Investments - Additional Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2023 USD ($) security	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Investment Holdings [Line Items]
Accrued investment income	$ 22,525		$ 21,259
Unrealized loss	260,939		280,222
Fixed Income Securities
Investment Holdings [Line Items]
Accrued investment income	$ 22,000		$ 20,000
Number of debt securities for which there is an allowance for credit losses | security	18
Losses on fixed income securities	$ 1,700	$ 100
Number of debt securities in an unrealized loss position for which an allowance for credit losses has not been recorded | security	1,474
Unrealized loss	$ 261,000
Unrealized losses as percentage of fixed income portfolio cost basis	9.00%
Unrealized losses relative to total invested assets (as a percent)	7.00%
Number of unrealized loss positions | security	1,474
Number of securities in unrealized loss positions for 12 months or longer | security	995