Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Debt - Additional Information (Detail) $ in Millions	3 Months Ended
Debt - Additional Information (Detail) $ in Millions	Mar. 31, 2018 USD ($)	Mar. 31, 2018 EUR (€)	Dec. 31, 2017
Debt Instrument [Line Items]
Deferred gain (loss) on net investment hedge recorded in AOCI, net of tax \| $	$ 29.3
3.75% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, face amount \| €		€ 300,000,000
Senior notes rate		3.75%	3.75%