DEFERRED POLICY ACQUISITION COSTS - Schedule Of Deferred Policy Acquisition Costs (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	$ 9,239	$ 9,848
Capitalization	1,086	1,052
Amortization expense	(816)	(792)	$ (835)
Foreign currency translation and other	(377)	(869)
Balance, end of year	9,132	9,239	9,848
Aflac Japan
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	5,776
Amortization expense	(326)	(338)	(393)
Balance, end of year	5,559	5,776
Aflac Japan | Cancer
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	3,035	3,464
Capitalization	317	291
Amortization expense	(184)	(188)
Foreign currency translation and other	(197)	(532)
Balance, end of year	2,971	3,035	3,464
Aflac Japan | Medical and other health
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	2,161	2,372
Capitalization	123	161
Amortization expense	(105)	(112)
Foreign currency translation and other	(138)	(260)
Balance, end of year	2,041	2,161	2,372
Aflac Japan | Life insurance
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	525	595
Capitalization	33	33
Amortization expense	(34)	(35)
Foreign currency translation and other	(33)	(68)
Balance, end of year	491	525	595
Aflac Japan | Other
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	55	51
Capitalization	8	12
Amortization expense	(3)	(3)
Foreign currency translation and other	(4)	(5)
Balance, end of year	56	55	51
Aflac U.S.
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	3,463
Amortization expense	(490)	(455)	(442)
Balance, end of year	3,573	3,463
Aflac U.S. | Life insurance
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	135	115
Capitalization	61	40
Amortization expense	(24)	(20)
Foreign currency translation and other	0	0
Balance, end of year	172	135	115
Aflac U.S. | Accident
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	904	887
Capitalization	151	147
Amortization expense	(138)	(130)
Foreign currency translation and other	0	0
Balance, end of year	917	904	887
Aflac U.S. | Disability
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	613	604
Capitalization	125	117
Amortization expense	(113)	(108)
Foreign currency translation and other	0	0
Balance, end of year	625	613	604
Aflac U.S. | Critical care
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	1,304	1,270
Capitalization	173	160
Amortization expense	(141)	(126)
Foreign currency translation and other	0	0
Balance, end of year	1,336	1,304	1,270
Aflac U.S. | Hospital indemnity
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	418	399
Capitalization	84	80
Amortization expense	(66)	(61)
Foreign currency translation and other	0	0
Balance, end of year	436	418	399
Aflac U.S. | Dental/vision
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	88	90
Capitalization	10	11
Amortization expense	(12)	(13)
Foreign currency translation and other	0	0
Balance, end of year	86	88	90
Aflac U.S. | Other
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	1	1
Capitalization	1	0
Amortization expense	4	4
Foreign currency translation and other	(5)	(4)
Balance, end of year	$ 1	$ 1	$ 1