Commitments and Contingencies Activity in Recorded Environmental Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance, beginning of year	$ 34,919	$ 31,436	$ 9,235
Expenditures	(1,818)	(2,667)	(4,039)
Divestitures	0	0	(1,826)
Accretion of discount	896	793	902
Additions and revisions of estimates	3,344	4,004	150
Reclass to liabilities held for sale	0	0	(5,253)
Foreign currency translation adjustments and other	2,467	1,353	(2,359)
Balance, end of year	34,919	31,436	9,235	$ 39,808	$ 34,919	$ 31,436
Less amounts reported in Accrued expenses				2,290	2,324	1,443
Amounts reported in Other noncurrent liabilities				$ 37,518	$ 32,595	$ 29,993
Rockwood Holdings, Inc.
Accrual for Environmental Loss Contingencies [Roll Forward]
Acquisition of Rockwood	$ 0	$ 0	$ 34,626