XML 53 R42.htm IDEA: XBRL DOCUMENT v3.7.0.1
Goodwill - Summary of Goodwill (Detail) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2017
Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]    
Gross cost, beginning balance $ 611.3  
Movement in the period (39.3)  
Gross cost, ending balance 572.0  
Accumulated impairment losses (236.5) $ (236.5)
Net book amount, beginning balance 374.8  
Movement in the period (39.3)  
Net book amount, ending balance $ 335.5