Investments - Schedule of Mortgage Loans by Geographic Region, Property Type and Loan-to-Value Ratio (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Allowance for credit losses, amount	$ (2,987)	$ (2,486)
Totals, amount	487,304	332,521
Real Estate
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 489,879	$ 335,007
Mortgage loans, percentage	100.00%	100.00%
Market value adjustment	$ 412	$ 0
Market value adjustment, percentage	0.10%	0.00%
Allowance for credit losses, amount	$ (2,987)	$ (2,486)
Allowance for credit losses, percentage	(0.60%)	(0.70%)
Totals, amount	$ 487,304	$ 332,521
Totals, percentage	99.50%	99.30%
Real Estate | Less than 50%
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 100,806	$ 66,635
Mortgage loans, percentage	20.60%	19.90%
Real Estate | 50% to 60%
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 128,191	$ 64,536
Mortgage loans, percentage	26.20%	19.30%
Real Estate | 60% to 70%
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 202,670	$ 153,414
Mortgage loans, percentage	41.30%	45.80%
Real Estate | 70% to 80%
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 58,212	$ 50,422
Mortgage loans, percentage	11.90%	15.00%
Real Estate | 80% and above
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 0	$ 0
Mortgage loans, percentage	0.00%	0.00%
Real Estate | Retail
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 164,895	$ 92,173
Mortgage loans, percentage	33.70%	27.50%
Real Estate | Office
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 142,824	$ 111,735
Mortgage loans, percentage	29.20%	33.30%
Real Estate | Storage facility
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 73,401	$ 53,591
Mortgage loans, percentage	15.00%	16.00%
Real Estate | Industrial
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 34,212	$ 29,131
Mortgage loans, percentage	7.00%	8.70%
Real Estate | Hotel
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 23,748	$ 8,372
Mortgage loans, percentage	4.80%	2.50%
Real Estate | Land/lots
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 4,597	$ 4,680
Mortgage loans, percentage	0.90%	1.40%
Real Estate | Apartments
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 38,920	$ 29,743
Mortgage loans, percentage	7.90%	8.90%
Real Estate | Residential
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 1,905	$ 0
Mortgage loans, percentage	0.40%	0.00%
Real Estate | All other
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 5,377	$ 5,582
Mortgage loans, percentage	1.10%	1.70%
Real Estate | West South Central
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 237,644	$ 201,501
Mortgage loans, percentage	48.50%	60.10%
Real Estate | East North Central
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 61,397	$ 16,478
Mortgage loans, percentage	12.60%	4.90%
Real Estate | South Atlantic
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 81,847	$ 51,857
Mortgage loans, percentage	16.70%	15.50%
Real Estate | East South Central
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 20,069	$ 27,590
Mortgage loans, percentage	4.10%	8.20%
Real Estate | West North Central
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 12,213	$ 12,423
Mortgage loans, percentage	2.50%	3.70%
Real Estate | Pacific
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 13,800	$ 6,228
Mortgage loans, percentage	2.80%	1.90%
Real Estate | Middle Atlantic
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 36,296	$ 1,975
Mortgage loans, percentage	7.40%	0.60%
Real Estate | Mountain
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate
Mortgage loans, amount	$ 26,613	$ 16,955
Mortgage loans, percentage	5.40%	5.10%