Note 2 - Revenue Recognition - Revenue Accounted for In Accordance With ASC 606, By Timing of Revenue Recognition (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Total revenue		$ 199,122	$ 199,210
Balance at beginning of period, contract assets		8,052	6,898
Contract additions, contract assets		3,070	4,881
Amortization, contract assets		(3,797)	(3,727)
Impairments		(83)
Balance at end of period, contract assets		7,242	8,052
Balance at beginning of period, contract liabilities		2,766	1,150
Contract additions, contract liabilities		2,575	2,407
Revenue recognized, contract liabilities		(1,438)	(791)
Balance at end of period, contract liabilities		3,903	2,766
Transferred over Time [Member]
Total revenue		174,482	170,101
Transferred at Point in Time [Member]
Total revenue		4,698	5,127
Regulatory Revenue, Access [Member]
Total revenue	[1]	$ 19,942	$ 23,982

[1] Includes customer ordered service and special access.