Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of segments | segment	2
Oil and natural gas revenues	$ 181,954	$ 114,847
Third-party midstream services revenues	3,068	1,555
Realized loss on derivatives	(4,258)	(2,219)
Unrealized gain on derivatives	10,416	20,631
Expenses	117,818	80,536
Operating (loss) income	73,362	54,278
Total assets	2,275,705	1,686,393	$ 2,145,690
Capital expenditures	235,688	222,717
Depletion, depreciation and amortization	55,369	33,992
Impairment charges	0	0
Corporate
Segment Reporting Information [Line Items]
Oil and natural gas revenues		0
Third-party midstream services revenues	0	0
Realized loss on derivatives		0
Unrealized gain on derivatives		0
Expenses	17,209	15,755
Operating (loss) income	(17,209)	(15,755)
Total assets	50,018	223,422
Capital expenditures	526	1,464
Depletion, depreciation and amortization	600	300
Consolidations and Eliminations
Segment Reporting Information [Line Items]
Oil and natural gas revenues		0
Third-party midstream services revenues	(12,744)	(8,061)
Realized loss on derivatives		0
Unrealized gain on derivatives		0
Expenses	(12,744)	(8,061)
Total assets	0	0
Capital expenditures	0	0
Exploration and Production | Operating Segments
Segment Reporting Information [Line Items]
Oil and natural gas revenues	180,260	114,165
Third-party midstream services revenues	0	0
Realized loss on derivatives	(4,258)	(2,219)
Unrealized gain on derivatives	10,416	20,631
Expenses	106,155	68,339
Operating (loss) income	80,263	64,238
Total assets	1,902,151	1,296,823
Capital expenditures	189,445	208,373
Depletion, depreciation and amortization	53,200	32,500
Midstream | Operating Segments
Segment Reporting Information [Line Items]
Oil and natural gas revenues	1,694	682
Third-party midstream services revenues	15,812	9,616
Realized loss on derivatives		0
Unrealized gain on derivatives		0
Expenses	7,198	4,503
Operating (loss) income	10,308	5,795
Total assets	323,536	166,148
Capital expenditures	45,717	12,880
Depletion, depreciation and amortization	1,500	1,200
Net income attributable to non-controlling interest in subsidiaries		1,900
Capital expenditures	22,400	$ 4,700
Operating Income (Loss) | Midstream | Operating Segments
Segment Reporting Information [Line Items]
Net income attributable to non-controlling interest in subsidiaries	$ 5,000