Industry Segment Information (Industry Segment Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Revenues:
Oil and natural gas	$ 188,471		$ 157,320		$ 575,176		$ 475,728
Contract drilling	147,866		119,105		407,905		357,118
Elimination of inter-segment revenue	(27,214)		(18,458)		(66,375)		(43,938)
Contract drilling net of inter-segment revenue	120,652		100,647		341,530		313,180
Gas gathering and processing	113,467		99,007		350,181		272,073
Elimination of inter-segment revenue	(21,616)		(23,198)		(72,494)		(68,252)
Gas gathering and processing net of inter-segment revenue	91,851		75,809		277,687		203,821
Total revenues	400,974		333,776		1,194,393		992,729
Operating income
Oil and natural gas	69,597		50,887		240,239		173,945
Contract drilling	31,365		24,257		83,311		72,030
Gas gathering and processing	3,021		3,938		9,549		7,613
Total operating income	103,983	[1]	79,082	[1]	333,099	[1]	253,588	[1]
General and administrative	(10,172)		(9,936)		(30,409)		(28,288)
Gain (loss) on disposition of assets	(529)		4,345		9,092		7,744
Gain (loss) on derivatives not designated as hedges and hedge ineffectiveness, net	19,841		(13,760)		(9,234)		(3,340)
Interest expense, net	(4,280)		(3,625)		(12,201)		(11,777)
Other	(68)		(14)		3		(171)
Income before income taxes	$ 108,775		$ 56,092		$ 290,350		$ 217,756

[1] Operating income is total operating revenues less operating expenses, depreciation, depletion, amortization, and impairment and does not include general corporate expenses, gain (loss) on disposition of assets, gain (loss) on non-designated hedges and hedge ineffectiveness, interest expense, other income (loss), or income taxes.