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

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Represents the total fair value of vested stock options.

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

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Represents the total fair value of options for granted during the period.

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No definition available.

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Represents the number of in-the-money stock options exercisable.

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No definition available.

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Represents the number of in-the-money stock options outstanding.

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No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 718
-SubTopic 10
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- Definition

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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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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- Definition

Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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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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- Definition

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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- Definition

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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-Publisher FASB
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- Definition

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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- Definition

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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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

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

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Number of options outstanding, including both vested and non-vested options.

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-Publisher FASB
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- Definition

Price of a single share of a number of saleable stocks of a company.

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No definition available.

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- Definition

Percentage of vesting of share-based compensation awards.

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Equity Incentive Plans and Stock-Based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Apr. 23, 2015
Stock-Based Compensation
Entity Closing Stock Price	$ 13.43
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	$ 0.2	$ 0.3
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%
Minimum [Member]
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	0.00%
Maximum [Member]
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	1,387,911		5,051,147
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	35,400,000			4,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	551,479
Employee Stock Option [Member]
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	4,552,901		4,310,361
Share Based Compensation Arrangement by Share Based Payment Award Options, In The Money Outstanding, Number	4,195,277
Share Based Compensation Arrangement By Share Based Payment Award, Options in the Money Exercisable, Number	2,962,040
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	551,479	458,426
Share Based Compensation Arrangement by Share Based Payment Award Options, Grants in Period, Total Fair Value	$ 2.3	$ 1.9
Stock-based compensation	0.6	0.8
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 5.0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	3 years 4 days
Total fair value of options vested	$ 15.6
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	1.0	2.0
Proceeds from Stock Options Exercised	$ 1.1
Employee Stock [Member]
Stock-Based Compensation
Shares available for issuance	836,273
Share Based Compensation Arrangement by Share Based Payment Award Discount from Market Price Specific Date	15.00%
Stock-based compensation	$ 0.5	$ 0.5
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 0.2
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 month
Restricted Stock and Stock Units [Member]
Stock-Based Compensation
Granted (in shares)	2,076,197	2,039,808
Stock-based compensation	$ 6.5	$ 5.3
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 57.2
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 8 months 1 day
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	$ 26.8	26.2
Performance Shares [Member] \| Restricted Stock and Stock Units [Member]
Stock-Based Compensation
Stock-based compensation	$ 1.3	$ 0.9
Director [Member] \| Restricted Stock and Stock Units [Member]
Stock-Based Compensation
Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Nonvested Requisite Service Period	1 year