Note 5 - Income Taxes - Summary of Operating Loss Carryforwards (Details) $ in Millions	12 Months Ended
	Mar. 31, 2023 USD ($)
Tax Year 2016 [Member]
Statement [Line Items]
Carryforward expiration	2034
Tax Year 2017 [Member]
Statement [Line Items]
Carryforward expiration	2036
Tax Year 2018 [Member]
Statement [Line Items]
Carryforward expiration	2037
Tax Year 2019 [Member]
Statement [Line Items]
Carryforward expiration	2038
Tax Year 2020 [Member]
Statement [Line Items]
Carryforward expiration	2039
Tax Year 2021 [Member]
Statement [Line Items]
Carryforward expiration	2040
Tax Year 2022 [Member]
Statement [Line Items]
Carryforward expiration	2041
Tax Year 2023 [Member]
Statement [Line Items]
Carryforward expiration	2042
Domestic Tax Authority [Member]
Statement [Line Items]
Operating loss carryforward	$ 15.8
Domestic Tax Authority [Member] | Tax Year 2016 [Member]
Statement [Line Items]
Operating loss carryforward	0.0
Domestic Tax Authority [Member] | Tax Year 2017 [Member]
Statement [Line Items]
Operating loss carryforward	0.0
Domestic Tax Authority [Member] | Tax Year 2018 [Member]
Statement [Line Items]
Operating loss carryforward	0.0
Domestic Tax Authority [Member] | Tax Year 2019 [Member]
Statement [Line Items]
Operating loss carryforward	3.3
Domestic Tax Authority [Member] | Tax Year 2020 [Member]
Statement [Line Items]
Operating loss carryforward	3.7
Domestic Tax Authority [Member] | Tax Year 2021 [Member]
Statement [Line Items]
Operating loss carryforward	4.0
Domestic Tax Authority [Member] | Tax Year 2022 [Member]
Statement [Line Items]
Operating loss carryforward	3.4
Domestic Tax Authority [Member] | Tax Year 2023 [Member]
Statement [Line Items]
Operating loss carryforward	1.4
State and Local Jurisdiction [Member]
Statement [Line Items]
Operating loss carryforward	19.0
State and Local Jurisdiction [Member] | Tax Year 2016 [Member]
Statement [Line Items]
Operating loss carryforward	1.4
State and Local Jurisdiction [Member] | Tax Year 2017 [Member]
Statement [Line Items]
Operating loss carryforward	0.8
State and Local Jurisdiction [Member] | Tax Year 2018 [Member]
Statement [Line Items]
Operating loss carryforward	2.6
State and Local Jurisdiction [Member] | Tax Year 2019 [Member]
Statement [Line Items]
Operating loss carryforward	2.7
State and Local Jurisdiction [Member] | Tax Year 2020 [Member]
Statement [Line Items]
Operating loss carryforward	3.0
State and Local Jurisdiction [Member] | Tax Year 2021 [Member]
Statement [Line Items]
Operating loss carryforward	3.7
State and Local Jurisdiction [Member] | Tax Year 2022 [Member]
Statement [Line Items]
Operating loss carryforward	3.4
State and Local Jurisdiction [Member] | Tax Year 2023 [Member]
Statement [Line Items]
Operating loss carryforward	$ 1.4