INVESTMENTS - Contractual Maturities of Investments in Fixed Maturities (Detail) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Held to maturity:
Total fixed maturities held to maturity, amortized cost	$ 33,293	$ 34,242
Held to maturity:
Total fixed maturities held to maturity, fair value	36,365	$ 38,497
Aflac Japan
Available for sale:
Due in one year or less	232
Due after one year through five years	2,137
Due after five years through 10 years	11,191
Due after 10 years	33,030
Mortgage- and asset-backed securities	380
Total fixed maturities available for sale, amortized cost	46,970
Held to maturity:
Due in one year or less	271
Due after one year through five years	1,430
Due after five years through 10 years	1,866
Due after 10 years	29,687
Mortgage- and asset-backed securities	39
Total fixed maturities held to maturity, amortized cost	33,293
Available for sale:
Due in one year or less	259
Due after one year through five years	2,547
Due after five years through 10 years	11,613
Due after 10 years	36,366
Mortgage- and asset-backed securities	431
Total fixed maturities available for sale, fair value	51,216
Held to maturity:
Due in one year or less	278
Due after one year through five years	1,529
Due after five years through 10 years	2,003
Due after 10 years	32,514
Mortgage- and asset-backed securities	41
Total fixed maturities held to maturity, fair value	36,365
Aflac U.S.
Available for sale:
Due in one year or less	77
Due after one year through five years	645
Due after five years through 10 years	1,787
Due after 10 years	9,126
Mortgage- and asset-backed securities	36
Total fixed maturities available for sale, amortized cost	11,671
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, amortized cost	0
Available for sale:
Due in one year or less	79
Due after one year through five years	736
Due after five years through 10 years	1,873
Due after 10 years	9,991
Mortgage- and asset-backed securities	44
Total fixed maturities available for sale, fair value	12,723
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, fair value	$ 0