Investments - Commercial Mortgage Loan Participations Recorded Investment (Details) - Commercial mortgage loan participations - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	$ 204,275	$ 181,305
Carrying value	207,344	183,094
Less allowance for credit losses	$ (3,069)	$ (1,789)	$ (827)	$ (827)
Carrying value, net of valuation allowance, percent	100.00%	100.00%
Less than 70%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 168,131	$ 144,395
Carrying value, net of valuation allowance, percent	81.00%	79.00%
70% to 80%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 8,460	$ 23,358
Carrying value, net of valuation allowance, percent	4.00%	13.00%
81% to 90%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 8,307	$ 8,307
Carrying value, net of valuation allowance, percent	4.00%	4.00%
Greater than 90%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value	$ 22,446	$ 7,034
Carrying value, net of valuation allowance, percent	11.00%	4.00%
Less Than 1.00x
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	$ 39,577	$ 39,562
Less Than 1.00x | Less than 70%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	24,235	24,221
Less Than 1.00x | 70% to 80%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	0	0
Less Than 1.00x | 81% to 90%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	8,307	8,307
Less Than 1.00x | Greater than 90%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	7,035	7,034
1.00x-1.20x
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	146,099	130,276
1.00x-1.20x | Less than 70%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	123,466	108,156
1.00x-1.20x | 70% to 80%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	7,222	22,120
1.00x-1.20x | 81% to 90%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	0	0
1.00x-1.20x | Greater than 90%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	15,411	0
Greater Than 1.20x
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	21,668	13,256
Greater Than 1.20x | Less than 70%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	20,430	12,018
Greater Than 1.20x | 70% to 80%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	1,238	1,238
Greater Than 1.20x | 81% to 90%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	0	0
Greater Than 1.20x | Greater than 90%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, net of valuation allowance	$ 0	$ 0