Acquisition Pro Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Business Combinations [Abstract]
Operating Revenues	$ 1,698.7	$ 1,689.8	$ 5,878.8	$ 6,898.0
Net Income	$ 185.5	$ 210.7	$ 664.9	$ 712.1
Earnings per share (Basic)	$ 0.59	$ 0.67	$ 2.11	$ 2.26
Earnings per share (Diluted)	$ 0.58	$ 0.66	$ 2.10	$ 2.24

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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