Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements (Details 5) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net loss	$ (13,119)	$ (919)	$ (17,921)	$ (88)
Stock based compensation			1,103	1,739
Partial extinguishment of Convertible 3.75% Senior Notes	2,467	$ 0	2,467	0
Accounts receivable			(4,227)	(4,008)
Accounts payable and accrued expenses			(4,086)	892
Net cash used in operating activities			(12,510)	(1,307)
Capital expenditures			(12,523)	(15,286)
Net cash used in investing activities			(12,523)	(15,286)
Capitalized stock compensation in capital expenditures			63	66
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net loss	(20,716)		(25,518)
Stock based compensation			1,113
Partial extinguishment of Convertible 3.75% Senior Notes	10,069		10,069
Accounts receivable			1,023	(5,530)
Accounts payable and accrued expenses			(9,604)	2,414
Net cash used in operating activities			(12,763)
Capital expenditures			(12,270)
Net cash used in investing activities			(12,270)
Capitalized stock compensation in capital expenditures			53
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net loss	7,597		7,597
Stock based compensation			(10)
Partial extinguishment of Convertible 3.75% Senior Notes	$ (7,602)		(7,602)
Accounts receivable			(5,250)	(1,522)
Accounts payable and accrued expenses			5,518	$ 1,522
Net cash used in operating activities			253
Capital expenditures			(253)
Net cash used in investing activities			(253)
Capitalized stock compensation in capital expenditures			$ 10