Note 5 - Derivative Instruments and Hedging Activities (Details Textual) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	May 31, 2020
Interest Rate Swap [Member]
Derivative, Notional Amount	$ 70.0	$ 70.0	$ 70.0
Forward Contracts [Member]
Derivative, Notional Amount	20.9	31.8
Forward Contracts [Member] | Designated as Hedging Instrument [Member]
Derivative, Notional Amount	$ 20.9	$ 26.8
Forward Contracts [Member] | Minimum [Member]
Derivative, Term of Contract (Month)	1 month
Forward Contracts [Member] | Maximum [Member]
Derivative, Term of Contract (Month)	18 months