Fair Value of Assets and Liabilities - Schedule of Valuation Changes Included in Net Income and OCI for Level 3 Assets and Liabilities Held (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	$ 37	$ 55	$ 91
Fair Value Recurring Basis Unobservable Input Reconciliation Liability Gain Loss Statement Of Income Extensible List Not Disclosed Flag	Total included in net income	Total included in net income	Total included in net income
Total included in net income	$ 37	$ 55	$ 91
Total included in net income	37	55	91
Changes in unrealized net capital gains and losses reported in OCI	$ 3	$ (4)	$ 3
Net investment income
Gains (losses) included in net income for Level 3 assets and liabilities:
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Property-Liability net investment income	Property-Liability net investment income	Property-Liability net investment income
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Property-Liability net investment income	Property-Liability net investment income	Property-Liability net investment income
Total included in net income	$ (1)	$ 14	$ 1
Net gains (losses) on investments and derivatives
Gains (losses) included in net income for Level 3 assets and liabilities:
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net gains (losses) on investments and derivatives	Net gains (losses) on investments and derivatives	Net gains (losses) on investments and derivatives
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net gains (losses) on investments and derivatives	Net gains (losses) on investments and derivatives	Net gains (losses) on investments and derivatives
Total included in net income	$ 38	$ 41	$ 90
Corporate - privately placed
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	(12)	1	(2)
Changes in unrealized net capital gains and losses reported in OCI	2	0	3
Fixed income securities
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	(12)	1	(2)
Equity securities
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	35	14	28
Other investments
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	(1)	2	0
Other assets
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	15	38	65
Municipal
Gains (losses) included in net income for Level 3 assets and liabilities:
Changes in unrealized net capital gains and losses reported in OCI	0	1	0
Corporate - public
Gains (losses) included in net income for Level 3 assets and liabilities:
Changes in unrealized net capital gains and losses reported in OCI	$ 1	$ (5)	$ 0