Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 2,167.3	$ 2,174.2
Less: accumulated depreciation and depletion	(1,063.0)	(992.1)
Property, plant and equipment, net	1,104.3	1,182.1
Depreciation and depletion expense	82.1	76.6	$ 44.7
Mineral rights and reserves [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	553.8	575.9
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	39.8	44.9
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	179.7	198.2
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,130.7	1,121.5
Furniture and Fixtures and Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	209.7	153.1
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 53.6	$ 80.6