Supplemental Condensed Consolidated Financial Information (Condensed Consolidating Statements of Cash Flows (Unaudited)) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
OPERATING ACTIVITIES:
Net cash provided by (used in) 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 provided by (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)
Intercompany borrowings (advances), net	0	0
Payments on finance leases	(1,980)	(1,901)
Employee taxes paid by withholding shares	(4,073)	(4,947)
Proceeds from investments of non-controlling interests	0	300,000
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 (used in) 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
Consolidating Adjustments [Member]
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	(34)	126,993
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	(126,993)
Payments on finance leases	0	0
Employee taxes paid by withholding shares	0	0
Proceeds from investments of non-controlling interests		0
Transaction costs associated with non-controlling interests		0
Distributions to non-controlling interest	0
Book overdrafts	0	0
Net cash provided by (used in) financing activities	34	(126,993)
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	(8,023)	(96,111)
INVESTING ACTIVITIES:
Capital expenditures	(100)	(13)
Producing properties and other acquisitions	0	0
Proceeds from disposition of assets	10	30
Net cash provided by (used in) investing activities	(90)	17
FINANCING ACTIVITIES:
Borrowings under credit agreement	238,800	69,200
Payments under credit agreement	(135,300)	(247,200)
Intercompany borrowings (advances), net	(96,311)	276,460
Payments on finance leases	0	0
Employee taxes paid by withholding shares	(4,073)	(4,947)
Proceeds from investments of non-controlling interests		102,958
Transaction costs associated with non-controlling interests		(2,254)
Distributions to non-controlling interest	919
Book overdrafts	4,183	(1,581)
Net cash provided by (used in) financing activities	8,218	192,636
Net increase (decrease) in cash and cash equivalents	105	96,542
Cash and cash equivalents, beginning of period	403	510
Cash and cash equivalents, end of period	508	97,052
Combined Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	111,615	145,227
INVESTING ACTIVITIES:
Capital expenditures	(212,982)	(173,097)
Producing properties and other acquisitions	(3,313)	(962)
Proceeds from disposition of assets	7,247	23,427
Net cash provided by (used in) investing activities	(209,048)	(150,632)
FINANCING ACTIVITIES:
Borrowings under credit agreement	0	0
Payments under credit agreement	0	0
Intercompany borrowings (advances), net	97,384	5,468
Payments on finance leases	0	0
Employee taxes paid by withholding shares	0	0
Proceeds from investments of non-controlling interests		0
Transaction costs associated with non-controlling interests		0
Distributions to non-controlling interest	0
Book overdrafts	0	0
Net cash provided by (used in) financing activities	97,384	5,468
Net increase (decrease) in cash and cash equivalents	(49)	63
Cash and cash equivalents, beginning of period	208	191
Cash and cash equivalents, end of period	159	254
Combined Non-Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	23,943	(16,469)
INVESTING ACTIVITIES:
Capital expenditures	(33,556)	(16,806)
Producing properties and other acquisitions	0	0
Proceeds from disposition of assets	83	71
Net cash provided by (used in) investing activities	(33,473)	(16,735)
FINANCING ACTIVITIES:
Borrowings under credit agreement	32,400	2,000
Payments under credit agreement	(24,900)	(2,000)
Intercompany borrowings (advances), net	(1,107)	(154,935)
Payments on finance leases	(1,980)	(1,901)
Employee taxes paid by withholding shares	0	0
Proceeds from investments of non-controlling interests		197,042
Transaction costs associated with non-controlling interests		0
Distributions to non-controlling interest	(1,837)
Book overdrafts	1,115	0
Net cash provided by (used in) financing activities	3,691	40,206
Net increase (decrease) in cash and cash equivalents	(5,839)	7,002
Cash and cash equivalents, beginning of period	5,841	0
Cash and cash equivalents, end of period	$ 2	$ 7,002