Note 5 - Accounts Receivable - Summary of Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounts receivable, gross	$ 32,023	$ 38,981
Less: allowance for doubtful accounts	(4,285)	(4,627)
Accounts receivable, net	27,738	34,354
Retail Customers [Member]
Accounts receivable, gross	20,085	22,101
Wholesale Carriers [Member]
Accounts receivable, gross	8,257	13,157
Other [Member]
Accounts receivable, gross	$ 3,681	$ 3,723