General (Effects of Adoption ASU 2018-12, Segment Results) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022		Dec. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net incurred claims and benefits	$ 1,818	$ 1,873	$ 5,236	$ 4,939
Core income (loss) before income tax	364	45	1,163	697
Income tax (expense) benefit on core income (loss)	(75)	(2)	(241)	(126)
Core income (loss)	289	43	922	571
Claim and claim adjustment expenses	22,836		22,836		$ 22,120	[1]
Future policy benefits	12,654	13,181	12,654	13,181	13,480	[1]	$ 19,132
Life & Group | Operating Segments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net incurred claims and benefits	343	525	998	1,140
Core income (loss) before income tax	(43)	(251)	(88)	(280)
Income tax (expense) benefit on core income (loss)	14	59	36	84
Core income (loss)	(29)	(192)	(52)	(196)
Claim and claim adjustment expenses	649		649		695
Future policy benefits	$ 12,654		$ 12,654		13,480
Prior to Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Claim and claim adjustment expenses					25,099
Future policy benefits					10,151		$ 13,318
Prior to Adoption | Life & Group | Operating Segments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net incurred claims and benefits		310		884
Core income (loss) before income tax		(36)		(24)
Income tax (expense) benefit on core income (loss)		14		31
Core income (loss)		(22)		7
Claim and claim adjustment expenses					3,674
Future policy benefits					10,151
Effect of Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Claim and claim adjustment expenses					(2,979)
Future policy benefits					3,329
Effect of Adoption | Life & Group | Operating Segments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net incurred claims and benefits		215		256
Core income (loss) before income tax		(215)		(256)
Income tax (expense) benefit on core income (loss)		45		53
Core income (loss)		$ (170)		$ (203)
Claim and claim adjustment expenses					(2,979)
Future policy benefits					$ 3,329

[1] As of January 1, 2023, the Company adopted 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 Condensed Consolidated Financial Statements for additional information.