Schedule II - Aflac Incorporated (Parent Only) - Supplemental Disclosure of Cash Flow Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Cash Flow, Supplemental [Line Items]
Interest paid	$ 210	$ 178	$ 164
Shareholder dividend reinvestment
Noncash financing activities:
Treasury stock issued for shareholder dividend reinvestment	25	24	23
Parent Company
Schedule of Cash Flow, Supplemental [Line Items]
Interest paid	205	181	163
Parent Company | Shareholder dividend reinvestment
Noncash financing activities:
Treasury stock issued for shareholder dividend reinvestment	$ 25	$ 25	$ 23