Note 10 - Accounts Receivable Securitization (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Debt Instrument, Fee Amount	$ 261		$ 341
Line of Credit [Member] | Accounts Receivable Securitization Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 100,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.60%
Accounts Receivable Eligible for Securitization	$ 25,197	$ 31,868
Line of Credit Facility, Fair Value of Amount Outstanding	0	0
Letters of Credit Outstanding, Amount	25,500	31,218
Line of Credit Facility, Remaining Borrowing Capacity	$ 303	$ 650
Line of Credit [Member] | Accounts Receivable Securitization Facility [Member] | Minimum [Member]
Line of Credit Facility, Commitment Fee Percentage	2.00%
Line of Credit [Member] | Accounts Receivable Securitization Facility [Member] | Maximum [Member]
Line of Credit Facility, Commitment Fee Percentage	2.50%