Schedule of Acquisition of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2013
TWB
Business Acquisition [Line Items]
Total acquired identifiable intangible assets	$ 22,028
TWB | Trade Names
Business Acquisition [Line Items]
Acquired indefinite lived intangible assets	4,120
TWB | Non-compete Agreements
Business Acquisition [Line Items]
Acquired indefinite lived intangible assets	470
Customer Relationships | TWB
Business Acquisition [Line Items]
Acquired finite lived intangible assets	$ 17,438
Customer Relationships | Minimum
Business Acquisition [Line Items]
Useful Life (Years)	5 years
Customer Relationships | Maximum
Business Acquisition [Line Items]
Useful Life (Years)	6 years