Note 10 - Accounts Receivable Securitization (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Payments of Financing Costs, Total			$ 9,002	$ 20,628
Line of Credit [Member] | Accounts Receivable Securitization Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 100,000		$ 100,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage			0.60%
Accounts Receivable Eligible for Securitization	30,660		$ 30,660		$ 41,282
Line of Credit Facility, Fair Value of Amount Outstanding	0		0		0
Letters of Credit Outstanding, Amount	30,100		30,100		41,211
Line of Credit Facility, Remaining Borrowing Capacity	560		560		$ 71
Payments of Financing Costs, Total	$ 249	$ 344	$ 882	$ 1,095
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%