Summary of Significant Accountant Policies - Additional Information (Detail) (USD $)	12 Months Ended
	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