REINSURANCE - Effect of Reinsurance on Premiums and Benefits and Claims (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Effects of Reinsurance [Line Items]
Direct earned premiums	$ 3,623	$ 3,792	$ 7,361	$ 7,907
Ceded premiums	(103)	(105)	(210)	(221)
Net earned premiums	3,573	3,764	7,262	7,844
Direct benefits and claims, excluding reserve remeasurement	2,182	2,317	4,438	4,851
Reserve remeasurement (gains) losses	(54)	(25)	(107)	(59)	$ (215)
Direct benefits and claims	2,128	2,292	4,331	4,792
Benefits and claims, net	2,098	2,274	4,247	4,757
Intercompany eliminations
Effects of Reinsurance [Line Items]
Ceded benefits and claims	70	4	83	9
Assumed benefits and claims from other companies	(47)	(10)	(76)	(17)
All other
Effects of Reinsurance [Line Items]
Ceded premiums	(23)	(18)	(45)	(36)
Assumed premiums earned	23	41	47	81
Ceded benefits and claims	(64)	(14)	(104)	(20)
Assumed benefits and claims from other companies	65	40	103	80
Aflac Japan
Effects of Reinsurance [Line Items]
Net earned premiums	2,064	2,334	4,234	4,959
Aflac Japan \| Closed Block
Effects of Reinsurance [Line Items]
Ceded premiums	(80)	(87)	(165)	(185)
Assumed premiums earned	30	36	64	77
Ceded benefits and claims	(74)	(77)	(151)	(165)
Assumed benefits and claims from other companies	$ 20	$ 39	$ 61	$ 78

Policyholder Benefits and Claims Incurred, Direct, Excluding Reserve Remeasurement

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Amount of earned premiums assumed from other entities.

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Amount of earned premiums ceded to other entities.

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Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

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Amount of remeasurement gain (loss) on liability for future policy benefit from application of revised benefit ratio as of contract issue. Includes, but is not limited to, remeasurement gain (loss) for annuitization insurance benefit, death and other insurance benefits, and traditional and limited-payment contracts.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount, before effect of policies assumed or ceded, of expense related to provision for policy benefits and costs incurred.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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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, after premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

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Amount of policy benefits and costs incurred for policies assumed.

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

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