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REINSURANCE Additional Information (Detail) - USD ($)
$ in Millions
1 Months Ended
Oct. 31, 2024
Dec. 31, 2023
Oct. 31, 2023
Jan. 31, 2023
Dec. 31, 2024
Effects of Reinsurance [Line Items]          
Deferred reinsurance gain liability   $ 175     $ 146
Reinsurance recoverable   183     163
Reinsurance recoverable, allowance for credit loss   10     $ 4
Aflac Re Bermuda | ALIJ          
Effects of Reinsurance [Line Items]          
Ceded insurance, percentage 30.00%   30.00% 28.00%  
Coinsurance, amount of reserves transferred $ 1,800   $ 1,900 $ 2,100  
Coinsurance, amount of assets transferred $ 1,700   $ 1,700 $ 1,900  
Pretax loss on reinsurance novation   $ (151)      
Reinsurer, Other | ALIJ          
Effects of Reinsurance [Line Items]          
Ceded insurance, percentage       1.50%