BUSINESS SEGMENT INFORMATION - Operations by Segment - Pretax Earnings (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[1]	$ 1,298	$ 1,106	$ 3,571	$ 3,407
Net investment gains (losses)	[2],[3],[4],[5],[6]	504	222	1,363	923
Other income (loss)		3	1	38	1
Earnings before income taxes		1,805	1,329	4,972	4,331
Income taxes applicable to pretax adjusted earnings		203	196	570	610
Effect of foreign currency translation on after-tax adjusted earnings		(33)	(97)	(100)	(192)
Remeasurement gain (loss), deferred profit liability for limited-payment contracts		22	(41)	22	(42)
Interest expense on debt		39	45	109	127
Aflac Japan
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[2],[5],[7]	869	817	2,479	2,560
Remeasurement gain (loss), deferred profit liability for limited-payment contracts		22	(41)	22	(42)
Hedge costs		26	28	148	84
Net interest cash flows from derivatives		(79)	(25)	(214)	(37)
Aflac U.S.
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[6]	478	345	1,199	1,020
Net interest cash flows from derivatives		(9)	(1)	(24)	1
Corporate and other
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[3],[4],[8]	(49)	(56)	(107)	(173)
Hedge income		25	19	92	44
Gain (loss) on change in fair value of derivative, interest rate component		8	13	32	38
Change in value of federal historic rehabilitation and solar tax credit investments		(64)	(19)	(169)	(61)
Federal historic rehabilitation and solar tax credits, amount		$ 63	$ 19	$ 171	$ 63

[1] Includes $39 and $45 for the three-month periods and $109 and $127 for the nine-month periods ended September 30, 2023, and 2022, respectively, of interest expense on debt.

[2] Amortized hedge costs of $26 and $28 for the three-month periods and $148 and $84 for the nine-month periods ended September 30, 2023, and 2022, 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 $8 and $13 for the three-month periods and $32 and $38 for the nine-month periods ended September 30, 2023, and 2022, 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 $25 and $19 for the three-month periods and $92 and $44 for the nine-month periods ended September 30, 2023, and 2022, 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 $(79) and $(25) for the three-month periods and $(214) and $(37) for the nine-month periods ended September 30, 2023, and 2022, 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 $(9) and $(1) for the three-month periods and $(24) and $1 for the nine-month periods ended September 30, 2023, and 2022, have been reclassified from net investment gains (losses) and included in adjusted earnings as a component of net investment income when analyzing operations.

[7] Includes a gain (loss) of $22 and $(41) for the three-month periods and $22 and $(42) for the nine-month periods ended September 30, 2023 and 2022, respectively, related to remeasurement of the deferred profit liability for limited-payment contracts.

[8] The change in value of federal historic rehabilitation and solar investments in partnerships of $64 and $19 for the three-month periods and $169 and $61 for the nine-month periods ended September 30, 2023, and 2022, respectively, is included as a reduction to net investment income. Tax credits on these investments of $63 and $19 for the three-month periods and $171 and $63 for the nine-month periods ended September 30, 2023, and 2022, respectively, have been recorded as an income tax benefit in the consolidated statements of earnings. See Note 3 for additional information on these investments.