Investments (Other Invested Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Other Invested Assets [Line Items]
Other invested assets	$ 1,403,405	$ 1,222,985
Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	1,375,721	1,204,869
Derivative Instruments
Other Invested Assets [Line Items]
Other invested assets	27,244	17,718
Other
Other Invested Assets [Line Items]
Other invested assets	440	398
Equity Method | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	1,325,403	1,137,562
Equity Method | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	358,116	333,863
Equity Method | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	869,690	720,360
Equity Method | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	97,597	83,339
Fair Value | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	50,318	67,307
Fair Value | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	33,140	48,483
Fair Value | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	25	137
Fair Value | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	$ 17,153	$ 18,687