Note 11 - Revenue Streams and Concentrations - Revenue Streams (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues		$ 15,507	$ 15,574	$ 15,468	$ 15,422	$ 15,591	$ 15,762	$ 15,658	$ 15,755	$ 61,971	$ 62,766	$ 66,068
Revenues, within scope of ASU 2014-09												$ 66,068
Revenue Benchmark [Member]
Concentration Risk, Percentage										100.00%	100.00%	100.00%
Month-to-Month Customers [Member]
Revenues, within scope of ASU 2014-09										$ 28,515	$ 27,617	$ 29,556
Revenues, percentage within scope of ASU 2014-09										64.20%	61.30%	61.30%
Month-to-Month Customers [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage										46.00%	44.00%	44.70%
Competitive Local Exchange Carrier Business Customers [Member]
Revenues, within scope of ASU 2014-09										$ 12,716	$ 13,162	$ 14,060
Revenues, percentage within scope of ASU 2014-09										28.60%	29.20%	29.10%
Competitive Local Exchange Carrier Business Customers [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage										20.60%	21.00%	21.30%
Network Access Customers [member]
Revenues, within scope of ASU 2014-09										$ 2,011	$ 2,513	$ 2,711
Revenues, percentage within scope of ASU 2014-09										4.50%	5.60%	5.60%
Network Access Customers [member] | Revenue Benchmark [Member]
Concentration Risk, Percentage										3.20%	4.00%	4.10%
Month-to-Month, Competitive Local Exchange Carrier Business, and Network Access Customers [Member]
Revenues, within scope of ASU 2014-09										$ 43,242	$ 43,292	$ 46,327
Revenues, percentage within scope of ASU 2014-09										97.30%	96.10%	96.00%
Month-to-Month, Competitive Local Exchange Carrier Business, and Network Access Customers [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage										69.80%	69.00%	70.10%
Global Access Customers [Member]
Revenues, within scope of ASU 2014-09	[1]									$ 1,207	$ 1,770	$ 1,932
Revenues, percentage within scope of ASU 2014-09	[1]									2.70%	3.90%	4.00%
Global Access Customers [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage	[1]									1.90%	2.80%	2.90%
Month-to-Month, Competitive Local Exchange Carrier Business, Network Access, and Global Access Customers [Member]
Revenues, within scope of ASU 2014-09										$ 44,449	$ 45,062	$ 48,259
Revenues, percentage within scope of ASU 2014-09										100.00%	100.00%	100.00%
Month-to-Month, Competitive Local Exchange Carrier Business, Network Access, and Global Access Customers [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage										71.70%	71.80%	73.00%
Managed Services [Member]
Revenues	[2]									$ 708	$ 626	$ 639
Managed Services [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage	[2]									1.20%	1.00%	1.00%
Sales Channel, Directly to Consumer [Member]
Revenues										$ 45,157	$ 45,688	$ 48,898
Revenues, within scope of ASU 2014-09												$ 48,898
Sales Channel, Directly to Consumer [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage										72.90%	72.80%	74.00%
Local services [Member]
Revenues										$ 18,367	$ 19,313	$ 20,948
Local services [Member] | Sales Channel, Directly to Consumer [Member]
Revenues										18,367	19,313	20,948
Network Access [Member]
Revenues										19,881	21,210	21,662
Network Access [Member] | Sales Channel, Directly to Consumer [Member]
Revenues										3,218	4,283	4,643
Internet [Member]
Revenues										15,812	14,646	15,221
Internet [Member] | Sales Channel, Directly to Consumer [Member]
Revenues										15,812	14,646	15,221
Transport Services [Member]
Revenues										4,363	4,236	4,774
Transport Services [Member] | Sales Channel, Directly to Consumer [Member]
Revenues										4,212	4,085	4,623
Video and Security [Member]
Revenues										2,840	2,735	2,824
Video and Security [Member] | Sales Channel, Directly to Consumer [Member]
Revenues										2,840	2,735	2,824
Management Service [Member]
Revenues										708	626	639
Management Service [Member] | Sales Channel, Directly to Consumer [Member]
Revenues										708	626	639
Indefeasible Rights-Of-Use Agreements, Outside of ASU 2014-09 Scope [Member]
Revenues	[2]									$ 151	$ 151	$ 151
Indefeasible Rights-Of-Use Agreements, Outside of ASU 2014-09 Scope [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage	[2]									0.20%	0.20%	0.20%
Network Access, Outside of ASU 2014-09 Scope [Member]
Revenues	[2]									$ 16,663	$ 16,927	$ 17,019
Network Access, Outside of ASU 2014-09 Scope [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage	[2]									26.90%	27.00%	25.80%

[1] Fixed fees charged to MTM customers and CLEC business customers.

[2] Revenue generated from sources not within the scope of ASU 2014-09. See Note 2, Summary of Significant Accounting Policies - Revenue Recognition, for accounting policies associated with these sources of revenue.