Note 2 - Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue Accounted for Under ASC 606		$ 51,503	$ 49,228	$ 101,727	$ 97,973
Revenue Accounted for Under Other Guidance		7,953	8,167	15,995	16,331
Total Revenue		59,456	57,395	117,722	114,304
Business and Wholesale Revenue, Business Broadband [Member]
Revenue Accounted for Under ASC 606		15,994	15,378	31,347	30,586
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		15,994	15,378	31,347	30,586
Business and Wholesale Revenue, Business Voice and Other [Member]
Revenue Accounted for Under ASC 606		6,802	6,953	13,659	13,657
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		6,802	6,953	13,659	13,657
Business and Wholesale Revenue, Managed IT Services [Member]
Revenue Accounted for Under ASC 606		1,300	1,517	2,527	3,176
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		1,300	1,517	2,527	3,176
Business and Wholesale Revenue, Equipment Sales and Installations [Member]
Revenue Accounted for Under ASC 606		1,192	1,008	2,606	1,888
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		1,192	1,008	2,606	1,888
Business and Wholesale Revenue, Wholesale Broadband [Member]
Revenue Accounted for Under ASC 606		11,123	8,720	21,376	17,271
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		11,123	8,720	21,376	17,271
Business and Wholesale Revenue, Wholesale Voice and Other [Member]
Revenue Accounted for Under ASC 606		1,344	1,392	2,632	2,818
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		1,344	1,392	2,632	2,818
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		2,269	2,070	4,660	4,137
Total Revenue		2,269	2,070	4,660	4,137
Business and Wholesale Revenue [Member]
Revenue Accounted for Under ASC 606		37,755	34,968	74,147	69,396
Revenue Accounted for Under Other Guidance		2,269	2,070	4,660	4,137
Total Revenue		40,024	37,038	78,807	73,533
Consumer Revenue, Broadband [Member]
Revenue Accounted for Under ASC 606		6,796	6,694	13,488	13,162
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		6,796	6,694	13,488	13,162
Consumer Revenue, Voice and Other [Member]
Revenue Accounted for Under ASC 606		2,380	2,647	4,829	5,380
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		2,380	2,647	4,829	5,380
Consumer Revenue [Member]
Revenue Accounted for Under ASC 606		9,176	9,341	18,317	18,542
Revenue Accounted for Under Other Guidance		0	0	0	0
Total Revenue		9,176	9,341	18,317	18,542
Regulatory Revenue, Access, Including Customer Ordered Service and Special Access [Member]
Revenue Accounted for Under ASC 606	[1]	4,572	4,919	9,263	10,035
Revenue Accounted for Under Other Guidance	[1]	0	0	0	0
Total Revenue	[1]	4,572	4,919	9,263	10,035
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]	761	1,174	1,488	2,347
Total Revenue	[2]	761	1,174	1,488	2,347
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	9,847	9,847
Total Revenue		4,923	4,923	9,847	9,847
Regulatory Revenue [Member]
Revenue Accounted for Under ASC 606		4,572	4,919	9,263	10,035
Revenue Accounted for Under Other Guidance		5,684	6,097	11,335	12,194
Total Revenue		$ 10,256	$ 11,016	$ 20,598	$ 22,229

[1] Includes customer ordered service and special access.

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