Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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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 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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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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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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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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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Stock-Based Compensation - Stock-Based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation
Unrecognized compensation expense	$ 94.6		$ 94.6
Weighted average period of unrecognized compensation expense (in years)			3 years
Employee Stock Option
Share-based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures			850
Granted (in dollars per share)			$ 48.30
Estimated weighted-average grant-date fair value (usd per share)			$ 13.50
Total intrinsic value of options exercised	1.9	$ 0.7	$ 2.6	$ 3.6
Net cash proceeds from the exercise of stock options	$ 1.2	$ 0.4	$ 1.9	$ 2.7
Restricted Stock Units (RSUs)
Share-based Compensation
Granted (in shares)			1,261
2015 Equity Incentive Plan \| Performance Based Restricted Stock
Share-based Compensation
Granted (in shares)			185
Vesting period of restricted stock			4 years
2015 Equity Incentive Plan \| Restricted Stock Units (RSUs)
Share-based Compensation
Vesting period of restricted stock			4 years