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

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Stock-Based Compensation, Assumptions Used to Estimate Fair Value of Options Granted (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended	9 Months Ended
	May 31, 2017	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued liabilities		$ 274.9	$ 274.9	$ 258.5
2013 Stock Incentive Plan [Member] \| Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		7.8	$ 69.2
Assumptions [Abstract]
Expected dividend rate			0.00%
2013 Stock Incentive Plan [Member] \| Stock Options [Member] \| Minimum [Member]
Assumptions [Abstract]
Expected life of options			5 years
Risk-free interest rate			1.94%
Assumed volatility			41.20%
2013 Stock Incentive Plan [Member] \| Stock Options [Member] \| Maximum [Member]
Assumptions [Abstract]
Expected life of options			6 years 3 months
Risk-free interest rate			2.12%
Assumed volatility			45.80%
2013 Stock Incentive Plan [Member] \| Deferred Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred stock units authorized (in shares)	5.5
Fair value of deferred stock units (in dollars per share)	$ 17.20
Initial public offering share price (in dollars per share)	$ 20.00
Stock-based compensation expense		2.0	$ 96.8
Accrued liabilities		$ 5.4	$ 5.4
Assumptions [Abstract]
Expected life of options			1 year 5 months 1 day
Assumed volatility			51.50%