Note 9 - Investments in Marketable Securities - Summary of Investments (Details) - USD ($)	Dec. 31, 2016	Sep. 30, 2016
Aggregate fair value	$ 196,486,000	$ 166,634,000
Amortized/Adjusted cost basis	63,391,000	58,378,000
Pretax unrealized gains	133,095,000	108,256,000
Equity Securities [Member]
Aggregate fair value	188,729,000	158,462,000
Amortized/Adjusted cost basis	58,449,000	53,436,000
Pretax unrealized gains	130,280,000	105,026,000
Debt Securities [Member]
Aggregate fair value	7,757,000	8,172,000
Amortized/Adjusted cost basis	4,942,000	4,942,000
Pretax unrealized gains	$ 2,815,000	$ 3,230,000