Note 4 - Other Assets - Schedule of Other Assets, Net (Parenthetical) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Other Assets Unclassified [Abstract]
Other receivables, net of allowance	$ 82	$ 82

Amount of valuation allowance for receivables classified as other, due within one year or the normal operating cycle, if longer.

No definition available.

Name:	us-gaap_AllowanceForDoubtfulOtherReceivablesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant