Premiums and Reinsurance Related Information - Premiums and Reinsurance, Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 25,218	$ 22,883
Cumulative effect adjustment resulting from changes in accounting principles	28,236	24,264
Provision for expected credit losses	3,018	1,381
Allowance for expected credit losses, end of period	28,236	24,264
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	7,713	7,801
Cumulative effect adjustment resulting from changes in accounting principles	7,655	7,373
Reinsurance Recoverable, Credit Loss Expense (Reversal)	(58)	(428)
Allowance for expected credit losses, end of period	$ 7,655	$ 7,373