Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities
Net income	$ 118,915	$ 33,403
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	124,210	99,652
Asset impairment	177	1,460
Accretion of discount on asset retirement obligations	1,533	1,414
Deferred income taxes	35,441	20,449
Change in derivative fair value	(13,085)	(71,686)
(Gain) loss on sale of assets	(33,587)	366
Stock-based compensation expense	4,145	3,197
Exploration, including dry holes	207	0
Other, net	1,983	(3,696)
Net change in:
Accounts receivable	7,974	(16,778)
Inventories	(6,409)	(1,143)
Accounts payable	22,879	9,314
Accrued taxes/income tax receivable	3,786	3,808
Other current assets and liabilities	(12,339)	(23,892)
Net cash provided by operating activities	255,830	55,868
Investing Activities
Additions to oil and natural gas properties	(199,852)	(183,714)
Acquisitions	(23,205)	(159,115)
Proceeds (payments) on the sale of assets, net	881	(308)
Net cash used in investing activities	(222,176)	(343,137)
Financing Activities
Taxes paid for shares withheld	(6,493)	(3,166)
Reduction of long-term debt	0	(7,000)
Net change in credit facility	(27,000)	0
Net cash used in financing activities	(33,493)	(10,166)
Net change in cash and cash equivalents	161	(297,435)
Cash and cash equivalents at beginning of period	439	386,093
Cash and cash equivalents at end of period	$ 600	$ 88,658