CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenues	$ 298,119	$ 189,095
Cost of revenues (exclusive of items shown below)	216,242	161,256
Selling, general and administrative expenses	37,157	43,546
Depreciation and amortization	44,663	60,636
Gain on disposition of assets, net	(1,517)	(1,256)
Operating income (loss)	1,574	(75,087)
Interest expense	(103)	(325)
Interest income	129	23
Other income, net	212	342
Income (loss) before income taxes	1,812	(75,047)
Income tax benefit	(1,822)	(42,536)
Net income (loss)	$ 3,634	$ (32,511)
Earnings (loss) per share
Basic (in dollars per share)	$ 0.02	$ (0.15)
Diluted (in dollars per share)	0.02	(0.15)
Dividends per share (in dollars per share)