Segment Reporting (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Oct. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of business segments | segment	2
Oil and natural gas revenues	$ 528,684,000	$ 291,156,000	$ 278,340,000
Third-party midstream services revenues	10,198,000	5,218,000	1,864,000
Realized gain on derivatives	(4,321,000)	9,286,000	77,094,000
Unrealized gain on derivatives	9,715,000	(41,238,000)	(39,265,000)
Total expenses	383,435,000	441,589,000	1,124,695,000
Operating income (loss)	160,841,000	(177,167,000)	(806,662,000)
Assets	2,145,690,000	1,464,665,000	1,140,861,000
Capital expenditures	872,958,000	454,360,000	698,437,000
Income (loss) attributable to noncontrolling interest	12,140,000	364,000	261,000
Depletion, depreciation and amortization	177,502,000	122,048,000	178,847,000
Impairment charge of net capitalized costs	0	158,633,000	801,166,000
Carrying value of net assets sold				$ 31,000,000
Operating Segments [Member] | Exploration and Production Segment [Member]
Segment Reporting Information [Line Items]
Oil and natural gas revenues	525,862,000	289,512,000	277,844,000
Third-party midstream services revenues	0	0	0
Realized gain on derivatives	(4,321,000)	9,286,000	77,094,000
Unrealized gain on derivatives	9,715,000	(41,238,000)	(39,265,000)
Total expenses	333,923,000	391,098,000	1,078,534,000
Operating income (loss)	197,333,000	(133,538,000)	(762,861,000)
Assets	1,768,393,000	1,098,525,000	1,000,075,000
Capital expenditures	753,157,000	379,881,000	622,642,000
Depletion, depreciation and amortization	170,500,000	118,400,000	176,700,000
Impairment charge of net capitalized costs		158,600,000	801,200,000
Operating Segments [Member] | Midstream Segment [Member]
Segment Reporting Information [Line Items]
Oil and natural gas revenues	2,822,000	1,644,000	496,000
Third-party midstream services revenues	47,037,000	18,982,000	11,485,000
Realized gain on derivatives	0	0
Unrealized gain on derivatives	0	0
Total expenses	23,420,000	8,254,000	5,178,000
Operating income (loss)	26,439,000	12,372,000	6,803,000
Assets	257,871,000	140,459,000	75,980,000
Capital expenditures	114,113,000	67,566,000	75,009,000
Income (loss) attributable to noncontrolling interest	12,100,000		300,000
Depletion, depreciation and amortization	5,200,000	2,700,000	1,600,000
Payments to acquire productive assets	54,900,000	400,000
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Oil and natural gas revenues	0	0
Third-party midstream services revenues	0	0	0
Realized gain on derivatives	0	0
Unrealized gain on derivatives	0	0
Total expenses	62,931,000	56,001,000	50,604,000
Operating income (loss)	(62,931,000)	(56,001,000)	(50,604,000)
Assets	119,426,000	225,681,000	64,806,000
Capital expenditures	5,688,000	6,913,000	786,000
Depletion, depreciation and amortization	1,700,000	900,000	500,000
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Oil and natural gas revenues	0	0
Third-party midstream services revenues	(36,839,000)	(13,764,000)	(9,621,000)
Realized gain on derivatives	0	0
Unrealized gain on derivatives	0	0
Total expenses	(36,839,000)	(13,764,000)	(9,621,000)
Assets	0	0	0
Capital expenditures	$ 0	$ 0	$ 0