Note 4 - Property and Equipment - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Property Plant and Equipment, Gross	$ 324,689	$ 315,843
Accumulated depreciation and amortization	(265,303)	(258,559)
Net property and equipment	59,386	57,284
Land [Member]
Property Plant and Equipment, Gross	1,157	1,164
Building Improvements [Member]
Property Plant and Equipment, Gross	$ 13,187	13,358
Estimated Life (Year)	40 years
Building Improvements [Member] \| Minimum [Member]
Estimated Life (Year)	20 years
Telephone Equipment [Member]
Property Plant and Equipment, Gross	$ 252,967	246,692
Estimated Life (Year)	20 years
Telephone Equipment [Member] \| Minimum [Member]
Estimated Life (Year)	6 years
Cable Television Equipment [Member]
Property Plant and Equipment, Gross	$ 13,921	13,258
Cable Television Equipment [Member] \| Maximum [Member]
Estimated Life (Year)	7 years
Furniture and Fixtures [Member]
Property Plant and Equipment, Gross	$ 3,082	3,082
Estimated Life (Year)	14 years
Furniture and Fixtures [Member] \| Minimum [Member]
Estimated Life (Year)	8 years
Vehicles [Member]
Property Plant and Equipment, Gross	$ 7,069	6,961
Estimated Life (Year)	9 years
Vehicles [Member] \| Minimum [Member]
Estimated Life (Year)	7 years
Computer Equipment [Member]
Property Plant and Equipment, Gross	$ 20,725	20,132
Estimated Life (Year)	7 years
Computer Equipment [Member] \| Minimum [Member]
Estimated Life (Year)	5 years
Computer Equipment [Member] \| Maximum [Member]
Estimated Life (Year)	7 years
Internet Equipment [Member]
Property Plant and Equipment, Gross	$ 12,581	$ 11,196
Internet Equipment [Member] \| Maximum [Member]
Estimated Life (Year)	5 years

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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