Debt Obligations (Details) - USD ($) $ in Thousands	9 Months Ended
	Oct. 31, 2015	Jan. 31, 2015
Debt Instrument [Line Items]
Total debt obligations	$ 174,864	$ 47,388
Less: Current portion of debt obligations	2,822	1,715
Long-term debt obligations	$ 172,042	45,673
Line of Credit Facility, Initiation Date	Oct. 06, 2014
Aggregate amount of revolving credit facility with seasonal increase	$ 350,000
Line of Credit Facility, Maximum Borrowing Capacity	300,000
Letter of Credit subfacility	$ 50,000
Revolving Credit Facility, expiration date	Oct. 06, 2019
Revolving Credit Facility, weighted average interest rate during period	1.50%
Revolving Credit Facility, average daily borrowings	$ 80,200
Letters of credit outstanding	5,000
Revolving Credit Facility, excess borrowing availability	129,100
Other financing	$ 5,100
Other financing, Interest Rate, Effective Percentage	1.40%
Other financing, Payments Due in 2016	$ 1,800
Other financing, Payments Due in 2017	3,300
Revolving Credit Facility
Debt Instrument [Line Items]
Total debt obligations	165,733	41,910
Finance lease obligations
Debt Instrument [Line Items]
Total debt obligations	4,012	4,725
Other financing [Member]
Debt Instrument [Line Items]
Total debt obligations	$ 5,119	$ 753