Supplemental Cash Flow Information - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Feb. 28, 2013	Feb. 29, 2012
Rental And Lease Equipment
Noncash or Part Noncash Acquisitions [Line Items]
Accounts payable related to acquired rental and lease equipment	$ 3,766	$ 4,323
Demonstration Equipment
Noncash or Part Noncash Acquisitions [Line Items]
Transferred demonstration equipment to rental and lease equipment during the period	2,418	623
Accounts Receivable And Net Investment In Sales-Type Leases
Noncash or Part Noncash Acquisitions [Line Items]
Sales of used equipment, not yet collected	$ 13,222	$ 9,724