Legal, Environmental and Other Contingencies - Overview (Details) - Pending litigation	Dec. 31, 2017 action
Welding rod-related injuries
Legal, Environmental and Other Contingencies
Number of actions in which the entity is involved	2
Asbestos in facilities
Legal, Environmental and Other Contingencies
Number of actions in which the entity is involved	1

Number of pending claims pertaining to a loss contingency.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Name:	us-gaap_LossContingencyPendingClaimsNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant