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, 2024	Dec. 31, 2023	Dec. 31, 2022
Present value of expected future policy benefits:
Beginning balance		$ 132,131
Ending balance		125,399	$ 132,131
Net liability for future policy benefits		79,672	83,718
Aflac Japan | Cancer
Present value of expected future net premiums:
Beginning balance		17,509	19,298
Beginning balance at original discount rate		16,452	18,221
Effect of changes in cash flow assumptions			(627)	$ (165)
Effect of actual variances from expected experience			(72)	(315)
Adjusted beginning of period balance			15,753	17,741
Issuances		735	1,034
Interest accrual		286	412
Net premiums collected	[1]	(1,099)	(1,564)
Foreign currency translation		(134)	(1,170)
Other		(1)	(1)
Ending balance at original discount rate		15,540	16,452
Effect of changes in discount rate assumptions		535	1,057
Ending balance		16,075	17,509
Present value of expected future policy benefits:
Beginning balance		50,161	54,766
Beginning balance at original discount rate		43,626	47,677
Effect of changes in cash flow assumptions			(817)	(147)
Effect of actual variances from expected experience			(107)	(385)
Adjusted beginning of period balance			42,702	47,145
Issuances		749	1,059
Interest accrual		1,026	1,473
Benefit payments		(2,066)	(2,987)
Foreign currency translation		(318)	(3,064)
Other		0	0
Ending balance at original discount rate		42,093	43,626
Effect of changes in discount rate assumptions		4,484	6,535
Ending balance		46,577	50,161
Net liability for future policy benefits		30,502	32,652
Less: reinsurance recoverable		3,896	4,135
Net liability for future policy benefits after reinsurance recoverable		26,606	28,517
Aflac Japan | Medical and other health
Present value of expected future net premiums:
Beginning balance		14,697	16,714
Beginning balance at original discount rate		14,040	16,195
Effect of changes in cash flow assumptions			(154)	(470)
Effect of actual variances from expected experience			(123)	(137)
Adjusted beginning of period balance			13,763	15,588
Issuances		277	418
Interest accrual		228	334
Net premiums collected	[1]	(861)	(1,261)
Foreign currency translation		(114)	(1,038)
Other		0	(1)
Ending balance at original discount rate		13,293	14,040
Effect of changes in discount rate assumptions		269	657
Ending balance		13,562	14,697
Present value of expected future policy benefits:
Beginning balance		25,257	27,419
Beginning balance at original discount rate		25,023	27,566
Effect of changes in cash flow assumptions			(229)	(507)
Effect of actual variances from expected experience			(145)	(154)
Adjusted beginning of period balance			24,649	26,905
Issuances		286	432
Interest accrual		430	608
Benefit payments		(766)	(1,153)
Foreign currency translation		(173)	(1,769)
Other		0	0
Ending balance at original discount rate		24,426	25,023
Effect of changes in discount rate assumptions		(761)	234
Ending balance		23,665	25,257
Net liability for future policy benefits		10,103	10,560
Less: reinsurance recoverable		1,430	1,521
Net liability for future policy benefits after reinsurance recoverable		8,673	9,039
Aflac Japan | Life insurance
Present value of expected future net premiums:
Beginning balance		6,488	7,485
Beginning balance at original discount rate		6,258	7,284
Effect of changes in cash flow assumptions			(191)	43
Effect of actual variances from expected experience			(60)	(42)
Adjusted beginning of period balance			6,007	7,285
Issuances		346	335
Interest accrual		83	124
Net premiums collected	[1]	(656)	(1,017)
Foreign currency translation		(59)	(469)
Other		0	0
Ending balance at original discount rate		5,721	6,258
Effect of changes in discount rate assumptions		125	230
Ending balance		5,846	6,488
Present value of expected future policy benefits:
Beginning balance		29,731	31,954
Beginning balance at original discount rate		30,256	32,800
Effect of changes in cash flow assumptions			(303)	65
Effect of actual variances from expected experience			(73)	(51)
Adjusted beginning of period balance			29,880	32,814
Issuances		352	341
Interest accrual		438	625
Benefit payments		(1,180)	(1,415)
Foreign currency translation		(218)	(2,109)
Other		0	0
Ending balance at original discount rate		29,272	30,256
Effect of changes in discount rate assumptions		(1,597)	(525)
Ending balance		27,675	29,731
Net liability for future policy benefits		21,829	23,243
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		21,829	23,243
Aflac Japan | Other
Present value of expected future net premiums:
Beginning balance		1,088	1,256
Beginning balance at original discount rate		1,069	1,242
Effect of changes in cash flow assumptions			(19)	(12)
Effect of actual variances from expected experience			(12)	(15)
Adjusted beginning of period balance			1,038	1,215
Issuances		13	26
Interest accrual		13	20
Net premiums collected	[1]	(76)	(112)
Foreign currency translation		(11)	(80)
Other		0	0
Ending balance at original discount rate		977	1,069
Effect of changes in discount rate assumptions		(2)	19
Ending balance		975	1,088
Present value of expected future policy benefits:
Beginning balance		5,178	5,582
Beginning balance at original discount rate		5,444	5,940
Effect of changes in cash flow assumptions			(7)	(27)
Effect of actual variances from expected experience			(21)	(15)
Adjusted beginning of period balance			5,416	5,898
Issuances		17	32
Interest accrual		70	100
Benefit payments		(157)	(206)
Foreign currency translation		(36)	(380)
Other		0	0
Ending balance at original discount rate		5,310	5,444
Effect of changes in discount rate assumptions		(460)	(266)
Ending balance		4,850	5,178
Net liability for future policy benefits		3,875	4,090
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		3,875	4,090
Aflac U.S. | Life insurance
Present value of expected future net premiums:
Beginning balance		853	724
Beginning balance at original discount rate		909	799
Effect of changes in cash flow assumptions			(5)	61
Effect of actual variances from expected experience			(18)	(25)
Adjusted beginning of period balance			886	835
Issuances		173	181
Interest accrual		27	31
Net premiums collected	[1]	(116)	(137)
Foreign currency translation		0	0
Other		(3)	(1)
Ending balance at original discount rate		967	909
Effect of changes in discount rate assumptions		(33)	(56)
Ending balance		934	853
Present value of expected future policy benefits:
Beginning balance		1,764	1,526
Beginning balance at original discount rate		1,971	1,778
Effect of changes in cash flow assumptions			(3)	72
Effect of actual variances from expected experience			(28)	(32)
Adjusted beginning of period balance			1,940	1,818
Issuances		179	185
Interest accrual		58	68
Benefit payments		(83)	(105)
Foreign currency translation		0	0
Other		0	5
Ending balance at original discount rate		2,094	1,971
Effect of changes in discount rate assumptions		(175)	(207)
Ending balance		1,919	1,764
Net liability for future policy benefits		985	911
Less: reinsurance recoverable		19	15
Net liability for future policy benefits after reinsurance recoverable		966	896
Aflac U.S. | Accident
Present value of expected future net premiums:
Beginning balance		2,488	2,534
Beginning balance at original discount rate		2,630	2,760
Effect of changes in cash flow assumptions			65	(16)
Effect of actual variances from expected experience			33	(58)
Adjusted beginning of period balance			2,728	2,686
Issuances		242	323
Interest accrual		79	102
Net premiums collected	[1]	(357)	(473)
Foreign currency translation		0	0
Other		(5)	(8)
Ending balance at original discount rate		2,687	2,630
Effect of changes in discount rate assumptions		(96)	(142)
Ending balance		2,591	2,488
Present value of expected future policy benefits:
Beginning balance		3,109	3,098
Beginning balance at original discount rate		3,302	3,391
Effect of changes in cash flow assumptions			109	(11)
Effect of actual variances from expected experience			38	(75)
Adjusted beginning of period balance			3,449	3,305
Issuances		247	331
Interest accrual		99	127
Benefit payments		(408)	(464)
Foreign currency translation		0	0
Other		0	3
Ending balance at original discount rate		3,387	3,302
Effect of changes in discount rate assumptions		(137)	(193)
Ending balance		3,250	3,109
Net liability for future policy benefits		659	621
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		659	621
Aflac U.S. | Disability
Present value of expected future net premiums:
Beginning balance		1,652	1,635
Beginning balance at original discount rate		1,738	1,775
Effect of changes in cash flow assumptions			(47)	(51)
Effect of actual variances from expected experience			8	(29)
Adjusted beginning of period balance			1,699	1,695
Issuances		288	376
Interest accrual		49	62
Net premiums collected	[1]	(301)	(390)
Foreign currency translation		0	0
Other		(4)	(5)
Ending balance at original discount rate		1,731	1,738
Effect of changes in discount rate assumptions		(46)	(86)
Ending balance		1,685	1,652
Present value of expected future policy benefits:
Beginning balance		2,422	2,445
Beginning balance at original discount rate		2,541	2,636
Effect of changes in cash flow assumptions			(73)	(59)
Effect of actual variances from expected experience			(11)	(59)
Adjusted beginning of period balance			2,457	2,518
Issuances		301	392
Interest accrual		74	96
Benefit payments		(349)	(465)
Foreign currency translation		0	0
Other		0	0
Ending balance at original discount rate		2,483	2,541
Effect of changes in discount rate assumptions		(66)	(119)
Ending balance		2,417	2,422
Net liability for future policy benefits		732	770
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		732	770
Aflac U.S. | Critical Care
Present value of expected future net premiums:
Beginning balance		4,074	4,486
Beginning balance at original discount rate		4,416	5,050
Effect of changes in cash flow assumptions			(106)	(494)
Effect of actual variances from expected experience			(55)	(223)
Adjusted beginning of period balance			4,255	4,333
Issuances		439	493
Interest accrual		130	179
Net premiums collected	[1]	(432)	(580)
Foreign currency translation		0	0
Other		(6)	(9)
Ending balance at original discount rate		4,386	4,416
Effect of changes in discount rate assumptions		(256)	(342)
Ending balance		4,130	4,074
Present value of expected future policy benefits:
Beginning balance		11,290	11,489
Beginning balance at original discount rate		12,120	12,846
Effect of changes in cash flow assumptions			(112)	(592)
Effect of actual variances from expected experience			(86)	(271)
Adjusted beginning of period balance			11,922	11,983
Issuances		452	505
Interest accrual		386	524
Benefit payments		(693)	(893)
Foreign currency translation		0	0
Other		0	1
Ending balance at original discount rate		12,067	12,120
Effect of changes in discount rate assumptions		(680)	(830)
Ending balance		11,387	11,290
Net liability for future policy benefits		7,257	7,216
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		7,257	7,216
Aflac U.S. | Hospital Indemnity
Present value of expected future net premiums:
Beginning balance		1,107	1,220
Beginning balance at original discount rate		1,193	1,365
Effect of changes in cash flow assumptions			(21)	(142)
Effect of actual variances from expected experience			16	(73)
Adjusted beginning of period balance			1,188	1,150
Issuances		187	249
Interest accrual		34	45
Net premiums collected	[1]	(182)	(247)
Foreign currency translation		0	0
Other		(3)	(4)
Ending balance at original discount rate		1,224	1,193
Effect of changes in discount rate assumptions		(60)	(86)
Ending balance		1,164	1,107
Present value of expected future policy benefits:
Beginning balance		1,943	2,074
Beginning balance at original discount rate		2,076	2,300
Effect of changes in cash flow assumptions			(31)	(194)
Effect of actual variances from expected experience			15	(99)
Adjusted beginning of period balance			2,060	2,007
Issuances		192	258
Interest accrual		63	84
Benefit payments		(235)	(274)
Foreign currency translation		0	0
Other		0	1
Ending balance at original discount rate		2,080	2,076
Effect of changes in discount rate assumptions		(95)	(133)
Ending balance		1,985	1,943
Net liability for future policy benefits		821	836
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		821	836
Aflac U.S. | Dental/Vision
Present value of expected future net premiums:
Beginning balance		206	211
Beginning balance at original discount rate		217	231
Effect of changes in cash flow assumptions			(17)	(9)
Effect of actual variances from expected experience			(9)	(17)
Adjusted beginning of period balance			191	205
Issuances		40	44
Interest accrual		6	8
Net premiums collected	[1]	(29)	(39)
Foreign currency translation		0	0
Other		(1)	(1)
Ending balance at original discount rate		207	217
Effect of changes in discount rate assumptions		(6)	(11)
Ending balance		201	206
Present value of expected future policy benefits:
Beginning balance		478	488
Beginning balance at original discount rate		506	532
Effect of changes in cash flow assumptions			(28)	(14)
Effect of actual variances from expected experience			(12)	(22)
Adjusted beginning of period balance			466	496
Issuances		42	46
Interest accrual		15	21
Benefit payments		(45)	(59)
Foreign currency translation		0	0
Other		0	2
Ending balance at original discount rate		478	506
Effect of changes in discount rate assumptions		(17)	(28)
Ending balance		461	478
Net liability for future policy benefits		260	272
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		260	272
Aflac U.S. | Other
Present value of expected future net premiums:
Beginning balance		277	110
Beginning balance at original discount rate		272	118
Effect of changes in cash flow assumptions			(8)	(9)
Effect of actual variances from expected experience			27	(2)
Adjusted beginning of period balance			291	107
Issuances		401	169
Interest accrual		16	6
Net premiums collected	[1]	(35)	(17)
Foreign currency translation		0	0
Other		(9)	7
Ending balance at original discount rate		664	272
Effect of changes in discount rate assumptions		35	5
Ending balance		699	277
Present value of expected future policy benefits:
Beginning balance		798	622
Beginning balance at original discount rate		769	624
Effect of changes in cash flow assumptions			(12)	(13)
Effect of actual variances from expected experience			25	(4)
Adjusted beginning of period balance			782	$ 607
Issuances		405	169
Interest accrual		36	33
Benefit payments		(69)	(48)
Foreign currency translation		0	0
Other		0	8
Ending balance at original discount rate		1,154	769
Effect of changes in discount rate assumptions		59	29
Ending balance		1,213	798
Net liability for future policy benefits		514	521
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		$ 514	$ 521

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