Fair Values of Financial Instruments - Quantitative Information About Level 3 Fair Value Measurements (Details) - Level 3 - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fixed maturity securities, available for sale	$ 6,287	$ 3,115
Real estate at fair value	1,279	0
Real estate partnerships at fair value	39	0
Investments funds	111	0
Other invested assets - other	425	0
Recurring | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments funds	111
Other invested assets - other	157
Separately managed accounts	89	105
Real estate investments | Recurring | Broker price opinion
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Real estate at fair value	1,279
Real estate partnerships | Recurring | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Real estate partnerships at fair value	39
Corporate debt securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fixed maturity securities, available for sale	2,914	$ 2,214
Corporate debt securities | Recurring | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fixed maturity securities, available for sale	83
Collateralized debt securities | Recurring | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fixed maturity securities, available for sale	$ 1,947