Fair Value Measurements - Additional Information (Detail)	3 Months Ended		3 Months Ended
	Aug. 31, 2014 USD ($)	Aug. 31, 2014 EUR (€)	Aug. 31, 2014 Unsecured Senior Notes	Aug. 31, 2014 Fair Value, Measurements, Recurring Foreign currency forward contract USD ($)	May 31, 2014 Fair Value, Measurements, Recurring Foreign currency forward contract USD ($)	Aug. 31, 2014 Fair Value, Measurements, Recurring Cross-currency swap USD ($)	May 31, 2014 Fair Value, Measurements, Recurring Cross-currency swap USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contracts, fair value of liability				$ 492,000		$ 13,415,000	$ 19,550,000
Debt, interest rate			6.70%
Debt, due date			Nov. 01, 2015
Effective euro fixed-rate borrowing	5.31%
Notional principal amount of cross-currency swap	150,000,000	125,000,000
Foreign currency forward contract					2,582,000
Reversal for contingent earn out targets	1,000,000
Settlements of contingent consideration obligations	$ 24,800,000