XML 93 R81.htm IDEA: XBRL DOCUMENT v3.7.0.1
Share-based compensation - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jul. 29, 2017
Jul. 30, 2016
Jul. 29, 2017
Jul. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]        
Share-based compensation expense $ 4.0 $ 5.0 $ 6.7 $ 8.8