Stock-Based Compensation - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)	3,636,000
Expected dividend	0.00%
Granted (in shares)	340,558,000	225,745,000
Award vesting period	4 years
Intrinsic value	$ 0.0	$ 0.2
Compensation expense	$ 0.0	$ 1.5
Stock issued (in shares)		91,168
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend	0.00%	0.00%
Granted (in shares)	340,558	225,745
Compensation expense	$ 0.8	$ 0.3
Unrecognized compensation cost	$ 2.7
Weighted average period	2 years 11 months 6 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 1.5	0.4
Unrecognized compensation cost	$ 4.0
Weighted average period	2 years 11 months 12 days
Intrinsic value for restricted stock outstanding	$ 5.2	$ 1.9

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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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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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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Gross number of share options (or share units) granted during the period.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of share instruments newly issued under a share-based compensation plan.

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Intrinsic value of equity-based compensation awards outstanding. Excludes stock and unit options.

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