Note 5 - Accounts Receivable - Summary of Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accounts receivable, gross	$ 42,856	$ 35,264
Less: allowance for doubtful accounts	(3,041)	(2,729)
Accounts receivable, net	39,815	32,535
Retail Customers [Member]
Accounts receivable, gross	30,101	22,227
Wholesale Carriers [Member]
Accounts receivable, gross	6,346	8,146
Other [Member]
Accounts receivable, gross	$ 6,409	$ 4,891

Amounts due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer) for goods or services (including trade receivables) that have been delivered or sold in the normal course of business.

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Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

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