Derivative Instruments and Hedging Activities - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Feb. 29, 2016	May. 31, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total cash collateral	$ 3,810,000
Impact to fair value of derivative assets and liabilities as a result of recognition on a net basis	995,000	$ 500,000
Losses in accumulated other comprehensive income expected to be reclassified into net earnings	(9,382,000)
Losses in accumulated other comprehensive income expected to be reclassified into net earnings, tax	$ (5,349,000)