Note 4 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities	$ 0	$ 0	$ 0	$ 0

Amount of credit risk valuation adjustment to derivative liabilities to properly reflect the credit quality of the entity.

No definition available.

Name:	us-gaap_DerivativeCreditRiskValuationAdjustmentDerivativeLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant