Investments - Schedule of Investment Funds (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Alternative Investment [Line Items]
Investment funds, unfunded commitments	$ 456,000
Minimum
Alternative Investment [Line Items]
Expected life of non-redeemable funds	7 years
Extension options term of non-redeemable funds	1 year
Expected life of redeemable funds	6 months
Maximum
Alternative Investment [Line Items]
Expected life of non-redeemable funds	12 years
Extension options term of non-redeemable funds	4 years
Expected life of redeemable funds	36 months
Commercial mortgage loans
Alternative Investment [Line Items]
Investment funds, Fair Value	$ 560,271	$ 566,142
Investment funds, unfunded commitments	192,336
Opportunistic and private credit
Alternative Investment [Line Items]
Investment funds, Fair Value	212,692	202,008
Investment funds, unfunded commitments	179,305
Infrastructure
Alternative Investment [Line Items]
Investment funds, Fair Value	179,980	179,627
Investment funds, unfunded commitments	25,000
Other
Alternative Investment [Line Items]
Investment funds, Fair Value	36,084	38,989
Investment funds, unfunded commitments	59,098
Investment funds
Alternative Investment [Line Items]
Investment funds, Fair Value	989,027	$ 986,766
Investment funds, unfunded commitments	455,739
Unfunded commitments, including past investment period	$ 595,000