BUSINESS SEGMENT INFORMATION AND SELECTED FOREIGN CURRENCY TRANSLATION ITEMS - Operations by Segment - Revenues (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	[1]	$ 13,548	$ 13,440	$ 14,123
Net investment income		4,076	4,116	3,811
Other income (loss)		112	100	177
Total revenues		17,164	18,927	18,701
Net investment gains (losses)		(572)	1,271	590
Remeasurement gain (loss), deferred profit liability for limited-payment contracts		(52)	(81)	20
Change in value of federal historic rehabilitation and solar tax credit investments		(65)	(165)	(343)
Federal historic rehabilitation and solar tax credits, amount		69	164	334
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		17,537	17,405	17,747
Segment Reconciling Items
Segment Reporting, Revenue Reconciling Item [Line Items]
Net investment gains (losses)		(572)	1,271	590
Amortized hedge costs		45	26	157
Amortized hedge income		(98)	(113)	(121)
Net interest (income) expense from derivatives associated with certain investment strategies		252	338	328
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		6,744	6,930	8,047
Net investment income		2,854	3,032	3,033
Aflac Japan | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	[1]	6,744	6,930	8,047
Net investment income		2,581	2,701	2,582
Other income (loss)		32	28	35
Total revenues	[1]	9,357	9,659	10,664
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		5,999	5,829	5,675
Net investment income		854	883	854
Aflac U.S. | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		5,999	5,829	5,675
Net investment income		830	847	820
Other income (loss)		74	63	128
Total revenues		6,903	6,739	6,623
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		805	681	400
Net investment income		368	201	(77)
Corporate and other | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[2]	$ 1,277	$ 1,007	$ 460

[1] Includes a gain (loss) of $(52), $(81) and $20 in 2025, 2024 and 2023, 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 $65, $165 and $343 in 2025, 2024 and 2023, respectively, is included as a reduction to net investment income. Tax credits on these investments of $69, $164 and $334 in 2025, 2024 and 2023, respectively, have been reported as an income tax benefit in the consolidated statements of earnings. See Note 1 for additional information on these investments.