Accumulated Other Comprehensive Income - Schedule of Components of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
AOCI [Roll Forward]
Beginning Balance	$ 3,736,191	$ 3,779,386
OCI before reclassifications	(40,955)	(38,652)
Amounts reclassified from AOCI	0	(25,793)
Other comprehensive income (loss)	(40,955)	(64,445)
Ending Balance	3,336,728	3,566,498
Unrealized gains (losses) on available-for-sale securities, net
AOCI [Roll Forward]
Beginning Balance	405,054	558,096
OCI before reclassifications	(40,955)	(38,652)
Amounts reclassified from AOCI	0	(25,793)
Other comprehensive income (loss)	(40,955)	(64,445)
Ending Balance	364,099	493,651
Total Accumulated OCI Balance
AOCI [Roll Forward]
Beginning Balance	405,054	558,096
Other comprehensive income (loss)	(40,955)	(64,445)
Ending Balance	$ 364,099	$ 493,651