Investments (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Gain (Loss) on Securities [Line Items]
Non-income producing fixed maturity securities	$ 0	$ 0
Non-income producing mortgage loans	20,000,000	7,000,000
Investments that exceed ten percent of stockholders' equity	0	0
Investment and derivative, realized gain (loss), coinsurance agreement		18,000,000
Gross gains	75,000,000	120,000,000		$ 186,000,000
Debt securities, available-for-sale, realized loss	166,000,000	261,000,000		90,000,000
Mortgage loan losses due to changes in expected credit losses	11,000,000	8,000,000		$ (10,000,000)
Limited partnership investments	2,174,000,000	1,926,000,000	[1]
Undistributed earnings of limited partnership investments	$ 250,000,000	$ 176,000,000
Percentage of limited partnerships reported on a current basis	17.00%
Percentage of limited partnerships reported on a one month lag	4.00%
Limited partnerships invested in private debt and equity	85.00%	76.00%
Percentage of limited partnerships employing hedge fund strategies focused on fixed income and equity investments	15.00%	24.00%
Carrying value of ten largest limited partnerships	$ 622,000,000	$ 633,000,000
Carrying value of limited partnerships as percentage of aggregate partnership equity	1.00%	1.00%
Income as percentage of change in partnership equity for all limited partnerships	1.00%	2.00%		2.00%
Obligation to return cash	$ 1,000,000
Derivative liability, subject to master netting arrangement, collateral, right to reclaim cash offset	0	$ 0
Increase (decrease) fixed maturity securities	224,000,000
Increase (decrease) short term investments	4,000,000
Increase (decrease) accrued investment income	2,000,000
Increase (decrease) funds withheld liability	216,000,000
Embedded derivative, fair value of embedded derivative liability	14,000,000
Commitments to purchase or fund privately placed debt securities	1,555,000,000
Commitments to sell various privately placed debt securities	35,000,000
Carrying value of securities deposited under requirements of regulatory authorities	3,100,000,000	2,800,000,000
Cash and securities deposited as collateral for letters of credit	900,000,000
Fixed maturity securities
Gain (Loss) on Securities [Line Items]
OCI, debt securities, available-for-sale, gain (loss), after adjustment, before tax	1,431,000,000	(7,850,000,000)		$ (1,272,000,000)
Debt securities, available-for-sale, accrued interest, after allowance for credit loss	435,000,000	394,000,000
Mortgage loans
Gain (Loss) on Securities [Line Items]
Financing receivable, accrued interest, after allowance for credit loss	$ 4,000,000
Funds Withheld Liability Securities
Gain (Loss) on Securities [Line Items]
Gross gains		62,000,000
Debt securities, available-for-sale, realized loss		$ 44,000,000

[1] As of January 1, 2023, the Company adopted ASU 2018-12, Financial Services-Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts (ASU 2018-12) using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance. See Note A to the Consolidated Financial Statements for additional information.