Share-based Compensation Awards (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock-settled awards
Stock-based Payment Award
Awards granted	2.1	0.8	1.1
Weighted-average grant-date fair value (per award)	$ 23.60	$ 24.18	$ 21.87
Total fair value of vested awards distributed	$ 24.2	$ 22.6	$ 17.5
Accrued dividends on non-vested stock-settled awards	2.4	1.5
Dividends paid for stock-settled awards	$ 1.5	$ 1.2
Cash-settled awards
Stock-based Payment Award
Awards granted	0.1	0.0	0.1
Weighted-average grant-date fair value (per award)	$ 23.62	$ 23.33	$ 22.54
Total fair value of vested awards distributed	$ 0.8	$ 0.9	$ 0.7
Performance-based awards
Stock-based Payment Award
Awards granted	2.9	4.8	3.3
Weighted-average grant-date fair value (per award)	$ 21.13	$ 20.06	$ 19.58
Total fair value of vested awards distributed	$ 87.2	$ 112.4	$ 27.9

Dividends paid for stock-settled awards vested during the period.

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- Definition

Stock based awards expected to be settled in cash

+ References

No definition available.

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- Definition

Amount of paid and unpaid stock dividends declared and applicable to holders of share-based compensation, for example, but not limited to, non-vested shares, stock options, or restricted stock units.

+ References

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ 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 (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ 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 (d)(2)
-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.

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