Investments (Other Invested Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	$ 1,582,094	$ 1,222,985
Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	1,533,210	1,191,808
Derivatives
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	24,499	17,718
Other
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	24,385	13,459
Equity Method | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	1,489,086	1,124,501
Equity Method | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	388,822	333,863
Equity Method | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	1,024,534	720,360
Equity Method | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	75,730	70,278
Fair Value | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	44,124	67,307
Fair Value | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	28,094	48,483
Fair Value | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	14	137
Fair Value | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets (includes $12,999 and $80,638 of assets measured at fair value at December 31, 2024 and 2023, respectively)	$ 16,016	$ 18,687