Derivative Financial Instruments - Outstanding Currency, Forward Exchange Contracts (Detail) - Foreign Currency Forward Contracts [Member] - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	$ 204,741	$ 456,372
Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	417,913	582,613
Euro [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	110,114	401,545
Euro [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	182,146	279,131
British Pound [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	18,987	21,012
British Pound [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	58,543	44,879
Japanese Yen [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	16,301	28,504
Japanese Yen [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	31,934	46,226
Australian Dollar [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	327	180
Australian Dollar [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	7,647	7,771
Hong Kong Dollar [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	53,935	1,209
Hong Kong Dollar [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	60,737	128,710
Singapore Dollar [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	1,082	794
Singapore Dollar [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	15,620	15,356
Others [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	3,995	3,128
Others [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	$ 61,286	$ 60,540