REINSURANCE - Effect of Reinsurance on Premiums and Benefits and Claims (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Effects of Reinsurance [Line Items]
Direct premium income	$ 4,214	$ 4,652
Net earned premiums	4,178	4,593
Direct benefits and claims	2,505	2,776
Benefits and claims, net	2,487	2,735
Intercompany eliminations
Effects of Reinsurance [Line Items]
Ceded benefits and claims	6	8
Assumed benefits and claims from other companies	(6)	(8)
All other
Effects of Reinsurance [Line Items]
Ceded premiums	(19)	(19)
Assumed premiums earned	40	26
Ceded benefits and claims	(4)	(8)
Assumed benefits and claims from other companies	39	24
Aflac Japan
Effects of Reinsurance [Line Items]
Net earned premiums	2,724	3,123
Aflac Japan \| Closed Block
Effects of Reinsurance [Line Items]
Ceded premiums	(98)	(114)
Assumed premiums earned	41	48
Ceded benefits and claims	(91)	(99)
Assumed benefits and claims from other companies	$ 38	$ 42

Amount of earned premiums assumed from other entities.

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