The number of shares under options that are converted to liability during the reporting period.

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Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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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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Aggregate number of common shares reserved for future issuance.

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Unrecognized cost of unvested share-based compensation awards.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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

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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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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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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Percentage of vesting of share-based compensation awards.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of share options (or share units) exercised during the current period.

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Stock-Based Compensation Plans, Stock-Based Award Plan Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued liabilities	$ 271.2	$ 258.5
2013 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant and reserved for issuance (in shares)	20,900
2013 Stock Incentive Plan [Member] \| Equity Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0.0
2013 Stock Incentive Plan [Member] \| Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued liabilities	16.8
2013 Stock Incentive Plan [Member] \| Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	77.6
2013 Stock Incentive Plan [Member] \| Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	77.6
Unrecognized compensation cost	$ 9.1	$ 68.0
2013 Stock Incentive Plan [Member] \| Stock Options and Stock Appreciation Rights [Member]
Shares [Roll Forward]
Outstanding, beginning balance (in shares)	13,285	17,033	18,214
Granted (in shares)	799	2,427	1,075
Settled (in shares)	(193)	(1,980)	(304)
Forfeited (in shares)	(1,057)	(2,931)	(1,952)
Converted to liability (in shares)		(1,264)
Outstanding, ending balance (in shares)	12,834	13,285	17,033
Vested (in shares)	9,459
Outstanding Weighted-Average Exercise Price [Abstract]
Outstanding, beginning balance (in dollars per share)	$ 8.85	$ 8.36	$ 8.23
Granted (in dollars per share)	20.00	10.75	10.61
Settled (in dollars per share)	8.17	8.18	8.33
Forfeited (in dollars per share)	8.34	8.31	8.43
Converted to liability (in dollars per share)		8.16
Outstanding, ending balance (in dollars per share)	9.54	$ 8.85	$ 8.36
Vested (in dollars per share)	$ 9.05
Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, weighted average remaining contractual term	6 years 9 months 22 days
Vested, weighted average remaining contractual term	6 years 7 months 2 days
Outstanding, aggregate intrinsic value of in-the-money options	$ 313.1
Vested, aggregate intrinsic value of in-the-money options	235.4
2013 Stock Incentive Plan [Member] \| Time Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 77.6
2013 Stock Incentive Plan [Member] \| 5 Years Vesting [Member] \| Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 5 Years Vesting [Member] \| Time Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 4 Years Vesting [Member] \| Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 4 Years Vesting [Member] \| Time Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 3 Years Vesting [Member] \| Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 3 Years Vesting [Member] \| Time Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%