CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Revenues	$ 291,924	$ 620,684	$ 995,754	$ 1,705,207
Cost of revenues (exclusive of items shown below)	234,640	398,306	768,702	1,102,596
Selling, general and administrative expenses	35,921	50,814	118,955	147,125
Depreciation and amortization	69,047	57,219	204,824	169,241
Loss on disposition of assets, net	3,791	7,684	1,115	11,321
Operating (loss) profit	(51,475)	106,661	(97,842)	274,924
Interest expense	(250)	(456)	(1,331)	(842)
Interest income	5	4	20	14
Other (expense) income, net	(2,219)	(454)	3,902	457
(Loss) income before income taxes	(53,939)	105,755	(95,251)	274,553
Income tax (benefit) provision	(18,766)	40,870	(33,571)	106,997
Net (loss) income	$ (35,173)	$ 64,885	$ (61,680)	$ 167,556
(Loss) earnings per share
Basic (in dollars per share)	$ (0.16)	$ 0.30	$ (0.29)	$ 0.78
Diluted (in dollars per share)	$ (0.16)	0.30	(0.29)	0.77
Dividends per share (in dollars per share)		$ 0.105	$ 0.155	$ 0.315
Weighted average shares outstanding
Basic (in shares)	213,679	215,202	213,617	215,200
Diluted (in shares)	213,679	216,334	213,617	216,316