Other Expense (Income), Net (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Nov. 30, 2018	Nov. 30, 2017	Nov. 30, 2018	Nov. 30, 2017
Other Income And Expenses [Abstract]
Royalty expense (income), net		$ 63	$ (178)	$ 66	$ 90
(Income) related to unconsolidated equity affiliates		(48)	(244)	(166)	(517)
Pension non-service costs		346		774
Loss on extinguishment of debt	[1]	3,051		3,051
Other expense (income), net		$ 3,412	$ (422)	$ 3,725	$ (427)

[1] In connection with the redemption of all of our outstanding 2.25% convertible senior notes in November 2018, we recognized a loss of $3.1 million, due to the fair value measurement of the instrument on the date of conversion.