Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
OPERATING ACTIVITIES:
Net income (loss)	$ (2,282)	$ 7,865
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion, and amortization	62,126	57,066
Amortization of debt issuance costs and debt discount (Note 6)	556	546
Loss on derivatives (Note 10)	6,932	6,762
Cash proceeds (payments) on derivatives settled, net (Note 10)	2,656	(2,073)
Deferred tax expense	(444)	3,607
(Gain) loss on disposition of assets	1,615	(161)
Stock compensation plans	5,134	6,609
Contracts assets and liabilities, net (Note 2)	(700)	(1,192)
Other, net	573	937
Changes in operating assets and liabilities increasing (decreasing) cash:
Accounts receivable	18,830	8,005
Accounts payable	(20,848)	(10,716)
Material and supplies	(22)	50
Accrued liabilities	2,749	6,757
Other, net	203	(494)
Net cash provided by operating activities	77,078	83,568
INVESTING ACTIVITIES:
Capital expenditures	(122,507)	(90,249)
Producing properties and other acquisitions	(1,580)	0
Proceeds from disposition of assets	3,190	22,084
Net cash used in investing activities	(120,897)	(68,165)
FINANCING ACTIVITIES:
Borrowings under credit agreement	109,800	67,400
Payments under credit agreement	(69,800)	(97,700)
Payments on finance leases	(985)	(946)
Distributions to non-controlling interest	(918)	0
Book overdrafts	3,161	15,894
Net cash provided by (used in) financing activities	41,258	(15,352)
Net increase (decrease) in cash and cash equivalents	(2,561)	51
Cash and cash equivalents, beginning of period	6,452	701
Cash and cash equivalents, end of period	3,891	752
Cash paid during the year for:
Interest paid (net of capitalized)	(3,307)	(1,731)
Income taxes	0	0
Changes in accounts payable and accrued liabilities related to purchases of property, plant, and equipment	(641)	(13,238)
Non-cash (addition) reduction to oil and natural gas properties related to asset retirement obligations	$ (3,070)	$ 6,340