CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Oil and natural gas properties, unproved property costs	$ 988,720	$ 605,736
Other property and equipment accumulated depreciation and amortization	$ 14,433	$ 14,327
Preferred Units
Partners' equity, preferred units, outstanding (in units)	26,363	52,691
Cumulative Convertible Preferred Units
Partners' equity, preferred units, outstanding (in units)	14,711,000	0
Common Units
Partners' equity - units, outstanding	103,456,000	95,721,000
Subordinated Units
Partners' equity - units, outstanding	95,388,000	95,164,000

Capitalized costs of unproved properties incurred for any combination mineral interests acquisitions and other costs not previously disclosed within this table.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-URI http://asc.fasb.org/topic&trid=2145477

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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