Premiums and Reinsurance Related Information - Premiums and Reinsurance, Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 30,660	$ 25,218
Cumulative effect adjustment resulting from changes in accounting principles	32,353	28,236
Change in expected credit losses	1,693	3,018
Allowance for expected credit losses, end of period	32,353	28,236
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	8,064	7,713
Cumulative effect adjustment resulting from changes in accounting principles	8,703	7,655
Reinsurance Recoverable, Credit Loss Expense (Reversal)	639	(58)
Allowance for expected credit losses, end of period	$ 8,703	$ 7,655