Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2024		Jun. 30, 2024
Accounts and other receivables, allowance for credit loss	$ 0		$ 0
Investments in available-for-sale debt securities, amortized cost	5,717	[1]	6,204
Investments in available-for-sale debt securities, allowance for credit loss	$ 0		$ 0
Treasury shares (in shares)	2,304,738		2,113,516
Common Class A [Member]
Common Stock, Par value (in dollars per share)	$ 0.025		$ 0.025
Common Stock, Shares Authorized (in shares)	28,000,000		28,000,000
Common Stock, Shares, Issued (in shares)	13,866,999		13,866,999
Common Stock, Shares, Outstanding (in shares)	11,562,261		11,753,483
Common Class B [Member]
Common Stock, Par value (in dollars per share)	$ 0.025		$ 0.025
Common Stock, Shares Authorized (in shares)	4,500,000		4,500,000
Common Stock, Shares, Issued (in shares)	0		0
Common Class C [Member]
Common Stock, Par value (in dollars per share)	$ 0.025		$ 0.025
Common Stock, Shares Authorized (in shares)	3,500,000		3,500,000
Common Stock, Shares, Issued (in shares)	2,068,549		2,068,549
Common Stock, Shares, Outstanding (in shares)	2,068,549		2,068,549

[1] Principal payments of $750,000 are due quarterly with a final maturity in January 2026.