Note 3 - Contracts With Customers - Information About Receivables, Contract Assets, and Contract Liabilities From Contracts With Customers (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Accounts receivable	$ 15,308		$ 11,922
Deferred revenue	(19,133)		(16,244)
Revenue recognized that was included in deferred revenue at beginning of year due to completion of services	(15,214)	$ (15,377)
Increases due to invoicing of client, net of amounts recognized as revenue	17,829	17,522
Decreases due to completion of services (or portion of services) and transferred to accounts receivable	(51)	(71)
Change due to cumulative catch-up adjustments arising from changes in expected contract consideration	274	(145)
Increases due to revenue recognized in the period with additional performance obligations before invoicing	131	$ 65
Other Current Assets [Member]
Contract assets included in other current assets	$ 133		$ 53