Summary of Significant Accounting Policies (Effects of Adoption ASU 2018-12, Segment Results) (Details) - USD ($) $ in Millions	3 Months Ended					12 Months Ended
	Dec. 31, 2022		Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net incurred claims and benefits						$ 7,039	$ 6,628		$ 6,349
Core income (loss) before income tax						1,617	1,013		1,342
Income tax (expense) benefit on core income (loss)						(333)	(177)		(254)
Core income (loss)	$ 265		$ 43	$ 230	$ 298	1,284	836		1,088
Insurance claims and policyholders benefits, including policyholders' dividends, remeasurement impact						(88)	(214)		(8)
Claim and claim adjustment expenses	22,120	[1]				23,304	22,120	[1]	21,268
Future policy benefits	13,480	[1]				13,959	13,480	[1]	18,010	$ 19,132
Life & Group | Operating Segments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net incurred claims and benefits						1,317	1,469		1,261
Core income (loss) before income tax						(90)	(320)		83
Income tax (expense) benefit on core income (loss)						42	99		25
Core income (loss)						(48)	(221)		108
Claim and claim adjustment expenses	695					675	695		848
Future policy benefits	13,480					$ 13,959	13,480
Prior to Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Core income (loss)	274		213	245	316		1,048
Claim and claim adjustment expenses	25,099						25,099
Future policy benefits	10,151						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							1,202		1,239
Core income (loss) before income tax							(53)		105
Income tax (expense) benefit on core income (loss)							44		21
Core income (loss)							(9)		126
Claim and claim adjustment expenses	3,674						3,674
Future policy benefits	10,151						10,151
Effect of Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Core income (loss)	(9)		$ (170)	$ (15)	$ (18)		(212)
Claim and claim adjustment expenses	(2,979)						(2,979)
Future policy benefits	3,329						3,329
Effect of Adoption | Life & Group | Operating Segments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net incurred claims and benefits							267		22
Core income (loss) before income tax							(267)		(22)
Income tax (expense) benefit on core income (loss)							55		4
Core income (loss)							(212)		$ (18)
Claim and claim adjustment expenses	(2,979)						(2,979)
Future policy benefits	$ 3,329						$ 3,329

[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.