Financial Instruments - Schedule of Financial Instruments and Balance Sheet Classification (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2025	Apr. 30, 2024	Apr. 30, 2023
Fair Value Measurement
Assets, fair value	$ 1,277,869	$ 1,195,001
Balance Sheet Classification
Cash and Cash Equivalents	1,006,964	941,005
Marketable Securities, Current	36,388	42,742
Marketable Securities, Non-current	233,626	211,681
Income Taxes & Other Receivables	891
Other Accrued Liabilities		(427)
Gain (loss) on marketable securities	17,100	29,800	$ 2,900
Mutual funds
Balance Sheet Classification
Obligations for which assets are held in trust	205,300	198,600
Unvested obligations under deferred compensation plans	19,500	22,400
Gain (loss) on marketable securities	17,100	29,800	$ 2,900
Level 2
Fair Value Measurement
Cost	40,086	38,550
Unrealized Gains	87	4
Unrealized Losses	(11)	(55)
Fair Value	40,162	38,499
Balance Sheet Classification
Cash and Cash Equivalents	500	3,932
Marketable Securities, Current	24,045	25,414
Marketable Securities, Non-current	15,617	9,153
Income Taxes & Other Receivables	0
Other Accrued Liabilities		0
Level 2 | Foreign currency forward contracts
Fair Value Measurement
Foreign currency forward contracts, fair value	891	(427)
Balance Sheet Classification
Cash and Cash Equivalents	0	0
Marketable Securities, Current	0	0
Marketable Securities, Non-current	0	0
Income Taxes & Other Receivables	891
Other Accrued Liabilities		(427)
Level 2 | Commercial paper
Fair Value Measurement
Cost	3,842	16,873
Unrealized Gains	0	1
Unrealized Losses	(1)	(19)
Fair Value	3,841	16,855
Balance Sheet Classification
Cash and Cash Equivalents	500	3,932
Marketable Securities, Current	3,341	12,923
Marketable Securities, Non-current	0	0
Income Taxes & Other Receivables	0
Other Accrued Liabilities		0
Level 2 | Corporate notes/bonds
Fair Value Measurement
Cost	32,747	17,322
Unrealized Gains	83	3
Unrealized Losses	(10)	(27)
Fair Value	32,820	17,298
Balance Sheet Classification
Cash and Cash Equivalents	0	0
Marketable Securities, Current	18,709	10,050
Marketable Securities, Non-current	14,111	7,248
Income Taxes & Other Receivables	0
Other Accrued Liabilities		0
Level 2 | U.S. Treasury and Agency Securities
Fair Value Measurement
Cost	3,497	4,355
Unrealized Gains	4	0
Unrealized Losses	0	(9)
Fair Value	3,501	4,346
Balance Sheet Classification
Cash and Cash Equivalents	0	0
Marketable Securities, Current	1,995	2,441
Marketable Securities, Non-current	1,506	1,905
Income Taxes & Other Receivables	0
Other Accrued Liabilities		0
Level 1 | Mutual funds
Fair Value Measurement
Equity securities, fair value	230,352	219,856
Balance Sheet Classification
Cash and Cash Equivalents	0	0
Marketable Securities, Current	12,343	17,328
Marketable Securities, Non-current	218,009	202,528
Income Taxes & Other Receivables	0
Other Accrued Liabilities		0
Level 1 | Total equity investments
Fair Value Measurement
Equity securities, fair value	230,352	219,856
Balance Sheet Classification
Cash and Cash Equivalents	0	0
Marketable Securities, Current	12,343	17,328
Marketable Securities, Non-current	218,009	202,528
Income Taxes & Other Receivables	0
Other Accrued Liabilities		0
Level 1 | Cash
Fair Value Measurement
Cash and cash equivalents, fair value	704,091	790,938
Balance Sheet Classification
Cash and Cash Equivalents	704,091	790,938
Marketable Securities, Current	0	0
Marketable Securities, Non-current	0	0
Income Taxes & Other Receivables	0
Other Accrued Liabilities		0
Level 1 | Money market funds
Fair Value Measurement
Cash and cash equivalents, fair value	302,373	146,135
Balance Sheet Classification
Cash and Cash Equivalents	302,373	146,135
Marketable Securities, Current	0	0
Marketable Securities, Non-current	0	0
Income Taxes & Other Receivables	$ 0
Other Accrued Liabilities		$ 0