Segment Reporting and Related Disclosures - Revenues from Rental, Lease and Sale Group (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Feb. 28, 2014		Feb. 28, 2013		Feb. 28, 2014		Feb. 28, 2013
Revenue from External Customer [Line Items]
Rentals and leases	$ 32,485		$ 32,837		$ 103,347		$ 101,077
Sales of equipment and other revenues	29,531		31,835		76,713		87,288
Total revenues	62,016	[1]	64,672	[1]	180,060	[1]	188,365	[1]
T&M
Revenue from External Customer [Line Items]
Rentals and leases	28,793		29,460		90,673		89,500
Sales of equipment and other revenues	29,221		31,327		75,334		85,418
Total revenues	58,014		60,787		166,007		174,918
DP
Revenue from External Customer [Line Items]
Rentals and leases	3,692		3,377		12,674		11,577
Sales of equipment and other revenues	310		508		1,379		1,870
Total revenues	$ 4,002		$ 3,885		$ 14,053		$ 13,447

[1] Revenues by country are based on the location of shipping destination, and not whether the order originates in the United States parent or a foreign subsidiary.