INVESTMENTS - Contractual Maturities of Investments in Fixed Maturities (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Held to maturity:
Total fixed maturities held to maturity, amortized cost	$ 37,743	$ 44,415
Held to maturity:
Total fixed maturities held to maturity, fair value	40,716	45,846
Aflac Japan
Available for sale:
Due in one year or less	344
Due after one year through five years	1,891
Due after five years through 10 years	12,883
Due after 10 years	35,201
Mortgage- and asset-backed securities	456
Total fixed maturities available for sale, amortized cost	50,775
Held to maturity:
Due in one year or less	14
Due after one year through five years	1,491
Due after five years through 10 years	2,323
Due after 10 years	33,864
Mortgage- and asset-backed securities	51
Total fixed maturities held to maturity, amortized cost	37,743
Available for sale:
Due in one year or less	357
Due after one year through five years	2,078
Due after five years through 10 years	13,258
Due after 10 years	38,084
Mortgage- and asset-backed securities	505
Total fixed maturities available for sale, fair value	54,282
Held to maturity:
Due in one year or less	14
Due after one year through five years	1,628
Due after five years through 10 years	2,532
Due after 10 years	36,489
Mortgage- and asset-backed securities	53
Total fixed maturities held to maturity, fair value	40,716
Aflac U.S.
Available for sale:
Due in one year or less	52
Due after one year through five years	647
Due after five years through 10 years	1,441
Due after 10 years	8,950
Mortgage- and asset-backed securities	37
Total fixed maturities available for sale, amortized cost	11,127
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	52
Due after one year through five years	755
Due after five years through 10 years	1,521
Due after 10 years	10,178
Mortgage- and asset-backed securities	46
Total fixed maturities available for sale, fair value	12,552
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