CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss		$ (160,843)	$ (757,744)	$ (447,710)
Adjustments to reconcile net loss to net cash provided by operating activities:
Net (gain) loss on divestiture activity		131,028	(37,074)	(43,031)
Depletion, depreciation, amortization, and asset retirement obligation liability accretion		557,036	790,745	921,009
Exploratory dry hole expense		2,381	(16)	36,612
Impairment of proved properties		3,806	354,614	468,679
Abandonment and impairment of unproved properties		12,272	80,367	78,643
Impairment of other property and equipment		0	0	49,369
Stock-based compensation expense		22,700	26,897	27,467
Net derivative (gain) loss		26,414	250,633	(408,831)
Derivative settlement gain		21,234	329,478	512,566
Amortization of debt discount and deferred financing costs		16,276	9,938	7,710
(Gain) loss on extinguishment of debt		35	(15,722)	16,578
Deferred income taxes		(192,066)	(448,643)	(276,722)
Plugging and abandonment		(2,735)	(6,214)	(7,496)
Other, net		8,239	(3,701)	(5,764)
Changes in current assets and liabilities:
Accounts receivable		13,997	(10,562)	140,200
Prepaid expenses and other		(1,953)	8,478	2,563
Accounts payable and accrued expenses		44,985	(53,210)	(86,267)
Accrued derivative settlements		12,584	34,540	5,232
Net cash provided by operating activities		515,390	552,804	990,807
Cash flows from investing activities:
Net proceeds from the sale of oil and gas properties		776,719	946,062	357,938
Capital expenditures		(888,353)	(629,911)	(1,493,608)
Acquisition of proved and unproved oil and gas properties		(89,896)	(2,183,790)	(7,984)
Other, net		0	0	(985)
Net cash used in investing activities		(201,530)	(1,867,639)	(1,144,639)
Cash flows from financing activities:
Proceeds from credit facility		406,000	947,000	1,872,500
Repayment of credit facility		(406,000)	(1,149,000)	(1,836,500)
Debt issuance costs related to credit facility		0	(3,132)	0
Net proceeds from Senior Notes		0	491,640	490,951
Cash paid to repurchase Senior Notes		(2,344)	(29,904)	(350,000)
Cash paid for extinguishment of debt		13	0	12,455
Net proceeds from Senior Convertible Notes		0	166,617	0
Cash paid for capped call transactions		0	(24,195)	0
Net proceeds from sale of common stock		2,623	938,268	4,844
Dividends paid		(11,144)	(7,751)	(6,772)
Net share settlement from issuance of stock awards		(1,240)	(2,354)	(8,678)
Other, net		(171)	0	(160)
Net cash provided by (used in) financing activities		(12,289)	1,327,189	153,730
Net change in cash, cash equivalents, and restricted cash	[1]	301,571	12,354	(102)
Cash, cash equivalents, and restricted cash at beginning of period	[1]	12,372	18	120
Cash, cash equivalents, and restricted cash at end of period	[1]	313,943	12,372	18
Supplemental schedule of additional cash flow information and non-cash activities:
Cash paid for interest, net of capitalized interest		(164,097)	(129,761)	(126,988)
Net cash (refunded) paid for income taxes		5,986	(4,690)	1,630
Changes in capital expenditure accruals and other		7,309	8,044	(210,819)
Carrying value of properties exchanged		293,963	733	0
Issuance of common stock for an asset acquisition	[2]	0	437,194	0
Non-cash (gain) loss on extinguishment of debt, net		$ 22	$ (15,722)	$ 4,123

[1] (1) Refer to Note 1 – Summary of Significant Accounting Policies for a reconciliation of cash, cash equivalents, and restricted cash reported to the amounts reported within the accompanying balance sheets.

[2] Refer to Note 3 – Divestitures, Assets Held for Sale, and Acquisitions and Note 13 – Equity for additional discussion.