	(25,648)
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	28,580	3,136	78,630	6,933
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, tax (expense) benefit	(450)	(159)	7,863	(521)
Other comprehensive income (loss), tax (expense) benefit	28,130	2,977	86,493	6,412
Other comprehensive income (loss), before reclassifications, net of tax amount	(85,737)	(9,407)	(235,887)	(20,798)
Other comprehensive income (loss), change in net unrealized holding loss on securities transferred to held to maturity, net of tax amount	1,350	477	(23,588)	1,562
Other comprehensive income (loss), net of tax amount	(84,387)	(8,930)	(259,475)	(19,236)
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	83	84
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(7)	(7)	(21)	(21)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	21	21	62	63
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	0	183
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	0	(46)	0	(46)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	0	137	0	137
Change in Net Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from accumulated other comprehensive income, current period, before tax amount	295	444	914	1,342
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(74)	(111)	(228)	(335)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	221	333	686	1,007
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	323	655	997	1,609
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	(81)	(164)	(249)	(402)
Reclassification from accumulated other comprehensive income, current period, net of tax amount	242	491	748	1,207
Cash Flow Hedge Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, before tax amount	(19,524)	0	(19,524)	0
Reclassification from accumulated other comprehensive income, current period, before tax amount	(643)	0	(643)	0
Other comprehensive income (loss), before tax amount	(20,167)	0	(20,167)	0
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	4,881	0	4,881	0
Reclassification from accumulated other comprehensive income, current period, tax (expense) benefit	161	0	161	0
Other comprehensive income (loss), tax (expense) benefit	5,042	0	5,042	0
Other comprehensive income (loss), before reclassifications, net of tax amount	(14,643)	0	(14,643)	0
Reclassification from accumulated other comprehensive income, current period, net of tax amount	(482)	0	(482)	0
Other comprehensive income (loss), net of tax amount	$ (15,125)	$ 0	$ (15,125)	$ 0