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Pension Benefits - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]      
Cost recognized for defined contribution pension plans $ 13.5 $ 15.2 $ 13.9
Accumulated benefit obligation 38.9 $ 67.1  
Estimations of contributions into benefit plan during 2017 $ 2.4    
Norway [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Percentage of ownership of defined benefit pension assets 65.00%    
Australia [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Percentage of ownership of defined benefit pension assets 35.00%