Acquisitions and Divestitures - Narrative (Details) MBoe in Thousands		12 Months Ended
	Apr. 03, 2017 USD ($) a MBoe wells	Dec. 31, 2017 USD ($) MBoe rig	Dec. 31, 2016 USD ($) MBoe rig	Dec. 31, 2015 USD ($) MBoe rig	Dec. 31, 2014 MBoe
Acquisitions and Divestitures [Line Items]
Proved Developed Reserves (Volume) | MBoe		112,961	99,079	115,296	136,790
EOG Acquisition
Acquisitions and Divestitures [Line Items]
Total consideration given	$ 54,332,000
Business Acquisition, Effective Date of Acquisition	Jan. 01, 2017
Proved Developed Reserves (Volume) | MBoe	3,200
Natural Gas Gathering System	1
Hoxbar | EOG Acquisition
Acquisitions and Divestitures [Line Items]
Area of Real Estate Property | a	8,300
Proved developed producing wells | wells	47
Acquired land with existing production capacity, percent	71.00%
Oil and Natural Gas
Acquisitions and Divestitures [Line Items]
Other acquisitions		$ 4,700,000
Proceeds from divestiture of assets		$ 18,600,000	$ 67,200,000	$ 1,900,000
Drilling Equipment
Acquisitions and Divestitures [Line Items]
Number of rigs sold | rig		0	1	31
Impairment of contract drilling equipment		$ 0	$ 0	$ 8,300,000
Net book value of drilling rigs sold			1,700,000.0	11,300,000
Gain (loss) on sale of drilling rigs			$ 1,600,000	$ (7,300,000)