Gains (Losses) Recognized in AOCI and Reclassified from AOCI on Derivatives (Effective Portion) (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments Gain Loss [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivative (Effective Portion)	$ (9.4)	$ (3.8)
Amount of Gain Reclassified from AOCI into Income (Effective Portion)	0.1	0.9
Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	(0.5)
Net Investment Hedging [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivative (Effective Portion)	(10.9)	(3.6)
Net Investment Hedging [Member] \| Long Term Debt [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivative (Effective Portion)	(10.9)	(3.6)
Cash Flow Hedging [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivative (Effective Portion)	1.5	(0.2)
Amount of Gain Reclassified from AOCI into Income (Effective Portion)	0.1	0.9
Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	(0.5)
Cash Flow Hedging [Member] \| Cross-Currency Swap [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivative (Effective Portion)	1.5	(0.2)
Amount of Gain Reclassified from AOCI into Income (Effective Portion)	0.1	1.0
Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	$ (0.5)
Cash Flow Hedging [Member] \| Interest Rate Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of Gain Reclassified from AOCI into Income (Effective Portion)		$ (0.1)

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- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624177-113959

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- Definition

The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1),(2)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

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