Investments - Strategic Investment in Fortitude Re Narrative (Details) - USD ($)			1 Months Ended					12 Months Ended
	Jun. 02, 2020	Nov. 13, 2018	Dec. 31, 2023	Dec. 31, 2022	May 31, 2022	Mar. 31, 2022	May 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Purchase of investment in Fortitude Re								$ 0	$ 0	$ 79,600,000
Investment				$ 2,922,000,000				2,922,000,000	2,128,600,000
Investment income (loss)								1,898,000,000	6,721,900,000	1,095,200,000
Principal investment income (loss) from equity method investments - realized
Schedule of Equity Method Investments [Line Items]
Investment income (loss)								73,100,000	266,200,000	$ 135,500,000
Fortitude Re | Fortitude Holdings
Schedule of Equity Method Investments [Line Items]
Percentage ownership		100.00%
Fortitude Holdings
Schedule of Equity Method Investments [Line Items]
Ownership percentage acquired		19.90%
Purchase of investment in Fortitude Re		$ 381,000,000
Deferred consideration, maximum		$ 95,000,000
Purchase price adjustment, maximum							$ 99,500,000
Purchase price adjustment, payable upon inability to make distribution							$ 79,600,000
Investment				646,000,000				646,000,000	$ 715,700,000
Fortitude Holdings | Scenario, Forecast
Schedule of Equity Method Investments [Line Items]
Purchase price adjustment, payable upon inability to make distribution			$ 19,900,000
Fortitude Holdings | Carlyle FRL
Schedule of Equity Method Investments [Line Items]
Ownership percentage acquired	51.60%
Percentage ownership	71.50%
Fortitude Holdings | T&D United Capital Co Ltd
Schedule of Equity Method Investments [Line Items]
Ownership percentage acquired	25.00%
Fortitude Holdings | Carlyle FRL and T&D
Schedule of Equity Method Investments [Line Items]
Percentage ownership	96.50%
Fortitude Holdings | Fortitude Re | Maximum
Schedule of Equity Method Investments [Line Items]
Committed capital				9,200,000,000				9,200,000,000
Fortitude Holdings | Carlyle FRL
Schedule of Equity Method Investments [Line Items]
Ownership interest transferred	19.90%
Carlyle FRL
Schedule of Equity Method Investments [Line Items]
Equity capital raised					$ 1,100,000,000	$ 2,000,000,000
Investment loss				121,000,000	$ 176,900,000			176,900,000
Investment				646,000,000				646,000,000
Investment cost				$ 389,400,000				$ 389,400,000
Carlyle FRL | T&D United Capital Co Ltd
Schedule of Equity Method Investments [Line Items]
Percentage committed capital						$ 100,000,000
Carlyle FRL | Fortitude Holdings
Schedule of Equity Method Investments [Line Items]
Business acquisition further decrease funding percentage					10.50%			10.50%
Carlyle FRL | Fortitude Holdings | Minimum
Schedule of Equity Method Investments [Line Items]
Percentage ownership					13.50%			13.50%
Carlyle FRL | Fortitude Holdings | Maximum
Schedule of Equity Method Investments [Line Items]
Percentage ownership					19.90%			19.90%