POLICY LIABILITIES - Schedule of Changes in Present Value of Expected Net Premiums and Expected Future Policy Benefits (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Present value of expected future policy benefits:
Beginning balance		$ 141,463
Ending balance		123,918	$ 141,463
Net liability for future policy benefits		78,448	88,241
Aflac Japan | Cancer
Present value of expected premiums:
Beginning balance		19,298	25,893
Beginning balance at original discount rate		18,221	22,470
Effect of changes in cash flow assumptions			(166)	$ (639)
Effect of actual variances from expected experience			(261)	(284)
Adjusted beginning of period balance			17,794	21,547
Issuances		770	947
Interest accrual		312	459
Net premiums collected	[1]	(1,182)	(1,734)
Foreign currency translation		(2,023)	(2,997)
Other		(1)	(1)
Ending balance at original discount rate		15,670	18,221	22,470
Effect of changes in discount rate assumptions		823	1,077
Ending balance		16,493	19,298	25,893
Present value of expected future policy benefits:
Beginning balance		54,766	72,747
Beginning balance at original discount rate		47,677	56,807
Effect of changes in cash flow assumptions			(148)	(721)
Effect of actual variances from expected experience			(314)	(333)
Adjusted beginning of period balance			47,215	55,753
Issuances		787	960
Interest accrual		1,116	1,599
Benefit payments		(2,245)	(3,050)
Foreign currency translation		(5,327)	(7,585)
Other		0	0
Ending balance at original discount rate		41,546	47,677	56,807
Effect of changes in discount rate assumptions		5,663	7,089
Ending balance		47,209	54,766	72,747
Net liability for future policy benefits		30,716	35,468
Less: reinsurance recoverable		1,952	0
Net liability for future policy benefits after reinsurance recoverable		28,764	35,468
Aflac Japan | Medical and other health
Present value of expected premiums:
Beginning balance		16,714	21,174
Beginning balance at original discount rate		16,195	18,681
Effect of changes in cash flow assumptions			(473)	317
Effect of actual variances from expected experience			(90)	61
Adjusted beginning of period balance			15,632	19,059
Issuances		285	639
Interest accrual		255	364
Net premiums collected	[1]	(959)	(1,376)
Foreign currency translation		(1,767)	(2,488)
Other		(1)	(3)
Ending balance at original discount rate		13,445	16,195	18,681
Effect of changes in discount rate assumptions		449	519
Ending balance		13,894	16,714	21,174
Present value of expected future policy benefits:
Beginning balance		27,419	36,021
Beginning balance at original discount rate		27,566	31,398
Effect of changes in cash flow assumptions			(510)	352
Effect of actual variances from expected experience			(102)	83
Adjusted beginning of period balance			26,954	31,833
Issuances		295	646
Interest accrual		461	642
Benefit payments		(883)	(1,375)
Foreign currency translation		(3,064)	(4,180)
Other		0	0
Ending balance at original discount rate		23,763	27,566	31,398
Effect of changes in discount rate assumptions		(170)	(147)
Ending balance		23,593	27,419	36,021
Net liability for future policy benefits		9,699	10,705
Less: reinsurance recoverable		1,422	1,579
Net liability for future policy benefits after reinsurance recoverable		8,277	9,126
Aflac Japan | Life insurance
Present value of expected premiums:
Beginning balance		7,485	10,847
Beginning balance at original discount rate		7,284	10,064
Effect of changes in cash flow assumptions			44	(494)
Effect of actual variances from expected experience			(34)	(81)
Adjusted beginning of period balance			7,294	9,489
Issuances		267	221
Interest accrual		94	146
Net premiums collected	[1]	(778)	(1,229)
Foreign currency translation		(798)	(1,343)
Other		0	0
Ending balance at original discount rate		6,079	7,284	10,064
Effect of changes in discount rate assumptions		171	201
Ending balance		6,250	7,485	10,847
Present value of expected future policy benefits:
Beginning balance		31,954	42,720
Beginning balance at original discount rate		32,800	39,002
Effect of changes in cash flow assumptions			66	(550)
Effect of actual variances from expected experience			(43)	(91)
Adjusted beginning of period balance			32,823	38,361
Issuances		272	222
Interest accrual		472	670
Benefit payments		(1,090)	(1,248)
Foreign currency translation		(3,681)	(5,205)
Other		0	0
Ending balance at original discount rate		28,796	32,800	39,002
Effect of changes in discount rate assumptions		(868)	(846)
Ending balance		27,928	31,954	42,720
Net liability for future policy benefits		21,678	24,469
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		21,678	24,469
Aflac Japan | Other
Present value of expected premiums:
Beginning balance		1,256	1,586
Beginning balance at original discount rate		1,242	1,461
Effect of changes in cash flow assumptions			(12)	25
Effect of actual variances from expected experience			(9)	(10)
Adjusted beginning of period balance			1,221	1,476
Issuances		19	62
Interest accrual		15	22
Net premiums collected	[1]	(85)	(123)
Foreign currency translation		(137)	(195)
Other		0	0
Ending balance at original discount rate		1,033	1,242	1,461
Effect of changes in discount rate assumptions		9	14
Ending balance		1,042	1,256	1,586
Present value of expected future policy benefits:
Beginning balance		5,582	7,322
Beginning balance at original discount rate		5,940	6,787
Effect of changes in cash flow assumptions			(27)	96
Effect of actual variances from expected experience			(7)	(10)
Adjusted beginning of period balance			5,906	6,873
Issuances		24	68
Interest accrual		76	106
Benefit payments		(154)	(202)
Foreign currency translation		(664)	(905)
Other		0	0
Ending balance at original discount rate		5,188	5,940	6,787
Effect of changes in discount rate assumptions		(332)	(358)
Ending balance		4,856	5,582	7,322
Net liability for future policy benefits		3,814	4,326
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		3,814	4,326
Aflac U.S. | Life insurance
Present value of expected premiums:
Beginning balance		724	834
Beginning balance at original discount rate		799	780
Effect of changes in cash flow assumptions			61	(1)
Effect of actual variances from expected experience			(9)	(16)
Adjusted beginning of period balance			851	763
Issuances		137	146
Interest accrual		23	27
Net premiums collected	[1]	(101)	(131)
Foreign currency translation		0	0
Other		1	(6)
Ending balance at original discount rate		911	799	780
Effect of changes in discount rate assumptions		(105)	(75)
Ending balance		806	724	834
Present value of expected future policy benefits:
Beginning balance		1,526	1,843
Beginning balance at original discount rate		1,778	1,694
Effect of changes in cash flow assumptions			72	(1)
Effect of actual variances from expected experience			(12)	(21)
Adjusted beginning of period balance			1,838	1,672
Issuances		140	149
Interest accrual		50	62
Benefit payments		(81)	(103)
Foreign currency translation		0	0
Other		5	(2)
Ending balance at original discount rate		1,952	1,778	1,694
Effect of changes in discount rate assumptions		(344)	(252)
Ending balance		1,608	1,526	1,843
Net liability for future policy benefits		802	802
Less: reinsurance recoverable		11	9
Net liability for future policy benefits after reinsurance recoverable		791	793
Aflac U.S. | Accident
Present value of expected premiums:
Beginning balance		2,534	3,283
Beginning balance at original discount rate		2,760	2,999
Effect of changes in cash flow assumptions			(16)	(52)
Effect of actual variances from expected experience			(44)	(152)
Adjusted beginning of period balance			2,700	2,795
Issuances		256	355
Interest accrual		77	105
Net premiums collected	[1]	(356)	(496)
Foreign currency translation		0	0
Other		(5)	1
Ending balance at original discount rate		2,672	2,760	2,999
Effect of changes in discount rate assumptions		(283)	(226)
Ending balance		2,389	2,534	3,283
Present value of expected future policy benefits:
Beginning balance		3,098	3,949
Beginning balance at original discount rate		3,391	3,594
Effect of changes in cash flow assumptions			(11)	(70)
Effect of actual variances from expected experience			(61)	(177)
Adjusted beginning of period balance			3,319	3,347
Issuances		265	364
Interest accrual		95	128
Benefit payments		(340)	(456)
Foreign currency translation		0	0
Other		0	8
Ending balance at original discount rate		3,339	3,391	3,594
Effect of changes in discount rate assumptions		(375)	(293)
Ending balance		2,964	3,098	3,949
Net liability for future policy benefits		575	564
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		575	564
Aflac U.S. | Disability
Present value of expected premiums:
Beginning balance		1,635	1,862
Beginning balance at original discount rate		1,775	1,760
Effect of changes in cash flow assumptions			(51)	5
Effect of actual variances from expected experience			(6)	(43)
Adjusted beginning of period balance			1,718	1,722
Issuances		293	384
Interest accrual		46	57
Net premiums collected	[1]	(292)	(382)
Foreign currency translation		0	0
Other		(6)	(6)
Ending balance at original discount rate		1,759	1,775	1,760
Effect of changes in discount rate assumptions		(162)	(140)
Ending balance		1,597	1,635	1,862
Present value of expected future policy benefits:
Beginning balance		2,445	2,871
Beginning balance at original discount rate		2,636	2,670
Effect of changes in cash flow assumptions			(59)	5
Effect of actual variances from expected experience			(21)	(48)
Adjusted beginning of period balance			2,556	2,627
Issuances		305	397
Interest accrual		72	94
Benefit payments		(349)	(483)
Foreign currency translation		0	0
Other		0	1
Ending balance at original discount rate		2,584	2,636	2,670
Effect of changes in discount rate assumptions		(233)	(191)
Ending balance		2,351	2,445	2,871
Net liability for future policy benefits		754	810
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		754	810
Aflac U.S. | Critical Care
Present value of expected premiums:
Beginning balance		4,486	6,023
Beginning balance at original discount rate		5,050	5,391
Effect of changes in cash flow assumptions			(494)	(38)
Effect of actual variances from expected experience			(154)	(421)
Adjusted beginning of period balance			4,402	4,932
Issuances		397	537
Interest accrual		137	193
Net premiums collected	[1]	(440)	(612)
Foreign currency translation		0	0
Other		(5)	0
Ending balance at original discount rate		4,491	5,050	5,391
Effect of changes in discount rate assumptions		(630)	(564)
Ending balance		3,861	4,486	6,023
Present value of expected future policy benefits:
Beginning balance		11,489	15,388
Beginning balance at original discount rate		12,846	13,079
Effect of changes in cash flow assumptions			(592)	(43)
Effect of actual variances from expected experience			(188)	(465)
Adjusted beginning of period balance			12,066	12,571
Issuances		408	550
Interest accrual		396	539
Benefit payments		(668)	(823)
Foreign currency translation		0	0
Other		1	9
Ending balance at original discount rate		12,203	12,846	13,079
Effect of changes in discount rate assumptions		(1,743)	(1,357)
Ending balance		10,460	11,489	15,388
Net liability for future policy benefits		6,599	7,003
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		6,599	7,003
Aflac U.S. | Hospital Indemnity
Present value of expected premiums:
Beginning balance		1,220	1,467
Beginning balance at original discount rate		1,365	1,380
Effect of changes in cash flow assumptions			(142)	42
Effect of actual variances from expected experience			(48)	(111)
Adjusted beginning of period balance			1,175	1,311
Issuances		203	273
Interest accrual		34	45
Net premiums collected	[1]	(187)	(261)
Foreign currency translation		0	0
Other		(3)	(3)
Ending balance at original discount rate		1,222	1,365	1,380
Effect of changes in discount rate assumptions		(150)	(145)
Ending balance		1,072	1,220	1,467
Present value of expected future policy benefits:
Beginning balance		2,074	2,552
Beginning balance at original discount rate		2,300	2,300
Effect of changes in cash flow assumptions			(194)	40
Effect of actual variances from expected experience			(68)	(130)
Adjusted beginning of period balance			2,038	2,210
Issuances		211	282
Interest accrual		64	85
Benefit payments		(207)	(277)
Foreign currency translation		0	0
Other		0	0
Ending balance at original discount rate		2,106	2,300	2,300
Effect of changes in discount rate assumptions		(259)	(226)
Ending balance		1,847	2,074	2,552
Net liability for future policy benefits		775	854
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		775	854
Aflac U.S. | Dental/Vision
Present value of expected premiums:
Beginning balance		211	264
Beginning balance at original discount rate		231	241
Effect of changes in cash flow assumptions			(9)	10
Effect of actual variances from expected experience			(13)	(20)
Adjusted beginning of period balance			209	231
Issuances		31	33
Interest accrual		6	9
Net premiums collected	[1]	(30)	(42)
Foreign currency translation		0	0
Other		1	0
Ending balance at original discount rate		217	231	241
Effect of changes in discount rate assumptions		(23)	(20)
Ending balance		194	211	264
Present value of expected future policy benefits:
Beginning balance		488	616
Beginning balance at original discount rate		532	549
Effect of changes in cash flow assumptions			(14)	13
Effect of actual variances from expected experience			(17)	(23)
Adjusted beginning of period balance			501	539
Issuances		33	34
Interest accrual		15	21
Benefit payments		(44)	(62)
Foreign currency translation		0	0
Other		3	0
Ending balance at original discount rate		508	532	549
Effect of changes in discount rate assumptions		(58)	(44)
Ending balance		450	488	616
Net liability for future policy benefits		256	277
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		256	277
Aflac U.S. | Other
Present value of expected premiums:
Beginning balance		110	153
Beginning balance at original discount rate		118	135
Effect of changes in cash flow assumptions			(9)	(12)
Effect of actual variances from expected experience			2	6
Adjusted beginning of period balance			111	129
Issuances		76	0
Interest accrual		4	5
Net premiums collected	[1]	(12)	(17)
Foreign currency translation		0	0
Other		8	1
Ending balance at original discount rate		187	118	135
Effect of changes in discount rate assumptions		(15)	(8)
Ending balance		172	110	153
Present value of expected future policy benefits:
Beginning balance		622	837
Beginning balance at original discount rate		624	645
Effect of changes in cash flow assumptions			(13)	(15)
Effect of actual variances from expected experience			2	7
Adjusted beginning of period balance			613	637
Issuances		76	0
Interest accrual		24	32
Benefit payments		(35)	(45)
Foreign currency translation		0	0
Other		9	0
Ending balance at original discount rate		687	624	645
Effect of changes in discount rate assumptions		(35)	(2)
Ending balance		652	622	$ 837
Net liability for future policy benefits		480	512
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		$ 480	$ 512

[1] Net premiums collected represent the portion of gross premiums collected from policyholders that is used to fund expected future benefit payments.