REINSURANCE - Effect of Reinsurance on Premiums and Benefits and Claims (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Effects of Reinsurance [Line Items]
Direct earned premiums		$ 3,360	$ 3,524	$ 10,194	$ 10,885
Ceded premiums		(71)	(99)	(206)	(309)
Net earned premiums	[1]	3,328	3,476	10,109	10,737
Direct benefits and claims, excluding reserve remeasurement		2,024	2,106	6,101	6,545
Benefits and claims, excluding reserve remeasurement		2,003	2,065	6,042	6,420
Reserve remeasurement (gains) losses, direct		(407)	(219)	(515)	(327)
Reserve remeasurement gains (losses), ceded		(1)	14	0	15
Reserve remeasurement (gains) losses		(408)	(205)	(515)	(312)
Benefits and claims, net		1,595	1,860	5,527	6,108
All other
Effects of Reinsurance [Line Items]
Ceded premiums		(39)	(24)	(109)	(69)
Assumed premiums earned		11	18	37	65
Ceded benefits and claims		(20)	(7)	(53)	(29)
Assumed benefits and claims from other companies		(2)	8	3	36
Aflac Japan | Closed Block
Effects of Reinsurance [Line Items]
Ceded premiums		(32)	(75)	(97)	(240)
Assumed premiums earned		28	33	84	96
Ceded benefits and claims		(16)	(71)	(51)	(222)
Assumed benefits and claims from other companies		$ 17	$ 29	$ 42	$ 90

[1] Includes a gain (loss) of $(75) and $22 for the three-month periods and $(80) and $22 for the nine-month periods ended September 30, 2024 and 2023, respectively, related to remeasurement of the deferred profit liability for limited-payment contracts.