Fair Value Measurements (Details)
3 Months Ended 9 Months Ended
Oct. 28, 2017
USD ($)
Apr. 29, 2017
USD ($)
Oct. 29, 2016
USD ($)
stores
Oct. 28, 2017
USD ($)
stores
Oct. 29, 2016
USD ($)
stores
Jan. 28, 2017
USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Impairment charge $ 0 $ 5,500,000 $ 800,000 $ 5,479,000 $ 829,000  
Number of stores impaired during the period | stores     2 17 2  
Recurring [Member] | Level 1 [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Financial assets 116,914,000     $ 116,914,000    
Recurring [Member] | Level 1 [Member] | Money market funds [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Financial assets 116,914,000     116,914,000   $ 177,551,000
Recurring [Member] | Level 1 [Member] | Commercial paper [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Financial assets 0     0    
Recurring [Member] | Level 2 [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Financial assets 59,916,000     59,916,000    
Recurring [Member] | Level 2 [Member] | Money market funds [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Financial assets 0     0   0
Recurring [Member] | Level 2 [Member] | Commercial paper [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Financial assets 59,916,000     59,916,000    
Recurring [Member] | Level 3 [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Financial assets 0     0    
Recurring [Member] | Level 3 [Member] | Money market funds [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Financial assets 0     0   $ 0
Recurring [Member] | Level 3 [Member] | Commercial paper [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Financial assets $ 0     $ 0