Fair Value of Financial Instruments - Carrying Value of Commercial Mortgage Loans and Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total amortized cost	$ 47,201	$ 47,690
Valuation allowance	(71)	(76)
Mortgage loans, net	47,130	47,614
Total mortgage loans | Mortgage Loans by Region
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 47,201	$ 47,690
Percent of Total	100.00%	100.00%
Total mortgage loans | Mortgage Loans by Region | East North Central
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 3,245	$ 3,245
Percent of Total	6.90%	6.80%
Total mortgage loans | Mortgage Loans by Region | Southern Atlantic
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 9,578	$ 9,752
Percent of Total	20.30%	20.50%
Total mortgage loans | Mortgage Loans by Region | East South Central
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 8,028	$ 8,197
Percent of Total	17.00%	17.20%
Total mortgage loans | Mortgage Loans by Region | New England
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 6,588	$ 6,588
Percent of Total	14.00%	13.80%
Total mortgage loans | Mortgage Loans by Region | Middle Atlantic
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 14,789	$ 14,936
Percent of Total	31.30%	31.20%
Total mortgage loans | Mortgage Loans by Region | Mountain
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 2,227	$ 2,227
Percent of Total	4.70%	4.70%
Total mortgage loans | Mortgage Loans by Region | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 2,746	$ 2,745
Percent of Total	5.80%	5.80%
Total mortgage loans | Mortgage Loans by Property Type
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 47,201	$ 47,690
Percent of Total	100.00%	100.00%
Total mortgage loans | Mortgage Loans by Property Type | Multifamily
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 16,986	$ 17,038
Percent of Total	36.00%	35.70%
Total mortgage loans | Mortgage Loans by Property Type | Office
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 11,571	$ 11,861
Percent of Total	24.50%	24.90%
Total mortgage loans | Mortgage Loans by Property Type | Industrials
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 10,124	$ 10,124
Percent of Total	21.50%	21.20%
Total mortgage loans | Mortgage Loans by Property Type | Retail
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 2,227	$ 2,227
Percent of Total	4.70%	4.70%
Total mortgage loans | Mortgage Loans by Property Type | Mixed use/Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans, net	$ 6,293	$ 6,440
Percent of Total	13.30%	13.50%
Less than 65%
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total amortized cost	$ 29,924	$ 30,361
65%-75%
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total amortized cost	$ 17,277	$ 17,329