Investments (Other Invested Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Other Invested Assets [Line Items]
Other invested assets	$ 1,222,985	$ 1,088,613
Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	1,204,869	1,040,992
Derivative Instruments
Other Invested Assets [Line Items]
Other invested assets	17,718	47,111
other
Other Invested Assets [Line Items]
Other invested assets	398	510
Equity Method | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	1,137,562	971,993
Equity Method | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	333,863	287,969
Equity Method | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	720,360	576,595
Equity Method | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	83,339	107,429
Fair Value | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	67,307	68,999
Fair Value | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	48,483	59,146
Fair Value | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	137	396
Fair Value | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	$ 18,687	$ 9,457