Comprehensive Income - Changes in Each Component of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Jan. 31, 2022		Jan. 31, 2021		Jan. 31, 2022		Jan. 31, 2021
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance						$ 1,366,389
Ending balance		$ 1,531,277				1,531,277
Foreign Currency Translation
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance		(49,051)		$ (61,426)		(33,666)		$ (83,652)
Unrealized (losses) gains arising during the period		(15,232)		25,083		(30,617)		47,309
Ending balance		(64,283)		(36,343)		(64,283)		(36,343)
Deferred Compensation and Pension Plan
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance		(17,443)	[1]	(22,229)	[2]	(18,135)	[1]	(23,554)	[2]
Unrealized (losses) gains arising during the period	[1]	824				839
Reclassification of realized net losses to net income		335	[1]	663	[2]	1,012	[1]	1,988	[2]
Ending balance		(16,284)	[1]	(21,566)	[2]	(16,284)	[1]	(21,566)	[2]
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance		(36)				(19)		34
Unrealized (losses) gains arising during the period		(115)		(5)		(133)		(39)
Reclassification of realized net losses to net income						1
Ending balance		(151)		(5)		(151)		(5)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance		(66,530)		(83,655)		(51,820)		(107,172)
Unrealized (losses) gains arising during the period		(14,523)		25,078		(29,911)		47,270
Reclassification of realized net losses to net income		335		663		1,013		1,988
Ending balance		$ (80,718)		$ (57,914)		$ (80,718)		$ (57,914)

[1] The tax effect on unrealized (losses) gains were $0.3 million for the three and nine months ended January 31, 2022. The tax effect on the reclassifications of realized net losses was $0.1 million and $0.3 million for the three and nine months ended January 31, 2022

[2] The tax effect on the reclassifications of realized net losses was $0.2 million and $0.7 million for the three and nine months ended January 31, 2021