Financial Instruments - Outstanding Currency, Forward Exchange Contracts (Detail) $ in Thousands	Apr. 30, 2017 USD ($)
Derivative [Line Items]
Fair Market Value of foreign currency derivative contracts	$ (1,940)
Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	458,941
Fair Market Value of foreign currency derivative contracts	465,739
Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	511,145
Fair Market Value of foreign currency derivative contracts	516,038
Euro [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	275,187
Fair Market Value of foreign currency derivative contracts	280,481
Euro [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	187,639
Fair Market Value of foreign currency derivative contracts	190,989
British Pound [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	78,912
Fair Market Value of foreign currency derivative contracts	80,911
British Pound [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	86,330
Fair Market Value of foreign currency derivative contracts	88,540
Japanese Yen [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	30,912
Fair Market Value of foreign currency derivative contracts	30,611
Japanese Yen [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	21,082
Fair Market Value of foreign currency derivative contracts	21,023
Australian Dollar [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	420
Fair Market Value of foreign currency derivative contracts	412
Australian Dollar [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	7,742
Fair Market Value of foreign currency derivative contracts	7,589
Hong Kong Dollar [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	70,321
Fair Market Value of foreign currency derivative contracts	70,105
Hong Kong Dollar [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	156,706
Fair Market Value of foreign currency derivative contracts	156,231
Singapore Dollar [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	1,154
Fair Market Value of foreign currency derivative contracts	1,170
Singapore Dollar [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	11,821
Fair Market Value of foreign currency derivative contracts	11,969
Others [Member] | Foreign Currency Forward Contracts [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	2,035
Fair Market Value of foreign currency derivative contracts	2,049
Others [Member] | Foreign Currency Forward Contracts [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	39,825
Fair Market Value of foreign currency derivative contracts	$ 39,697