Note 3 - Income Taxes - Operating Loss Carryforwards (Details) - State and Local Jurisdiction [Member] $ in Millions	Sep. 30, 2022 USD ($)
Other State [Member]
Operating Loss Carryforward	$ 2.6
Operating Loss Carryforward, No Expiration	2.1
Other State [Member] | Expires at Fiscal Year Ended September 30, 2023 [Member]
Operating Loss Carryforward	0.1
Other State [Member] | Expires at Fiscal Year Ended September 30, 2037 [Member]
Operating Loss Carryforward	0.1
Other State [Member] | Expires at Fiscal Year Ended September 30, 2038 [Member]
Operating Loss Carryforward	0.2
Other State [Member] | Expires at Fiscal Year Ended September 30, 2039 [Member]
Operating Loss Carryforward	0.1
California Franchise Tax Board [Member]
Operating Loss Carryforward	5.5
California Franchise Tax Board [Member] | Expires at Fiscal Year Ended September 30, 2038 [Member]
Operating Loss Carryforward	4.8
California Franchise Tax Board [Member] | Expires at Fiscal Year Ended September 30, 2039 [Member]
Operating Loss Carryforward	$ 0.7