Fair Value Measurements - Quantitative Information About Unobservable Inputs (Details) - Recurring - Significant Unobservable Inputs (Level 3) $ in Millions	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Debt securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, including held for sale assets	$ 422	$ 447
Corporate \| Securities Priced by the Company
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, including held for sale assets	$ 369	$ 401
Corporate \| Securities Priced by the Company \| Minimum \| Liquidity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable Adjustment, including held for sale assets	0.0055	0.0070
Corporate \| Securities Priced by the Company \| Maximum \| Liquidity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable Adjustment, including held for sale assets	0.1230	0.1235
Corporate \| Securities Priced by the Company \| Weighted Average \| Liquidity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable Adjustment, including held for sale assets	0.0280	0.0310
Mortgage and other asset-backed securities \| Securities Priced by the Company
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, including held for sale assets	$ 53	$ 46
Mortgage and other asset-backed securities \| Securities Priced by the Company \| Minimum \| Liquidity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable Adjustment, including held for sale assets	0.0110	0.0095
Mortgage and other asset-backed securities \| Securities Priced by the Company \| Maximum \| Liquidity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable Adjustment, including held for sale assets	0.0605	0.0640
Mortgage and other asset-backed securities \| Securities Priced by the Company \| Weighted Average \| Liquidity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable Adjustment, including held for sale assets	0.0280	0.0310