DEFERRED POLICY ACQUISITION COSTS - Schedule Of Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	$ 8,758	$ 9,132	$ 9,132
Capitalization	246		1,056
Amortization expense	(216)	(215)	(851)
Foreign currency translation and other	295		(579)
Ending balance	9,083		8,758
Aflac Japan | Cancer
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	2,776	2,971	2,971
Capitalization	61		300
Amortization expense	(46)		(184)
Foreign currency translation and other	160		(311)
Ending balance	2,951		2,776
Aflac Japan | Medical and other health
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	1,833	2,041	2,041
Capitalization	27		103
Amortization expense	(25)		(100)
Foreign currency translation and other	107		(211)
Ending balance	1,942		1,833
Aflac Japan | Life insurance
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	441	491	491
Capitalization	9		36
Amortization expense	(8)		(34)
Foreign currency translation and other	27		(52)
Ending balance	469		441
Aflac Japan | Other
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	52	56	56
Capitalization	1		4
Amortization expense	0		(3)
Foreign currency translation and other	1		(5)
Ending balance	54		52
Aflac U.S. | Life insurance
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	219	172	172
Capitalization	22		77
Amortization expense	(9)		(30)
Foreign currency translation and other	0		0
Ending balance	232		219
Aflac U.S. | Accident
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	915	917	917
Capitalization	33		141
Amortization expense	(36)		(143)
Foreign currency translation and other	0		0
Ending balance	912		915
Aflac U.S. | Disability
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	636	625	625
Capitalization	31		129
Amortization expense	(31)		(118)
Foreign currency translation and other	0		0
Ending balance	636		636
Aflac U.S. | Critical Care
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	1,348	1,336	1,336
Capitalization	38		165
Amortization expense	(39)		(153)
Foreign currency translation and other	0		0
Ending balance	1,347		1,348
Aflac U.S. | Hospital Indemnity
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	452	436	436
Capitalization	21		89
Amortization expense	(19)		(73)
Foreign currency translation and other	0		0
Ending balance	454		452
Aflac U.S. | Dental/Vision
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	86	86	86
Capitalization	3		12
Amortization expense	(3)		(12)
Foreign currency translation and other	0		0
Ending balance	86		86
Aflac U.S. | Other
Deferred Policy Acquisition Cost [Line Items]
Beginning balance	0	$ 1	1
Capitalization	0		0
Amortization expense	0		(1)
Foreign currency translation and other	0		0
Ending balance	$ 0		$ 0