Commitments and Contingencies - Legal Matters (Details)	Dec. 31, 2017 USD ($) LegalMatter
Asbestos Litigation
Loss Contingencies [Line Items]
Unresolved asbestos cases pending \| LegalMatter	59
Socorro Litigation \| James Chavez, Andrew Baca, and Spouses
Loss Contingencies [Line Items]
Litigation liability accrued \| $	$ 0

Amount of loss contingency liability.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

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