Fair Value of Financial Instruments - Carrying Value of Commercial Mortgage Loans and Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Total amortized cost	$ 37,912	$ 37,947
Allowance for mortgage loan losses	(49)	(49)
Mortgage loans, net	37,863	37,898
Total mortgage loans | Mortgage Loans by Region
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 37,912	$ 37,947
Percent of Total	100.00%	100.00%
Total mortgage loans | Mortgage Loans by Region | East North Central
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 3,245	$ 3,245
Percent of Total	8.60%	8.60%
Total mortgage loans | Mortgage Loans by Region | Southern Atlantic
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 9,351	$ 9,397
Percent of Total	24.60%	24.70%
Total mortgage loans | Mortgage Loans by Region | East South Central
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 7,719	$ 7,783
Percent of Total	20.30%	20.50%
Total mortgage loans | Mortgage Loans by Region | New England
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 6,588	$ 6,588
Percent of Total	17.40%	17.40%
Total mortgage loans | Mortgage Loans by Region | Middle Atlantic
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 6,100	$ 6,139
Percent of Total	16.10%	16.20%
Total mortgage loans | Mortgage Loans by Region | Mountain
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 1,992	$ 1,992
Percent of Total	5.30%	5.20%
Total mortgage loans | Mortgage Loans by Region | West North Central
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 2,917	$ 2,803
Percent of Total	7.70%	7.40%
Total mortgage loans | Mortgage Loans by Property Type
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 37,912	$ 37,947
Percent of Total	100.00%	100.00%
Total mortgage loans | Mortgage Loans by Property Type | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 8,593	$ 8,493
Percent of Total	22.70%	22.40%
Total mortgage loans | Mortgage Loans by Property Type | Office
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 11,189	$ 11,267
Percent of Total	29.40%	29.70%
Total mortgage loans | Mortgage Loans by Property Type | Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 10,038	$ 10,056
Percent of Total	26.50%	26.50%
Total mortgage loans | Mortgage Loans by Property Type | Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 1,992	$ 1,992
Percent of Total	5.30%	5.20%
Total mortgage loans | Mortgage Loans by Property Type | Mixed use/Other
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 6,100	$ 6,139
Percent of Total	16.10%	16.20%
Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Total amortized cost	$ 29,113	$ 29,231
65%-75%
Financing Receivable, Credit Quality Indicator [Line Items]
Total amortized cost	$ 8,799	$ 8,716