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Accounts Receivable - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 12 Months Ended |  |  | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Jan. 31, 2010 | Jan. 31, 2014 | Jan. 31, 2013 | Jan. 31, 2014 Minimum [Member] | Jan. 31, 2014 Maximum [Member] | Jan. 31, 2014 Construction Contracts Retainage [Member] | Jan. 31, 2013 Construction Contracts Retainage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |  |
Contract payment amounts retained by project owners |  |  |  |  |  | $ 22.7 | $ 20.2
Length of retention period of amount given to project owners |  |  |  | 10 months | 29 months |  |
Allowance for doubtful accounts |  | 5.5 | 5.5 |  |  |  |
The amount of the net proceeds remaining from public auction of the partially completed project | $ 5.5 |  |  |  |  |  |

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