BUSINESS SEGMENT INFORMATION - Operations by Segment - Pretax Earnings (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023		Jun. 30, 2022
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings		$ 1,139	$ 1,141	$ 2,273	[1]	$ 2,301	[1]
Net investment gains (losses)	[2],[3],[4],[5],[6]	651	567	859		701
Other income (loss)		35	0	35		0
Earnings before income taxes		1,825	1,708	3,167		3,002
Income taxes applicable to pretax adjusted earnings		186	195	366		414
Effect of foreign currency translation on after-tax adjusted earnings		(25)	(59)	(66)		(94)
Interest expense on debt		36	41	70		82
Aflac Japan
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[2],[5]	822	873	1,610		1,743
Hedge costs		63	30	122		55
Net interest cash flows from derivatives		(73)	(2)	(135)		(12)
Aflac U.S.
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[6]	369	343	721		675
Net interest cash flows from derivatives		(8)	1	(15)		2
Corporate and other
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[3],[4],[7]	(52)	(75)	(58)		(117)
Hedge income		38	14	67		25
Gain (loss) on change in fair value of derivative, interest rate component		12	12	24		25
Change in value of federal historic rehabilitation and solar tax credit investments		(53)	(31)	(105)		(42)
Federal historic rehabilitation and solar tax credits, amount		$ 56	$ 28	$ 108		$ 44

[1] Includes $36 and $41 for the three-month periods and $70 and $82 for the six-month periods ended June 30, 2023, and 2022, respectively, of interest expense on debt.

[2] Amortized hedge costs of $63 and $30 for the three-month periods and $122 and $55 for the six-month periods ended June 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 $12 and $12 for the three-month periods and $24 and $25 for the six-month periods ended June 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 $38 and $14 for the three-month periods and $67 and $25 for the six-month periods ended June 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 $(73) and $(2) for the three-month periods and $(135) and $(12) for the six-month periods ended June 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 $(8) and $1 for the three-month periods and $(15) and $2 for the six-month periods ended June 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] The change in value of federal historic rehabilitation and solar investments in partnerships of $53 and $31 for the three-month periods and $105 and $42 for the six-month periods ended June 30, 2023, and 2022, respectively, is included as a reduction to net investment income. Tax credits on these investments of $56 and $28 for the three-month periods and $108 and $44 for the six-month periods ended June 30, 2023, and 2022, 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.