Share-Based Compensation (Share-Based Compensation Expense) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share based compensation expense	$ 13.4	$ 14.3	$ 58.1	$ 67.6
Tax benefit	(3.3)	(3.5)	(14.1)	(16.5)
After-tax expense	10.1	10.8	44.0	51.1
Stock Options [Member]
Share based compensation expense	2.9	3.1	17.5	21.1
Restricted Stock Units (RSUs) [Member]
Share based compensation expense	4.1	4.6	22.9	26.6
Performance Shares [Member]
Share based compensation expense	5.8	4.7	12.7	16.0
Deferred Compensation [Member]
Share based compensation expense	0.8	0.9	2.3	2.6
Other share based compensation [Member]
Share based compensation expense	$ (0.2)	$ 1.0	$ 2.7	$ 1.3

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: 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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration