Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net loss	$ (49,011)	$ (75,118)	$ (128,391)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation	93,554	98,777	114,312
Allowance for doubtful accounts, net of recoveries	271	53	156
Write-off of obsolete inventory	0	0	101
Gain on dispositions of property and equipment, net	(3,121)	(3,608)	(1,892)
Stock-based compensation expense	4,444	4,349	3,944
Phantom stock compensation expense	46	1,609	1,971
Amortization of debt issuance costs and discount	2,900	1,548	1,776
Loss on extinguishment of debt	0	1,476	299
Impairment	4,422	1,902	12,815
Deferred income taxes	538	(5,030)	(11,608)
Change in other noncurrent assets	565	(1)	662
Change in other noncurrent liabilities	(426)	385	(1,493)
Changes in current assets and liabilities:
Receivables	(8,644)	(49,750)	16,341
Inventory	(4,841)	(4,397)	(630)
Prepaid expenses and other current assets	(1,139)	744	310
Accounts payable	(1,272)	12,409	1,969
Deferred revenues	420	(348)	(3,985)
Accrued expenses	950	9,183	(1,526)
Net cash provided by (used in) operating activities	39,656	(5,817)	5,131
Cash flows from investing activities:
Purchases of property and equipment	(67,148)	(63,277)	(32,381)
Proceeds from sale of property and equipment	5,864	12,569	7,577
Proceeds from insurance recoveries	1,082	3,344	37
Net cash used in investing activities	(60,202)	(47,364)	(24,767)
Cash flows from financing activities:
Debt repayments	0	(120,000)	(71,000)
Proceeds from issuance of debt	0	245,500	22,000
Debt issuance costs	0	(6,332)	(819)
Proceeds from exercise of options	11	0	183
Proceeds from issuance of common stock, net of offering costs of $4,001	0	0	65,430
Net cash provided by (used in) financing activities	(538)	118,635	15,670
Net increase (decrease) in cash, cash equivalents and restricted cash	(21,084)	65,454	(3,966)
Beginning cash, cash equivalents, and restricted cash	75,648	10,194	14,160
Ending cash, cash equivalents, and restricted cash	54,564	75,648	10,194
Supplementary disclosure:
Interest paid	36,624	25,082	24,516
Change in capital expenditure accruals	5,706	(1,830)	175
Income tax paid	3,556	1,431	671
Purchase of treasury stock	$ (549)	$ (533)	$ (124)