POLICY LIABILITIES - Schedule of Weighted-Average Interest Rate and Liability for Future Policy Benefit (Details)		Mar. 31, 2024	Dec. 31, 2023
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	3.90%	3.90%
Weighted-average interest, current discount rate	[1]	2.00%	1.80%
Weighted-average liability duration		13 years	13 years 1 month 6 days
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	2.50%	2.60%
Weighted-average interest, current discount rate	[1]	2.50%	2.30%
Weighted-average liability duration		24 years 8 months 12 days	24 years 10 months 24 days
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	2.10%	2.10%
Weighted-average interest, current discount rate	[1]	1.90%	1.70%
Weighted-average liability duration		16 years 3 months 18 days	16 years 3 months 18 days
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	3.80%	3.70%
Weighted-average interest, current discount rate	[1]	5.30%	5.30%
Weighted-average liability duration		13 years 9 months 18 days	13 years 7 months 6 days
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	3.90%	3.90%
Weighted-average interest, current discount rate	[1]	5.30%	5.30%
Weighted-average liability duration		8 years	8 years 1 month 6 days
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	4.30%	4.20%
Weighted-average interest, current discount rate	[1]	5.20%	5.30%
Weighted-average liability duration		5 years 7 months 6 days	5 years 7 months 6 days
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	4.60%	4.60%
Weighted-average interest, current discount rate	[1]	5.30%	5.30%
Weighted-average liability duration		11 years 2 months 12 days	11 years 3 months 18 days
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	4.50%	4.40%
Weighted-average interest, current discount rate	[1]	5.30%	5.30%
Weighted-average liability duration		9 years 3 months 18 days	9 years 3 months 18 days
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	4.30%	4.30%
Weighted-average interest, current discount rate	[1]	5.30%	5.30%
Weighted-average liability duration		7 years 10 months 24 days	7 years 10 months 24 days
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	1.80%	1.80%
Weighted-average interest, current discount rate	[1]	2.30%	2.10%
Weighted-average liability duration		17 years 1 month 6 days	17 years 3 months 18 days
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average interest, original discount rate	[1]	5.40%	5.40%
Weighted-average interest, current discount rate	[1]	5.30%	5.30%
Weighted-average liability duration		9 years 2 months 12 days	9 years 4 months 24 days

[1] The weighted-average interest rates are calculated using the reserve balances as the weights. No adjustments were made to observable market information.