Comprehensive Income - Schedule of Changes in Each Component of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2025	Apr. 30, 2024	Apr. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,737,325	$ 1,653,005	$ 1,549,589
Ending balance	1,872,139	1,737,325	1,653,005
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(107,671)	(92,764)	(92,185)
Unrealized (losses) gains arising during the period	21,571	(15,233)	(788)
Reclassification of realized net losses (gains) to net income	(143)	326	209
Ending balance	(86,243)	(107,671)	(92,764)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(116,004)	(96,860)	(92,717)
Unrealized (losses) gains arising during the period	22,100	(19,144)	(4,143)
Reclassification of realized net losses (gains) to net income	0	0	0
Ending balance	(93,904)	(116,004)	(96,860)
Deferred Compensation and Pension Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	8,370	4,381	961
Unrealized (losses) gains arising during the period	(625)	3,663	3,211
Reclassification of realized net losses (gains) to net income	(141)	326	209
Ending balance	7,604	8,370	4,381
Tax effect on unrealized (losses) gains, tax expense	(300)	1,300	1,100
Tax effect on reclassification of realized net gains (losses), tax benefit	(100)	100	100
Unrealized (Losses) Gains on Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(37)	(285)	(429)
Unrealized (losses) gains arising during the period	96	248	144
Reclassification of realized net losses (gains) to net income	(2)	0	0
Ending balance	$ 57	(37)	(285)
Tax effect on unrealized gains, tax expense (benefit)		$ 100	$ 100