Note 2 - Revenue Recognition - 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 Accounted for Under ASC 606		$ 49,228	$ 51,382	$ 97,973	$ 99,140
Revenue Accounted for Under Other Guidance		8,167	8,196	16,331	16,410
Total Revenue		57,395	59,578	114,304	115,550
Business and Wholesale Revenue, Business Broadband [Member]
Revenue Accounted for Under ASC 606		15,378	16,950	30,586	30,550
Revenue Accounted for Under Other Guidance
Total Revenue		15,378	16,950	30,586	30,550
Business and Wholesale Revenue, Business Voice and Other [Member]
Revenue Accounted for Under ASC 606		6,953	7,038	13,657	13,889
Revenue Accounted for Under Other Guidance
Total Revenue		6,953	7,038	13,657	13,889
Business and Wholesale Revenue, Managed IT Services [Member]
Revenue Accounted for Under ASC 606		1,517	1,191	3,176	2,456
Revenue Accounted for Under Other Guidance
Total Revenue		1,517	1,191	3,176	2,456
Business and Wholesale Revenue, Equipment Sales and Installations [Member]
Revenue Accounted for Under ASC 606		1,008	1,460	1,888	2,382
Revenue Accounted for Under Other Guidance
Total Revenue		1,008	1,460	1,888	2,382
Business and Wholesale Revenue, Wholesale Broadband [Member]
Revenue Accounted for Under ASC 606		8,720	7,795	17,271	15,851
Revenue Accounted for Under Other Guidance
Total Revenue		8,720	7,795	17,271	15,851
Business and Wholesale Revenue, Wholesale Voice and Other [Member]
Revenue Accounted for Under ASC 606		1,392	1,442	2,818	2,930
Revenue Accounted for Under Other Guidance
Total Revenue		1,392	1,442	2,818	2,930
Business and Wholesale Revenue, Operating Leases and Other Deferred Revenue [Member]
Revenue Accounted for Under ASC 606
Revenue Accounted for Under Other Guidance		2,070	1,602	4,137	3,183
Total Revenue		2,070	1,602	4,137	3,183
Business and Wholesale Revenue [Member]
Revenue Accounted for Under ASC 606		34,968	35,876	69,396	68,058
Revenue Accounted for Under Other Guidance		2,070	1,602	4,137	3,183
Total Revenue		37,038	37,478	73,533	71,241
Consumer Revenue, Broadband [Member]
Revenue Accounted for Under ASC 606		6,694	6,695	13,162	13,187
Revenue Accounted for Under Other Guidance
Total Revenue		6,694	6,695	13,162	13,187
Consumer Revenue, Voice and Other [Member]
Revenue Accounted for Under ASC 606		2,647	2,759	5,380	5,636
Revenue Accounted for Under Other Guidance
Total Revenue		2,647	2,759	5,380	5,636
Consumer Revenue [Member]
Revenue Accounted for Under ASC 606		9,341	9,454	18,542	18,823
Revenue Accounted for Under Other Guidance
Total Revenue		9,341	9,454	18,542	18,823
Regulatory Revenue, Access, Including Customer Ordered Service and Special Access [Member]
Revenue Accounted for Under ASC 606	[1]	4,919	6,052	10,035	12,259
Revenue Accounted for Under Other Guidance	[1]
Total Revenue	[1]	4,919	6,052	10,035	12,259
Regulatory Revenue, Access, Including Carrier of Last Resort and Carrier Common Line [Member]
Revenue Accounted for Under ASC 606	[2]
Revenue Accounted for Under Other Guidance	[2]	1,174	1,670	2,347	3,380
Total Revenue	[2]	1,174	1,670	2,347	3,380
Regulatory, High-cost Support [Member]
Revenue Accounted for Under ASC 606
Revenue Accounted for Under Other Guidance		4,923	4,924	9,847	9,847
Total Revenue		4,923	4,924	9,847	9,847
Regulatory Revenue [Member]
Revenue Accounted for Under ASC 606		4,919	6,052	10,035	12,259
Revenue Accounted for Under Other Guidance		6,097	6,594	12,194	13,227
Total Revenue		$ 11,016	$ 12,646	$ 22,229	$ 25,486

[1] Includes customer ordered service and special access.

[2] Includes carrier of last resort and carrier common line.