Divestitures - Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations (net of tax)	$ 0	$ 23,185	$ 0	$ (357,843)
Chemetall Surface Treatment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales		211,347		637,889
Cost of goods sold		100,061		333,832
Operating expenses, net		70,604		203,052
Interest and financing expenses		9,864		29,912
Other expenses, net		134
Other (income), net				(1,636)
Income before income taxes		30,684		72,729
Income tax expense		7,499		430,572
Income (loss) from discontinued operations (net of tax)		$ 23,185		(357,843)
Depreciation and amortization				35,194
Capital expenditures				$ 15,525