Comprehensive Income - Changes in Each Component of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,544,346
Unrealized (losses) gains arising during the period	(788)	$ (41,715)	$ 52,593
Reclassification of realized net losses (gains) to net income	209	1,350	2,759
Ending balance	1,648,071	1,544,346
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(92,185)	(51,820)	(107,172)
Ending balance	(92,764)	(92,185)	(51,820)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(92,717)	(33,666)	(83,652)
Unrealized (losses) gains arising during the period	(4,143)	(59,051)	49,986
Reclassification of realized net losses (gains) to net income	0	0	0
Ending balance	(96,860)	(92,717)	(33,666)
Deferred Compensation and Pension Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	961	(18,135)	(23,554)
Unrealized (losses) gains arising during the period	3,211	17,747	2,660
Reclassification of realized net losses (gains) to net income	209	1,349	2,759
Ending balance	4,381	961	(18,135)
Tax effect on unrealized gains, tax expense	1,100	6,000	1,100
Tax effect on reclassification of realized net losses, tax benefit	100	500	1,000
Unrealized Gains (Losses) on Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(429)	(19)	34
Unrealized (losses) gains arising during the period	144	(411)	(53)
Reclassification of realized net losses (gains) to net income	0	1	0
Ending balance	(285)	(429)	$ (19)
Tax effect on unrealized gains (losses), tax expense (benefit)	$ 100	$ (100)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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