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The percentage of payroll deductions per employee under the employee stock purchase plan during the period.

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Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

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Amount of the cumulative effect on retained earnings net of related income tax effect.

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Amount of net periodic benefit cost (credit) for defined benefit plan.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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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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Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

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Note 1 - Description of Company and Summary of Significant Accounting Policies (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Jan. 08, 2018	Dec. 31, 2016
Restricted Cash and Cash Equivalents, Current, Total		$ 1,634	$ 11,814
Equipment and Buildings Under Capital Leases, Expiration Period		2033
Preferred Stock, Shares Authorized		5,000	5,000	145,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01			$ 0.01
Preferred Stock, Shares Issued, Total		0	0
Advertising Expense		$ 3,074	$ 3,656
Contract with Customer, Asset, Net, Current, Total	$ 6,898
Deferred Income Tax Liability from Contract Asset	1,960
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total		$ 225	$ 615
Preferred Stock, Shares Outstanding, Ending Balance		0	0
Other Nonoperating Income (Expense) [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total		$ 225	$ 615
Accounting Standards Update 2014-09 [Member]
Cumulative Effect on Retained Earnings, Net of Tax, Total	$ 4,938
Unionized Employees Concentration Risk [Member] \| Workforce Subject to Collective Bargaining Arrangements [Member] \| IBEW [Member]
Concentration Risk, Percentage		53.00%
Product Concentration Risk [Member] \| Sales Revenue, Net [Member] \| High Cost Support [Member]
Concentration Risk, Percentage		8.00%
Product Concentration Risk [Member] \| Sales Revenue, Net [Member] \| Rural Health Care Universal Service Support [Member]
Concentration Risk, Percentage		8.00%
Minimum [Member]
Property, Plant and Equipment, Useful Life		2 years
Employee Stock Purchase Plan, Payroll Deduction Per Employee, Percent		1.00%
Maximum [Member]
Property, Plant and Equipment, Useful Life		50 years
Employee Stock Purchase Plan, Payroll Deduction Per Employee, Percent		15.00%
Certificates of Deposit [Member]
Restricted Cash and Cash Equivalents, Current, Total		$ 1,600
Other Restricted Cash [Member]
Restricted Cash and Cash Equivalents, Current, Total		$ 34
Noncontrolling Interest [Member] \| Quintillion Holdings, LLC [Member]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage		50.00%
ACS Cable Systems LLC and Quintillion Holdings, LLC Joint Venture [Member]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage		50.00%