Note 8 - Commitments and Contingencies (Details Textual) $ in Millions	6 Months Ended
Jun. 30, 2021 USD ($)
Purchase Obligation, Total	$ 28.9
Long-term Purchase Commitment, Period (Month)	30 months

Period covered by the long-term purchase commitment, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_LongtermPurchaseCommitmentPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration