XML 98 R79.htm IDEA: XBRL DOCUMENT v3.8.0.1
Revenue and segmental analysis - Schedule of geographic destination (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Disclosure of operating segments [line items]      
REVENUE $ 441.3 $ 414.8 $ 460.3
United Kingdom      
Disclosure of operating segments [line items]      
REVENUE 40.7 36.4 53.5
Rest of Europe      
Disclosure of operating segments [line items]      
REVENUE 102.9 94.2 98.9
Africa      
Disclosure of operating segments [line items]      
REVENUE 3.0 2.4 2.7
North America      
Disclosure of operating segments [line items]      
REVENUE 238.7 226.3 245.9
South America      
Disclosure of operating segments [line items]      
REVENUE 8.6 9.9 13.4
Asia Pacific      
Disclosure of operating segments [line items]      
REVENUE $ 47.4 $ 45.6 $ 45.9