CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
REVENUE - Service revenue	$ 981,865,000	$ 436,920,000	$ 569,618,000
COSTS AND EXPENSES:
Cost of services (exclusive of depreciation and amortization)	813,823,000	404,140,000	483,338,000
General and administrative (inclusive of stock‑based compensation)	49,215,000	26,613,000	27,370,000
Depreciation and amortization	55,628,000	43,542,000	50,134,000
Property and equipment impairment expense	0	6,305,000	36,609,000
Goodwill impairment expense	0	1,177,000	0
Loss on disposal of assets	39,086,000	22,529,000	21,268,000
Total costs and expenses	957,752,000	504,306,000	618,719,000
OPERATING INCOME (LOSS)	24,113,000	(67,386,000)	(49,101,000)
OTHER INCOME (EXPENSE):
Interest expense	(7,347,000)	(20,387,000)	(21,641,000)
Gain on extinguishment of debt	0	6,975,000	0
Other expense	(1,025,000)	(321,000)	(499,000)
Total other income (expense)	(8,372,000)	(13,733,000)	(22,140,000)
INCOME (LOSS) BEFORE INCOME TAXES	15,741,000	(81,119,000)	(71,241,000)
INCOME TAX (EXPENSE)/BENEFIT	(3,128,000)	27,972,000	25,388,000
NET INCOME (LOSS)	$ 12,613,000	$ (53,147,000)	$ (45,853,000)
NET INCOME (LOSS) PER COMMON SHARE:
Basic (in dollars per share)	$ 0.17	$ (1.19)	$ (1.31)
Diluted (in dollars per share)	$ 0.16	$ (1.19)	$ (1.31)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (in shares)	76,371	44,787	34,993
Diluted (in shares)	79,583	44,787	34,993