INVESTMENTS - Economic Maturities of Investments in Perpetual Securities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014
Aflac Japan
Investments Classified by Economic Maturity Date [Line Items]
Due in one year or less	$ 291
Due after one year through five years	730
Due after five years through 10 years	214
Due after 10 years	1,718
Total perpetual securities available for sale, amortized cost	2,953
Due in one year or less	275
Due after one year through five years	701
Due after five years through 10 years	229
Due after 10 years	1,698
Total perpetual securities available for sale, fair value	2,903
Aflac U.S.
Investments Classified by Economic Maturity Date [Line Items]
Due in one year or less	0
Due after one year through five years	5
Due after five years through 10 years	0
Due after 10 years	99
Total perpetual securities available for sale, amortized cost	104
Due in one year or less	0
Due after one year through five years	5
Due after five years through 10 years	0
Due after 10 years	108
Total perpetual securities available for sale, fair value	$ 113