The cash outflow to purchase of mineral interests in oil and gas properties for use in the normal oil and gas operations and not intended for resale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3213-108585

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

Acquisitions (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
Acquisitions (Narrative) (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 14, 2016
Business Acquisition [Line Items]
Deferred Purchase Price				$ 16,800
Payments to acquire oil and gas property		$ 7,032	$ 0
Subsequent Event [Member]
Business Acquisition [Line Items]
Payments to acquire oil and gas property	$ 9,800