Financial Instruments and Fair Value Measurements - Schedule of Fair Value and Classification of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives Fair Value [Line Items]
Asset	$ 19,139	$ 47,114
Liability	32,229	1,268
Forwards and Options [Member] \| GBP
Derivatives Fair Value [Line Items]
Asset	2,440	16,985
Liability	8,103	0
Forwards and Options [Member] \| CAD
Derivatives Fair Value [Line Items]
Asset	0	831
Liability	1,698	197
Forwards and Options [Member] \| EUR
Derivatives Fair Value [Line Items]
Asset	2	10,933
Liability	14,234	0
Forwards and Options [Member] \| JPY
Derivatives Fair Value [Line Items]
Asset	6,474	9,246
Liability	931	1,071
Interest Rate Hedges [Member]
Derivatives Fair Value [Line Items]
Asset	0	0
Liability	0	0
Net Investment Hedges [Member] \| GBP
Derivatives Fair Value [Line Items]
Asset	0	7,439
Liability	0	0
Net Investment Hedges [Member] \| CAD
Derivatives Fair Value [Line Items]
Asset	0	1,245
Liability	7,263	0
Cash Flow Hedges [Member]
Derivatives Fair Value [Line Items]
Asset	10,223	435
Liability	$ 0	$ 0

Aggregate fair value of all derivative assets designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

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