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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of income (loss) for proportionate share of equity method investee's income (loss).

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Carrying amount of the unpaid portion of the fee payable to the managing member or general partner for management of the fund or trust.

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Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Gross number of share options (or share units) granted during the period.

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Percentage of vesting of award under share-based payment arrangement.

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Value, after forfeiture, of shares granted under share-based payment arrangement. Excludes employee stock ownership plan (ESOP).

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AFFILIATE AND RELATED PARTY TRANSACTIONS - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Apr. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jun. 30, 2017
Related Party Transaction [Line Items]
Equity in net income (loss) from investment in related party				$ 0	$ (10,849)
Related party expense		$ 5,040	$ 2,031	$ 11,992	20,298
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				4 years
Related Party Transaction [Domain]
Related Party Transaction [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				4 years
Fees for Executive Services \| Affiliates
Related Party Transaction [Line Items]
Related party expense					13,250	$ 13,250
Equipment Purchase Costs \| Altice Management International
Related Party Transaction [Line Items]
Capital expenditures				$ 9,346
Equipment Purchase Costs \| Altice Labs S.A.
Related Party Transaction [Line Items]
Capital expenditures		3,456	3,945		6,679
I24News
Related Party Transaction [Line Items]
Equity in net income (loss) from investment in related party					(1,130)
Ownership percentage	24.00%
Newsday
Related Party Transaction [Line Items]
Equity in net income (loss) from investment in related party	$ 13,298				9,719
Ownership percentage	25.00%
Other Operating Expense \| Transition Services \| Affiliates
Related Party Transaction [Line Items]
Other operating expenses, charges for related party services		$ 1,602	$ 905	$ 5,868	$ 1,904
Altice N.V. \| Altice N.V. Distribution
Related Party Transaction [Line Items]
Management advisory and consulting fee							$ 30,000
Share-based Payment Arrangement, Tranche One [Member]
Related Party Transaction [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				50.00%
Share-based Payment Arrangement, Tranche One [Member] \| Related Party Transaction [Domain]
Related Party Transaction [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				50.00%
Share-based Payment Arrangement, Tranche Two [Member]
Related Party Transaction [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				25.00%
Share-based Payment Arrangement, Tranche Two [Member] \| Related Party Transaction [Domain]
Related Party Transaction [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				25.00%
Share-based Payment Arrangement, Tranche Three [Member]
Related Party Transaction [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				25.00%
Share-based Payment Arrangement, Tranche Three [Member] \| Related Party Transaction [Domain]
Related Party Transaction [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				25.00%
Equity Option [Member] \| Related Party Transaction [Domain]
Related Party Transaction [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross				370,923
Shares Granted, Value, Share-based Payment Arrangement, after Forfeiture				$ 3,516