Asset Retirement Obligations Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2016	Jun. 30, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligation increase	$ 1.9	$ 12.0

Amount of increase (decrease) in asset retirement obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Name:	us-gaap_AssetRetirementObligationPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration