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Schedule of Investments and Unrealized Gains/Losses (Details) $ in Thousands	3 Months Ended
	Jul. 31, 2022 USD ($)
Net Investment Income [Line Items]
Market Value	$ 42,648
Unrealized Gains (Losses)	(76)
Total Cost	42,724
Corporate Bonds [Member]
Net Investment Income [Line Items]
Market Value	31,853
Unrealized Gains (Losses)	151
Total Cost	32,004
Government Bonds and Notes [Member]
Net Investment Income [Line Items]
Market Value	7,986
Unrealized Gains (Losses)	15
Total Cost	8,001
Government Agency [Member]
Net Investment Income [Line Items]
Market Value	2,498
Unrealized Gains (Losses)	11
Total Cost	2,509
Accured Interest [Member]
Net Investment Income [Line Items]
Market Value	311
Unrealized Gains (Losses)	(101)
Total Cost	$ 210

X

- Definition

Cost of the investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section 50
-Paragraph 6
-Subparagraph (b)
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Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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