Derivative Instruments and Hedging Activities - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Aug. 31, 2013	May 31, 2013
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Impact to fair value of derivative assets and liabilities as a result of recognition on a net basis	$ 240,000	$ 740,000
Losses in accumulated other comprehensive income expected to be reclassified into net earnings	(2,558,000)
Losses in accumulated other comprehensive income expected to be reclassified into net earnings, tax	$ 1,554,000