BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	[1]	$ 3,372	$ 3,328	$ 10,223	$ 10,109
Net investment income		1,067	1,006	3,103	3,100
Other income		26	23	81	76
Total revenues		4,740	2,949	12,298	13,524
Net investment gains (losses)		275	(1,408)	(1,109)	239
Remeasurement gain (loss), deferred profit liability for limited-payment contracts		(55)	(75)	(55)	(80)
Change in value of federal historic rehabilitation and solar tax credit investments		(6)	(57)	(22)	(119)
Federal historic rehabilitation and solar tax credits, amount		7	78	24	142
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		4,406	4,287	13,261	13,088
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment
Segment Reporting, Revenue Reconciling Item [Line Items]
Net investment gains (losses)		275	(1,408)	(1,109)	239
Amortized hedge costs		13	7	31	19
Amortized hedge income		(20)	(25)	(80)	(87)
Net interest (income) expense from derivatives associated with certain investment strategies		66	88	195	265
Aflac Japan | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	[1]	1,663	1,709	5,105	5,241
Net investment income		665	662	1,950	2,036
Other income		7	7	24	20
Total revenues	[1]	2,335	2,378	7,079	7,297
Aflac U.S. | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		1,495	1,459	4,501	4,388
Net investment income		214	210	623	634
Other income		19	15	53	46
Total revenues		1,728	1,684	5,177	5,068
Corporate and other | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[2]	$ 343	$ 225	$ 1,005	$ 723

[1] Includes a gain (loss) of $(55) and $(75) for the three-month periods and $(55) and $(80) for the nine-month periods ended September 30, 2025 and 2024, respectively, related to remeasurement of the deferred profit liability for limited-payment contracts.

[2] The change in value of federal historic rehabilitation and solar investments in partnerships of $6 and $57 for the three-month periods and $22 and $119 for the nine-month periods ended September 30, 2025, and 2024, respectively, is included as a reduction to net investment income. Tax credits on these investments of $7 and $78 for the three-month periods and $24 and $142 for the nine-month periods ended September 30, 2025, and 2024, respectively, have been recorded as an income tax benefit in the consolidated statements of earnings. See Note 3 for additional information on these investments.