BUSINESS SEGMENT AND FOREIGN INFORMATION - Operations by Segment - Revenues (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		$ 15,263	$ 17,647	$ 18,622
Total revenues		19,502	22,106	22,147
Total adjusted revenues		19,005	21,589	22,320
Net investment gains (losses)	[1],[2],[3],[4]	497	517	(173)
Life insurance
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		2,354	2,956	3,253
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		9,548	11,853	12,670
Adjusted net investment income	[1],[4]	2,669	3,031	2,659
Other income (loss)		35	41	42
Total revenues		12,252	14,925	15,371
Hedge costs		112	76	206
Net interest cash flows from derivatives		(86)	(33)	9
Aflac Japan | Cancer
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		4,791	5,829	6,119
Aflac Japan | Medical and other health
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		2,775	3,400	3,596
Aflac Japan | Life insurance
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		1,982	2,624	2,955
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		5,570	5,614	5,758
Adjusted net investment income	[3]	755	754	705
Other income (loss)		161	121	102
Total revenues		6,486	6,489	6,565
Net interest cash flows from derivatives		(4)	2	3
Aflac U.S. | Accident
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		1,314	1,362	1,449
Aflac U.S. | Disability
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		1,171	1,162	1,165
Aflac U.S. | Critical care
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		1,753	1,797	1,856
Aflac U.S. | Hospital indemnity
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		722	730	747
Aflac U.S. | Dental/vision
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		199	188	196
Aflac U.S. | Life insurance
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		372	332	298
Aflac U.S. | Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		39	43	47
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums, principally supplemental health insurance		145	180	194
Total revenues	[2],[5]	267	175	384
Hedge income		68	57	$ 97
Change in value of federal historic rehabilitation and solar tax credit investments		(91)	(138)
Federal historic rehabilitation and solar tax credits, amount		$ 83	$ 115

[1] Amortized hedge costs of $112, $76 and $206 in 2022, 2021 and 2020, 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 $68, $57 and $97 in 2022, 2021 and 2020, 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 $(4), $2 and $3 in 2022, 2021 and 2020, 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 $(86), $(33) and $9 in 2022, 2021 and 2020, 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 $91 and $138 in 2022 and 2021, respectively, is included as a reduction to net investment income. Tax credits on these investments of $83 and $115 in 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.