Note 2 - Revenues 1 (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Revenue from Contract with Customer, Including Assessed Tax	$ 13,448	$ 15,402
Individual Customer Advances Used or Refunded to Customer, Period	180 days
Contract with Customer, Liability, Revenue Recognized	$ 59	$ 74
Contract with Customer, Liability, Total	$ 1,463		$ 934
Minimum [Member]
Capitalized Contract Cost, Amortization Period	2 years
Maximum [Member]
Capitalized Contract Cost, Amortization Period	3 years
Accrued Expense and Other Current Liabilities [Member]
Contract with Customer, Liability, Total	$ 1,463		934
Google LLC [Member]
Revenue from Contract with Customer, Including Assessed Tax	2,921
Accounts Receivable, after Allowance for Credit Loss, Total	$ 3,450		$ 3,867