Note 7 - Investments in Marketable Securities - Summary of Investments (Details) - USD ($)	Jun. 30, 2017	Sep. 30, 2016
Amortized/Adjusted cost basis	$ 63,392,000	$ 58,378,000
Pretax unrealized gains	147,161,000	108,256,000
Aggregate fair value	210,553,000	166,634,000
Equity Securities [Member]
Amortized/Adjusted cost basis	58,449,000	53,436,000
Pretax unrealized gains	143,700,000	105,026,000
Aggregate fair value	202,149,000	158,462,000
Debt Securities [Member]
Amortized/Adjusted cost basis	4,943,000	4,942,000
Pretax unrealized gains	3,461,000	3,230,000
Aggregate fair value	$ 8,404,000	$ 8,172,000