Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Changes in AOCI by component
Beginning balance	$ 6,766,777	$ 6,608,634
Ending balance	6,729,916	6,624,696
Cumulative Unrealized Gain (Loss) on Available-for- Sale Securities
Changes in AOCI by component
Beginning balance	13,594	15,352
OCI before reclassifications	(867)	(1,291)
Amounts reclassified from AOCI	0	0
Net period OCI	(867)	(1,291)
Ending balance	$ 12,727	$ 14,061