REINSURANCE Effect of Reinsurance on Premiums and Benefits and Claims (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Effects of Reinsurance [Line Items]
Direct premium income	$ 17,857	$ 18,955	$ 19,122
Ceded premiums	(504)	(553)	(547)
Assumed premiums earned	294	220	205
Net premium income	17,647	18,622	18,780
Direct benefits and claims	10,716	12,080	12,237
Benefits and claims, net	10,576	11,796	11,942
Intercompany eliminations
Effects of Reinsurance [Line Items]
Ceded benefits and claims	31	39	41
Assumed benefits and claims from other companies	(31)	(39)	(41)
All other
Effects of Reinsurance [Line Items]
Ceded premiums	(73)	(87)	(69)
Assumed premiums earned	114	25	5
Ceded benefits and claims	(36)	(63)	(57)
Assumed benefits and claims from other companies	110	18	1
Aflac Japan
Effects of Reinsurance [Line Items]
Net premium income	11,853	12,670	12,772
Benefits and claims, net	7,963	8,851	8,877
Aflac Japan \| Closed block
Effects of Reinsurance [Line Items]
Ceded premiums	(431)	(466)	(478)
Assumed premiums earned	180	195	200
Ceded benefits and claims	(379)	(419)	(433)
Assumed benefits and claims from other companies	$ 165	$ 180	$ 194

Amount of earned premiums assumed from other entities.

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