POLICY LIABILITIES - Schedule of Changes in Present Value of Expected Net Premiums and Expected Future Policy Benefits (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Present value of expected future policy benefits:
Beginning balance		$ 111,508
Ending balance		113,348	$ 111,508
Net liability for future policy benefits		71,197	70,381
Aflac Japan | Cancer
Present value of expected premiums:
Beginning balance		14,184	17,509
Beginning balance at original discount rate		14,008	16,452
Effect of changes in cash flow assumptions			0	$ (625)
Effect of actual variances from expected experience			(6)	(71)
Adjusted beginning of period balance			14,002
Issuances		211	983
Interest accrual		91	378
Net premiums collected	[1]	(350)	(1,453)
Foreign currency translation		812	(1,655)
Other		0	(1)
Ending balance at original discount rate		14,766	14,008
Effect of changes in discount rate assumptions		(270)	176
Ending balance		14,496	14,184
Present value of expected future policy benefits:
Beginning balance		40,781	50,161
Beginning balance at original discount rate		37,856	43,626
Effect of changes in cash flow assumptions			0	(815)
Effect of actual variances from expected experience			(20)	(117)
Adjusted beginning of period balance			37,836	42,694
Issuances		215	1,004
Interest accrual		324	1,356
Benefit payments		(666)	(2,773)
Foreign currency translation		2,191	(4,425)
Other		0	0
Ending balance at original discount rate		39,900	37,856
Effect of changes in discount rate assumptions		1,538	2,925
Ending balance		41,438	40,781
Net liability for future policy benefits		26,942	26,597
Less: reinsurance recoverable		5,156	5,085
Net liability for future policy benefits after reinsurance recoverable		21,786	21,512	15,756
Aflac Japan | Medical and other health
Present value of expected premiums:
Beginning balance		11,817	14,697
Beginning balance at original discount rate		11,845	14,040
Effect of changes in cash flow assumptions			0	(154)
Effect of actual variances from expected experience			(45)	(164)
Adjusted beginning of period balance			11,800
Issuances		72	361
Interest accrual		72	302
Net premiums collected	[1]	(268)	(1,135)
Foreign currency translation		685	(1,405)
Other		0	0
Ending balance at original discount rate		12,361	11,845
Effect of changes in discount rate assumptions		(415)	(28)
Ending balance		11,946	11,817
Present value of expected future policy benefits:
Beginning balance		20,606	25,257
Beginning balance at original discount rate		21,957	25,023
Effect of changes in cash flow assumptions			0	(228)
Effect of actual variances from expected experience			(55)	(193)
Adjusted beginning of period balance			21,902	24,602
Issuances		75	373
Interest accrual		138	570
Benefit payments		(246)	(1,033)
Foreign currency translation		1,270	(2,555)
Other		0	0
Ending balance at original discount rate		23,139	21,957
Effect of changes in discount rate assumptions		(2,291)	(1,351)
Ending balance		20,848	20,606
Net liability for future policy benefits		8,902	8,789
Less: reinsurance recoverable		1,259	1,245
Net liability for future policy benefits after reinsurance recoverable		7,643	7,544	13,722
Aflac Japan | Life insurance
Present value of expected premiums:
Beginning balance		5,156	6,488
Beginning balance at original discount rate		5,084	6,258
Effect of changes in cash flow assumptions			0	(190)
Effect of actual variances from expected experience			(10)	(97)
Adjusted beginning of period balance			5,074
Issuances		120	478
Interest accrual		27	110
Net premiums collected	[1]	(201)	(862)
Foreign currency translation		292	(613)
Other		0	0
Ending balance at original discount rate		5,312	5,084
Effect of changes in discount rate assumptions		(29)	72
Ending balance		5,283	5,156
Present value of expected future policy benefits:
Beginning balance		24,265	29,731
Beginning balance at original discount rate		26,330	30,256
Effect of changes in cash flow assumptions			0	(302)
Effect of actual variances from expected experience			(7)	(110)
Adjusted beginning of period balance			26,323	29,844
Issuances		122	488
Interest accrual		141	582
Benefit payments		(604)	(1,510)
Foreign currency translation		1,518	(3,074)
Other		0	0
Ending balance at original discount rate		27,500	26,330
Effect of changes in discount rate assumptions		(3,022)	(2,065)
Ending balance		24,478	24,265
Net liability for future policy benefits		19,195	19,109
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		19,195	19,109	5,971
Aflac Japan | Other
Present value of expected premiums:
Beginning balance		846	1,088
Beginning balance at original discount rate		864	1,069
Effect of changes in cash flow assumptions			0	(19)
Effect of actual variances from expected experience			(2)	(14)
Adjusted beginning of period balance			862
Issuances		3	16
Interest accrual		4	17
Net premiums collected	[1]	(24)	(101)
Foreign currency translation		50	(104)
Other		0	0
Ending balance at original discount rate		895	864
Effect of changes in discount rate assumptions		(42)	(18)
Ending balance		853	846
Present value of expected future policy benefits:
Beginning balance		4,225	5,178
Beginning balance at original discount rate		4,765	5,444
Effect of changes in cash flow assumptions			0	(7)
Effect of actual variances from expected experience			(7)	(24)
Adjusted beginning of period balance			4,758	5,413
Issuances		4	22
Interest accrual		22	93
Benefit payments		(57)	(208)
Foreign currency translation		276	(555)
Other		0	0
Ending balance at original discount rate		5,003	4,765
Effect of changes in discount rate assumptions		(736)	(540)
Ending balance		4,267	4,225
Net liability for future policy benefits		3,414	3,379
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		3,414	3,379	1,036
Aflac U.S. | Life insurance
Present value of expected premiums:
Beginning balance		909	853
Beginning balance at original discount rate		976	909
Effect of changes in cash flow assumptions			0	(5)
Effect of actual variances from expected experience			(9)	(29)
Adjusted beginning of period balance			967
Issuances		70	226
Interest accrual		10	37
Net premiums collected	[1]	(41)	(157)
Foreign currency translation		0	0
Other		0	(5)
Ending balance at original discount rate		1,006	976
Effect of changes in discount rate assumptions		(53)	(67)
Ending balance		953	909
Present value of expected future policy benefits:
Beginning balance		1,847	1,764
Beginning balance at original discount rate		2,126	1,971
Effect of changes in cash flow assumptions			0	(3)
Effect of actual variances from expected experience			(14)	(43)
Adjusted beginning of period balance			2,112	1,925
Issuances		77	231
Interest accrual		21	78
Benefit payments		(27)	(108)
Foreign currency translation		0	0
Other		0	0
Ending balance at original discount rate		2,183	2,126
Effect of changes in discount rate assumptions		(255)	(279)
Ending balance		1,928	1,847
Net liability for future policy benefits		975	938
Less: reinsurance recoverable		20	18
Net liability for future policy benefits after reinsurance recoverable		955	920	875
Aflac U.S. | Accident
Present value of expected premiums:
Beginning balance		2,497	2,488
Beginning balance at original discount rate		2,687	2,630
Effect of changes in cash flow assumptions			0	65
Effect of actual variances from expected experience			(14)	66
Adjusted beginning of period balance			2,673
Issuances		108	307
Interest accrual		27	106
Net premiums collected	[1]	(119)	(479)
Foreign currency translation		0	0
Other		0	(8)
Ending balance at original discount rate		2,689	2,687
Effect of changes in discount rate assumptions		(160)	(190)
Ending balance		2,529	2,497
Present value of expected future policy benefits:
Beginning balance		3,127	3,109
Beginning balance at original discount rate		3,386	3,302
Effect of changes in cash flow assumptions			0	109
Effect of actual variances from expected experience			(13)	91
Adjusted beginning of period balance			3,373	3,502
Issuances		113	311
Interest accrual		34	133
Benefit payments		(144)	(560)
Foreign currency translation		0	0
Other		0	0
Ending balance at original discount rate		3,376	3,386
Effect of changes in discount rate assumptions		(221)	(259)
Ending balance		3,155	3,127
Net liability for future policy benefits		626	630
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		626	630	2,761
Aflac U.S. | Disability
Present value of expected premiums:
Beginning balance		1,635	1,652
Beginning balance at original discount rate		1,726	1,738
Effect of changes in cash flow assumptions			0	(47)
Effect of actual variances from expected experience			(18)	12
Adjusted beginning of period balance			1,708
Issuances		118	364
Interest accrual		17	66
Net premiums collected	[1]	(99)	(401)
Foreign currency translation		0	0
Other		0	(6)
Ending balance at original discount rate		1,744	1,726
Effect of changes in discount rate assumptions		(72)	(91)
Ending balance		1,672	1,635
Present value of expected future policy benefits:
Beginning balance		2,330	2,422
Beginning balance at original discount rate		2,466	2,541
Effect of changes in cash flow assumptions			0	(73)
Effect of actual variances from expected experience			(24)	(16)
Adjusted beginning of period balance			2,442	2,452
Issuances		125	381
Interest accrual		24	98
Benefit payments		(120)	(465)
Foreign currency translation		0	0
Other		0	0
Ending balance at original discount rate		2,471	2,466
Effect of changes in discount rate assumptions		(109)	(136)
Ending balance		2,362	2,330
Net liability for future policy benefits		690	695
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		690	695	1,703
Aflac U.S. | Critical Care
Present value of expected premiums:
Beginning balance		3,901	4,074
Beginning balance at original discount rate		4,340	4,416
Effect of changes in cash flow assumptions			0	(106)
Effect of actual variances from expected experience			(9)	(100)
Adjusted beginning of period balance			4,331
Issuances		214	543
Interest accrual		44	173
Net premiums collected	[1]	(142)	(578)
Foreign currency translation		0	0
Other		0	(8)
Ending balance at original discount rate		4,447	4,340
Effect of changes in discount rate assumptions		(389)	(439)
Ending balance		4,058	3,901
Present value of expected future policy benefits:
Beginning balance		10,701	11,290
Beginning balance at original discount rate		12,013	12,120
Effect of changes in cash flow assumptions			0	(112)
Effect of actual variances from expected experience			(13)	(144)
Adjusted beginning of period balance			12,000	11,864
Issuances		226	559
Interest accrual		129	515
Benefit payments		(249)	(925)
Foreign currency translation		0	0
Other		0	0
Ending balance at original discount rate		12,106	12,013
Effect of changes in discount rate assumptions		(1,184)	(1,312)
Ending balance		10,922	10,701
Net liability for future policy benefits		6,864	6,800
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		6,864	6,800	4,210
Aflac U.S. | Hospital Indemnity
Present value of expected premiums:
Beginning balance		1,122	1,107
Beginning balance at original discount rate		1,221	1,193
Effect of changes in cash flow assumptions			0	(21)
Effect of actual variances from expected experience			(1)	21
Adjusted beginning of period balance			1,220
Issuances		88	231
Interest accrual		12	46
Net premiums collected	[1]	(61)	(244)
Foreign currency translation		0	0
Other		0	(5)
Ending balance at original discount rate		1,259	1,221
Effect of changes in discount rate assumptions		(86)	(99)
Ending balance		1,173	1,122
Present value of expected future policy benefits:
Beginning balance		1,897	1,943
Beginning balance at original discount rate		2,073	2,076
Effect of changes in cash flow assumptions			0	(31)
Effect of actual variances from expected experience			(3)	21
Adjusted beginning of period balance			2,070	2,066
Issuances		92	237
Interest accrual		21	84
Benefit payments		(84)	(314)
Foreign currency translation		0	0
Other		0	0
Ending balance at original discount rate		2,099	2,073
Effect of changes in discount rate assumptions		(154)	(176)
Ending balance		1,945	1,897
Net liability for future policy benefits		772	775
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		772	775	1,193
Aflac U.S. | Dental/Vision
Present value of expected premiums:
Beginning balance		196	206
Beginning balance at original discount rate		209	217
Effect of changes in cash flow assumptions			0	(17)
Effect of actual variances from expected experience			(4)	(12)
Adjusted beginning of period balance			205
Issuances		17	52
Interest accrual		2	9
Net premiums collected	[1]	(10)	(39)
Foreign currency translation		0	0
Other		0	(1)
Ending balance at original discount rate		214	209
Effect of changes in discount rate assumptions		(11)	(13)
Ending balance		203	196
Present value of expected future policy benefits:
Beginning balance		441	478
Beginning balance at original discount rate		477	506
Effect of changes in cash flow assumptions			0	(28)
Effect of actual variances from expected experience			(4)	(16)
Adjusted beginning of period balance			473	462
Issuances		15	55
Interest accrual		5	20
Benefit payments		(15)	(60)
Foreign currency translation		0	0
Other		0	0
Ending balance at original discount rate		478	477
Effect of changes in discount rate assumptions		(30)	(36)
Ending balance		448	441
Net liability for future policy benefits		245	245
Less: reinsurance recoverable		0	0
Net liability for future policy benefits after reinsurance recoverable		245	245	188
Aflac U.S. | Other
Present value of expected premiums:
Beginning balance		826	277
Beginning balance at original discount rate		824	272
Effect of changes in cash flow assumptions			0	(8)
Effect of actual variances from expected experience			3	13
Adjusted beginning of period balance			827
Issuances		229	592
Interest accrual		11	25
Net premiums collected	[1]	(22)	(53)
Foreign currency translation		0	0
Other		(10)	(17)
Ending balance at original discount rate		1,035	824
Effect of changes in discount rate assumptions		55	2
Ending balance		1,090	826
Present value of expected future policy benefits:
Beginning balance		1,288	798
Beginning balance at original discount rate		1,293	769
Effect of changes in cash flow assumptions			0	(12)
Effect of actual variances from expected experience			4	(7)
Adjusted beginning of period balance			1,297	750
Issuances		232	597
Interest accrual		17	50
Benefit payments		(41)	(104)
Foreign currency translation		0	0
Other		0	0
Ending balance at original discount rate		1,505	1,293
Effect of changes in discount rate assumptions		52	(5)
Ending balance		1,557	1,288
Net liability for future policy benefits		467	462
Less: reinsurance recoverable		2	0
Net liability for future policy benefits after reinsurance recoverable		$ 465	$ 462	$ 277

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