Investments - Available-for Sale Debt Securities by Contractual Maturity (Details) - Debt Securities, Available-For-Sale, Excluding Money Market Accounts - USD ($) $ in Thousands	Oct. 31, 2021	Apr. 30, 2021
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
AFS Debt Maturities, Within one year, Amortized Cost	$ 803,037	$ 977,939
AFS Debt Maturities, After one year through five years, Amortized Cost	101,908	0
Amortized Cost	904,945	977,939
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
AFS Debt Maturities, Within one year, Fair Value	802,986	978,020
AFS Debt Maturities, After one year through five years, Fair Value	101,719	0
AFS Debt Maturities, Total Fair Value	$ 904,705	$ 978,020

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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