Accounts Receivable (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012
Accounts Receivable (Additional Textual) [Abstract]
Amount outstanding collectible period	12 months
Allowance for doubtful accounts	$ 5.5	$ 5.5
Account receivable from Solar Energy field project owner	2.1
Grant for Advanced Payment for Project	7.8
Maximum [Member]
Accounts Receivable (Textual) [Abstract]
Length of retention period of amount given to project owner	3 years
Minimum [Member]
Accounts Receivable (Textual) [Abstract]
Length of retention period of amount given to project owner	9 months
Construction Contracts Retainages [Member]
Accounts Receivable (Textual) [Abstract]
Contract payment amounts retained by project owners	$ 20.2	$ 9.8