INVESTMENTS - Contractual Maturities of Investments in Fixed Maturities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Held to maturity:
Total fixed maturities held to maturity, amortized cost	$ 40,858	$ 44,415
Held to maturity:
Total fixed maturities held to maturity, fair value	42,816	45,846
Aflac Japan
Available for sale:
Due in one year or less	607
Due after one year through five years	1,819
Due after five years through 10 years	10,783
Due after 10 years	36,378
Mortgage- and asset-backed securities	509
Total fixed maturities available for sale, amortized cost	50,096
Held to maturity:
Due in one year or less	101
Due after one year through five years	1,605
Due after five years through 10 years	2,180
Due after 10 years	36,914
Mortgage- and asset-backed securities	58
Total fixed maturities held to maturity, amortized cost	40,858
Available for sale:
Due in one year or less	616
Due after one year through five years	1,953
Due after five years through 10 years	10,868
Due after 10 years	37,916
Mortgage- and asset-backed securities	553
Total fixed maturities available for sale, fair value	51,906
Held to maturity:
Due in one year or less	102
Due after one year through five years	1,756
Due after five years through 10 years	2,316
Due after 10 years	38,581
Mortgage- and asset-backed securities	61
Total fixed maturities held to maturity, fair value	42,816
Aflac U.S.
Available for sale:
Due in one year or less	50
Due after one year through five years	565
Due after five years through 10 years	1,562
Due after 10 years	8,675
Mortgage- and asset-backed securities	38
Total fixed maturities available for sale, amortized cost	10,890
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	662
Due after five years through 10 years	1,653
Due after 10 years	9,608
Mortgage- and asset-backed securities	47
Total fixed maturities available for sale, fair value	12,022
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