Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES:
Net income (loss)	$ (39,767)	$ 117,848	$ (135,624)
Adjustments to reconcile net income (loss) to net cash provided (used) by operating activities:
Depreciation, depletion, and amortization	243,605	209,257	208,353
Impairments (Note 2)	147,884	0	161,563
Amortization of debt issuance costs and debt discount	2,198	2,159	2,122
(Gain) loss on derivatives	3,184	(14,732)	22,813
Cash receipts (payments) on derivatives settled	(22,803)	173	9,658
Gain on disposition of assets	(704)	(327)	(3,127)
Deferred tax benefit	(10,865)	(57,683)	(71,209)
Employee stock compensation plans	22,899	17,747	13,812
Bad debt expense	81	348	785
ARO liability accretion	2,393	2,886	2,779
Contract assets and liabilities, net (Note 3)	(4,970)	0	0
Other, net	2,032	(865)	(6,037)
Changes in operating assets and liabilities increasing (decreasing) cash:
Accounts receivable	(12,955)	(32,073)	(11,796)
Materials and supplies	32	2,835	225
Prepaid expenses and other	(4,950)	1,527	2,585
Accounts payable	26,272	8,192	27,400
Accrued liabilities	(3,724)	6,996	(4,388)
Income taxes	(1,993)	38	20,903
Contract advances	(90)	1,630	(687)
Net cash provided by operating activities	347,759	265,956	240,130
INVESTING ACTIVITIES:
Capital expeditures	(446,282)	(255,553)	(186,149)
Producing property and other acquisitions	(29,970)	(58,026)	(564)
Proceeds from disposition of property and equipment	25,910	21,713	74,823
Other	0	(1,500)	919
Net cash used in investing activities	(450,342)	(293,366)	(110,971)
FINANCING ACTIVITIES:
Borrowings under line of credit	99,100	343,900	251,398
Payments under line of credit	(277,100)	(326,700)	(371,600)
Payments on capitalized leases	(3,843)	(3,694)	(3,694)
Proceeds from common stock issued, net of issue costs (Note 17)	0	18,623	0
Tax expense from stock compensation	0	0	(376)
Proceeds from investments of non-contolling interests	300,000	0	0
Transaction costs associated with sale of non-controlling interest	(2,503)	0	0
Decrease in book overdrafts (Note 2)	(7,320)	(4,911)	(4,829)
Net cash provided by (used in) financing activities	108,334	27,218	(129,101)
Net increase (decrease) in cash and cash equivalents	5,751	(192)	58
Cash and cash equivalents, beginning of year	701	893	835
Cash and cash equivalents, end of year	6,452	701	893
Supplemental disclosure of cash flow information:
Interest paid (net of capitalization)	34,535	33,931	35,690
Income taxes	3,600	0	42
Changes in accounts payable and accrued liabilities related to purchases of property, plant, and equipment	(18,119)	(20,574)	21,190
Non-cash reductions to oil and natural gas properties related to asset retirement obligations	$ 7,629	$ 3,613	$ 30,897