Acquisitions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	6 Months Ended		6 Months Ended
	Aug. 31, 2012	Nov. 30, 2012	Aug. 31, 2012 Common Stock	Nov. 30, 2012 Customer relationships	Nov. 03, 2010 Quest	Aug. 31, 2012 Specialty Remote Digital Video Inspection Company
Business Acquisition [Line Items]
Business acquisition, purchase price	$ 26.0		$ 23.8			$ 2.7
Cash paid for acquisition of common stock			16.1
Deferred payments for common stock			7.7
Increase in net working capital	4.1	1.2
Increase in fixed assets	3.1	3.0
Increase in intangible assets	8.0			7.5
Increase in goodwill	8.6	7.7
Increase in other current liabilities	1
Increase in other long-term liabilities	6.7
Future contingent consideration liability	3
Combined annual revenues from acquired businesses	24
Total consideration paid to shareholders		19.4
Purchase percentage of quest					95.00%
Remaining purchase consideration based upon future financial performance		5.00%
Common stock aggregate value		2.4
Percentage of aggregate value consideration of outstanding common stock		20.00%
Value of Acquisition		$ 4.9