Accumulated Other Comprehensive Income - Changes in AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in AOCI by component
Beginning balance	$ 6,835,917	$ 6,433,892	$ 4,862,576
OCI before reclassifications	(5,648)	(19,998)	(3,101)
Amounts reclassified from AOCI	45	0	61
Net period OCI	(5,603)	(19,998)	(3,040)
Ending balance	6,608,634	6,835,917	6,433,892
Cumulative Unrealized Gain (Loss) on Available-for- Sale Securities
Changes in AOCI by component
Beginning balance	20,955	40,953	44,057
OCI before reclassifications	(5,648)	(19,998)	(3,101)
Amounts reclassified from AOCI	45	0	(3)
Net period OCI	(5,603)	(19,998)	(3,104)
Ending balance	15,352	20,955	40,953
Foreign Currency Translation
Changes in AOCI by component
Beginning balance	0	0	(64)
OCI before reclassifications	0	0	0
Amounts reclassified from AOCI	0	0	64
Net period OCI	0	0	64
Ending balance	0	0	0
Accumulated Other Comprehensive Income
Changes in AOCI by component
Beginning balance	20,955	40,953	43,993
Ending balance	$ 15,352	$ 20,955	$ 40,953