|
Accounts Receivable (Details) (USD $)
In Millions, unless otherwise specified |
12 Months Ended | 3 Months Ended | |||||
|---|---|---|---|---|---|---|---|
|
Jan. 31, 2010
|
Apr. 30, 2013
|
Jan. 31, 2013
|
Apr. 30, 2013
Maximum [Member]
|
Apr. 30, 2013
Minimum [Member]
|
Apr. 30, 2013
Construction contracts retainages [Member]
|
Jan. 31, 2013
Construction contracts retainages [Member]
|
|
| Accounts Receivable (Textual) [Abstract] | |||||||
| Contract payment amounts retained by project owners | $ 17.0 | $ 20.2 | |||||
| Length of retention period of amount given to project owners | 3 years | 9 months | |||||
| Accounts Receivable (Additional Textual) [Abstract] | |||||||
| 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 | ||||||