Reserve for Loss and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Insurance [Abstract]
Reserve for reported loss and LAE	$ 804,771		$ 851,950
Reserve for losses incurred but not reported ("IBNR")	581,252		637,423
Reserve for loss and LAE	1,386,023	$ 1,784,508	$ 1,489,373
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross loss and LAE reserves, January 1	1,489,373	1,893,299
Less: reinsurance recoverable on unpaid losses, January 1	562,845	592,571
Net loss and LAE reserves, January 1	926,528	1,300,728
Net incurred losses related to Current year	5,002	7,913
Net incurred losses related to Prior year	(7,285)	(5,554)
Net loss and loss adjustment expenses	(2,283)	2,359
Net paid losses related to Current year	(49)	(82)
Net paid losses related to Prior years	(101,669)	(92,563)
Net paid losses	(101,718)	(92,645)
Change in deferred gain on retroactive reinsurance	1,339	9,845
Assumed retroactive reinsurance business	14,350	0
Effect of foreign exchange rate movements	(10,455)	(16,488)
Net loss and LAE reserves, March 31	827,761	1,203,799
Reinsurance recoverable on unpaid losses, March 31	558,262	580,709
Gross loss and LAE reserves, March 31	$ 1,386,023	$ 1,784,508