Stockholders' Investment (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 88,538	$ 177,940	$ 111,733	$ 197,468
Net Income	(41,955)	(37,863)	(65,598)	(57,806)
Share-based compensation	372	658	895	1,268
Issuance of warrants	0	2,571	0	2,571
Issuance of restricted stock units, net of taxes paid	(1)	(20)	(76)	(215)
Ending balance	46,954	$ 143,286	46,954	$ 143,286
Retained Earnings (Accumulated Deficit)	$ (357,415)		$ (357,415)			$ (292,703)
Difference between Revenue Guidance in Effect before and after Topic 606
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Retained Earnings (Accumulated Deficit)					$ 900

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The cash inflow from issuance of rights to purchase common shares at predetermined price (usually issued together with corporate debt).

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The value of restricted shares issued as compensation, net of the value of shares for the payment of withholding taxes. This element is to be used only if shares are used in lieu of cash to satisfy all or a portion of withholding taxes.

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The cumulative amount of the reporting entity's undistributed earnings or deficit.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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