BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) $ in Millions		3 Months Ended
		Mar. 31, 2023 USD ($) segment	Mar. 31, 2022 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of reportable insurance business segments | segment		2
Net earned premiums		$ 3,688	$ 4,079
Other income		46	69
Total revenues		4,800	5,173
Total adjusted revenues		4,579	5,027
Net investment gains (losses)	[1],[2],[3],[4]	221	146
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		2,170	2,625
Adjusted net investment income	[1],[3]	611	680
Other income		9	9
Total revenues		2,790	3,314
Hedge costs		58	26
Net interest cash flows from derivatives		(62)	(10)
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		1,428	1,413
Adjusted net investment income	[4]	197	184
Other income		35	42
Total revenues		1,660	1,639
Net interest cash flows from derivatives		(7)	1
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		90	42
Total revenues	[2],[5]	129	74
Hedge income		29	11
Change in value of federal historic rehabilitation and solar tax credit investments		(51)	(12)
Federal historic rehabilitation and solar tax credits, amount		$ 52	$ 16

[1] Amortized hedge costs of $58 and $26 for the three-month periods ended March 31, 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.

[2] Amortized hedge income of $29 and $11 for the three-month periods ended March 31, 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 to net investment income when analyzing operations.

[3] Net interest cash flows from derivatives associated with certain investment strategies of $(62) and $(10) for the three-month periods ended March 31, 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.

[4] Net interest cash flows from derivatives associated with certain investment strategies of $(7) and $1 for the three-month periods ended March 31, 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.

[5] The change in value of federal historic rehabilitation and solar investments in partnerships of $51 and $12 for the three-month periods ended March 31, 2023, and 2022, respectively, is included as a reduction to net investment income. Tax credits on these investments of $52 and $16 for the three-month periods ended March 31, 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.