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Accounting Policies (Accounting Pronouncements) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of new accounting principle on prior period operating income	$ 81.5	$ 66.9
Unfavorable impact on pre-tax operating results	(65.5)	(23.1)
Accounting Standards Update 2017-07 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of new accounting principle on prior period operating income		$ 13.6
Unfavorable impact on pre-tax operating results	$ 5.4

X

- Definition

Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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- Definition

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+ References

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

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