Note 10 - Income Taxes (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Percent, Total	21.00%	21.00%	35.00%
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards, After Tax Effects	$ 21.9
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	20.0
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	1.9
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | NewWave and Clearwav [Member]
Operating Loss Carryforwards, After Tax Effects	8.5
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, After Tax Effects	3.6
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	0.2
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	$ 3.4