CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension and other post retirement obligations:
Amortization of actuarial losses (gains) included in net periodic pension cost and (increase) decrease in unrecognized actuarial (gain) loss, gross	$ 4,774	$ (21,587)	$ 17,443
Tax effect	(1,162)	5,243	(4,192)
Amortization of actuarial losses (gains) included in net periodic pension cost and (increase) decrease in unrecognized actuarial (gain) loss, net	3,612	(16,344)	13,251
Amortization of prior service cost included in net periodic pension cost, gross	641	678	200
Tax effect	(156)	(165)	(48)
Amortization of prior service cost included in net periodic pension cost, net	485	513	152
Other comprehensive income (loss) related to pension and other post retirement obligations, net of taxes	4,097	(15,831)	13,403
Net unrealized gains (losses) on investment securities:
Net unrealized holding gains (losses) on investment securities, gross	113,464	(818,890)	(166,007)
Tax effect	(27,629)	198,909	39,900
Net unrealized holding gains (losses) on investment securities, net	85,835	(619,981)	(126,107)
Reclassification adjustment for net losses included in net income, gross	52,329	0	0
Tax effect	(12,714)	0	0
Reclassification adjustment for net losses included in net income, net	39,615	0	0
Other comprehensive income (loss) related to unrealized gains (losses) on investment securities, net of taxes	125,450	(619,981)	(126,107)
Other comprehensive income (loss), net of tax	129,547	(635,812)	(112,704)
Net income	131,924	188,081	189,694
Comprehensive income (loss)	261,471	(447,731)	76,990
Accumulated Other Comprehensive Loss By Component:
Unrealized loss for pension and other postretirement obligations	(36,118)	(41,533)	(20,624)
Tax effect	8,914	10,232	5,154
Net unrealized loss for pension and other postretirement obligations	(27,204)	(31,301)	(15,470)
Unrealized loss on investment securities	(698,990)	(864,783)	(45,893)
Tax effect	169,302	209,645	10,736
Net unrealized loss on investment securities	(529,688)	(655,138)	(35,157)
Accumulated other comprehensive loss	$ (556,892)	$ (686,439)	$ (50,627)