Comprehensive (Loss) Income - Changes in Each Component of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2023	Oct. 31, 2022	Oct. 31, 2023	Oct. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 1,648,071
Unrealized gains (losses) arising during the period	$ (25,430)	$ (28,275)	(23,164)	$ (44,585)
Reclassification of realized net losses to net income	28	54	55	105
Ending balance	1,656,153		1,656,153
Tax effect on unrealized gains (losses), securities, tax expense (benefit)		(100)	100	(100)
Tax effect on reclassification of realized net losses, tax benefit				100
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(90,471)	(108,444)	(92,764)	(92,185)
Ending balance	(115,873)	(136,665)	(115,873)	(136,665)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(94,729)	(108,974)	(96,860)	(92,717)
Unrealized gains (losses) arising during the period	(25,467)	(28,017)	(23,336)	(44,274)
Reclassification of realized net losses to net income	0	0	0	0
Ending balance	(120,196)	(136,991)	(120,196)	(136,991)
Deferred Compensation and Pension Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	4,408	1,012	4,381	961
Unrealized gains (losses) arising during the period	0	0	0	0
Reclassification of realized net losses to net income	28	54	55	105
Ending balance	4,436	1,066	4,436	1,066
Unrealized Losses on Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(150)	(482)	(285)	(429)
Unrealized gains (losses) arising during the period	37	(258)	172	(311)
Reclassification of realized net losses to net income	0	0	0	0
Ending balance	$ (113)	$ (740)	$ (113)	$ (740)