POLICY LIABILITIES - Liability for Future Policy Benefits (Detail) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 90,588	$ 97,783
Intercompany eliminations
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	[1]	$ (456)	$ (545)
Liability for future policy benefits, interest rate		2.00%
Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		3.10%	3.10%	3.20%
Aflac U.S.
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		5.10%	5.20%	5.30%
Health insurance | Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 49,421	$ 54,659
Health insurance | Aflac Japan | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		0.60%
Health insurance | Aflac Japan | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		6.75%
Health insurance | Aflac U.S.
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 8,949	8,834
Health insurance | Aflac U.S. | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		3.00%
Health insurance | Aflac U.S. | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		8.00%
Life insurance | Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 31,756	33,993
Life insurance | Aflac Japan | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		0.60%
Life insurance | Aflac Japan | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		4.50%
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 918	$ 842
Life insurance | Aflac U.S. | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		2.50%
Life insurance | Aflac U.S. | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		6.00%

[1] Elimination entry necessary due to recapture of a portion of policy liabilities ceded externally, as a result of the reinsurance retrocession transaction as described in Note 8 of the Notes to the Consolidated Financial Statements