Note 6 - Accounts Receivable, Accounts Payable and Accrued Liabilities (Details Textual) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Provision for Doubtful Accounts	[1]	$ 5,101	$ 4,925	$ 2,316
New Wave [Member]
Provision for Doubtful Accounts			$ 1,100

[1] Additions for 2017 include a $1.1 million allowance for doubtful accounts assumed as part of the NewWave acquisition.