Business and Summary of Significant Accounting Policies Business and Summary of Significant Accounting Policies (Vendor Concentrations) (Details) - Sales Revenue, Goods, Net - Supplier Concentration Risk	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Apple
Concentration Risk [Line Items]
Concentration Risk, Percentage	20.00%	15.00%	13.00%
Hewlett-Packard
Concentration Risk [Line Items]
Concentration Risk, Percentage	18.00%	19.00%	21.00%