Supplemental Condensed Consolidated Financial Information (Condensed Consolidating Statements of Cash Flows (Unaudited)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
OPERATING ACTIVITIES:
Net cash provided by (used in) 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 provided by (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)
Intercompany borrowings (advances), net	0	0
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
Consolidating Adjustments [Member]
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	(34)	0
INVESTING ACTIVITIES:
Capital expenditures	0	0
Producing properties and other acquisitions	0	0
Proceeds from disposition of assets	0	0
Net cash provided by (used in) investing activities	0	0
FINANCING ACTIVITIES:
Borrowings under credit agreement	0	0
Payments under credit agreement	0	0
Intercompany borrowings (advances), net	34	0
Payments on finance leases	0	0
Distributions to non-controlling interest	0
Book overdrafts	0	0
Net cash provided by (used in) financing activities	34	0
Net increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
Parent [Member]
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	(562)	(5,452)
INVESTING ACTIVITIES:
Capital expenditures	(321)	(56)
Producing properties and other acquisitions	0	0
Proceeds from disposition of assets	10	30
Net cash provided by (used in) investing activities	(311)	(26)
FINANCING ACTIVITIES:
Borrowings under credit agreement	106,900	67,400
Payments under credit agreement	(66,900)	(97,700)
Intercompany borrowings (advances), net	(43,103)	19,880
Payments on finance leases	0	0
Distributions to non-controlling interest	919
Book overdrafts	3,161	15,894
Net cash provided by (used in) financing activities	977	5,474
Net increase (decrease) in cash and cash equivalents	104	(4)
Cash and cash equivalents, beginning of period	403	510
Cash and cash equivalents, end of period	507	506
Combined Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	64,168	74,277
INVESTING ACTIVITIES:
Capital expenditures	(110,089)	(79,855)
Producing properties and other acquisitions	(1,580)	0
Proceeds from disposition of assets	3,142	22,028
Net cash provided by (used in) investing activities	(108,527)	(57,827)
FINANCING ACTIVITIES:
Borrowings under credit agreement	0	0
Payments under credit agreement	0	0
Intercompany borrowings (advances), net	44,407	(16,395)
Payments on finance leases	0	0
Distributions to non-controlling interest	0
Book overdrafts	0	0
Net cash provided by (used in) financing activities	44,407	(16,395)
Net increase (decrease) in cash and cash equivalents	48	55
Cash and cash equivalents, beginning of period	208	191
Cash and cash equivalents, end of period	256	246
Combined Non-Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	13,506	14,743
INVESTING ACTIVITIES:
Capital expenditures	(12,097)	(10,338)
Producing properties and other acquisitions	0	0
Proceeds from disposition of assets	38	26
Net cash provided by (used in) investing activities	(12,059)	(10,312)
FINANCING ACTIVITIES:
Borrowings under credit agreement	2,900	0
Payments under credit agreement	(2,900)	0
Intercompany borrowings (advances), net	(1,338)	(3,485)
Payments on finance leases	(985)	(946)
Distributions to non-controlling interest	(1,837)
Book overdrafts	0	0
Net cash provided by (used in) financing activities	(4,160)	(4,431)
Net increase (decrease) in cash and cash equivalents	(2,713)	0
Cash and cash equivalents, beginning of period	5,841	0
Cash and cash equivalents, end of period	$ 3,128	$ 0