Business and Geographic Segments - Net Property and Equipment by Segment (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net property and equipment:
Net property and equipment	$ 733.6	$ 796.4	$ 763.1
United States
Net property and equipment:
Net property and equipment	234.4	232.8	211.9
Germany
Net property and equipment:
Net property and equipment	259.5	292.9	271.2
Canada
Net property and equipment:
Net property and equipment	63.4	67.1	73.0
Norway
Net property and equipment:
Net property and equipment	85.5	100.9	109.5
Belgium
Net property and equipment:
Net property and equipment	$ 90.8	$ 102.7	$ 97.5