Note 8 - Fair Value Measurement - Schedule of Fair Value Measurement of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Jun. 30, 2021
Debt Securities, Available-for-sale	$ 26,580	$ 27,351
Reported Value Measurement [Member]
Debt Securities, Available-for-sale	26,580	27,351
Estimate of Fair Value Measurement [Member]
Debt Securities, Available-for-sale	26,580	27,351
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-sale	26,580	27,351
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-sale	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-sale	0	0
Corporate & Government Debt Securities [Member] | Mutual Fund [Member]
Debt Securities, Available-for-sale	19,487	19,985
Corporate & Government Debt Securities [Member] | Mutual Fund [Member] | Reported Value Measurement [Member]
Debt Securities, Available-for-sale	19,487	19,985
Corporate & Government Debt Securities [Member] | Mutual Fund [Member] | Estimate of Fair Value Measurement [Member]
Debt Securities, Available-for-sale	19,487	19,985
Corporate & Government Debt Securities [Member] | Mutual Fund [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-sale	19,487	19,985
Corporate & Government Debt Securities [Member] | Mutual Fund [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-sale	0	0
Corporate & Government Debt Securities [Member] | Mutual Fund [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-sale	0	0
Corporate & Government Debt Securities [Member] | Exchange Traded Funds [Member]
Debt Securities, Available-for-sale	7,093	7,366
Corporate & Government Debt Securities [Member] | Exchange Traded Funds [Member] | Reported Value Measurement [Member]
Debt Securities, Available-for-sale	7,093	7,366
Corporate & Government Debt Securities [Member] | Exchange Traded Funds [Member] | Estimate of Fair Value Measurement [Member]
Debt Securities, Available-for-sale	7,093	7,366
Corporate & Government Debt Securities [Member] | Exchange Traded Funds [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-sale	7,093	7,366
Corporate & Government Debt Securities [Member] | Exchange Traded Funds [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-sale	0	0
Corporate & Government Debt Securities [Member] | Exchange Traded Funds [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-sale	$ 0	$ 0