Revenues from Rental, Lease and Sale Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Feb. 28, 2013		Feb. 29, 2012		Feb. 28, 2013		Feb. 29, 2012
Revenue from External Customer [Line Items]
Rentals and leases	$ 32,837		$ 31,704		$ 101,077		$ 95,925
Sales of equipment and other revenues	31,835		28,375		87,288		84,447
Total revenues	64,672	[1]	60,079	[1]	188,365	[1]	180,372	[1]
T&M
Revenue from External Customer [Line Items]
Rentals and leases	29,460		28,281		89,500		83,534
Sales of equipment and other revenues	31,327		27,882		85,418		82,711
Total revenues	60,787		56,163		174,918		166,245
DP
Revenue from External Customer [Line Items]
Rentals and leases	3,377		3,423		11,577		12,391
Sales of equipment and other revenues	508		493		1,870		1,736
Total revenues	$ 3,885		$ 3,916		$ 13,447		$ 14,127

[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.