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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% |

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