Industry Segment Information (Industry Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Revenues:
Oil and natural gas	$ 102,318		$ 83,173		$ 205,417		$ 170,771
Contract drilling	46,926		39,255		92,915		76,440
Gas gathering and processing	54,059		48,153		110,103		99,094
Total revenues	203,303		170,581		408,435		346,305
Operating costs:
Oil and natural gas	32,418		32,758		68,380		61,962
Contract drilling	31,894		27,239		63,561		56,466
Gas gathering and processing	39,703		36,042		81,307		73,746
Total operating costs	104,015		96,039		213,248		192,174
Depreciation, depletion, and amortization	58,373		50,080		115,439		97,012
Total expenses	162,388		146,119		328,687		289,186
General and administrative expense	(8,712)		(8,713)		(19,474)		(17,667)
Gain on disposition of assets	161		248		322		1,072
Gain (loss) on derivatives	(14,461)		8,902		(21,223)		23,633
Interest, net	(7,729)		(9,467)		(17,733)		(18,863)
Other	5		6		11		9
Income (loss) before income taxes	10,179		15,438		21,651		45,303
Oil and Natural Gas [Member]
Revenues:
Oil and natural gas	102,318	[1]	83,173		205,417	[2]	170,771
Contract drilling	0	[1]	0		0	[2]	0
Gas gathering and processing	0	[1]	0		0	[2]	0
Total revenues	102,318	[1]	83,173		205,417	[2]	170,771
Operating costs:
Oil and natural gas	33,682		33,941		70,834		64,267
Contract drilling	0		0		0		0
Gas gathering and processing	0		0		0		0
Total operating costs	33,682		33,941		70,834		64,267
Depreciation, depletion, and amortization	31,554		23,558		62,337		45,084
Total expenses	65,236		57,499		133,171		109,351
Total operating income (loss)	37,082	[3]	25,674	[4]	72,246	[5]	61,420	[6]
General and administrative expense	0		0		0		0
Gain on disposition of assets	59		168		129		177
Gain (loss) on derivatives	0		0		0		0
Interest, net	0		0		0		0
Other	0		0		0		0
Income (loss) before income taxes	37,141		25,842		72,375		61,597
Drilling [Member]
Revenues:
Oil and natural gas	0	[1]	0		0	[2]	0
Contract drilling	52,767	[1]	44,844		103,477	[2]	82,029
Gas gathering and processing	0	[1]	0		0	[2]	0
Total revenues	52,767	[1]	44,844		103,477	[2]	82,029
Operating costs:
Oil and natural gas	0		0		0		0
Contract drilling	36,921		32,452		72,875		61,679
Gas gathering and processing	0		0		0		0
Total operating costs	36,921		32,452		72,875		61,679
Depreciation, depletion, and amortization	13,726		13,769		27,038		26,616
Total expenses	50,647		46,221		99,913		88,295
Total operating income (loss)	2,120	[3]	(1,377)	[4]	3,564	[5]	(6,266)	[6]
General and administrative expense	0		0		0		0
Gain on disposition of assets	57		31		84		38
Gain (loss) on derivatives	0		0		0		0
Interest, net	0		0		0		0
Other	0		0		0		0
Income (loss) before income taxes	2,177		(1,346)		3,648		(6,228)
Mid-Stream [Member]
Revenues:
Oil and natural gas	0	[1]	0		0	[2]	0
Contract drilling	0	[1]	0		0	[2]	0
Gas gathering and processing	75,406	[1]	63,111		150,056	[2]	129,575
Total revenues	75,406	[1]	63,111		150,056	[2]	129,575
Operating costs:
Oil and natural gas	0		0		0		0
Contract drilling	0		0		0		0
Gas gathering and processing	59,786		49,817		118,806		101,922
Total operating costs	59,786		49,817		118,806		101,922
Depreciation, depletion, and amortization	11,175		10,849		22,228		21,667
Total expenses	70,961		60,666		141,034		123,589
Total operating income (loss)	4,445	[3]	2,445	[4]	9,022	[5]	5,986	[6]
General and administrative expense	0		0		0		0
Gain on disposition of assets	45		44		79		44
Gain (loss) on derivatives	0		0		0		0
Interest, net	(304)		0		(453)		0
Other	0		0		0		0
Income (loss) before income taxes	4,186		2,489		8,648		6,030
Other Segments [Member]
Revenues:
Oil and natural gas	0	[1]	0		0	[2]	0
Contract drilling	0	[1]	0		0	[2]	0
Gas gathering and processing	0	[1]	0		0	[2]	0
Total revenues	0	[1]	0		0	[2]	0
Operating costs:
Oil and natural gas	0		0		0		0
Contract drilling	0		0		0		0
Gas gathering and processing	3,576		0		3,576		0
Total operating costs	3,576		0		3,576		0
Depreciation, depletion, and amortization	1,918		1,904		3,836		3,645
Total expenses	5,494		1,904		7,412		3,645
Total operating income (loss)	(5,494)	[3]	(1,904)	[4]	(7,412)	[5]	(3,645)	[6]
General and administrative expense	(8,712)		(8,713)		(19,474)		(17,667)
Gain on disposition of assets	0		5		30		813
Gain (loss) on derivatives	(14,461)		8,902		(21,223)		23,633
Interest, net	(7,425)		(9,467)		(17,280)		(18,863)
Other	3,581		6		3,587		9
Income (loss) before income taxes	(32,511)		(11,171)		(61,772)		(15,720)
Eliminations [Member]
Revenues:
Oil and natural gas	0		0		0		0
Contract drilling	(5,841)		(5,589)		(10,562)		(5,589)
Gas gathering and processing	(21,347)		(14,958)		(39,953)		(30,481)
Total revenues	(27,188)		(20,547)		(50,515)		(36,070)
Operating costs:
Oil and natural gas	(1,264)		(1,183)		(2,454)		(2,305)
Contract drilling	(5,027)		(5,213)		(9,314)		(5,213)
Gas gathering and processing	(23,659)		(13,775)		(41,075)		(28,176)
Total operating costs	(29,950)		(20,171)		(52,843)		(35,694)
Depreciation, depletion, and amortization	0		0		0		0
Total expenses	(29,950)		(20,171)		(52,843)		(35,694)
Total operating income (loss)	2,762	[3]	(376)	[4]	2,328	[5]	(376)	[6]
General and administrative expense	0		0		0		0
Gain on disposition of assets	0		0		0		0
Gain (loss) on derivatives	0		0		0		0
Interest, net	0		0		0		0
Other	(3,576)		0		(3,576)		0
Income (loss) before income taxes	$ (814)		$ (376)		$ (1,248)		$ (376)

[1] The revenues for oil and natural gas occur at a point in time. The revenues for contract drilling and gas gathering and processing occur over time.

[2] The revenues for oil and natural gas occur at a point in time. The revenues for contract drilling and gas gathering and processing occur over time.

[3] Operating income (loss) is total operating revenues less operating expenses, depreciation, depletion, and amortization and does not include general corporate expenses, gain on disposition of assets, loss on derivatives, interest, net, other income, or income taxes.

[4] Operating income (loss) is total operating revenues less operating expenses, depreciation, depletion, and amortization and does not include general corporate expenses, gain on disposition of assets, gain on derivatives, interest, net, other income, or income taxes.

[5] Operating income (loss) is total operating revenues less operating expenses, depreciation, depletion, and amortization and does not include general corporate expenses, gain on disposition of assets, loss on derivatives, interest, net, other income, or income taxes.

[6] Operating income (loss) is total operating revenues less operating expenses, depreciation, depletion, and amortization and does not include general corporate expenses, gain on disposition of assets, gain on derivatives, interest, net, other income, or income taxes.