Financial Assets and Liabilities that are Accounted For at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Feb. 28, 2015	May 31, 2014
Contingent Consideration Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net liabilities	$ 1,261	$ 2,015
Net Investment Hedge
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net liabilities	4,195	1,229
Significant Other Observable Inputs (Level 2) | Net Investment Hedge
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net liabilities	4,195	1,229
Significant Unobservable Inputs (Level 3) | Contingent Consideration Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net liabilities	$ 1,261	$ 2,015