Investments - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) security	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Investment Holdings [Line Items]
Accrued investment income | $	$ 17,477		$ 17,505
Fixed Income Securities
Investment Holdings [Line Items]
Accrued investment income | $	$ 16,500		16,400
Number of debt securities for which there is an allowance for credit losses | security	7
Number of debt securities in an unrealized loss position for which an allowance for credit losses has not been recorded | security	988
Unrealized loss | $	$ 97,986		$ 16,891
Unrealized losses as percentage of fixed income portfolio cost basis	4.10%
Unrealized losses relative to total invested assets (as a percent)	3.20%
Number of unrealized loss positions | security	988
Number of securities in unrealized loss positions for 12 months or longer | security	117
Losses on fixed income securities | $	$ 100	$ 0