Financial Instruments - Outstanding Currency, Forward Exchange Contracts (Detail) $ in Thousands	Apr. 30, 2018 USD ($)
Derivative [Line Items]
Fair Value of foreign currency derivative contracts	$ (2,281)
Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	236,338
Fair Value of foreign currency derivative contracts	231,213
Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	361,399
Fair Value of foreign currency derivative contracts	353,994
Euro [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	152,436
Fair Value of foreign currency derivative contracts	149,658
Euro [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	82,687
Fair Value of foreign currency derivative contracts	80,189
British Pound [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	43,914
Fair Value of foreign currency derivative contracts	42,617
British Pound [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	58,981
Fair Value of foreign currency derivative contracts	57,370
Japanese Yen [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	32,610
Fair Value of foreign currency derivative contracts	31,785
Japanese Yen [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	35,260
Fair Value of foreign currency derivative contracts	34,116
Australian Dollar [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	194
Fair Value of foreign currency derivative contracts	188
Australian Dollar [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	8,137
Fair Value of foreign currency derivative contracts	7,774
Hong Kong Dollar [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	2,170
Fair Value of foreign currency derivative contracts	2,166
Hong Kong Dollar [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	110,723
Fair Value of foreign currency derivative contracts	111,005
Singapore Dollar [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	616
Fair Value of foreign currency derivative contracts	608
Singapore Dollar [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	13,143
Fair Value of foreign currency derivative contracts	12,967
Others [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	4,398
Fair Value of foreign currency derivative contracts	4,191
Others [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	52,468
Fair Value of foreign currency derivative contracts	$ 50,573