Major Customers - Additional Information (Detail) (Power Industry Services [Member])	3 Months Ended		6 Months Ended
	Jul. 31, 2014 Customer	Jul. 31, 2013	Jul. 31, 2014	Jul. 31, 2013 Customer
Revenue, Major Customer [Line Items]
Percentage of consolidated net revenue accounted by major segment	98.00%	96.00%	98.00%	95.00%
Number of major power industry service customers	3			2
Major Customer One [Member] | Revenue [Member]
Revenue, Major Customer [Line Items]
Percentage of consolidated net revenue accounted by major customers	51.00%	43.00%	47.00%	43.00%
Major Customer Two [Member] | Revenue [Member]
Revenue, Major Customer [Line Items]
Percentage of consolidated net revenue accounted by major customers	33.00%	36.00%	34.00%	40.00%
Major Customer Three [Member] | Revenue [Member]
Revenue, Major Customer [Line Items]
Percentage of consolidated net revenue accounted by major customers	14.00%	12.00%	17.00%