Note 2 - Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue Accounted for Under ASC 606		$ 52,623	$ 50,925	$ 154,350	$ 148,898
Revenue Accounted for Under Other Guidance		7,891	8,203	23,886	24,534
Total Revenue		60,514	59,128	178,236	173,432
Business and Wholesale Revenue, Business Broadband [Member]
Revenue Accounted for Under ASC 606		15,789	15,595	47,136	46,181
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		15,789	15,595	47,136	46,181
Business and Wholesale Revenue, Business Voice and Other [Member]
Revenue Accounted for Under ASC 606		6,955	6,889	20,614	20,546
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		6,955	6,889	20,614	20,546
Business and Wholesale Revenue, Managed IT Services [Member]
Revenue Accounted for Under ASC 606		1,377	1,789	3,904	4,965
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		1,377	1,789	3,904	4,965
Business and Wholesale Revenue, Equipment Sales and Installations [Member]
Revenue Accounted for Under ASC 606		2,102	942	4,708	2,830
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		2,102	942	4,708	2,830
Business and Wholesale Revenue, Wholesale Broadband [Member]
Revenue Accounted for Under ASC 606		11,105	9,550	32,481	26,821
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		11,105	9,550	32,481	26,821
Business and Wholesale Revenue, Wholesale Voice and Other [Member]
Revenue Accounted for Under ASC 606		1,342	1,870	3,974	4,688
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		1,342	1,870	3,974	4,688
Business and Wholesale Revenue, Operating Leases and Other Deferred Revenue [Member]
Revenue Accounted for Under ASC 606		0	0	0	0
Revenue Accounted for Under Other Guidance		2,228	2,104	6,888	6,241
Total Revenue		2,228	2,104	6,888	6,241
Business and Wholesale Revenue [Member]
Revenue Accounted for Under ASC 606		38,670	36,635	112,817	106,031
Revenue Accounted for Under Other Guidance		2,228	2,104	6,888	6,241
Total Revenue		40,898	38,739	119,705	112,272
Consumer Revenue, Broadband [Member]
Revenue Accounted for Under ASC 606		6,986	6,718	20,474	19,880
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		6,986	6,718	20,474	19,880
Consumer Revenue, Voice and Other [Member]
Revenue Accounted for Under ASC 606		2,305	2,567	7,134	7,947
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		2,305	2,567	7,134	7,947
Consumer Revenue [Member]
Revenue Accounted for Under ASC 606		9,291	9,285	27,608	27,827
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		9,291	9,285	27,608	27,827
Regulatory Revenue, Access, Including Customer Ordered Service and Special Access [Member]
Revenue Accounted for Under ASC 606	[1]	4,662	5,005	13,925	15,040
Revenue Accounted for Under Other Guidance	[1]	0	0	0	0
Total Revenue	[1]	4,662	5,005	13,925	15,040
Regulatory Revenue, Access, Including Carrier of Last Resort and Carrier Common Line [Member]
Revenue Accounted for Under ASC 606	[2]	0	0	0	0
Revenue Accounted for Under Other Guidance	[2]	740	1,176	2,228	3,523
Total Revenue	[2]	740	1,176	2,228	3,523
Regulatory, High-cost Support [Member]
Revenue Accounted for Under ASC 606		0	0	0	0
Revenue Accounted for Under Other Guidance		4,923	4,923	14,770	14,770
Total Revenue		4,923	4,923	14,770	14,770
Regulatory Revenue [Member]
Revenue Accounted for Under ASC 606		4,662	5,005	13,925	15,040
Revenue Accounted for Under Other Guidance		5,663	6,099	16,998	18,293
Total Revenue		$ 10,325	$ 11,104	$ 30,923	$ 33,333

[1] Includes customer ordered service and special access.

[2] Includes Essential Network Support ("ENS").