SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION - (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	$ 9,132				$ 9,239				$ 9,132		$ 9,239		$ 9,848
Future policy benefits & unpaid policy claims	83,979				88,442				83,979		88,442
Unearned premiums	1,451				1,825				1,451		1,825
Other policyholders’ funds	6,169				6,643				6,169		6,643
Net premium income	3,385	$ 3,476	$ 3,573	$ 3,688	3,523	$ 3,535	$ 3,764	$ 4,079	14,123	[1]	14,901	[1]	17,095	[1]
Net investment income	865	$ 1,004	$ 999	$ 943	896	$ 920	$ 937	$ 903	3,811		3,656		3,818
Benefits and claims, net									8,211		8,887		10,476
Amortization of deferred policy acquisition costs									816		792		835
Other operating expenses									4,412		4,592		5,035
Premiums written									14,237		14,943		17,137
Intercompany eliminations
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	0				0				0		0
Future policy benefits & unpaid policy claims	(5,121)				(667)				(5,121)		(667)
Unearned premiums	(26)				0				(26)		0
Other policyholders’ funds	0				0				0		0
Aflac Japan
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	5,559				5,776				5,559		5,776
Future policy benefits & unpaid policy claims	73,641				77,733				73,641		77,733
Unearned premiums	1,358				1,716				1,358		1,716
Other policyholders’ funds	6,169				6,639				6,169		6,639
Net premium income									8,047		9,186		11,301
Net investment income									3,033		2,867		3,139
Benefits and claims, net									5,313		6,191		7,675
Amortization of deferred policy acquisition costs									326		338		393
Other operating expenses									1,790		2,080		2,549
Premiums written									8,571		9,474		11,600
Aflac U.S.
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	3,573				3,463				3,573		3,463
Future policy benefits & unpaid policy claims	11,492				11,070				11,492		11,070
Unearned premiums	107				113				107		113
Other policyholders’ funds	0				4				0		4
Net premium income									5,675		5,570		5,614
Net investment income									854		759		752
Benefits and claims, net									2,431		2,555		2,639
Amortization of deferred policy acquisition costs									490		455		442
Other operating expenses									2,201		2,117		2,052
Premiums written									5,666		5,469		5,537
Corporate and other
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	0				0				0		0
Future policy benefits & unpaid policy claims	3,967				306				3,967		306
Unearned premiums	12				(4)				12		(4)
Other policyholders’ funds	$ 0				$ 0				0		0
Net premium income									400		145		180
Net investment income									(77)		30		(73)
Benefits and claims, net									467		141		161
Amortization of deferred policy acquisition costs									0		0		0
Other operating expenses									421		395		434
Premiums written									$ 0		$ 0		$ 0

[1] Includes a gain (loss) of $20, $(42) and $(11) in 2023, 2022 and 2021, respectively, related to remeasurement of the deferred profit liability for limited-payment contracts.