Investments - Other Than Temporarily Impaired and Credit Ratings (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Schedule of Fixed Maturities Table [Line Items]
Other-than-temporary impairment losses	$ 0	$ 0
Amortized cost	492,131,000		$ 595,344,000
Fair value	$ 471,230,000		$ 597,145,000
% of Total fair value	100.00%		100.00%
AAA
Schedule of Fixed Maturities Table [Line Items]
Amortized cost	$ 147,966,000		$ 161,179,000
Fair value	$ 138,999,000		$ 156,706,000
% of Total fair value	29.50%		26.20%
AA+, AA, AA-
Schedule of Fixed Maturities Table [Line Items]
Amortized cost	$ 35,298,000		$ 38,999,000
Fair value	$ 34,864,000		$ 39,140,000
% of Total fair value	7.40%		6.60%
A+, A, A-
Schedule of Fixed Maturities Table [Line Items]
Amortized cost	$ 49,221,000		$ 99,748,000
Fair value	$ 46,267,000		$ 99,962,000
% of Total fair value	9.80%		16.70%
BBB+, BBB, BBB-
Schedule of Fixed Maturities Table [Line Items]
Amortized cost	$ 102,157,000		$ 126,770,000
Fair value	$ 96,386,000		$ 129,618,000
% of Total fair value	20.50%		21.70%
BB+ or lower
Schedule of Fixed Maturities Table [Line Items]
Amortized cost	$ 5,773,000		$ 12,105,000
Fair value	$ 5,595,000		$ 13,050,000
% of Total fair value	1.20%		2.20%
U.S. treasury bonds
Schedule of Fixed Maturities Table [Line Items]
Amortized cost	$ 66,109,000		$ 59,989,000
Fair value	$ 65,730,000		$ 59,879,000
% of Total fair value	13.90%		10.00%
U.S. agency bonds
Schedule of Fixed Maturities Table [Line Items]
Amortized cost	$ 85,607,000		$ 96,554,000
Fair value	$ 83,389,000		$ 98,790,000
% of Total fair value	17.70%		16.60%