CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Oil and natural gas properties, unproved property costs	$ 1,073,447	$ 1,063,883
Other property and equipment accumulated depreciation and amortization	$ 11,622	$ 11,048
Cumulative Convertible Preferred Units
Partners' equity, preferred units, outstanding (in units)	14,711	14,711
Common Units
Partners' equity - units, outstanding	205,960	108,363
Subordinated Units
Partners' equity - units, outstanding	0	96,329

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

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The number of each class of partnership units outstanding at the balance sheet date. Units represent shares of ownership of the general, limited, and preferred partners.

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