BUSINESS SEGMENT INFORMATION - Additional Information (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) segment	Sep. 30, 2024 USD ($)	Dec. 31, 2024
Segment Reporting Information [Line Items]
Number of reportable insurance business segments | segment				2
Net earned premiums	[1]	$ 3,372	$ 3,328	$ 10,223	$ 10,109
Aflac Re Bermuda
Segment Reporting Information [Line Items]
Net earned premiums		$ 173	$ 132	$ 529	$ 396
Aflac Japan
Segment Reporting Information [Line Items]
Percentage of the Company's total revenues		53.00%	55.00%	53.00%	56.00%
Percentage of the Company's total assets		77.00%		77.00%		77.00%

[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.