Commitments and Contingencies (Details) - Surface Rights Use Violation Case - USD ($) $ in Millions	3 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Litigation
Accrued liability on settlement offer		$ 1.5
General and administrative expenses
Litigation
Additional charge	$ 1.4

The amount of loss pertaining to the specified contingency that was charged against earnings in the period, including the effects of revisions in previously reported estimates.

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

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration