Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXESOn July 1, 2015 (the Distribution Date), the Company completed the spin-off of Cable ONE as an independent, publicly traded company. The transaction was structured as a tax-free spin-off of Cable ONE to the stockholders of the Company. Since July 1, 2015, Cable One has been an independent public company trading on the New York Stock Exchange under the symbol “CABO”. In connection with the Coronavirus Aid, Relief and Economic Security (CARES) Act, Cable One has the ability to carryback its 2019 taxable losses to the tax period from January 1, 2015 to June 30, 2015, the period in which Cable One was included in the Company’s 2015 tax return. As a result, the Company amended its 2015 tax returns in order to accommodate Cable One's request to carryback its 2019 taxable losses. The Company expects that this action will have no impact on the results or the financial position of the Company. To reflect the expected refund due to Cable One, the Company has included an estimated $15.9 million current income tax receivable and a corresponding current liability to Cable One on its balance sheet as of September 30, 2021.The Company's effective tax rate for the first nine months of 2021 and 2020 was 22.6% and 29.6%, respectively. The Company’s effective tax rate for 2021 was favorably impacted by a $15.7 million deferred tax adjustment arising from a change in the estimated deferred state income tax rate attributable to the apportionment formula used in the calculation of deferred taxes related to the Company’s pension and other postretirement plans.