v3.3.1.900
Defined benefit plan (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2015
Jan. 01, 2015
Dec. 31, 2014
Jan. 01, 2014
Defined benefit plan            
Expected contribution to pension plans $ 0.7          
Net annual periodic pension cost            
Service cost benefits earned 0.9 $ 0.8        
Interest cost on benefit obligation 0.7 0.7        
Expected return on plan assets (0.9) (0.8)        
Net period benefit cost 0.7 0.7        
Change in benefit obligation            
Benefit obligation at beginning of the year (19.4)          
Service cost (0.9) (0.8)        
Interest cost (0.7) (0.7)        
Actuarial (gain) loss 2.2 (3.3)        
Employee contributions (0.1) (0.1)        
Benefit paid 0.7 0.1        
Foreign currency translation adjustment (0.1) (0.1)        
Benefit obligation at end of year (15.0) (19.4)        
Change in plan assets            
Fair value of plan assets at beginning of the year 16.3 13.8        
Actual return on plan assets 1.0 1.7        
Employer contributions 0.5 0.7        
Employee contributions 0.1 0.1        
Benefit paid (0.7) (0.1)        
Foreign currency translation adjustment (0.1) 0.1        
Fair value of plan assets at end of year 14.4 16.3        
Funded status at end of year - excess of obligation over assets     $ (0.6)   $ (3.1)  
Amount recognized in the balance sheet            
Non-current liabilities     0.6   3.1  
Amounts recognized in accumulated OCI            
Unrecognized loss     1.6   1.7  
Amortization of net loss for the pension plan from accumulated OCI to net periodic cost over the next fiscal year 0.0          
Balances of significant components of the pension plan            
Projected benefit obligation 19.4 19.4 15.0 $ 16.2 19.4 $ 14.5
Accumulated benefit obligation     12.6   15.4  
Fair value of plan assets $ 16.3 $ 13.8 $ 14.4 $ 13.6 $ 16.3