Investments - Schedule of Available-for-Sale Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	$ 2,046,249
Fixed maturity securities, available-for-sale	1,875,695	$ 1,783,417
Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	2,046,249	1,969,783
Total investments available-for-sale, Gross Unrealized Gains	3,222	3,125
Total investments available-for-sale, Gross Unrealized Losses	(173,776)	(189,491)
Fixed maturity securities, available-for-sale	1,875,695	1,783,417
State and municipal
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	381,802	386,456
Total investments available-for-sale, Gross Unrealized Gains	1,420	712
Total investments available-for-sale, Gross Unrealized Losses	(45,252)	(56,316)
Fixed maturity securities, available-for-sale	337,970	330,852
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	467,134	437,702
Total investments available-for-sale, Gross Unrealized Gains	575	801
Total investments available-for-sale, Gross Unrealized Losses	(37,461)	(37,254)
Fixed maturity securities, available-for-sale	430,248	401,249
Corporate
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	784,248	734,976
Total investments available-for-sale, Gross Unrealized Gains	1,217	1,528
Total investments available-for-sale, Gross Unrealized Losses	(63,064)	(66,292)
Fixed maturity securities, available-for-sale	722,401	670,212
Commercial mortgage and asset-backed
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	340,212	335,066
Total investments available-for-sale, Gross Unrealized Gains	10	76
Total investments available-for-sale, Gross Unrealized Losses	(24,716)	(26,127)
Fixed maturity securities, available-for-sale	315,506	309,015
U.S. Treasury securities and obligations guaranteed by the U.S. government
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	72,853	75,583
Total investments available-for-sale, Gross Unrealized Gains	0	8
Total investments available-for-sale, Gross Unrealized Losses	(3,283)	(3,502)
Fixed maturity securities, available-for-sale	$ 69,570	$ 72,089