Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Operating revenues:
Oil and natural gas	$ 14,717		$ 14,690		$ 31,502		$ 29,407
Total operating revenues	659,316		681,112		1,326,355		1,427,033
Operating costs and expenses:
Contract drilling	242,748		272,720		489,820		555,369
Pressure pumping	188,280		138,051		356,436		304,908
Oil and natural gas	3,214		2,583		6,136		5,313
Depreciation, depletion, amortization and impairment	137,182		128,477		273,617		251,430
Selling, general and administrative	18,319		16,719		35,716		30,587
Net gain on asset disposals	(1,033)	[1]	(28,332)	[1]	(908)	[1]	(30,732)	[1]
Provision for bad debts							1,600
Total operating costs and expenses	588,710		530,218		1,160,817		1,118,475
Operating income	70,606		150,894		165,538		308,558
Other income (expense):
Interest income	250		179		423		233
Interest expense	(6,941)		(5,051)		(13,707)		(9,633)
Other	381		(144)		400		(89)
Total other expense	(6,310)		(5,016)		(12,884)		(9,489)
Income before income taxes	64,296		145,878		152,654		299,069
Income tax expense (benefit):
Current	2,335		(829)		9,908		6,681
Deferred	21,193		54,169		45,748		102,576
Total income tax expense	23,528		53,340		55,656		109,257
Net income	40,768		92,538		96,998		189,812
Net income per common share:
Basic	$ 0.28		$ 0.60		$ 0.66		$ 1.22
Diluted	$ 0.28		$ 0.60		$ 0.66		$ 1.22
Weighted average number of common shares outstanding:
Basic	145,465		153,269		145,148		153,947
Diluted	146,374		153,655		146,292		154,544
Cash dividends per common share	$ 0.05		$ 0.05		$ 0.10		$ 0.10
Contract Drilling
Operating revenues:
Oil and gas services	389,979		460,249		809,073		949,731
Pressure Pumping
Operating revenues:
Oil and gas services	$ 254,620		$ 206,173		$ 485,780		$ 447,895

[1] Net gains or losses associated with the disposal of assets relate to corporate strategy decisions of the executive management group. Accordingly, the related gains or losses have been separately presented and excluded from the results of specific segments.