Schedule II - Aflac Incorporated (Parent Only) - Additional Information (Detail) (Parent Company, Yen Denominated Uridashi and Samurai Notes, JPY ¥) In Billions, unless otherwise specified	12 Months Ended
	Dec. 31, 2009
Parent Company | Yen Denominated Uridashi and Samurai Notes
Condensed Financial Statements, Captions [Line Items]
Extinguishment of notes	¥ 2.0