BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of reportable insurance business segments | segment				2
Net earned premiums		$ 3,573	$ 3,764	$ 7,262	$ 7,844
Other income		45	50	90	118
Total revenues		5,172	5,315	9,972	10,488
Total adjusted revenues		4,513	4,736	9,091	9,762
Net investment gains (losses)	[1],[2],[3],[4]	659	579	881	726
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		2,064	2,334	4,234	4,959
Adjusted net investment income	[1],[3]	637	723	1,248	1,402
Other income		9	9	18	18
Total revenues		2,710	3,066	5,500	6,379
Hedge costs		63	30	122	55
Net interest cash flows from derivatives		(73)	(2)	(135)	(12)
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		1,425	1,394	2,853	2,807
Adjusted net investment income	[4]	203	193	400	377
Other income		35	41	70	83
Total revenues		1,663	1,628	3,323	3,267
Net interest cash flows from derivatives		(8)	1	(15)	2
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		84	36	175	82
Total revenues	[2],[5]	140	42	268	116
Hedge income		38	14	67	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] 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.

[2] 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 to net investment income when analyzing operations.

[3] 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.

[4] 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.

[5] 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.