Stock-Based Compensation (Intrinsic Value and Tax Deductions of Stock Appreciation Rights) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Realized tax benefits from tax deductions	$ 10.5	$ 23.6	$ 0.0
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeiture Rate	12.90%
Instrinsic value of stock appreciation rights exercised	$ 35.9	25.1	36.9
Realized tax benefits from tax deductions	$ 8.9	$ 9.6	$ 14.1

Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other Than Options Exercises in Period Intrinsic Value.

No definition available.

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Forfeiture Rate.

+ References

No definition available.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

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.

+ References

No definition available.

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