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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

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	Jun. 30, 2018 USD ($)	Jun. 30, 2018 EUR (€)	Dec. 31, 2017
Debt Instrument [Line Items]
Deferred gain (loss) on net investment hedge recorded in AOCI, net of tax \| $	$ 10.1
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%