Represents the weighted average price per share of shares issued under the Employee Stock Purchase Plan.

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- Definition

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

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No definition available.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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).

+ References

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued 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 number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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No definition available.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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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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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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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

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

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- Definition

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

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

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 3) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate			0.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans			429,396	297,497
Employee Stock Purchase Plans, Weighted Average Price Per Share			$ 7.95	$ 11.66
Options
Stock-Based Compensation
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
Valuation assumptions
Expected stock price volatility (as a percent)		24.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		2.70%
Expected term		5 years 9 months 18 days		5 years 9 months 18 days
Weighted-average fair value of stock options granted (in dollars per share)		$ 3.94		$ 4.21
Employee Stock Purchase Plan
Valuation assumptions
Expected stock price volatility (as a percent)			32.00%	27.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate			2.44%	2.05%
Expected term			6 months	6 months
Weighted-average fair value of stock options granted (in dollars per share)			$ 2.80	$ 3.14
Restricted Stock and Stock Units
Nonvested equity stock and stock units
Nonvested at the beginning of the period (in shares)			4,859,135
Granted (in shares)	300,000	300,000	3,691,157	2,400,000
Vested (in shares)			(1,201,894)
Forfeited (in shares)			(674,764)
Nonvested at the end of the period (in shares)	6,673,634		6,673,634
Weighted-Average Grant-Date Fair Value
Nonvested at the beginning of the period (in dollars per share)			$ 12.71
Granted (in dollars per share)			9.70
Vested (in dollars per share)			12.55
Forfeited (in dollars per share)			11.63
Nonvested at the end of the period (in dollars per share)	$ 11.18		$ 11.18
Minimum \| Options
Valuation assumptions
Expected stock price volatility (as a percent)				24.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate				2.60%
Maximum \| Options
Valuation assumptions
Expected stock price volatility (as a percent)				29.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate				2.70%