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Equity Incentive Plans and Stock-Based Compensation (Details Textual) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate			0.00%
Minimum
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			0.00%
Maximum
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			200.00%
Stock Compensation Plan [Member]
Stock-Based Compensation
Shares available for issuance	5,206,741		5,206,741		10,074,046
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures			0
Options
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	1,964,585		1,964,585		3,235,891
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures		100,000	0	600,000
Share Based Compensation Arrangement by Share Based Payment Award Options, Grants in Period, Total Fair Value		$ 0.3		$ 2.6
Stock-based compensation	$ 0.2	0.5	$ 0.5	1.0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 3.0		$ 3.0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			2 years 3 months 18 days
Employee Stock
Stock-Based Compensation
Shares available for issuance	1,900,000		1,900,000
Share Based Compensation Arrangement by Share Based Payment Award Discount from Market Price Specific Date			15.00%
Stock-based compensation	$ 0.3	$ 0.3	$ 0.8	$ 0.8
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 0.4		$ 0.4
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			4 months
Restricted Stock and Stock Units
Stock-Based Compensation
Granted (in shares)	300,000	300,000	3,691,157	2,400,000
Stock-based compensation	$ 6.5	$ 1.1	$ 12.9	$ 7.6
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	45.5		$ 45.5
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			2 years 7 months 6 days
Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Nonvested Requisite Service Period			4 years
Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Nonvested Grants in Period Total Fair Value	$ 3.4	$ 4.5	$ 35.6	$ 31.5
Director [Member] | Restricted Stock and Stock Units
Stock-Based Compensation
Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Nonvested Requisite Service Period			1 year

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- Definition

The discount rate from market value on specific date that participants pay for shares.

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Represents the total fair value of nonvested equity stock units granted during the period.

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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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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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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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

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