Stockholder's Equity (Deficit) - Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value per share (usd per share)	$ 1.08	$ 25.40	$ 6.17	$ 45.60
2016 Employee Equity Compensation Plan and 2018 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense	$ 0.8	$ 1.0	$ 1.9	$ 2.0
Fair Value per share (usd per share)	$ 1.08	$ 25.40	$ 6.17	$ 45.60
Grant date fair value		$ 0.1	$ 1.4	$ 1.2
Options exercised (shares)			0
Unrecognized share-based compensation expense	$ 4.9		$ 4.9
Weighted average grant date fair value, period			1 year 8 months 27 days

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

Amount of cost expensed and capitalized for award under share-based payment arrangement.

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- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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- Definition

Number of share options (or share units) exercised during the current period.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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