Summary of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Feb. 28, 2013	May 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 35,017	$ 24,166
Accumulated Amortization	(8,118)	(5,658)
Net Carrying Amount	26,899	18,508
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21,462	12,198
Accumulated Amortization	(3,559)	(1,973)
Net Carrying Amount	17,903	10,225
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,719	3,136
Accumulated Amortization	(3,164)	(2,844)
Net Carrying Amount	555	292
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,075	2,962
Accumulated Amortization	(362)	(207)
Net Carrying Amount	3,713	2,755
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,112	5,112
Accumulated Amortization	(1,033)	(634)
Net Carrying Amount	4,079	4,478
Licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	649	758
Net Carrying Amount	$ 649	$ 758