Summary of Significant Accounting Policies and Practices - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		12 Months Ended
	Nov. 30, 2010	Aug. 31, 2014	Aug. 31, 2013	May 31, 2014
Significant Accounting Policies [Line Items]
Goodwill		$ 113,141,000		$ 113,763,000
Percentage of stakeholders' in which the agreement rewards	5.00%
Percentage of agreed incremental value	35.00%
Actual EBITDA				14,400,000
Stock price		$ 40.81
Number of shares estimated to be issued to acquire non-controlling interests				573,000
Number of securities included as dilutive securities in earnings per share calculation				225,000
Deferred tax assets recovery from future taxable income percentage		50.00%
Workers compensation our self-insured retention		1,000,000
Automobile liability self-insured retention		500,000
General liability claims we have an effective self-insured retention		3,000,000
Medical claims, our self-insured retention		175,000
Environmental liability claims, our self-insured retention		500,000
Amount of earned but unbilled revenue included in accounts receivable		$ 21,258,000		$ 14,901,000
Options to purchase shares of common stock excluded from the computation of diluted earnings per share		0	0
Quest Integrity Group
Significant Accounting Policies [Line Items]
Purchase percentage of quest	95.00%
Remaining purchase consideration based upon future financial performance	5.00%