Acquisitions (Details) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2012	May 31, 2012	Aug. 24, 2011
Estimated fair values of the assets acquired and liabilities assumed
Total cash consideration			$ 10,673
Preliminary purchase price allocation
Accounts receivable	972		542
Rental and lease equipment	243,388	243,173	15,896
Deferred tax liability			(2,092)
Deferred revenue			(479)
Net assets acquired			13,867
Bargain purchase gain, net of deferred taxes of $2,092			$ (3,194)