Comprehensive Income (Loss) - Changes in Each Component of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2024	Oct. 31, 2023	Oct. 31, 2024	Oct. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,759,242	$ 1,692,530	$ 1,737,325	$ 1,653,005
Ending balance	1,782,865	1,660,500	1,782,865	1,660,500
Accumulated Other Comprehensive Loss, Net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(104,860)	(90,471)	(107,671)	(92,764)
Unrealized gains arising during the period	4,456	(25,430)	7,317	(23,164)
Reclassification of realized net gains to net income	(97)	28	(147)	55
Ending balance	(100,501)	(115,873)	(100,501)	(115,873)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(113,207)	(94,729)	(116,004)	(96,860)
Unrealized gains arising during the period	4,426	(25,467)	7,223	(23,336)
Reclassification of realized net gains to net income	0	0	0	0
Ending balance	(108,781)	(120,196)	(108,781)	(120,196)
Deferred Compensation and Pension Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	8,320	4,408	8,370	4,381
Unrealized gains arising during the period	0	0	0	0
Reclassification of realized net gains to net income	(97)	28	(147)	55
Ending balance	8,223	4,436	8,223	4,436
Unrealized (Losses) Gains on Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	27	(150)	(37)	(285)
Unrealized gains arising during the period	30	37	94	172
Reclassification of realized net gains to net income	0	0	0	0
Ending balance	$ 57	$ (113)	$ 57	(113)
Tax effect on unrealized gains (losses), securities, tax expense (benefit)				$ 100