Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2019

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:

(millions of dollars)	Performance Materials			Specialty Minerals			Refractories			Consolidated
Balance at December 31, 2017	$	720.9		$	12.7		$	45.7		$	779.3
Change in goodwill relating to:
Acquisition of Sivomatic		35.0			—			—			35.0
Foreign exchange translation		—			(0.4	)		(1.5	)		(1.9	)
Total Changes	$	35.0		$	(0.4	)	$	(1.5	)	$	33.1
Balance at December 31, 2018	$	755.9		$	12.3		$	44.2		$	812.4
Change in goodwill relating to:
Foreign exchange translation		(4.7	)		0.2			(0.5	)		(5.0	)
Total Changes	$	(4.7	)	$	0.2		$	(0.5	)	$	(5.0	)
Balance at December 31, 2019	$	751.2		$	12.5		$	43.7		$	807.4

Acquired Intangible Assets Subject to Amortization

Acquired intangible assets subject to amortization as of December 31, 2019 and December 31, 2018 were as follows:

			December 31, 2019				December 31, 2018
	Weighted Average Useful Life (Years)		Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Tradenames		35	$	203.9	$	32.5	$	204.2	$	26.6
Technology		13		18.8		8.0		18.8		6.4
Patents and trademarks		19		6.4		5.9		6.4		5.6
Customer relationships		22		24.7		4.4		26.5		3.2
		32	$	253.8	$	50.8	$	255.9	$	41.8