Note 3 - Contracts With Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue	$ 31,414	$ 28,017	$ 62,894	$ 59,034
Transferred over Time [Member] | Subscription Services [Member]
Revenue	27,918	25,653	55,831	51,419
Transferred over Time [Member] | Fixed, Non-subscription Services [Member]
Revenue	506	400	1,040	1,587
Transferred over Time [Member] | Unit Price Services [Member]
Revenue	1,365	1,720	3,398	3,912
Transferred at Point in Time [Member] | Subscription Services [Member]
Revenue	$ 1,625	$ 244	$ 2,625	$ 2,116