DEBT - Senior Guaranteed Notes and Senior Notes and Debentures (Details) - USD ($)		1 Months Ended		9 Months Ended
	Jun. 21, 2016	Apr. 30, 2018	Feb. 28, 2018	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal Amount				$ 6,282,938,000	$ 4,693,675,000
Carrying Amount				15,355,738,000	15,860,432,000
Less: current portion				531,206,000	507,744,000
Long-term debt				14,824,532,000	15,352,688,000
Senior Notes
Debt Instrument [Line Items]
Principal Amount				$ 15,739,245,000	16,289,245,000
Senior Notes | 7.875% Notes due February 15, 2018
Debt Instrument [Line Items]
Interest Rate				7.875%
Principal Amount				$ 0	300,000,000
Carrying Amount				$ 0	301,184,000
Senior Notes | CSC Holdings 7.625% Notes due July 15, 2018 [Member]
Debt Instrument [Line Items]
Interest Rate				7.625%
Principal Amount				$ 0	500,000,000
Carrying Amount				$ 0	507,744,000
Senior Notes | 8.625% Notes due February 15, 2019
Debt Instrument [Line Items]
Interest Rate				8.625%
Principal Amount				$ 526,000,000	526,000,000
Carrying Amount				$ 531,206,000	541,165,000
Senior Notes | 6.75% Notes due November 15, 2021
Debt Instrument [Line Items]
Interest Rate				6.75%
Principal Amount				$ 1,000,000,000	1,000,000,000
Carrying Amount				$ 966,913,000	960,146,000
Senior Notes | 5.25% Notes due June 1, 2024
Debt Instrument [Line Items]
Interest Rate				5.25%
Principal Amount				$ 750,000,000	750,000,000
Carrying Amount				$ 668,918,000	660,601,000
Senior Notes | 10.125% Notes due January 15, 2023
Debt Instrument [Line Items]
Interest Rate				10.125%
Principal Amount				$ 1,800,000,000	1,800,000,000
Carrying Amount				$ 1,780,504,000	1,777,914,000
Senior Notes | Senior Notes due in 2025
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage				100.00%
Senior Notes | 10.875% Notes due October 15, 2025
Debt Instrument [Line Items]
Interest Rate				10.875%
Principal Amount				$ 1,684,221,000	1,684,221,000
Carrying Amount				$ 1,662,507,000	1,661,135,000
Senior Notes | 6.625% Notes due October 15, 2025
Debt Instrument [Line Items]
Interest Rate				6.625%
Principal Amount				$ 1,000,000,000	1,000,000,000
Carrying Amount				$ 987,707,000	986,717,000
Senior Notes | 5.5% Notes due April 15, 2027
Debt Instrument [Line Items]
Interest Rate				5.50%
Principal Amount				$ 1,310,000,000	1,310,000,000
Carrying Amount				$ 1,304,816,000	1,304,468,000
Debt Instrument, Redemption Price, Percentage				105.50%
Senior Notes | 5.375% Notes Due February 1, 2028
Debt Instrument [Line Items]
Interest Rate				5.375%
Principal Amount				$ 1,000,000,000	0
Carrying Amount				$ 991,896,000	0
Debt Instrument, Redemption Price, Percentage				105.375%
Senior Notes | 7.75% Notes due April 15, 2018
Debt Instrument [Line Items]
Interest Rate				7.75%
Principal Amount				$ 0	750,000,000
Carrying Amount				$ 0	754,035,000
Extinguishment of debt			$ 7,019,000
Senior Notes | 8.0% Notes due April 15, 2020
Debt Instrument [Line Items]
Interest Rate				8.00%
Principal Amount				$ 500,000,000	500,000,000
Carrying Amount				$ 494,445,000	492,009,000
Senior Notes | 5.875% Notes due September 15, 2022
Debt Instrument [Line Items]
Interest Rate				5.875%
Principal Amount				$ 649,024,000	649,024,000
Carrying Amount				$ 582,236,000	572,071,000
Senior Notes | Cequel and Cequel Capital 6.375% Senior Notes due September 15, 2020 [Member]
Debt Instrument [Line Items]
Interest Rate				6.375%
Principal Amount				$ 0	1,050,000,000
Carrying Amount				$ 0	1,027,493,000
Extinguishment of debt		$ 16,737,000
Senior Notes | Cequel and Cequel Capital 5.125% Senior Notes due December 15, 2021 [Member]
Debt Instrument [Line Items]
Interest Rate				5.125%
Principal Amount				$ 1,250,000,000	1,250,000,000
Carrying Amount				$ 1,157,405,000	1,138,870,000
Senior Notes | Cequel and Cequel Capital 7.75% Senior Notes due July 15, 2025 [Member]
Debt Instrument [Line Items]
Interest Rate				7.75%
Principal Amount				$ 620,000,000	620,000,000
Carrying Amount				$ 605,540,000	604,374,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed				40.00%
Debt Instrument, Redemption Price, Percentage				107.75%
Senior Notes | Cequel and Cequel Capital 7.5% Senior Notes due April 1, 2028 [Member] [Domain]
Debt Instrument [Line Items]
Interest Rate				7.50%
Principal Amount				$ 1,050,000,000	0
Carrying Amount				$ 1,048,222,000	0
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed				40.00%
Debt Instrument, Redemption Price, Percentage				107.50%
Senior Notes | Altice US Finance I Corporation Senior Secured Notes 5.375% Senior Notes due July 15, 2023 [Member]
Debt Instrument [Line Items]
Interest Rate				5.375%
Principal Amount				$ 1,100,000,000	1,100,000,000
Carrying Amount				$ 1,084,542,000	1,082,482,000
Senior Notes | Cequel and Cequel Capital 5.5% Senior Notes due May 15, 2026 [Member]
Debt Instrument [Line Items]
Interest Rate				5.50%
Principal Amount				$ 1,500,000,000	1,500,000,000
Carrying Amount				$ 1,488,881,000	$ 1,488,024,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed				40.00%
Debt Instrument, Redemption Price, Percentage				105.50%
Cablevision | Senior Notes | CSC Holdings Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed				40.00%
Adjustment to fair value	$ 52,788,000
Cablevision | Senior Notes | 10.125% Notes due January 15, 2023
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage				110.125%
Cablevision | Senior Notes | 10.875% Notes due October 15, 2025
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage				110.875%
Cablevision | Senior Notes | 6.625% Notes due October 15, 2025
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage				106.625%