Investments - Commercial Mortgage Loan Participations (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses	$ (827)	$ (3,505)
Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 142,670	$ 164,107
Carrying value, gross, percent	101.00%	102.00%
Allowance for credit losses	$ (827)	$ (3,505)	$ 0
Allowance for credit losses, percent	(1.00%)	(2.00%)
Carrying value, net of valuation allowance	$ 141,843	$ 160,602
Carrying value, net, percent	100.00%	100.00%
California | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 67,659	$ 61,610
Carrying value, gross, percent	48.00%	38.00%
New York | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 18,373	$ 16,602
Carrying value, gross, percent	13.00%	10.00%
Pennsylvania | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 11,673	$ 11,314
Carrying value, gross, percent	8.00%	7.00%
Indiana | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 9,717	$ 9,717
Carrying value, gross, percent	7.00%	6.00%
Florida | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 8,213	$ 12,420
Carrying value, gross, percent	6.00%	8.00%
Texas | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 5,898	$ 4,215
Carrying value, gross, percent	4.00%	3.00%
Other | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 21,137	$ 48,229
Carrying value, gross, percent	15.00%	30.00%
Virginia | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 0	$ 27,000
Mixed use | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 57,996	$ 49,002
Carrying value, gross, percent	41.00%	31.00%
Office | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 8,905	$ 36,153
Carrying value, gross, percent	6.00%	22.00%
Hospitality | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 23,186	$ 22,605
Carrying value, gross, percent	16.00%	14.00%
Retail | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 19,811	$ 19,319
Carrying value, gross, percent	14.00%	12.00%
Industrial | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 17,900	$ 17,900
Carrying value, gross, percent	13.00%	11.00%
Multi-family | Commercial mortgage participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 14,872	$ 19,128
Carrying value, gross, percent	11.00%	12.00%