Derivative Instruments - Fair Values of Derivative Contracts Recorded in Consolidated Balance Sheets (Parenthetical) (Detail)	May 31, 2013
Derivatives, Fair Value [Line Items]
Strike price of put option exercised	0.9750

The strike price on the price risk option contract such as a put option or a call option.

No definition available.

Name:	us-gaap_DerivativePriceRiskOptionStrikePrice
Namespace Prefix:	us-gaap_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	instant