Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Net income (loss)	$ 87,396	$ (166,980)
Net loss	87,396	(166,980)
Adjustments to net income (loss) to reconcile to net cash provided by operating activities:
Net change in fair value of unsettled derivatives	(126,070)	201,825
Depreciation, depletion and amortization	235,329	204,402
Impairment of properties and equipment	29,759	5,171
Provision for uncollectible notes receivable	(40,203)	44,738
Accretion of asset retirement obligation	3,434	3,623
Non-cash stock-based compensation	9,826	11,126
(Gain) loss on sale of properties and equipment	(692)	176
Amortization of debt discount and issuance costs	6,399	3,077
Deferred income taxes	50,767	(102,319)
Other	670	(1,287)
Changes in assets and liabilities	6,582	(5,754)
Net cash from operating activities	263,197	197,798
Cash flows from investing activities:
Capital expenditures for development of crude oil and natural gas properties	(334,406)	(234,677)
Capital expenditures for other properties and equipment	(2,299)	(1,030)
Acquisition of crude oil and natural gas properties, including final settlement adjustments	5,372	0
Proceeds from sale of properties and equipment	1,293	4,903
Sale of promissory note	40,203	0
Restricted cash	(9,250)	0
Sale of short-term investments	49,890	0
Purchases of short-term investments	(49,890)	0
Net cash from investing activities	(299,087)	(230,804)
Cash flows from financing activities:
Proceeds from issuance of equity, net of issuance costs	0	296,575
Proceeds from revolving credit facility	0	85,000
Repayment of revolving credit facility	0	(122,000)
Redemption of convertible notes	0	(115,000)
Treasury Stock, Value, Acquired, Cost Method	(5,274)	(4,055)
Other	(645)	735
Net cash from financing activities	(5,919)	141,255
Net change in cash and cash equivalents	(41,809)	108,249
Cash and cash equivalents, beginning of period	244,100	850
Cash and cash equivalents, end of period	202,291	109,099
Cash payments (receipts) for:
Interest, net of capitalized interest	32,647	19,988
Income taxes	(39)	167
Non-cash investing and financing activities:
Change in accounts payable related to purchases of properties and equipment	81,891	(28,999)
Change in asset retirement obligation, with a corresponding change to crude oil and natural gas properties, net of disposals	2,415	843
Purchase of properties and equipment under capital leases	$ 2,160	$ 1,074