Investments - Schedule of Commercial Mortgage Loan Participations (Details) - Commercial mortgage loan participations - USD ($) $ in Thousands	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 224,394		$ 183,094
Carrying value, gross, percent	101.00%		101.00%
Less allowance for credit losses	$ (2,928)	$ (3,069)	$ (1,789)	$ (1,109)	$ (827)	$ (827)
Allowance for credit losses, percent	(1.00%)		(1.00%)
Carrying value, net of valuation allowance	$ 221,466		$ 181,305
Carrying value, net, percent	100.00%		100.00%
California
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 67,189		$ 64,477
Carrying value, gross, percent	30.00%		36.00%
Texas
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 43,051		$ 22,905
Carrying value, gross, percent	19.00%		13.00%
New York
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 25,116		$ 19,167
Carrying value, gross, percent	11.00%		11.00%
Washington
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 14,954		$ 14,925
Carrying value, gross, percent	7.00%		8.00%
Massachusetts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 14,941		$ 0
Carrying value, gross, percent	7.00%		0.00%
Florida
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 33,324		$ 33,182
Carrying value, gross, percent	15.00%		18.00%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 25,819		$ 28,438
Carrying value, gross, percent	12.00%		15.00%
Mixed use
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 42,406		$ 62,375
Carrying value, gross, percent	19.00%		34.00%
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 25,074		$ 27,796
Carrying value, gross, percent	11.00%		15.00%
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 23,818		$ 15,342
Carrying value, gross, percent	11.00%		9.00%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 27,266		$ 27,248
Carrying value, gross, percent	12.00%		15.00%
Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 94,693		$ 42,232
Carrying value, gross, percent	43.00%		23.00%
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 11,137		$ 8,101
Carrying value, gross, percent	5.00%		5.00%