Accumulated Other Comprehensive Income (Loss) - Accumulated Other Comprehensive Income, Changes In (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax	$ 751,030	$ 784,241	$ 745,997	$ 912,172
Income tax (expense) benefit	(4,683)	15,700	(5,785)	52,909
Ending balance, net of tax	765,161	731,782	765,161	731,782
Unrealized Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax	(135,627)	(72,699)	(149,181)	84,716
Other comprehensive (loss) income before reclassifications	6,831	(85,883)	19,850	(286,928)
Reclassification adjustments included in net income	5,444	3,487	9,582	5,273
Income tax (expense) benefit	(2,577)	17,303	(6,180)	59,147
Net current-period other comprehensive income (loss), net of tax	9,698	(65,093)	23,252	(222,508)
Ending balance, net of tax	(125,929)	(137,792)	(125,929)	(137,792)
Unrealized Gains (Losses) on Derivatives
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax	21,680	16,018	31,227	(1,257)
Other comprehensive (loss) income before reclassifications	15,876	7,047	8,900	27,593
Reclassification adjustments included in net income	(6,054)	344	(11,162)	1,666
Income tax (expense) benefit	(2,063)	(1,552)	474	(6,145)
Net current-period other comprehensive income (loss), net of tax	7,759	5,839	(1,788)	23,114
Ending balance, net of tax	29,439	21,857	29,439	21,857
Retirement Plans
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax	(19,365)	(23,590)	(19,502)	(23,754)
Other comprehensive (loss) income before reclassifications	0	0	0	0
Reclassification adjustments included in net income	205	241	378	447
Income tax (expense) benefit	(43)	(51)	(79)	(93)
Net current-period other comprehensive income (loss), net of tax	162	190	299	354
Ending balance, net of tax	(19,203)	(23,400)	(19,203)	(23,400)
Total
AOCI Attributable to Parent, Net of Tax
Beginning balance, net of tax	(133,312)	(80,271)	(137,456)	59,705
Other comprehensive (loss) income before reclassifications	22,707	(78,836)	28,750	(259,335)
Reclassification adjustments included in net income	(405)	4,072	(1,202)	7,386
Income tax (expense) benefit	(4,683)	15,700	(5,785)	52,909
Net current-period other comprehensive income (loss), net of tax	17,619	(59,064)	21,763	(199,040)
Ending balance, net of tax	$ (115,693)	$ (139,335)	$ (115,693)	$ (139,335)