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

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

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

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

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

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

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

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Percentage of vesting of share-based compensation awards.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Equity Incentive Plans and Stock-Based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Apr. 23, 2015
Stock-Based Compensation
Entity Closing Stock Price	$ 13.35		$ 13.35
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	$ 0.2		$ 0.8
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			150.00%
Stock Compensation Plan [Member]
Stock-Based Compensation
Shares available for issuance	5,287,247		5,287,247		7,305,368
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	35,400,000		35,400,000			4,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures			498,426
Employee Stock Option [Member]
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	4,658,993		4,658,993		7,008,833
Share Based Compensation Arrangement by Share Based Payment Award Options, In The Money Outstanding, Number	4,156,223		4,156,223
Share Based Compensation Arrangement By Share Based Payment Award, Options in the Money Exercisable, Number	3,132,148		3,132,148
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures			498,426	440,000
Share Based Compensation Arrangement by Share Based Payment Award Options, Grants in Period, Total Fair Value			$ 2.1	$ 2.1
Stock-based compensation	$ 0.7	$ 1.0	2.1	3.3
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	4.0		$ 4.0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			2 years 5 months 5 days
Total fair value of options vested	18.9		$ 18.9
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 1.9	3.0	5.7	7.0
Proceeds from Stock Options Exercised			$ 7.1
Employee Stock [Member]
Stock-Based Compensation
Shares available for issuance	1,089,649		1,089,649
Share Based Compensation Arrangement by Share Based Payment Award Discount from Market Price Specific Date			15.00%
Stock-based compensation	$ 0.4	$ 0.3	$ 1.3	$ 1.1
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 0.1		$ 0.1
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 month
Stock Issued During Period, Shares, Employee Stock Purchase Plans			361,994	340,349
Employee Stock Purchase Plans Price Per Share			$ 10.33	$ 8.96
Restricted Stock and Stock Units [Member]
Stock-Based Compensation
Granted (in shares)	463,346	884,724	2,654,508	2,909,364
Stock-based compensation	$ 5.9	$ 4.1	$ 16.7	$ 10.9
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 46.4		$ 46.4
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 5 months 27 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	$ 6.0	12.6	$ 34.1	37.6
Stock Options with Market Condition [Member] \| Employee Stock Option [Member]
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	50,000		50,000		1,135,000
Performance Shares [Member] \| Restricted Stock and Stock Units [Member]
Stock-Based Compensation
Stock-based compensation	$ 1.2	$ 0.7	$ 3.1	$ 2.0
Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Nonvested Requisite Service Period	2 years 4 months 24 days
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