Oil And Natural Gas Properties And Related Equipment (Gathering and Transportation Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Midstream assets	$ 176,195	$ 152,209
Less: Accumulated depreciation and amortization	(685,112)	(674,338)
Midstream
Property, Plant and Equipment [Line Items]
Midstream assets	176,195	152,209
Less: Accumulated depreciation and amortization	(23,203)	(15,020)
Total gathering and transportation assets	$ 152,992	$ 137,189

Amount of accumulated depreciation, depletion and amortization of oil and gas property carried under the successful effort method. Oil and gas property include, but not limited to, the entity's wells and related equipment and facilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61901-109447

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-10.(b))
-URI http://asc.fasb.org/extlink&oid=50486907&loc=d3e511914-122862

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant