Derivative Instruments (Details) number in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Oct. 31, 2015 USD ($)	Oct. 31, 2015 USD ($)
Fuel [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	6,775	6,775
Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative, Fair Value, Net	$ (2,224)	$ (2,224)
Energy Related Derivative [Member] | Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Sale of Commodity Contracts	(163)	(163)
Unrealized Gain (Loss) on Commodity Contracts	(510)	(2,224)
Derivative, Gain (Loss) on Derivative, Net	(673)	(2,387)
Energy Related Derivative [Member] | Other Current Assets [Member]
Derivative Asset [Abstract]
Derivative Asset, Current	134	134
Energy Related Derivative [Member] | Other Assets [Member]
Derivative Asset [Abstract]
Derivative Asset	308	308
Energy Related Derivative [Member] | Accrued Operating Expenses [Member]
Derivative Liability [Abstract]
Derivative Liability, Current	(1,476)	(1,476)
Energy Related Derivative [Member] | Other Liabilities [Member]
Derivative Liability [Abstract]
Derivative Liability	$ (1,190)	$ (1,190)