INVESTMENTS - Contractual Maturities of Investments in Fixed Maturities (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Aflac Japan
Available for sale:
Due in one year or less	$ 1,980
Due after one year through five years	2,455
Due after five years through 10 years	4,133
Due after 10 years	28,095
Mortgage- and asset-backed securities	1,104
Total fixed maturities available for sale	37,767
Held to maturity:
Due in one year or less	412
Due after one year through five years	839
Due after five years through 10 years	3,298
Due after 10 years	47,749
Mortgage- and asset-backed securities	115
Total fixed maturities held to maturity	52,413
Available for sale:
Due in one year or less	2,012
Due after one year through five years	2,569
Due after five years through 10 years	4,447
Due after 10 years	28,889
Mortgage- and asset-backed securities	1,217
Total fixed maturities available for sale	39,134
Held to maturity:
Due in one year or less	419
Due after one year through five years	908
Due after five years through 10 years	3,635
Due after 10 years	47,458
Mortgage- and asset-backed securities	120
Total fixed maturities held to maturity	52,540
Aflac U.S.
Available for sale:
Due in one year or less	13
Due after one year through five years	352
Due after five years through 10 years	984
Due after 10 years	7,681
Mortgage- and asset-backed securities	44
Total fixed maturities available for sale	9,074
Held to maturity:
Due in one year or less	0
Due after one year through five years	0
Due after five years through 10 years	0
Due after 10 years	0
Mortgage- and asset-backed securities	0
Total fixed maturities held to maturity	0
Available for sale:
Due in one year or less	13
Due after one year through five years	379
Due after five years through 10 years	1,138
Due after 10 years	8,919
Mortgage- and asset-backed securities	57
Total fixed maturities available for sale	10,506
Held to maturity:
Due in one year or less	0
Due after one year through five years	0
Due after five years through 10 years	0
Due after 10 years	0
Mortgage- and asset-backed securities	0
Total fixed maturities held to maturity	$ 0