SUBSEQUENT EVENT (Details) - USD ($)		1 Months Ended	9 Months Ended
	Oct. 15, 2018	Apr. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Oct. 16, 2018	Oct. 02, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Repayments of Senior Debt			$ 635,738,000	$ 3,684,668,000
Debt face amount			6,282,938,000				$ 4,693,675,000
Senior Notes
Subsequent Event [Line Items]
Debt face amount			15,739,245,000				16,289,245,000
Cequel and Cequel Capital 5.5% Senior Notes due May 15, 2026 [Member] | Senior Notes
Subsequent Event [Line Items]
Debt face amount			$ 1,500,000,000				1,500,000,000
Stated interest rate			5.50%
Cequel and Cequel Capital 7.75% Senior Notes due July 15, 2025 [Member] | Senior Notes
Subsequent Event [Line Items]
Debt face amount			$ 620,000,000				620,000,000
Stated interest rate			7.75%
Cequel and Cequel Capital 5.125% Senior Notes due December 15, 2021 [Member] | Senior Notes
Subsequent Event [Line Items]
Debt face amount			$ 1,250,000,000				1,250,000,000
Stated interest rate			5.125%
CSC Holdings 7.625% Notes due July 15, 2018 [Member] | Senior Notes
Subsequent Event [Line Items]
Debt face amount			$ 0				500,000,000
Stated interest rate			7.625%
Cequel and Cequel Capital 6.375% Senior Notes due September 15, 2020 [Member] | Senior Notes
Subsequent Event [Line Items]
Debt face amount			$ 0				1,050,000,000
Stated interest rate			6.375%
Extinguishment of debt		$ 16,737,000
Cequel and Cequel Capital 7.5% Senior Notes due April 1, 2028 [Member] [Domain] | Senior Notes
Subsequent Event [Line Items]
Debt face amount			$ 1,050,000,000				0
Stated interest rate			7.50%
Altice US Finance I Corporation Senior Secured Notes 5.375% Senior Notes due July 15, 2023 [Member] | Senior Notes
Subsequent Event [Line Items]
Debt face amount			$ 1,100,000,000				$ 1,100,000,000
Stated interest rate			5.375%
Subsequent Event
Subsequent Event [Line Items]
Repayments of Senior Debt	$ 125,000,000
Maximum amount of senior notes exchanged						$ 5,520,000,000
Par value of senior notes					$ 1,000
Cash Consideration for Senior Notes Exchanged					2.50
Discounted Par Value After Early Tender					950
Deferred Financing Costs Netted Against Debt			$ 143,326,000
Subsequent Event | Cequel and Cequel Capital 5.5% Senior Notes due May 15, 2026 [Member] | Senior Notes
Subsequent Event [Line Items]
Amount of Notes Early Tendered					1,495,642,000
Amount of Notes Tendered After Early Tender					3,309,000
Unexchanged Original Notes					1,049,000
Subsequent Event | Cequel and Cequel Capital 7.75% Senior Notes due July 15, 2025 [Member] | Senior Notes
Subsequent Event [Line Items]
Amount of Notes Early Tendered					610,698,000
Amount of Notes Tendered After Early Tender					7,562,000
Unexchanged Original Notes					1,740,000
Subsequent Event | CSC Holdings Senior Secured Incremental Term Loan B Facility [Member] | Term Loan
Subsequent Event [Line Items]
Debt face amount	$ 1,275,000,000
Subsequent Event | Cequel and Cequel Capital 5.125% Senior Notes due December 15, 2021 [Member] | Senior Notes
Subsequent Event [Line Items]
Amount of Notes Early Tendered					1,232,328,000
Amount of Notes Tendered After Early Tender					8,786,000
Unexchanged Original Notes					8,886,000
Subsequent Event | Cequel and Cequel Capital 7.5% Senior Notes due April 1, 2028 [Member] [Domain] | Senior Notes
Subsequent Event [Line Items]
Amount of Notes Early Tendered					1,045,443,000
Amount of Notes Tendered After Early Tender					439,000
Unexchanged Original Notes					4,118,000
Subsequent Event | Altice US Finance I Corporation Senior Secured Notes 5.375% Senior Notes due July 15, 2023 [Member] | Senior Notes
Subsequent Event [Line Items]
Amount of Notes Early Tendered					1,095,493,000
Amount of Notes Tendered After Early Tender					350,000
Unexchanged Original Notes					$ 4,157,000