Supplemental Condensed Consolidated Financial Information (Condensed Consolidating Statements of Cash Flow) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES:
Net cash provided by (used in) 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 provided by (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)
Intercompany borrowings (advances), net	0	0	0
Payments on capitalized leases	(3,843)	(3,694)	(3,694)
Proceeds from common stock issued, net of issue costs	0	18,623	0
Proceeds from investments of non-contolling interests	300,000	0	0
Contributions from Unit	0
Transaction costs associated with sale of non-controlling interest	(2,503)	0	0
Tax expense from stock compensation	0	0	(376)
Book overdrafts	(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
Consolidating Adjustments
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	128,872	0	0
INVESTING ACTIVITIES:
Capital expeditures	0	0	0
Producing property and other acquisitions	0	0	0
Proceeds from disposition of property and equipment	0	0	0
Other		0	0
Net cash provided by (used in) investing activities	0	0	0
FINANCING ACTIVITIES:
Borrowings under line of credit	0	0	0
Payments under line of credit	0	0	0
Intercompany borrowings (advances), net	(128,080)	0	0
Payments on capitalized leases	0	0	0
Proceeds from common stock issued, net of issue costs		0
Proceeds from investments of non-contolling interests	0
Contributions from Unit	(792)
Transaction costs associated with sale of non-controlling interest	0
Tax expense from stock compensation			0
Book overdrafts	0	0	0
Net cash provided by (used in) financing activities	(128,872)	0	0
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of year	0	0	0
Cash and cash equivalents, end of year	0	0	0
Parent
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	(120,317)	(1,683)	1,781
INVESTING ACTIVITIES:
Capital expeditures	236	(3,594)	(3,927)
Producing property and other acquisitions	0	0	0
Proceeds from disposition of property and equipment	30	964	13
Other		0	750
Net cash provided by (used in) investing activities	266	(2,630)	(3,164)
FINANCING ACTIVITIES:
Borrowings under line of credit	97,100	343,900	251,398
Payments under line of credit	(275,100)	(326,700)	(371,600)
Intercompany borrowings (advances), net	204,809	(26,606)	126,797
Payments on capitalized leases	0	0	0
Proceeds from common stock issued, net of issue costs		18,623
Proceeds from investments of non-contolling interests	102,958
Contributions from Unit	0
Transaction costs associated with sale of non-controlling interest	(2,503)
Tax expense from stock compensation			(376)
Book overdrafts	(7,320)	(4,911)	(4,829)
Net cash provided by (used in) financing activities	119,944	4,306	1,390
Net increase (decrease) in cash and cash equivalents	(107)	(7)	7
Cash and cash equivalents, beginning of year	510	517	510
Cash and cash equivalents, end of year	403	510	517
Combined Guarantor Subsidiaries
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	327,075	224,446	197,132
INVESTING ACTIVITIES:
Capital expeditures	(400,990)	(233,254)	(158,983)
Producing property and other acquisitions	(29,970)	(58,026)	(564)
Proceeds from disposition of property and equipment	25,777	20,674	74,694
Other		(1,500)	0
Net cash provided by (used in) investing activities	(405,183)	(272,106)	(84,853)
FINANCING ACTIVITIES:
Borrowings under line of credit	0	0	0
Payments under line of credit	0	0	0
Intercompany borrowings (advances), net	78,125	47,475	(112,228)
Payments on capitalized leases	0	0	0
Proceeds from common stock issued, net of issue costs		0
Proceeds from investments of non-contolling interests	0
Transaction costs associated with sale of non-controlling interest	0
Tax expense from stock compensation			0
Book overdrafts	0	0	0
Net cash provided by (used in) financing activities	78,125	47,475	(112,228)
Net increase (decrease) in cash and cash equivalents	17	(185)	51
Cash and cash equivalents, beginning of year	191	376	325
Cash and cash equivalents, end of year	208	191	376
Combined Non-Guarantor Subsidiaries
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	12,129	43,193	41,217
INVESTING ACTIVITIES:
Capital expeditures	(45,528)	(18,705)	(23,239)
Producing property and other acquisitions	0	0	0
Proceeds from disposition of property and equipment	103	75	116
Other		0	169
Net cash provided by (used in) investing activities	(45,425)	(18,630)	(22,954)
FINANCING ACTIVITIES:
Borrowings under line of credit	2,000	0	0
Payments under line of credit	(2,000)	0	0
Intercompany borrowings (advances), net	(154,854)	(20,869)	(14,569)
Payments on capitalized leases	(3,843)	(3,694)	(3,694)
Proceeds from common stock issued, net of issue costs		0
Proceeds from investments of non-contolling interests	197,042
Contributions from Unit	792
Transaction costs associated with sale of non-controlling interest	0
Tax expense from stock compensation			0
Book overdrafts	0	0	0
Net cash provided by (used in) financing activities	39,137	(24,563)	(18,263)
Net increase (decrease) in cash and cash equivalents	5,841	0	0
Cash and cash equivalents, beginning of year	0	0	0
Cash and cash equivalents, end of year	$ 5,841	$ 0	$ 0