BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) segment	Jun. 30, 2021 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of reportable insurance business segments | segment				2
Net earned premiums		$ 3,849	$ 4,441	$ 8,028	$ 9,034
Total adjusted revenues		4,821	5,466	9,946	11,017
Net investment gains (losses)	[1],[2],[3],[4]	579	98	726	416
Total revenues		5,400	5,564	10,672	11,433
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		2,419	2,987	5,143	6,111
Adjusted net investment income	[1],[3]	723	792	1,402	1,497
Other income		9	10	18	22
Total adjusted revenues		3,151	3,789	6,563	7,630
Hedge costs		30	17	55	36
Net interest cash flows from derivatives		(2)	(9)	(12)	(17)
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		1,394	1,408	2,807	2,830
Adjusted net investment income	[4]	193	189	377	366
Other income		41	30	83	58
Total adjusted revenues		1,628	1,627	3,267	3,254
Net interest cash flows from derivatives		1		2
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Total adjusted revenues	[2],[5]	42	50	116	133
Hedge income		14	16	25	33
Income (loss) from federal historic rehabilitation and solar tax credit investments		(31)	(30)	(42)	(30)
Federal historic rehabilitation and solar tax credits, amount		$ 28	$ 12	$ 44	$ 25

[1] Amortized hedge costs of $30 and $17 for the three-month periods and $55 and $36 for the six-month periods ended June 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 $14 and $16 for the three-month periods and $25 and $33 for the six-month periods ended June 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 $(2) and $(9) for the three-month periods and $(12) and $(17) for the six-month periods ended June 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.

[4] Net interest cash flows from derivatives associated with certain investment strategies of $1 for the three-month period and $2 for the six-month period ended June 30, 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 $31 and $30 for the three-month periods and $42 and $30 for the six-month periods ended June 30, 2022, and 2021, respectively, is included as a reduction to net investment income. Tax credits on these investments of $28 and $12 for the three-month periods and $44 and $25 for the six-month periods ended June 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.