Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
OPERATING ACTIVITIES:
Net income (loss)	$ (10,299)	$ 16,015
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion, and amortization	128,418	115,439
Amortization of debt issuance costs and debt discount (Note 6)	1,115	1,095
(Gain) loss on derivatives (Note 10)	(995)	21,223
Cash proceeds (payments) on derivatives settled, net (Note 10)	5,314	(8,928)
Deferred tax (benefit) expense	(2,318)	5,636
(Gain) loss on disposition of assets	1,193	(322)
Stock compensation plans	11,187	12,073
Contracts assets and liabilities, net (Note 2)	(1,283)	(2,371)
Other, net	1,117	1,998
Changes in operating assets and liabilities increasing (decreasing) cash:
Accounts receivable	26,939	(1,865)
Accounts payable	(30,374)	(403)
Material and supplies	(43)	4
Accrued liabilities	(1,245)	1,572
Other, net	(1,225)	(1,526)
Net cash provided by operating activities	127,501	159,640
INVESTING ACTIVITIES:
Capital expenditures	(246,638)	(189,916)
Producing properties and other acquisitions	(3,313)	(962)
Proceeds from disposition of assets	7,340	23,528
Net cash used in investing activities	(242,611)	(167,350)
FINANCING ACTIVITIES:
Borrowings under credit agreement	271,200	71,200
Payments under credit agreement	(160,200)	(249,200)
Payments on finance leases	(1,980)	(1,901)
Proceeds from investments of non-controlling interests	0	300,000
Employee taxes paid by withholding shares	(4,073)	(4,947)
Transaction costs associated with non-controlling interests	0	(2,254)
Distributions to non-controlling interest	(918)	0
Book overdrafts	5,298	(1,581)
Net cash provided by financing activities	109,327	111,317
Net increase (decrease) in cash and cash equivalents	(5,783)	103,607
Cash and cash equivalents, beginning of period	6,452	701
Cash and cash equivalents, end of period	669	104,308
Cash paid during the year for:
Interest paid (net of capitalized)	15,748	18,246
Income taxes	0	0
Changes in accounts payable and accrued liabilities related to purchases of property, plant, and equipment	(6,260)	(3,747)
Non-cash (addition) reduction to oil and natural gas properties related to asset retirement obligations	$ (2,057)	$ 7,854