Quarterly report pursuant to Section 13 or 15(d)

Summary of significant accounting policies ??? Share-based compensation (Details)

v3.8.0.1
Summary of significant accounting policies – Share-based compensation (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
3 Months Ended
May 05, 2018
Apr. 29, 2017
Stock options    
Weighted-average assumptions to estimate fair value    
Volatility rate (as a percent) 29.00% 31.00%
Average risk-free interest rate (as a percent) 2.40% 1.60%
Average expected life 3 years 4 months 24 days 3 years 6 months
Dividend yield (as a percent) 0.00% 0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures 163 103
Compensation expense $ 2,208 $ 2,142
Weighted-average grant date fair value of options granted (in dollars per share) $ 50.10 $ 70.12
Unrecognized compensation expense $ 23,943  
Restricted stock units    
Weighted-average assumptions to estimate fair value    
Compensation expense 2,505 $ 2,099
Unrecognized compensation expense $ 26,810  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 83 35
Performance-based restricted stock units    
Weighted-average assumptions to estimate fair value    
Compensation expense $ 1,457 $ 1,250
Unrecognized compensation expense $ 12,273  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 33 21