Legal and Environmental Matters (Details) $ in Thousands	Dec. 31, 2017 USD ($) Civil_complaints
Loss Contingency [Abstract]
Accruals for legal and environmental matters \| $	$ 1,597
Number of Putative Shareholder Derivative Complaints \| Civil_complaints	2

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=25496072&loc=d3e14326-108349

Name:	us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant