BUSINESS SEGMENT INFORMATION - Additional Information (Details) $ in Millions		3 Months Ended
		Mar. 31, 2025 USD ($) segment	Mar. 31, 2024 USD ($)	Dec. 31, 2024
Segment Reporting Information [Line Items]
Number of reportable insurance business segments | segment		2
Net earned premiums	[1]	$ 3,381	$ 3,456
Aflac Re Bermuda
Segment Reporting Information [Line Items]
Net earned premiums		$ 178	$ 136
Aflac Japan
Segment Reporting Information [Line Items]
Percentage of the Company's total revenues		53.00%	56.00%
Percentage of the Company's total assets		78.00%		77.00%

[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.