Revenue Recognition - Adoption of ASC 606 (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Oil, natural gas liquids and natural gas sales	$ 357,866	$ 176,375
Oil, natural gas liquids and natural gas production	52,635	41,288
Net income	118,915	$ 33,403
Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Oil, natural gas liquids and natural gas sales	359,022
Oil, natural gas liquids and natural gas production	53,791
Net income	118,915
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Disaggregation of Revenue [Line Items]
Oil, natural gas liquids and natural gas sales	(1,156)
Oil, natural gas liquids and natural gas production	(1,156)
Net income	$ 0