DEFERRED POLICY ACQUISITION COSTS - Schedule Of Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			$ 9,132	$ 9,239	$ 9,239
Capitalization			767		1,086
Amortization expense	$ (214)	$ (201)	(638)	(608)	(816)
Foreign currency translation and other			(29)		(377)
Balance, end of period	9,232		9,232		9,132
Aflac Japan | Cancer
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			2,971	3,035	3,035
Capitalization			221		317
Amortization expense			(139)		(184)
Foreign currency translation and other			(14)		(197)
Balance, end of period	3,039		3,039		2,971
Aflac Japan | Medical and other health
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			2,041	2,161	2,161
Capitalization			79		123
Amortization expense			(75)		(105)
Foreign currency translation and other			(13)		(138)
Balance, end of period	2,032		2,032		2,041
Aflac Japan | Life insurance
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			491	525	525
Capitalization			25		33
Amortization expense			(26)		(34)
Foreign currency translation and other			(2)		(33)
Balance, end of period	488		488		491
Aflac Japan | Other
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			56	55	55
Capitalization			3		8
Amortization expense			(2)		(3)
Foreign currency translation and other			0		(4)
Balance, end of period	57		57		56
Aflac U.S. | Life insurance
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			172	135	135
Capitalization			55		61
Amortization expense			(23)		(24)
Foreign currency translation and other			0		0
Balance, end of period	204		204		172
Aflac U.S. | Accident
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			917	904	904
Capitalization			101		151
Amortization expense			(107)		(138)
Foreign currency translation and other			0		0
Balance, end of period	911		911		917
Aflac U.S. | Disability
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			625	613	613
Capitalization			93		125
Amortization expense			(88)		(113)
Foreign currency translation and other			0		0
Balance, end of period	630		630		625
Aflac U.S. | Critical Care
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			1,336	1,304	1,304
Capitalization			119		173
Amortization expense			(114)		(141)
Foreign currency translation and other			0		0
Balance, end of period	1,341		1,341		1,336
Aflac U.S. | Hospital Indemnity
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			436	418	418
Capitalization			63		84
Amortization expense			(55)		(66)
Foreign currency translation and other			0		0
Balance, end of period	444		444		436
Aflac U.S. | Dental/Vision
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			86	88	88
Capitalization			9		10
Amortization expense			(9)		(12)
Foreign currency translation and other			0		0
Balance, end of period	86		86		86
Aflac U.S. | Other
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period			1	$ 1	1
Capitalization			(1)		1
Amortization expense			0		4
Foreign currency translation and other			0		(5)
Balance, end of period	$ 0		$ 0		$ 1