Divestitures Divestitures - Other Assets and Liabilities Held for Sale (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Apr. 03, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash proceeds from divestitures, net				$ 416,711	$ 6,857
Gain on sale of business, before income taxes		$ 218,705	$ 0	218,705	$ 0
Current assets		0		0		$ 39,152
Goodwill						14,400
Other intangibles, net of amortization						3,600
Current liabilities		0		$ 0		1,938
Assets held for sale, excluding discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash proceeds from divestitures, net	$ 416,700
Gain on sale of business, before income taxes		$ 218,700
Current assets						39,152
Net, property, plant and equipment						121,759
Goodwill						14,422
Other intangibles, net of amortization						3,632
Assets held for sale						178,965
Current liabilities						1,938
Noncurrent liabilities						614
Liabilities held for sale						$ 2,552
Chemetall Surface Treatment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Working capital settlement			$ 6,900