Derivative Financial Instruments - Outstanding Currency, Forward Exchange Contracts (Detail) - Foreign Currency Forward Contracts [Member] - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	$ 456,372	$ 236,338
Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	582,613	361,399
Euro [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	401,545	152,436
Euro [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	279,131	82,687
British Pound [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	21,012	43,914
British Pound [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	44,879	58,981
Japanese Yen [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	28,504	32,610
Japanese Yen [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	46,226	35,260
Australian Dollar [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	180	194
Australian Dollar [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	7,771	8,137
Hong Kong Dollar [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	1,209	2,170
Hong Kong Dollar [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	128,710	110,723
Singapore Dollar [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	794	616
Singapore Dollar [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	15,356	13,143
Others [Member] | Sell [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	3,128	4,398
Others [Member] | Buy [Member]
Derivative [Line Items]
Notional Amounts of foreign currency derivative contracts	$ 60,540	$ 52,468