Commitments and Contingencies (Detail Textuals) $ in Thousands	6 Months Ended	12 Months Ended
Dec. 31, 2018 USD ($) PRPs	Jun. 30, 2018 USD ($)
Commitments And Contingencies [Line Items]
Number of potentially responsible parties \| PRPs	140
Current and long-term liabilities
Commitments And Contingencies [Line Items]
Accrual for environmental loss contingencies payments \| $	$ 6,598	$ 6,833

Amount of cash outflow to settle environmental loss contingencies.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 5.Y.Q1)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 17
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3367-108585

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesPayments1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration