Schedule II - Aflac Incorporated (Parent Only) - Additional Information (Detail)		1 Months Ended		12 Months Ended		1 Months Ended
	Dec. 31, 2010 Senior Notes USD ($)	Jul. 31, 2011 Variable interest rate yen-denominated Samurai notes due July 2014 JPY (¥)	Dec. 31, 2011 Variable interest rate yen-denominated Samurai notes due July 2014 JPY (¥)	Dec. 31, 2009 Parent Company Yen Denominated Uridashi and Samurai Notes JPY (¥)	Feb. 29, 2012 Parent Company Senior Notes Issuance of Debt USD ($)	Feb. 29, 2012 Parent Company 2.65% senior notes due February 2017 Issuance of Debt USD ($)	Feb. 29, 2012 Parent Company 2.65% senior notes due February 2017 Issuance of Debt JPY (¥)	Feb. 29, 2012 Parent Company 4.00% senior notes due February 2022 Issuance of Debt USD ($)	Feb. 29, 2012 Parent Company 4.00% senior notes due February 2022 Issuance of Debt JPY (¥)	Dec. 31, 2011 Parent Company Variable interest rate yen-denominated Samurai notes due July 2014 JPY (¥)	Dec. 31, 2011 Parent Company Variable interest rate yen-denominated Samurai notes due July 2014 Swaps JPY (¥)
Condensed Financial Statements, Captions [Line Items]
Extinguishment of notes				¥ 5,400,000,000
Debt instrument face amount	2,000,000,000	5,500,000,000	5,500,000,000		750,000,000	400,000,000		350,000,000		5,500,000,000
Debt instrument interest rate stated percentage			1.34%			2.65%	2.65%	4.00%	4.00%	1.34%
Debt instrument maturity period		3 years				5 years	5 years	10 years	10 years
Interest rate swaps related to 5.5 billion yen variable interest rate Samurai notes, notional amount											5,500,000,000
Notes payable, principal amount							¥ 30,900,000,000		¥ 27,000,000,000
Notes payable, effective interest rate		1.475%	1.475%			1.22%	1.22%	2.07%	2.07%