Fair Value of Financial Instruments - Carrying Value of Commercial Mortgage Loans and Additional Information (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Total amortized cost	$ 45,756	$ 37,947
Allowance for mortgage loan losses	(55)	(49)
Mortgage loans, net	45,701	37,898
Total mortgage loans | Mortgage Loans by Region
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 45,756	$ 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	7.10%	8.60%
Total mortgage loans | Mortgage Loans by Region | Southern Atlantic
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 17,312	$ 9,397
Percent of Total	37.90%	24.70%
Total mortgage loans | Mortgage Loans by Region | East South Central
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 7,656	$ 7,783
Percent of Total	16.70%	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	14.40%	17.40%
Total mortgage loans | Mortgage Loans by Region | Middle Atlantic
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 6,060	$ 6,139
Percent of Total	13.20%	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	4.40%	5.20%
Total mortgage loans | Mortgage Loans by Region | West North Central
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 2,903	$ 2,803
Percent of Total	6.30%	7.40%
Total mortgage loans | Mortgage Loans by Property Type
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 45,756	$ 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	$ 8,565	$ 8,493
Percent of Total	18.70%	22.40%
Total mortgage loans | Mortgage Loans by Property Type | Office
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 11,110	$ 11,267
Percent of Total	24.30%	29.70%
Total mortgage loans | Mortgage Loans by Property Type | Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 10,021	$ 10,056
Percent of Total	21.90%	26.50%
Total mortgage loans | Mortgage Loans by Property Type | Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 10,000	$ 1,992
Percent of Total	21.90%	5.20%
Total mortgage loans | Mortgage Loans by Property Type | Mixed use/Other
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage loans, net	$ 6,060	$ 6,139
Percent of Total	13.20%	16.20%
Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Total amortized cost	$ 37,003	$ 29,231
65%-75%
Financing Receivable, Credit Quality Indicator [Line Items]
Total amortized cost	$ 8,753	$ 8,716