Accumulated Other Comprehensive Income - Changes in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Changes in AOCI by component
Beginning balance	$ 6,774,387	$ 4,851,700	$ 6,433,892	$ 4,862,576
OCI before reclassifications	(6,194)	(822)	(18,177)	(3,569)
Amounts reclassified from AOCI	0	(2)	0	62
Net period OCI	(6,194)	(824)	(18,177)	(3,507)
Ending balance	6,821,185	4,847,112	6,821,185	4,847,112
Cumulative Unrealized Gain (Loss) on Available-for- Sale Securities
Changes in AOCI by component
Beginning balance	28,970	41,310	40,953	44,057
OCI before reclassifications	(6,194)	(822)	(18,177)	(3,569)
Amounts reclassified from AOCI	0	(2)	0	(2)
Net period OCI	(6,194)	(824)	(18,177)	(3,571)
Ending balance	22,776	40,486	22,776	40,486
Foreign Currency Translation
Changes in AOCI by component
Beginning balance	0	0	0	(64)
OCI before reclassifications	0	0	0	0
Amounts reclassified from AOCI	0	0	0	64
Net period OCI	0	0	0	64
Ending balance	0	0	0	0
Accumulated Other Comprehensive Income
Changes in AOCI by component
Beginning balance	28,970	41,310	40,953	43,993
Ending balance	$ 22,776	$ 40,486	$ 22,776	$ 40,486