Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Other Intangible Assets [Abstract]

Carrying amount of goodwill by reportable segment

The balance of goodwill by segment and the activity occurring in the past two fiscal years is as follows:

	Specialty Minerals			Refractories			Performance Materials		Consolidated
	(millions of dollars)
Balance at December 31, 2015	$	13.3		$	47.0		$	720.9	$	781.2
Change in goodwill relating to:
Foreign exchange translation		(1.2	)		(1.3	)		-		(2.5	)
Total Changes	$	(1.2	)	$	(1.3	)	$	-	$	(2.5	)
Balance at December 31, 2016	$	12.1		$	45.7		$	720.9	$	778.7
Change in goodwill relating to:
Foreign exchange translation		0.6						-		0.6
Total Changes		0.6			-			-		0.6
Balance at December 31, 2017	$	12.7		$	45.7		$	720.9	$	779.3

Acquired intangible assets subject to amortization

Acquired intangible assets subject to amortization as of December 31, 2017 and December 31, 2016 were as follows:

		December 31, 2017				December 31, 2016
	Weighted Average Useful Life (Years)	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
		(millions of dollars)
Tradenames	34	$	199.8	$	20.7	$	199.8	$	15.3
Technology	12		18.8		4.8		18.8		3.6
Patents and trademarks	17		6.4		5.3		6.4		4.8
Customer relationships	30		4.5		2.2		4.5		1.4
	28	$	229.5	$	33.0	$	229.5	$	25.1