Allowance for Expected Credit Losses - Reinsurance recoverables (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Credit Loss [Abstract]
Balance at beginning of period	$ 5,941,000	$ 4,041,076	$ 5,880,735	$ 4,500,802
Balance at end of period	5,938,511	4,314,515	5,938,511	4,314,515
Allowance for Expected Credit Losses
Balance at beginning of period	18,483	10,872	13,230	11,636
Change for provision of expected credit losses	(3,743)	157	1,510	(607)
Balance at end of period	$ 14,740	$ 11,029	$ 14,740	$ 11,029