Accumulated Other Comprehensive Income (Loss) - Changes in components of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accumulated Other Comprehensive (Loss) Income
Balance at the beginning of the period			$ (582,536)
Net comprehensive income (loss)	$ 2,783	$ (48,614)	(37,675)	$ 14,690
Balance at the end of the period	(620,211)		(620,211)
Benefit Plans
Accumulated Other Comprehensive (Loss) Income
Balance at the beginning of the period	627	(673)	627	(673)
Balance at the end of the period	627	(673)	627	(673)
Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive (Loss) Income
Balance at the beginning of the period	(623,621)	(613,111)	(583,163)	(676,415)
Other comprehensive income (loss) before reclassifications	2,783	(48,614)	(37,675)	14,723
Amounts reclassified from accumulated other comprehensive loss				(33)
Net comprehensive income (loss)	2,783	(48,614)	(37,675)	14,690
Balance at the end of the period	(620,838)	(661,725)	(620,838)	(661,725)
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive (Loss) Income
Balance at the beginning of the period	(622,994)	(613,784)	(582,536)	(677,088)
Other comprehensive income (loss) before reclassifications	2,783	(48,614)	(37,675)	14,723
Amounts reclassified from accumulated other comprehensive loss				(33)
Net comprehensive income (loss)	2,783	(48,614)	(37,675)	14,690
Balance at the end of the period	$ (620,211)	$ (662,398)	$ (620,211)	$ (662,398)