Derivative Financial Instruments - Additional Information (Detail) - Interest Rate Swap Derivatives [Member]	May 31, 2013 USD ($)
4.875% [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Outstanding long-term debt	$ 3,450,000
Fixed rate percentage	4.875%
4.37% [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Outstanding long-term debt	$ 2,600,000
Fixed rate percentage	4.37%
3.07% [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Outstanding long-term debt	$ 1,218,000
Fixed rate percentage	3.07%