Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating Activities
Net income	$ 160,617	$ 44,398
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	392,398	352,957
Asset impairment	428	1,589
Accretion of discount on asset retirement obligations	4,704	4,330
Deferred income taxes	48,103	39,240
Change in derivative fair value	152,120	(47,030)
Gain on sale of assets	(34,474)	(3,972)
Stock-based compensation expense	13,839	11,101
Exploration, including dry holes	712	0
Other, net	(3,086)	(3,491)
Net change in:
Accounts receivable	(25,029)	(55,897)
Inventories	(15,475)	(316)
Accounts payable	48,169	31,614
Accrued taxes/income tax receivable	21,021	24,888
Other current assets and liabilities	(939)	(16,634)
Net cash provided by operating activities	763,108	382,777
Investing Activities
Additions to oil and natural gas properties	(833,284)	(720,243)
Acquisitions	(81,135)	(263,364)
Proceeds on the sale of assets, net	1,051	4,009
Net cash used in investing activities	(913,368)	(979,598)
Financing Activities
Issuance of common stock, net	5,034	273
Taxes paid for shares withheld	(8,156)	(3,293)
Reduction of long-term debt	0	(24,000)
Net change in credit facility	170,000	238,000
Net cash provided by financing activities	166,878	210,980
Net change in cash and cash equivalents	16,618	(385,841)
Cash and cash equivalents at beginning of period	439	386,093
Cash and cash equivalents at end of period	$ 17,057	$ 252