Comprehensive Income - Changes in Each Component of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,648,071
Unrealized (losses) gains arising during the period	(15,233)	$ (788)	$ (41,715)
Reclassification of realized net losses to net income	326	209	1,350
Ending balance	1,733,058	1,648,071
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(96,860)	(92,717)	(33,666)
Unrealized (losses) gains arising during the period	(19,144)	(4,143)	(59,051)
Reclassification of realized net losses to net income	0	0	0
Ending balance	(116,004)	(96,860)	(92,717)
Deferred Compensation and Pension Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	4,381	961	(18,135)
Unrealized (losses) gains arising during the period	3,663	3,211	17,747
Reclassification of realized net losses to net income	326	209	1,349
Ending balance	8,370	4,381	961
Tax effect on unrealized gains, tax expense	1,300	1,100	6,000
Tax effect on reclassification of realized net losses, tax benefit	100	100	500
Unrealized (Losses) Gains on Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(285)	(429)	(19)
Unrealized (losses) gains arising during the period	248	144	(411)
Reclassification of realized net losses to net income	0	0	1
Ending balance	(37)	(285)	(429)
Tax effect on unrealized gains (losses), tax expense (benefit)	100	100	(100)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(92,764)	(92,185)	(51,820)
Ending balance	$ (107,671)	$ (92,764)	$ (92,185)