BUSINESS SEGMENT INFORMATION - Operations by Segment - Pretax Earnings (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[1]	$ 880	$ 1,293	$ 3,156	$ 3,940
Net investment gains (losses)	[2],[3],[4],[5],[6]	222	(172)	923	216
Other income (loss)		1	(8)	1	(66)
Earnings before income taxes		1,103	1,113	4,080	4,090
Income taxes applicable to pretax adjusted earnings		156	262	565	771
Effect of foreign currency translation on after tax adjusted earnings		(53)	(14)	(147)	(8)
Interest expense on debt		45	40	127	130
Aflac Japan
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[2],[5]	630	976	2,351	2,867
Hedge costs		28	20	84	55
Net interest cash flows from derivatives		(25)	(7)	(37)	(24)
Aflac U.S.
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[6]	309	358	984	1,217
Net interest cash flows from derivatives		(1)	1	1	1
Corporate and other
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[3],[4],[7]	(59)	(41)	(179)	(144)
Hedge income		19	13	44	45
Gain (loss) on change in fair value of derivative, interest rate component		13	14	38	41
Income (loss) from federal historic rehabilitation and solar tax credit investments		(19)	(5)	(61)	(35)
Federal historic rehabilitation and solar tax credits, amount		$ 19	$ 10	$ 63	$ 35

[1] Includes $45 and $40 for the three-month periods and $127 and $130 for the nine-month periods ended September 30, 2022, and 2021, respectively, of interest expense on debt.

[2] Amortized hedge costs of $28 and $20 for the three-month periods and $84 and $55 for the nine-month periods ended September 30, 2022, and 2021, respectively, related to certain foreign currency exposure management strategies have been reclassified from net investment gains (losses) and reported as a deduction from net investment income when analyzing operations.

[3] A gain of $13 and $14 for the three-month periods and $38 and $41 for the nine-month periods ended September 30, 2022, and 2021, respectively, related to the interest rate component of the change in fair value of foreign currency swaps on notes payable has been reclassified from net investment gains (losses) and included in adjusted earnings when analyzing operations.

[4] Amortized hedge income of $19 and $13 for the three-month periods and $44 and $45 for the nine-month periods ended September 30, 2022, and 2021, respectively, related to certain foreign currency exposure management strategies has been reclassified from net investment gains (losses) and reported as an increase in net investment income when analyzing operations.

[5] Net interest cash flows from derivatives associated with certain investment strategies of $(25) and $(7) for the three-month periods and $(37) and $(24) for the nine-month periods ended September 30, 2022, and 2021, respectively, have been reclassified from net investment gains (losses) and included in adjusted earnings as a component of net investment income when analyzing operations.

[6] Net interest cash flows from derivatives associated with certain investment strategies of $(1) and $1 for the three-month periods and $1 and $1 for the nine-month periods ended September 30, 2022, and 2021, have been reclassified from net investment gains (losses) and included in adjusted earnings as a component of net investment income when analyzing operations.

[7] The change in value of federal historic rehabilitation and solar investments in partnerships of $19 and $5 for the three-month periods and $61 and $35 for the nine-month periods ended September 30, 2022, and 2021, respectively, is included as a reduction to net investment income. Tax credits on these investments of $19 and $10 for the three-month periods and $63 and $35 for the nine-month periods ended September 30, 2022, and 2021, respectively, have been recorded as an income tax benefit in the consolidated statement of earnings. See Note 3 of the Notes to the Consolidated Financial Statements for additional information on these investments.