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Properties and Equipment, Net - Schedule of PPE (Details) - USD ($)
$ in Thousands
Mar. 31, 2017
Dec. 31, 2016
Property, Plant and Equipment [Abstract]    
Proved oil and gas properties $ 7,589,749 $ 7,437,604
Unproved oil and gas properties 296,279 260,543
Gathering and pipeline systems 188,466 187,846
Land, building and other equipment 85,257 84,462
Properties and equipment, gross, total 8,159,751 7,970,455
Accumulated depreciation, depletion and amortization (3,831,391) (3,720,330)
Properties and equipment, net $ 4,328,360 $ 4,250,125