Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Revenues	$ 126,287	$ 117,281	$ 107,130	$ 95,757	$ 71,481	$ 68,353	$ 62,290	$ 74,952	$ 446,455	$ 277,076	$ 540,778
Costs and expenses:
Operating costs									330,880	203,949	358,016
Depreciation and amortization									98,777	114,312	150,939
General and administrative									69,681	61,184	73,903
Bad debt expense (recovery)									53	156	(188)
Impairment									1,902	12,815	129,152
Gain on dispositions of property and equipment, net									(3,608)	(1,892)	(4,344)
Total costs and expenses									497,685	390,524	707,478
Loss from operations	(8,736)	(10,892)	(12,729)	(18,873)	(34,524)	(29,885)	(26,025)	(23,014)	(51,230)	(113,448)	(166,700)
Other income (expense):
Interest expense, net of interest capitalized									(27,039)	(25,934)	(21,222)
Loss on extinguishment of debt									(1,476)	(299)	(2,186)
Other income (expense), net									424	558	(2,611)
Total other expense, net									(28,091)	(25,675)	(26,019)
Loss before income taxes									(79,321)	(139,123)	(192,719)
Income tax benefit	5,403	(17)	(1,135)	(48)	5,086	1,698	1,990	1,958	4,203	10,732	37,579
Net loss	$ (12,558)	$ (17,227)	$ (20,209)	$ (25,124)	$ (36,081)	$ (34,620)	$ (29,991)	$ (27,699)	$ (75,118)	$ (128,391)	$ (155,140)
Loss per common share - Basic	$ (0.16)	$ (0.22)	$ (0.26)	$ (0.33)	$ (0.53)	$ (0.53)	$ (0.46)	$ (0.43)	$ (0.97)	$ (1.96)	$ (2.41)
Loss per common share - Diluted	$ (0.16)	$ (0.22)	$ (0.26)	$ (0.33)	$ (0.53)	$ (0.53)	$ (0.46)	$ (0.43)	$ (0.97)	$ (1.96)	$ (2.41)
Weighted average number of shares outstanding - Basic									77,390	65,452	64,310
Weighted-average number of shares outstanding - Diluted									77,390	65,452	64,310