Net Carrying Values of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	May 31, 2021	May 31, 2020
Available-for-Sale Debt Securities, Amortized Cost
Less than one year, amortized cost	$ 3,892
One year through five years, amortized cost	14,591
Six years through ten years, amortized cost	5,221
After ten years, amortized cost	2,593
Available-for-Sale Debt Securities, Amortized Cost	26,297	$ 25,605
Available-for-Sale Debt Securities, Fair Value
Less than one year, fair value	3,890
One year through five years, fair value	14,964
Six years through ten years, fair value	5,318
After ten years, fair value	2,573
Available-for-sale debt securities, fair value	$ 26,745	$ 26,922

Amortized cost 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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