Marketable Securities (Tables)

12 Months Ended

May 31, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of Available-for-Sale Debt Securities by Asset Type

The following tables summarize available-for-sale debt securities held at May 31, 2023 and 2022 by asset type:

	Available-For-Sale Debt Securities
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value (Net Carrying Amount)
May 31, 2023
Fixed maturity:
U.S. treasury and other government	$	28,841	$	23	$	(1,843	)	$	27,021
Corporate bonds		147		6		(12	)		141
Total available-for-sale debt securities	$	28,988	$	29	$	(1,855	)	$	27,162

	Available-For-Sale Debt Securities
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value (Net Carrying Amount)
May 31, 2022
Fixed maturity:
U.S. treasury and other government	$	26,522	$	55	$	(1,338	)	$	25,239
Corporate bonds		147		12		(4	)		155
Total available-for-sale debt securities	$	26,669	$	67	$	(1,342	)	$	25,394

Summary of Available-for-Sale Debt Securities in Unrealized Loss Position and Included in Accumulated Other Comprehensive (Loss), Aggregated by Length of Time Investments

Summarized below are the available-for-sale debt securities we held at May 31, 2023 and 2022 that were in an unrealized loss position and that were included in accumulated other comprehensive income (loss), aggregated by the length of time the investments had been in that position:

	May 31, 2023					May 31, 2022
(In thousands)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Total investments with unrealized losses	$	24,245	$	(1,855	)	$	22,702	$	(1,342	)
Unrealized losses with a loss position for less than 12 months		6,285		(72	)		16,273		(543	)
Unrealized losses with a loss position for more than 12 months		17,960		(1,783	)		6,429		(799	)

Net Carrying Values of Debt Securities by Contractual Maturity

The net carrying values of available-for-sale debt securities at May 31, 2023, by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties.

(In thousands)	Amortized Cost		Fair Value
Due:
Less than one year	$	5,308	$	5,143
One year through five years		19,172		18,334
Six years through ten years		2,023		1,742
After ten years		2,485		1,943
	$	28,988	$	27,162