Financial Instruments and Fair Value Measurements - Schedule of Fair Value of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives Fair Value [Line Items]
Asset	$ 23,043	$ 19,139
Liability	7,618	32,229
Undesignated Derivatives [Member] | Forwards [Member] | GBP
Derivatives Fair Value [Line Items]
Asset	342	2,440
Liability	2,128	8,103
Undesignated Derivatives [Member] | Forwards [Member] | CAD
Derivatives Fair Value [Line Items]
Asset	695	0
Liability	379	1,698
Undesignated Derivatives [Member] | Forwards [Member] | EUR
Derivatives Fair Value [Line Items]
Asset	4,969	2
Liability	4,531	14,234
Undesignated Derivatives [Member] | Forwards [Member] | JPY
Derivatives Fair Value [Line Items]
Asset	7,086	6,474
Liability	127	931
Undesignated Derivatives [Member] | Interest Rate Hedges [Member]
Derivatives Fair Value [Line Items]
Asset	147	0
Liability	0	0
Designated As Hedging Instrument [Member] | Net Investment Hedges [Member] | CAD
Derivatives Fair Value [Line Items]
Asset	371	0
Liability	0	7,263
Designated As Hedging Instrument [Member] | Net Investment Hedges [Member] | BRL
Derivatives Fair Value [Line Items]
Asset	9,433	0
Liability	0	0
Designated As Hedging Instrument [Member] | Cash Flow Hedges [Member] | Interest Rate Hedges [Member] | CAD
Derivatives Fair Value [Line Items]
Asset	0	10,223
Liability	0	0
Designated As Hedging Instrument [Member] | Cash Flow Hedges [Member] | Interest Rate Hedges [Member] | EUR
Derivatives Fair Value [Line Items]
Asset	0	0
Liability	$ 453	$ 0