SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Impact from Adoption to Liability For Future Policy Benefit, Expected Future Policy Benefits (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2021	Dec. 31, 2020
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	$ 47,049	$ 47,677	$ 56,807
Effect of change in discount rate assumptions	8,750	7,089
Ending balance	55,799	54,766	72,747
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	27,275	27,566	31,398
Effect of change in discount rate assumptions	1,164	(147)
Ending balance	28,439	27,419	36,021
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	32,370	32,800	39,002
Effect of change in discount rate assumptions	344	(846)
Ending balance	32,714	31,954	42,720
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	1,816	1,778	1,694
Effect of change in discount rate assumptions	(210)	(252)
Ending balance	1,606	1,526	1,843
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	3,376	3,391	3,594
Effect of change in discount rate assumptions	(227)	(293)
Ending balance	3,149	3,098	3,949
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	2,644	2,636	2,670
Effect of change in discount rate assumptions	(149)	(191)
Ending balance	2,495	2,445	2,871
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	12,836	12,846	13,079
Effect of change in discount rate assumptions	(1,019)	(1,357)
Ending balance	11,817	11,489	15,388
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	2,315	2,300	2,300
Effect of change in discount rate assumptions	(176)	(226)
Ending balance	2,139	2,074	2,552
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	527	532	549
Effect of change in discount rate assumptions	(33)	(44)
Ending balance	494	488	616
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	5,880	5,940	6,787
Effect of change in discount rate assumptions	(110)	(358)
Ending balance	5,770	5,582	7,322
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance	641	624	645
Effect of change in discount rate assumptions	15	(2)
Ending balance	$ 656	$ 622	837
Accounting Standards Update 2018-12 | Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			56,807		$ 64,056
Effect of change in discount rate assumptions			15,940
Ending balance			72,747	$ 82,567	82,567
Accounting Standards Update 2018-12 | Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			31,398		34,638
Effect of change in discount rate assumptions			4,623
Ending balance			36,021	39,618	39,618
Accounting Standards Update 2018-12 | Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			39,002		43,729
Effect of change in discount rate assumptions			3,718
Ending balance			42,720	47,951	47,951
Accounting Standards Update 2018-12 | Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			1,694		1,562
Effect of change in discount rate assumptions			149
Ending balance			1,843	1,789	1,789
Accounting Standards Update 2018-12 | Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			3,594		3,818
Effect of change in discount rate assumptions			355
Ending balance			3,949	4,389	4,389
Accounting Standards Update 2018-12 | Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			2,670		2,919
Effect of change in discount rate assumptions			201
Ending balance			2,871	3,265	3,265
Accounting Standards Update 2018-12 | Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			13,079		13,427
Effect of change in discount rate assumptions			2,309
Ending balance			15,388	16,733	16,733
Accounting Standards Update 2018-12 | Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			2,300		2,258
Effect of change in discount rate assumptions			252
Ending balance			2,552	2,635	2,635
Accounting Standards Update 2018-12 | Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			549		599
Effect of change in discount rate assumptions			67
Ending balance			616	705	705
Accounting Standards Update 2018-12 | Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			6,787		7,620
Effect of change in discount rate assumptions			535
Ending balance			7,322	8,201	8,201
Accounting Standards Update 2018-12 | Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance			645		661
Effect of change in discount rate assumptions			192
Ending balance			$ 837	906	906
Accounting Standards Update 2018-12 | As Previously Reported | Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					64,056
Accounting Standards Update 2018-12 | As Previously Reported | Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					34,638
Accounting Standards Update 2018-12 | As Previously Reported | Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					43,729
Accounting Standards Update 2018-12 | As Previously Reported | Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					1,562
Accounting Standards Update 2018-12 | As Previously Reported | Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					3,818
Accounting Standards Update 2018-12 | As Previously Reported | Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					2,919
Accounting Standards Update 2018-12 | As Previously Reported | Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					13,427
Accounting Standards Update 2018-12 | As Previously Reported | Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					2,258
Accounting Standards Update 2018-12 | As Previously Reported | Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					599
Accounting Standards Update 2018-12 | As Previously Reported | Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					7,620
Accounting Standards Update 2018-12 | As Previously Reported | Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Beginning balance					$ 661
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				18,511
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				4,980
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				4,222
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				227
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				571
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				346
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				3,306
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				377
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				106
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				581
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Effect of change in discount rate assumptions				$ 245