Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Oil and Natural Gas Properties:
Subject to depletion	$ 5,126,829	$ 3,429,742
Not subject to depletion	4,105,865	1,730,519
Gross oil and natural gas properties	9,232,694	5,160,261
Accumulated impairment	(1,143,498)	(1,143,498)
Oil and natural gas properties, net	7,079,303	3,329,078
Midstream Assets	191,519	8,362
Other property, equipment and land	80,776	58,290
Accumulated depreciation	(2,161,372)	(1,836,056)
Property and equipment, net of accumulated depreciation, depletion, amortization and impairment	7,343,617	3,390,857
Capitalized internal costs	21,978	17,183	$ 15,200
Impairment of oil and natural gas properties	0	245,536	814,798
Exploration costs or development costs not subject to depletion	26,040	0
Capitalized interest not subject to depletion	$ 22,097	0
Minimum [Member]
Oil and Natural Gas Properties:
Anticipated Timing of Inclusion of Costs in Amortization Calculation	3 years
Maximum [Member]
Oil and Natural Gas Properties:
Anticipated Timing of Inclusion of Costs in Amortization Calculation	5 years
Oil and Gas Properties [Member]
Oil and Natural Gas Properties:
Subject to depletion	$ 5,126,829	3,429,742
Not subject to depletion	4,105,865	1,730,519
Gross oil and natural gas properties	9,232,694	5,160,261
Accumulated impairment	(1,143,498)	(1,143,498)
Oil and natural gas properties, net	7,079,303	3,329,078
Accumulated depreciation	(1,009,893)	(687,685)
Balance of costs not subject to depletion:	2,746,936	727,411	$ 301,879	$ 316,455	$ 13,184
Other Property and Equipment, Net [Member]
Oil and Natural Gas Properties:
Other property, equipment and land	80,776	58,290
Accumulated depreciation	$ (7,981)	$ (4,873)