Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Balance Beginning	$ 770.9	$ 64.4
Change in goodwill relating to [Abstract]
Acquisition		708.2
Purchase price finalization	12.8
Foreign exchange translation	(2.5)	(1.7)
Total	10.3	706.5
Balance Ending	781.2	770.9
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	232.4	223.6
Accumulated Amortization	$ 19.7	11.5
Weighted Average Useful Life	28 years
Specialty Minerals [Member]
Goodwill [Roll Forward]
Balance Beginning	$ 13.7	14.3
Change in goodwill relating to [Abstract]
Purchase price finalization	0.0
Foreign exchange translation	(0.4)	(0.6)
Total	(0.4)	(0.6)
Balance Ending	13.3	13.7
Refractories [Member]
Goodwill [Roll Forward]
Balance Beginning	49.0	50.1
Change in goodwill relating to [Abstract]
Purchase price finalization	0.0
Foreign exchange translation	(2.0)	(1.1)
Total	(2.0)	(1.1)
Balance Ending	47.0	49.0
Performance Materials [Member]
Goodwill [Roll Forward]
Balance Beginning	453.2	0.0
Change in goodwill relating to [Abstract]
Acquisition		453.2
Purchase price finalization	91.1
Foreign exchange translation	(0.1)	0.0
Total	91.0	453.2
Balance Ending	544.2	453.2
Construction Technologies [Member]
Goodwill [Roll Forward]
Balance Beginning	255.0	0.0
Change in goodwill relating to [Abstract]
Acquisition		255.0
Purchase price finalization	(78.3)
Foreign exchange translation	0.0	0.0
Total	(78.3)	255.0
Balance Ending	176.7	255.0
Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	199.8	191.2
Accumulated Amortization	$ 9.3	3.7
Weighted Average Useful Life	34 years
Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 18.8	18.7
Accumulated Amortization	$ 2.5	1.0
Weighted Average Useful Life	12 years
Patents & Trademarks [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 6.4	6.4
Accumulated Amortization	$ 4.4	4.0
Weighted Average Useful Life	17 years
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4.5	4.4
Accumulated Amortization	$ 0.6	0.1
Weighted Average Useful Life	30 years
Customer Lists [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2.9	2.9
Accumulated Amortization	$ 2.9	$ 2.7
Weighted Average Useful Life	15 years