The increase (decrease) during the reporting period in the aggregate amount of expenses incurred.

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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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-Publisher FASB
-Name Accounting Standards Codification
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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

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

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No definition available.

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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.

+ References

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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

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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Stock-Based Compensation, Stock-Based Award Plan Activity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Share-based Compensation Arrangement [Abstract]
Stock-based compensation expense	$ 1.8	$ 61.4	$ 5.2	$ 61.4
Accrued liabilities	252.6		$ 252.6		$ 271.2
Risk-free interest rate			2.00%
Expected dividend rate			0.00%
Unrecognized compensation expense	25.9		$ 25.9
Minimum [Member]
Share-based Compensation Arrangement [Abstract]
Expected life of options			1 year
Assumed volatility			26.80%
Maximum [Member]
Share-based Compensation Arrangement [Abstract]
Expected life of options			1 year 3 months 18 days
Assumed volatility			27.30%
2013 Stock Incentive Plan [Member] \| Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement [Abstract]
Accrued liabilities	$ 14.3		$ 14.3
2013 and 2017 Plan [Member] \| Former Employee [Member]
Share-based Compensation Arrangement [Abstract]
Stock-based compensation expense			3.8
2013 and 2017 Plan [Member] \| Equity Awards [Member]
Share-based Compensation Arrangement [Abstract]
Stock-based compensation expense			3.9
2013 and 2017 Plan [Member] \| Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement [Abstract]
Reduction in liability			$ 2.5