Equity Based Compensation (Schedule of Stock Options Activity) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Option Awards
Exercised (in Shares)	(291,689)	(2,331,388)	(47,979)
Weighted Average Exercise Price
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 26.49	$ 26.63	$ 16.50
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period	(14,159)		(1,097)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 11.14		$ 63.74
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 4.6	$ 25.8	$ 0.9
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	964,840	1,270,688	3,602,076	3,651,152
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 27.30	$ 26.93	$ 26.74	$ 26.62
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	$ 1.1	$ 4.0	$ 0.3

Amount of tax benefit from exercise of stock options granted under share-based compensation arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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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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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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

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

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

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