Note 2 - Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Revenue Accounted for Under ASC 606		$ 199,122	$ 199,210
Revenue Accounted for Under Other Guidance		32,572	33,258
Operating revenues		231,694	232,468
Business and Wholesale Revenue, Business Broadband [Member]
Revenue Accounted for Under ASC 606		61,549	60,697
Revenue Accounted for Under Other Guidance
Operating revenues		61,549	60,697
Business and Wholesale Revenue, Business Voice and Other [Member]
Revenue Accounted for Under ASC 606		27,394	28,429
Revenue Accounted for Under Other Guidance
Operating revenues		27,394	28,429
Business and Wholesale Revenue, Managed IT Services [Member]
Revenue Accounted for Under ASC 606		6,494	5,742
Revenue Accounted for Under Other Guidance
Operating revenues		6,494	5,742
Business and Wholesale Revenue, Equipment Sales and Installations [Member]
Revenue Accounted for Under ASC 606		4,698	5,127
Revenue Accounted for Under Other Guidance
Operating revenues		4,698	5,127
Business and Wholesale Revenue, Wholesale Broadband [Member]
Revenue Accounted for Under ASC 606		36,408	31,931
Revenue Accounted for Under Other Guidance
Operating revenues		36,408	31,931
Business and Wholesale Revenue, Wholesale Voice and Other [Member]
Revenue Accounted for Under ASC 606		5,617	6,000
Revenue Accounted for Under Other Guidance
Operating revenues		5,617	6,000
Business and Wholesale Revenue, Operating Leases and Other Deferred Revenue [Member]
Revenue Accounted for Under ASC 606
Revenue Accounted for Under Other Guidance		8,404	6,668
Operating revenues		8,404	6,668
Business and Wholesale Revenue [Member]
Revenue Accounted for Under ASC 606		142,160	137,926
Revenue Accounted for Under Other Guidance		8,404	6,668
Operating revenues		150,564	144,594
Consumer Revenue, Broadband [Member]
Revenue Accounted for Under ASC 606		26,589	26,144
Revenue Accounted for Under Other Guidance
Operating revenues		26,589	26,144
Consumer Revenue, Voice and Other [Member]
Revenue Accounted for Under ASC 606		10,431	11,158
Revenue Accounted for Under Other Guidance
Operating revenues		10,431	11,158
Consumer Revenue [Member]
Revenue Accounted for Under ASC 606		37,020	37,302
Revenue Accounted for Under Other Guidance
Operating revenues		37,020	37,302
Regulatory Revenue, Access, Including Customer Ordered Service and Special Access [Member]
Revenue Accounted for Under ASC 606	[1]	19,942	23,982
Revenue Accounted for Under Other Guidance	[1]
Operating revenues	[1]	19,942	23,982
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]	4,474	6,896
Operating revenues	[2]	4,474	6,896
Regulatory, High-cost Support [Member]
Revenue Accounted for Under ASC 606
Revenue Accounted for Under Other Guidance		19,694	19,694
Operating revenues		19,694	19,694
Regulatory Revenue [Member]
Revenue Accounted for Under ASC 606		19,942	23,982
Revenue Accounted for Under Other Guidance		24,168	26,590
Operating revenues		$ 44,110	$ 50,572

[1] Includes customer ordered service and special access.

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