Consolidated Statements of Operations (Audited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Crude oil, natural gas, and NGLs sales									$ 913,084	$ 497,353	$ 378,713
Commodity price risk management gain (loss), net									(3,936)	(125,681)	203,183
Other income									12,468	11,243	13,430
Total revenues					$ 108,097	$ 163,890	$ 20,097	$ 90,831	921,616	382,915	595,326
Costs, expenses and other:
Lease operating expenses									89,641	59,950	56,992
Production taxes									60,717	31,410	18,443
Transportation, gathering, and processing expenses									33,220	18,415	10,151
Exploration, geologic, and geophysical expense									47,334	4,669	1,102
Impairment of properties and equipment									285,887	9,973	161,620
Impairment of goodwill									75,121	0	0
General and administrative expense									120,370	112,470	89,959
Depreciation, depletion and amortization									469,084	416,874	303,258
Provision for uncollectible notes receivable									(40,203)	44,038	0
Accretion of asset retirement obligations									6,306	7,080	6,293
Gain on sale of properties and equipment									766	43	385
Other expenses									13,157	10,193	11,717
Total costs, expenses and other					178,608	179,178	163,379	193,864	1,159,868	715,029	659,150
Loss from operations					(70,511)	(15,288)	(143,282)	(103,033)	(238,252)	(332,114)	(63,824)
Loss on extinguishment of debt									24,747	0	0
Interest expense									(78,694)	(61,972)	(47,571)
Interest income									2,261	963	4,807
Loss before income taxes					(90,636)	(35,341)	(153,777)	(113,369)	(339,432)	(393,123)	(106,588)
Income tax benefit									211,928	147,195	38,308
Net loss					$ (55,639)	$ (23,309)	$ (95,450)	$ (71,530)	$ (127,504)	$ (245,928)	$ (68,280)
Earnings per share attributable to shareholders:
Diluted	$ 1.17	$ (4.44)	$ 0.62	$ 0.70	$ (0.94)	$ (0.48)	$ (2.04)	$ (1.72)	$ (1.94)	$ (5.01)	$ (1.74)
Basic	$ 1.18	$ (4.44)	$ 0.63	$ 0.70	$ (0.94)	$ (0.48)	$ (2.04)	$ (1.72)	$ (1.94)	$ (5.01)	$ (1.74)
Weighted-average common shares outstanding:
Basic									65,837	49,052	39,153
Diluted									65,837	49,052	39,153