XML 135 R51.htm IDEA: XBRL DOCUMENT v3.20.1
Acquisitions and disposals Acquisition and disposals (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Business Acquisition [Line Items]      
Cash proceeds $ 4.4 $ 0.0 $ 0.1
Magnesium Elektron CZ s.r.o. Subsidiary | Disposal Group, Disposed of by Sale, Not Discontinued Operations      
Business Acquisition [Line Items]      
Cash proceeds 5.9    
Cash held in business (1.3)    
Purchase price adjustment (0.2)    
Net proceeds 4.4    
Net assets less cash (3.6)    
Gain on disposal 0.8    
Disposal costs (0.4)    
Realized translation gain on disposal 2.5    
Net gain on disposal $ 2.9