Reserve for Claims and Claim Expenses - Schedule of Liability for Unpaid Claims and Claims Adjustment Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Reserve for claims and claim expenses, net of reinsurance recoverable, as of beginning of period	$ 9,025,961	$ 7,455,128	$ 6,593,052
Net incurred related to:
Current year	4,586,422	4,125,557	3,108,421
Prior years	(247,582)	(249,470)	(183,812)
Total net incurred	4,338,840	3,876,087	2,924,609
Net paid related to:
Current year	105,885	574,230	412,172
Prior years	1,924,271	1,649,872	1,592,456
Total net paid	2,030,156	2,224,102	2,004,628
Foreign exchange	(152,997)	(81,152)	97,273
Amounts disposed	0	0	(155,178)
Reserve for claims and claim expenses, net of reinsurance recoverable, as of end of period	11,181,648	9,025,961	7,455,128
Reinsurance recoverable as of end of period	4,710,925	4,268,669	2,926,010
Reserve for claims and claim expenses as of end of period	$ 15,892,573	$ 13,294,630	$ 10,381,138