Business and Geographic Segments - Net Property and Equipment by Segment (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net property and equipment:
Net property and equipment	$ 563.5	$ 588.7	$ 516.0
United States
Net property and equipment:
Net property and equipment	74.5	80.8	76.2
Germany
Net property and equipment:
Net property and equipment	245.8	259.2	223.7
Canada
Net property and equipment:
Net property and equipment	66.1	69.0	60.5
Norway
Net property and equipment:
Net property and equipment	81.0	81.7	75.5
Belgium
Net property and equipment:
Net property and equipment	$ 96.1	$ 98.0	$ 80.1