Note 15 - Income Taxes - Open Tax Years and Jurisdictions That the Company Used in Its Evaluation of Tax Positions (Details)	12 Months Ended
	Mar. 31, 2020
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Earliest Tax Year [Member]
Open tax year	2017
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Latest Tax Year [Member]
Open tax year	2020
State and Local Jurisdiction [Member] | Hawaii Department of Taxation [Member] | Earliest Tax Year [Member]
Open tax year	2017
State and Local Jurisdiction [Member] | Hawaii Department of Taxation [Member] | Latest Tax Year [Member]
Open tax year	2020
State and Local Jurisdiction [Member] | California Franchise Tax Board [Member] | Earliest Tax Year [Member]
Open tax year	2016
State and Local Jurisdiction [Member] | California Franchise Tax Board [Member] | Latest Tax Year [Member]
Open tax year	2020