SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Impact from Adoption to Liability For Future Policy Benefit, Expected Net Premium (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]
Balance	$ 17,912	$ 18,221	$ 22,470
Effect of change in discount rate assumptions	1,542	1,077
Ending balance	19,454	19,298	25,893
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance	15,922	16,195	18,681
Effect of change in discount rate assumptions	1,045	519
Ending balance	16,967	16,714	21,174
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance	7,084	7,284	10,064
Effect of change in discount rate assumptions	319	201
Ending balance	7,403	7,485	10,847
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance	822	799	780
Effect of change in discount rate assumptions	(60)	(75)
Ending balance	762	724	834
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance	2,736	2,760	2,999
Effect of change in discount rate assumptions	(173)	(226)
Ending balance	2,563	2,534	3,283
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance	1,795	1,775	1,760
Effect of change in discount rate assumptions	(112)	(140)
Ending balance	1,683	1,635	1,862
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance	5,037	5,050	5,391
Effect of change in discount rate assumptions	(444)	(564)
Ending balance	4,593	4,486	6,023
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance	1,378	1,365	1,380
Effect of change in discount rate assumptions	(117)	(145)
Ending balance	1,261	1,220	1,467
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance	228	231	241
Effect of change in discount rate assumptions	(15)	(20)
Ending balance	213	211	264
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance	1,214	1,242	1,461
Effect of change in discount rate assumptions	42	14
Ending balance	1,256	1,256	1,586
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance	137	118	135
Effect of change in discount rate assumptions	(6)	(8)
Ending balance	$ 131	$ 110	153
Accounting Standards Update 2018-12 | Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance			22,470		$ 25,616	[1]
Effect of change in discount rate assumptions			3,423
Ending balance			25,893	$ 29,598	29,598
Accounting Standards Update 2018-12 | Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance			18,681		21,276	[1]
Effect of change in discount rate assumptions			2,493
Ending balance			21,174	23,874	23,874
Accounting Standards Update 2018-12 | Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance			10,064		12,476	[1]
Effect of change in discount rate assumptions			783
Ending balance			10,847	13,384	13,384
Accounting Standards Update 2018-12 | Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance			780		705	[1]
Effect of change in discount rate assumptions			54
Ending balance			834	783	783
Accounting Standards Update 2018-12 | Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance			2,999		3,350	[1]
Effect of change in discount rate assumptions			284
Ending balance			3,283	3,829	3,829
Accounting Standards Update 2018-12 | Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance			1,760		1,921	[1]
Effect of change in discount rate assumptions			102
Ending balance			1,862	2,118	2,118
Accounting Standards Update 2018-12 | Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance			5,391		5,894	[1]
Effect of change in discount rate assumptions			632
Ending balance			6,023	6,942	6,942
Accounting Standards Update 2018-12 | Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance			1,380		1,376	[1]
Effect of change in discount rate assumptions			87
Ending balance			1,467	1,530	1,530
Accounting Standards Update 2018-12 | Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance			241		281	[1]
Effect of change in discount rate assumptions			23
Ending balance			264	322	322
Accounting Standards Update 2018-12 | Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance			1,461		1,708	[1]
Effect of change in discount rate assumptions			125
Ending balance			1,586	1,856	1,856
Accounting Standards Update 2018-12 | Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance			135		152	[1]
Effect of change in discount rate assumptions			18
Ending balance			$ 153	179	179
Accounting Standards Update 2018-12 | As Previously Reported | Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance					25,601
Accounting Standards Update 2018-12 | As Previously Reported | Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance					21,270
Accounting Standards Update 2018-12 | As Previously Reported | Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance					12,440
Accounting Standards Update 2018-12 | As Previously Reported | Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance					710
Accounting Standards Update 2018-12 | As Previously Reported | Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance					3,350
Accounting Standards Update 2018-12 | As Previously Reported | Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance					1,921
Accounting Standards Update 2018-12 | As Previously Reported | Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance					5,898
Accounting Standards Update 2018-12 | As Previously Reported | Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance					1,376
Accounting Standards Update 2018-12 | As Previously Reported | Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance					281
Accounting Standards Update 2018-12 | As Previously Reported | Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance					2,080
Accounting Standards Update 2018-12 | As Previously Reported | Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Balance					154
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance					25,616
Impact of capping net premium ratio to retained earnings					0
Impact of deferred profit liability					15
Effect of change in discount rate assumptions				3,982
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]
Balance					21,276
Impact of capping net premium ratio to retained earnings					(1)
Impact of deferred profit liability					7
Effect of change in discount rate assumptions				2,598
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]
Balance					12,476
Impact of capping net premium ratio to retained earnings					0
Impact of deferred profit liability					36
Effect of change in discount rate assumptions				908
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]
Balance					705
Impact of capping net premium ratio to retained earnings					(5)
Impact of deferred profit liability					0
Effect of change in discount rate assumptions				78
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]
Balance					3,350
Impact of capping net premium ratio to retained earnings					0
Impact of deferred profit liability					0
Effect of change in discount rate assumptions				479
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]
Balance					1,921
Impact of capping net premium ratio to retained earnings					0
Impact of deferred profit liability					0
Effect of change in discount rate assumptions				197
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]
Balance					5,894
Impact of capping net premium ratio to retained earnings					(4)
Impact of deferred profit liability					0
Effect of change in discount rate assumptions				1,048
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]
Balance					1,376
Impact of capping net premium ratio to retained earnings					0
Impact of deferred profit liability					0
Effect of change in discount rate assumptions				154
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]
Balance					281
Impact of capping net premium ratio to retained earnings					0
Impact of deferred profit liability					0
Effect of change in discount rate assumptions				41
Accounting Standards Update 2018-12 | Revision of Prior Period, Accounting Standards Update, Adjustment | Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Balance					1,708
Impact of capping net premium ratio to retained earnings					(398)
Impact of deferred profit liability					26
Effect of change in discount rate assumptions				148
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]
Balance					152
Impact of capping net premium ratio to retained earnings					(2)
Impact of deferred profit liability					$ 0
Effect of change in discount rate assumptions				$ 27

[1] Includes the adjustment for capping the Transition Date NPR.