Accumulated Other Comprehensive Income (Loss) - Changes in components of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	$ (677,088)
Net comprehensive (loss) income	63,304	$ (272,810)
Balance at the end of the period	(613,784)
Benefit Plans
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	(673)	57
Balance at the end of the period	(673)	57
Unrealized Gains and (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	(676,415)	(21,203)
Other comprehensive income (loss) before reclassifications	63,271	(272,810)
Amounts reclassified from accumulated other comprehensive loss	33
Net comprehensive (loss) income	63,304	(272,810)
Balance at the end of the period	(613,111)	(294,013)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	(677,088)	(21,146)
Other comprehensive income (loss) before reclassifications	63,271	(272,810)
Amounts reclassified from accumulated other comprehensive loss	33
Net comprehensive (loss) income	63,304	(272,810)
Balance at the end of the period	$ (613,784)	$ (293,956)