Summary of Significant Accounting Policies - Sales Incentives (Details)	12 Months Ended
	Jan. 31, 2015
Accounting Policies [Abstract]
Number of Ways to Earn Loyalty Points	2
Period of Expiration for Customer Loyalty Certificates, Low End of Range	2 months
Period of Expiration for Customer Loyalty Certificates, High End of Range	12 months
Period of Expiration for Customer Loyalty Certificates, Credit Card, Low end of Range	2 months
Period of Expiration for Customer Loyalty Certificates, Credit Card, High end of Range	12 months