Venezuela's Highly Inflationary Economy - Additional Information (Detail) (USD $)	12 Months Ended					3 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011	Feb. 28, 2013	Jan. 31, 2013	Feb. 28, 2013 Venezuela	May 31, 2013 Venezuela
Investment in Country with High Inflationary Economy [Line Items]
Percentage of consolidated revenues from small service location	1.00%
Official published exchange rate				6.30	5.30
Recognized losses related to the Venezuelan currency	$ (943,000)	$ 31,000	$ (147,000)			$ (600,000)
Net assets of Venezuelan subsidiary							2,800,000
Denominated receivables and cash of Venezuelan subsidiary							$ 1,200,000