Industry Segment Information (Industry Segment Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Revenues:
Oil and natural gas	$ 153,609		$ 135,765
Contract drilling	119,353		152,459
Elimination of inter-segment revenue	(11,825)		(11,553)
Contract drilling net of inter-segment revenue	107,528		140,906
Gas gathering and processing	80,156		74,255
Elimination of inter-segment revenue	(22,761)		(16,960)
Gas gathering and processing net of inter-segment revenue	57,395		57,295
Total revenues	318,532		333,966
Operating income
Oil and natural gas	58,588		47,959
Contract drilling	24,266		43,405
Gas gathering and processing	829		4,548
Total operating income	83,683	[1]	95,912	[1]
General and administrative expense	(8,673)		(7,004)
Loss on derivatives not designated as hedges and hedge ineffectiveness, net	(5,924)		(1,993)
Interest expense, net	(3,561)		(1,826)
Other Income	(150)		455
Income before income taxes	$ 65,375		$ 85,544

[1] Total operating income is total operating revenues less operating expenses, depreciation, depletion, and amortization and does not include non-operating revenues, general corporate expenses, interest expense, or income taxes.