Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,031,596	$ 1,230,575
Other comprehensive loss before reclassifications	27,908	(140,019)
Amounts reclassified from accumulated other comprehensive income	33	34
Net current-period other comprehensive (loss) income	27,941	(139,985)
Ending balance	1,299,961	1,117,490
Unrealized Loss on Securities Available for Sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(342,017)	(24,698)
Other comprehensive loss before reclassifications	27,908	(140,019)
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive (loss) income	27,908	(140,019)
Ending balance	(314,109)	(164,717)
Postretirement Plans Asset (Liability)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	42	(272)
Other comprehensive loss before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income	33	34
Net current-period other comprehensive (loss) income	33	34
Ending balance	75	(238)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(341,975)	(24,970)
Ending balance	$ (314,034)	$ (164,955)