Fair Value of Assets and Liabilities - Schedule of Valuation Changes Included in Net Income and OCI for Level 3 Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	$ 12	$ 24	$ 21	$ 19
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
Total included in net income	$ 12	$ 24	$ 21	$ 19
Total included in net income	12	24	21	19
Changes in unrealized net capital gains and losses reported in OCI	$ 0	$ (2)	$ 1	$ 0
Net investment income
Gains (losses) included in net income for Level 3 assets and liabilities:
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net investment income	Net investment income	Net investment income	Net investment income
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net investment income	Net investment income	Net investment income	Net investment income
Total included in net income	$ 0	$ (1)	$ 1	$ (3)
Net gains (losses) on investments and derivatives
Gains (losses) included in net income for Level 3 assets and liabilities:
Total included in net income	$ 10	$ 16	$ 15	$ 12
Operating costs and expenses
Gains (losses) included in net income for Level 3 assets and liabilities:
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating costs and expenses	Operating costs and expenses	Operating costs and expenses	Operating costs and expenses
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating costs and expenses	Operating costs and expenses	Operating costs and expenses	Operating costs and expenses
Total included in net income	$ 2	$ 9	$ 5	$ 10
Municipal
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	(2)	0	(2)	0
Corporate - public
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	0	0	1	0
Changes in unrealized net capital gains and losses reported in OCI	0	(1)	1	0
Corporate - privately placed
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	0	0	(6)	(11)
Changes in unrealized net capital gains and losses reported in OCI	0	(1)	0	0
Fixed income securities
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	(2)	0	(7)	(11)
Equity securities
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	12	15	23	21
Other investments
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	0	0	0	(1)
Other assets
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	$ 2	$ 9	$ 5	$ 10