SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Schedule of Impact from Adoption to AOCI and Retained Earnings (Details) - USD ($) $ in Millions		Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jan. 01, 2021	Dec. 31, 2020
Total transition impact, net of income taxes		$ (22,669)	$ (20,439)	$ (19,784)	$ (20,140)	$ (19,946)	$ (19,558)	$ (17,560)	$ (17,031)		$ (33,559)
Retained Earnings
Total transition impact, net of income taxes		(48,257)	(46,937)	(45,555)	(44,367)	(44,680)	(43,150)	(42,010)	(40,963)		(37,984)
Accumulated Other Comprehensive Income (Loss)
Total transition impact, net of income taxes		$ 5,760	$ 7,338	$ 7,278	$ 6,429	$ 7,505	$ 6,980	$ 8,451	$ 8,411		$ (8,934)
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12
Total transition impact, net of income taxes										$ 18,894
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings
Transition impact before income taxes										410
Less: income taxes										86
Total transition impact, net of income taxes										324
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Corporate and other
Transition impact before income taxes										0
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Cancer | Aflac Japan
Transition impact before income taxes										0
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Medical and other health | Aflac Japan
Transition impact before income taxes										1
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Life insurance | Aflac Japan
Transition impact before income taxes										0
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Life insurance | Aflac U.S.
Transition impact before income taxes										5
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Other | Aflac Japan
Transition impact before income taxes	[1]									398
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Other | Aflac U.S.
Transition impact before income taxes										2
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Accident | Aflac U.S.
Transition impact before income taxes										0
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Disability | Aflac U.S.
Transition impact before income taxes										0
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Critical Care | Aflac U.S.
Transition impact before income taxes										4
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Hospital Indemnity | Aflac U.S.
Transition impact before income taxes										0
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Retained Earnings | Dental/Vision | Aflac U.S.
Transition impact before income taxes										0
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss)
Transition impact before income taxes										23,507
Less: income taxes										4,937
Total transition impact, net of income taxes										18,570
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Corporate and other
Transition impact before income taxes										(305)
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Cancer | Aflac Japan
Transition impact before income taxes										14,529
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Medical and other health | Aflac Japan
Transition impact before income taxes										2,382
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Life insurance | Aflac Japan
Transition impact before income taxes										3,314
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Life insurance | Aflac U.S.
Transition impact before income taxes										149
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Other | Aflac Japan
Transition impact before income taxes	[1]									433
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Other | Aflac U.S.
Transition impact before income taxes										218
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Accident | Aflac U.S.
Transition impact before income taxes										92
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Disability | Aflac U.S.
Transition impact before income taxes										149
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Critical Care | Aflac U.S.
Transition impact before income taxes										2,258
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Hospital Indemnity | Aflac U.S.
Transition impact before income taxes										223
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Dental/Vision | Aflac U.S.
Transition impact before income taxes										$ 65

[1] Impact to retained earnings is driven primarily by capping the Transition Date NPR on Care products.