BUSINESS SEGMENT INFORMATION - Operations by Segment - Pretax Earnings (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Other income (loss)		$ (2)	$ 0
Net investment gains (losses)		951	123
Earnings before income taxes		2,170	1,342
Income taxes applicable to pretax adjusted earnings		202	180
Effect of foreign currency translation on after-tax adjusted earnings		(44)	(41)
Operating Segments
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings		1,163	1,133
Segment Reconciling Items
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Amortized hedge costs		6	58
Amortized hedge income		(28)	(29)
Net interest (income) expense from from derivatives associated with certain investment strategies		88	69
Impact of interest from derivatives associated with notes payable		(8)	(12)
Aflac Japan | Operating Segments
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings		810	788
Aflac U.S. | Operating Segments
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings		356	352
Corporate and other
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Change in value of federal historic rehabilitation and solar tax credit investments		(32)	(51)
Federal historic rehabilitation and solar tax credits, amount		33	52
Corporate and other | Operating Segments
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[1]	$ (3)	$ (7)

[1] The change in value of federal historic rehabilitation and solar investments in partnerships of $32 and $51 for the three-month periods ended March 31, 2024, and 2023, respectively, is included as a reduction to net investment income. Tax credits on these investments of $33 and $52 for the three-month periods ended March 31, 2024, and 2023, respectively, have been recorded as an income tax benefit in the consolidated statements of earnings. See Note 3 for additional information on these investments.