Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (75,118)	$ (128,391)	$ (155,140)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	98,777	114,312	150,939
Allowance for doubtful accounts, net of recoveries	53	156	248
Write-off of obsolete inventory	0	101	0
Gain on dispositions of property and equipment, net	(3,608)	(1,892)	(4,344)
Stock-based compensation expense	4,349	3,944	3,629
Amortization of debt issuance costs and discount	1,548	1,776	1,691
Loss on extinguishment of debt	1,476	299	2,186
Impairment	1,902	12,815	129,152
Deferred income taxes	(5,030)	(11,608)	(39,286)
Change in other long-term assets	(1)	662	420
Change in other long-term liabilities	1,994	478	(132)
Changes in current assets and liabilities:
Receivables	(49,750)	16,341	114,644
Inventory	(4,397)	(630)	1,267
Prepaid expenses and other current assets	744	310	1,769
Accounts payable	12,409	1,969	(30,514)
Deferred revenues	(348)	(3,985)	1,922
Accrued expenses	9,183	(1,526)	(35,732)
Net cash provided by (used in) operating activities	(5,817)	5,131	142,719
Cash flows from investing activities:
Purchases of property and equipment	(63,277)	(32,381)	(159,615)
Proceeds from sale of property and equipment	12,569	7,577	57,674
Proceeds from insurance recoveries	3,344	37	285
Net cash used in investing activities	(47,364)	(24,767)	(101,656)
Cash flows from financing activities:
Debt repayments	(120,000)	(71,000)	(60,002)
Proceeds from issuance of debt	245,500	22,000	0
Debt issuance costs	(6,332)	(819)	(1,877)
Proceeds from exercise of options	0	183	781
Proceeds from issuance of common stock, net of offering costs of $4,001	0	65,430	0
Purchase of treasury stock	(533)	(124)	(729)
Net cash provided by (used in) financing activities	118,635	15,670	(61,827)
Net increase (decrease) in cash, cash equivalents and restricted cash	65,454	(3,966)	(20,764)
Beginning cash, cash equivalents, and restricted cash	10,194	14,160	34,924
Ending cash, cash equivalents, and restricted cash	75,648	10,194	14,160
Supplementary disclosure:
Interest paid	25,082	24,516	22,506
Income tax paid	1,431	671	2,691
Noncash investing and financing activity:
Change in capital expenditure accruals	$ (1,830)	$ 175	$ (16,708)