Note 5 - Income Taxes - Summary of Operating Loss Carryforwards (Details) $ in Millions	12 Months Ended
	Mar. 31, 2024 USD ($) item yr
Operating Loss Carryforwards, Expiration Year (Year) | yr	2,034
Tax Year 2014 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,034
Tax Year 2016 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,036
Tax Year 2017 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,037
Tax Year 2018 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,038
Tax Year 2019 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,039
Tax Year 2020 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,040
Tax Year 2021 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,041
Tax Year 2022 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,042
Tax Year 2023 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,043
Tax Year 2024 [Member]
Operating Loss Carryforwards, Expiration Year (Year) | item	2,044
Domestic Tax Jurisdiction [Member]
Operating loss carryforward	$ 14.8
Domestic Tax Jurisdiction [Member] | Tax Year 2014 [Member]
Operating loss carryforward	0.0
Domestic Tax Jurisdiction [Member] | Tax Year 2016 [Member]
Operating loss carryforward	0.0
Domestic Tax Jurisdiction [Member] | Tax Year 2017 [Member]
Operating loss carryforward	0.0
Domestic Tax Jurisdiction [Member] | Tax Year 2018 [Member]
Operating loss carryforward	0.0
Domestic Tax Jurisdiction [Member] | Tax Year 2019 [Member]
Operating loss carryforward	3.3
Domestic Tax Jurisdiction [Member] | Tax Year 2020 [Member]
Operating loss carryforward	3.6
Domestic Tax Jurisdiction [Member] | Tax Year 2021 [Member]
Operating loss carryforward	4.0
Domestic Tax Jurisdiction [Member] | Tax Year 2022 [Member]
Operating loss carryforward	3.4
Domestic Tax Jurisdiction [Member] | Tax Year 2023 [Member]
Operating loss carryforward	(1.4)
Domestic Tax Jurisdiction [Member] | Tax Year 2024 [Member]
Operating loss carryforward	1.9
State and Local Jurisdiction [Member]
Operating loss carryforward	14.9
State and Local Jurisdiction [Member] | Tax Year 2014 [Member]
Operating loss carryforward	0.2
State and Local Jurisdiction [Member] | Tax Year 2016 [Member]
Operating loss carryforward	1.5
State and Local Jurisdiction [Member] | Tax Year 2017 [Member]
Operating loss carryforward	0.8
State and Local Jurisdiction [Member] | Tax Year 2018 [Member]
Operating loss carryforward	2.7
State and Local Jurisdiction [Member] | Tax Year 2019 [Member]
Operating loss carryforward	2.8
State and Local Jurisdiction [Member] | Tax Year 2020 [Member]
Operating loss carryforward	3.1
State and Local Jurisdiction [Member] | Tax Year 2021 [Member]
Operating loss carryforward	1.9
State and Local Jurisdiction [Member] | Tax Year 2022 [Member]
Operating loss carryforward	1.9
State and Local Jurisdiction [Member] | Tax Year 2023 [Member]
Operating loss carryforward	(1.6)
State and Local Jurisdiction [Member] | Tax Year 2024 [Member]
Operating loss carryforward	$ 1.6