Securities Lending (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Schedule of Investments [Line Items]
Security loans outstanding, fair value	$ 812	$ 186
Cash collateral on loaned securities	$ 838	$ 191

The cash or fair value of collateral received by the entity associated with securities borrowed that must be returned if the counterparty fulfills its obligations. It appears on the balance sheet as a liability and has a corresponding asset on the balance sheet, either cash or securities, depending on which was received as the collateral.

No definition available.

Name:	afl_ObligationToReturnCashOrSecuritiesReceivedAsCollateral
Namespace Prefix:	afl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant