Accumulated Other Comprehensive (Loss) Income - Changes in components of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	$ (21,146)
Net comprehensive (loss) income	(272,810)	$ (48,620)
Balance at the end of the period	(293,956)
Other comprehensive (loss) income before reclassifications	0	0
Benefit Plans
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	57	(151)
Balance at the end of the period	57	(151)	$ (151)
Unrealized Gains and (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	(21,203)	47,740
Other comprehensive loss before reclassifications	(272,810)		(48,620)
Net comprehensive (loss) income	(272,810)	(48,620)
Balance at the end of the period	(294,013)	(880)	47,740
Accumulated Other Comprehensive (Loss) Gain
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	(21,146)	47,589
Other comprehensive loss before reclassifications	(272,810)		(48,620)
Net comprehensive (loss) income	(272,810)	(48,620)
Balance at the end of the period	$ (293,956)	$ (1,031)	$ 47,589