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Summary of Significant Accountant Policies - Additional Information (Detail) (USD $) | 12 Months Ended
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Jan. 31, 2014 Category | Jan. 31, 2013 Category | Jan. 31, 2012 Category
Summary Of Significant Accounting Policies [Line Items] |  |  |
Amount of unapproved change orders | $ 0 |  |
Number of categories | 2 | 2 | 2
Minimum [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful lives of the assets | 5 years |  |
Minimum [Member] | Power Industry Services [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Revenue recognition period | 1 year |  |
Maximum [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful lives of the assets | 39 years |  |
Maximum [Member] | Power Industry Services [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Revenue recognition period | 3 years |  |

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- Details
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