Accounts Receivable - Additional Information (Detail) (USD $)	3 Months Ended	1 Months Ended
	Apr. 30, 2015	May 30, 2015	Jan. 31, 2015	Jan. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Length of retention period of amount given to project owners	18 months
Allowance for doubtful accounts			$ 5,500,000
Accounts receivable from the owner of a partially completed construction project				5,500,000
Provision for accounts receivable loss	0
Subsequent Event [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash received		1,600,000
Construction Contracts Retainage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contract payment amounts retained by project owners	$ 30,100,000		$ 26,100,000