BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) segment	Sep. 30, 2021 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of reportable insurance business segments | segment				2
Net earned premiums		$ 3,651	$ 4,372	$ 11,679	$ 13,406
Other income		50	45	168	132
Total adjusted revenues		4,584	5,395	14,530	16,412
Net investment gains (losses)	[1],[2],[3],[4]	236	(158)	962	258
Total revenues		4,820	5,237	15,492	16,670
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		2,241	2,934	7,384	9,045
Adjusted net investment income	[1],[4]	663	763	2,066	2,260
Other income		9	10	26	32
Total adjusted revenues		2,913	3,707	9,476	11,337
Hedge costs		28	20	84	55
Net interest cash flows from derivatives		(25)	(7)	(37)	(24)
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		1,375	1,393	4,182	4,223
Adjusted net investment income	[3]	185	191	563	557
Other income		38	32	120	90
Total adjusted revenues		1,598	1,616	4,865	4,870
Net interest cash flows from derivatives		(1)	1	1	1
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Total adjusted revenues	[2],[5]	73	72	189	205
Hedge income		19	13	44	45
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] 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.

[2] 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 to net investment income when analyzing operations.

[3] 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.

[4] 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.

[5] 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.