Note 6 - Investments in Marketable Securities - Summary of Investments (Details) - USD ($)	Jun. 30, 2018	Sep. 30, 2017
Aggregate fair value	$ 207,499,000	$ 229,265,000
Amortized/Adjusted cost basis	58,449,000	63,393,000
Pretax unrealized gains	149,050,000	165,872,000
Common Stock [Member]
Aggregate fair value	207,499,000	220,973,000
Amortized/Adjusted cost basis	58,449,000	58,449,000
Pretax unrealized gains	149,050,000	162,524,000
Bonds [Member]
Aggregate fair value		8,292,000
Amortized/Adjusted cost basis		4,944,000
Pretax unrealized gains		$ 3,348,000