DEFERRED POLICY ACQUISITION COSTS - Schedule Of Deferred Policy Acquisition Costs (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	$ 8,758	$ 9,132
Capitalization	1,105	1,056
Amortization expense	(874)	(851)	$ (816)
Foreign currency translation and other	45	(579)
Balance, end of year	9,034	8,758	9,132
Aflac Japan
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	5,102
Amortization expense	(323)	(321)	(326)
Balance, end of year	5,302	5,102
Aflac Japan | Cancer
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	2,776	2,971
Capitalization	357	300
Amortization expense	(188)	(184)
Foreign currency translation and other	20	(311)
Balance, end of year	2,965	2,776	2,971
Aflac Japan | Medical and other health
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	1,833	2,041
Capitalization	85	103
Amortization expense	(99)	(100)
Foreign currency translation and other	21	(211)
Balance, end of year	1,840	1,833	2,041
Aflac Japan | Life insurance
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	441	491
Capitalization	33	36
Amortization expense	(33)	(34)
Foreign currency translation and other	5	(52)
Balance, end of year	446	441	491
Aflac Japan | Other
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	52	56
Capitalization	3	4
Amortization expense	(3)	(3)
Foreign currency translation and other	(1)	(5)
Balance, end of year	51	52	56
Aflac U.S.
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	3,656
Amortization expense	(551)	(530)	(490)
Balance, end of year	3,732	3,656
Aflac U.S. | Life insurance
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	219	172
Capitalization	98	77
Amortization expense	(40)	(30)
Foreign currency translation and other	0	0
Balance, end of year	277	219	172
Aflac U.S. | Accident
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	915	917
Capitalization	137	141
Amortization expense	(143)	(143)
Foreign currency translation and other	0	0
Balance, end of year	909	915	917
Aflac U.S. | Disability
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	636	625
Capitalization	127	129
Amortization expense	(122)	(118)
Foreign currency translation and other	0	0
Balance, end of year	641	636	625
Aflac U.S. | Critical care
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	1,348	1,336
Capitalization	162	165
Amortization expense	(155)	(153)
Foreign currency translation and other	0	0
Balance, end of year	1,355	1,348	1,336
Aflac U.S. | Hospital indemnity
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	452	436
Capitalization	90	89
Amortization expense	(79)	(73)
Foreign currency translation and other	0	0
Balance, end of year	463	452	436
Aflac U.S. | Dental/vision
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	86	86
Capitalization	13	12
Amortization expense	(12)	(12)
Foreign currency translation and other	0	0
Balance, end of year	87	86	86
Aflac U.S. | Other
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of year	0	1
Capitalization	0	0
Amortization expense	0	(1)
Foreign currency translation and other	0	0
Balance, end of year	$ 0	$ 0	$ 1