CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
REVENUE - Service revenue	$ 459,888	$ 213,492	$ 845,107	$ 385,423
COSTS AND EXPENSES
Cost of services (exclusive of depreciation and amortization)	351,888	176,777	650,010	326,342
General and administrative (inclusive of stock-based compensation)	14,178	7,916	26,122	27,776
Depreciation and amortization	21,276	12,706	40,211	23,857
Loss on disposal of assets	18,990	9,787	26,655	20,229
Total costs and expenses	406,332	207,186	742,998	398,204
OPERATING INCOME (LOSS)	53,556	6,306	102,109	(12,781)
OTHER INCOME (EXPENSE):
Interest expense	(2,231)	(650)	(3,492)	(5,825)
Other income (expense)	(182)	(627)	(412)	(602)
Total other income (expense)	(2,413)	(1,277)	(3,904)	(6,427)
INCOME (LOSS) BEFORE INCOME TAXES	51,143	5,029	98,205	(19,208)
INCOME TAX EXPENSE	(12,052)	(108)	(22,406)	(223)
NET INCOME (LOSS)	$ 39,091	$ 4,921	$ 75,799	$ (19,431)
NET INCOME (LOSS) PER COMMON SHARE:
Basic (in dollars per share)	$ 0.47	$ 0.06	$ 0.91	$ (0.28)
Diluted (in dollars per share)	$ 0.45	$ 0.06	$ 0.87	$ (0.28)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (in shares)	83,447	83,040	83,265	69,593
Diluted (in shares)	86,878	86,279	87,124	69,593