Derivative Financial Instruments - Summary of Outstanding Foreign Exchange Derivatives Designated as Net Investment Hedges of Foreign Currency Risk (Detail) - Sell [Member] - Designated as Hedging Instrument [Member] - Foreign Exchange Forward [Member] - Net Investment Hedges [Member] € in Thousands, £ in Thousands, $ in Thousands, $ in Thousands	Jun. 30, 2019 AUD ($) DerivativeInstrument	Jun. 30, 2019 CAD ($) DerivativeInstrument	Jun. 30, 2019 EUR (€) DerivativeInstrument	Jun. 30, 2019 GBP (£) DerivativeInstrument	Dec. 31, 2018 AUD ($) DerivativeInstrument	Dec. 31, 2018 CAD ($) DerivativeInstrument	Dec. 31, 2018 EUR (€) DerivativeInstrument	Dec. 31, 2018 GBP (£) DerivativeInstrument
CAD [Member]
Derivative [Line Items]
Number of Instruments	2	2	2	2	1	1	1	1
Notional Amount | $		$ 39,100				$ 70,600
GBP [Member]
Derivative [Line Items]
Number of Instruments	4	4	4	4	3	3	3	3
Notional Amount | £				£ 360,600				£ 192,300
EUR [Member]
Derivative [Line Items]
Number of Instruments	2	2	2	2	1	1	1	1
Notional Amount | €			€ 339,200				€ 185,000
AUD [Member]
Derivative [Line Items]
Number of Instruments	4	4	4	4	2	2	2	2
Notional Amount | $	$ 123,900				$ 187,600