BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	[1]	$ 3,381	$ 3,456
Net investment income		955	1,000
Other income		25	29
Total revenues		3,398	5,436
Net investment gains (losses)		(963)	951
Remeasurement gain (loss), deferred profit liability for limited-payment contracts		0	(3)
Change in value of federal historic rehabilitation and solar tax credit investments		(8)	(32)
Federal historic rehabilitation and solar tax credits, amount		7	33
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		4,319	4,419
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment
Segment Reporting, Revenue Reconciling Item [Line Items]
Net investment gains (losses)		(963)	951
Amortized hedge costs		7	6
Amortized hedge income		(30)	(28)
Net interest (income) expense from derivatives associated with certain investment strategies		65	88
Aflac Japan | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	[1]	1,681	1,816
Net investment income		586	648
Other income		5	9
Total revenues	[1]	2,272	2,473
Aflac U.S. | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		1,502	1,475
Net investment income		202	206
Other income		17	18
Total revenues		1,721	1,699
Corporate and other | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[2]	$ 326	$ 247

[1] Includes a gain (loss) of an immaterial amount and $(3) for the three-month periods ended March 31, 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 $8 and $32 for the three-month periods ended March 31, 2025 and 2024, respectively, is included as a reduction to net investment income. Tax credits on these investments of $7 and $33 for the three-month periods ended March 31, 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.