Schedule II - Valuation And Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance as of Beginning of Period	$ 478.4	$ 530.1	$ 536.0
Additions	41.4	20.6	66.0
Retirements	(95.6)	(66.3)	(30.4)
Other Changes	19.8	(6.0)	(41.5)
Balance as of End of Period	444.0	478.4	530.1
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance as of Beginning of Period	32.8	34.4	27.5
Additions	16.4	12.0	14.1
Retirements	(3.7)	(12.7)	(4.5)
Other Changes	(3.7)	(0.9)	(2.7)
Balance as of End of Period	41.8	32.8	34.4
Allowance for deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance as of Beginning of Period	445.6	495.7	508.5
Additions	25.0	8.6	51.9
Retirements	(91.9)	(53.6)	(25.9)
Other Changes	23.5	(5.1)	(38.8)
Balance as of End of Period	$ 402.2	$ 445.6	$ 495.7

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of increase (decrease) in the allowances and reserves, which consist of the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs, from adjustments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

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Amount of increase in the allowances and reserves, which consist of the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs, from charges to costs and expenses.

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Total of the deductions in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, representing receivables written off as uncollectible and portions of the reserves utilized, respectively.

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