10-K Reinsurance (Effect Of Reinsurance On Benefit Expense) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reinsurance Disclosures [Abstract]
Direct									$ 112,964	$ 98,933	$ 85,168
Assumed									3,730	3,719	2,967
Ceded									(52)	(81)	(90)
Net benefit expense	$ 30,606	$ 31,604	$ 30,786	$ 29,421	$ 28,795	$ 28,231	$ 92,996	$ 86,447	$ 116,642	$ 102,571	$ 88,045

Amount, before effect of policies assumed or ceded, of expense related to provision for policy benefits and costs incurred.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

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Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred.

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Amount of policy benefits and costs incurred for policies assumed.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479838/944-20-50-3

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

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