CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONSOLIDATED STATEMENTS OF OPERATIONS
REVENUES	$ 1,222,409	$ 1,721,005	$ 1,595,227
Cost of revenues (exclusive of items shown separately below)	919,595	1,183,048	1,050,809
Selling, general and administrative expenses	168,127	168,151	159,194
Impairment and other charges	82,273
Depreciation and amortization	170,409	163,120	163,537
Gain on disposition of assets, net	(3,707)	(3,344)	(4,530)
Operating (loss) profit	(114,288)	210,030	226,217
Interest expense	(334)	(489)	(426)
Interest income	1,906	2,426	1,494
Other (expense) income, net	(385)	9,313	5,531
(Loss) income before income taxes	(113,101)	221,280	232,816
Income tax (benefit) provision	(25,990)	45,878	70,305
Net (loss) income	$ (87,111)	$ 175,402	$ 162,511
(LOSS) EARNINGS PER SHARE
Basic (in dollars per share)	$ (0.41)	$ 0.82	$ 0.75
Diluted (in dollars per share)	(0.41)	0.82	0.75
Dividends paid per share (in dollars per share)	$ 0.15	$ 0.47	$ 0.20