Share-Based Compensation (Share-Based Compensation Expense) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share based compensation expense	$ 14.0	$ 14.2	$ 57.9	$ 54.2
Tax benefit	(5.4)	(5.4)	(22.2)	(20.7)
After-tax expense	8.6	8.8	35.7	33.5
Stock Options [Member]
Share based compensation expense	3.6	3.3	16.3	14.7
Restricted Stock Units (RSUs) [Member]
Share based compensation expense	5.0	5.1	21.9	21.5
Performance Shares [Member]
Share based compensation expense	4.7	4.6	15.9	14.1
Other share based compensation [Member]
Share based compensation expense	$ 0.7	$ 1.2	$ 3.8	$ 3.9

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://www.xbrl.org/2003/role/presentationRef
-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=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-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=96867065&loc=d3e5070-113901

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