DESCRIPTION OF BUSINESS AND RELATED MATTERS (Details)				1 Months Ended				12 Months Ended			19 Months Ended
	Jun. 06, 2018 USD ($)	May 22, 2018 $ / shares	May 31, 2017 USD ($)	Dec. 31, 2019 USD ($) shares	Jan. 31, 2018 USD ($)	Jul. 31, 2017 USD ($)	Jun. 30, 2017 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) segment $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	Jul. 31, 2019 USD ($)	Jun. 08, 2018 USD ($) shares	Jun. 21, 2016 USD ($)
Business Acquisition [Line Items]
Number of segments | segment								1
Goodwill				$ 8,142,309,000				$ 8,142,309,000	$ 8,012,416,000	$ 8,019,861,000	$ 8,142,309,000
Conversion of debt								$ 0	$ 0	$ 2,264,252,000
Cash dividends declared per common share (in dollars per share) | $ / shares		$ 2.035						$ 0	$ 2.035	$ 1.29
Dividend paid	$ 1,499,935,000
Common stock, shares outstanding (in shares) | shares				632,995,139				632,995,139			632,995,139
Share repurchase authorized													$ 2,000,000,000.0
Value of shares repurchased								$ 1,686,873,000	$ 500,000,000		$ 2,186,874,000
Shares repurchased (in shares) | shares								72,668,712			100,697,392
Availability remaining under its stock repurchase program				$ 4,813,126,000				$ 4,813,126,000			$ 4,813,126,000
Principal Amount				$ 24,817,366,000				$ 24,817,366,000	$ 23,296,581,000		$ 24,817,366,000
Altice Technical Services
Business Acquisition [Line Items]
Percentage of shares acquired					70.00%
Consideration transfered					$ 1.00
Consolidation, Wholly Owned Subsidiary, Parent Ownership Interest, Percent								100.00%
Goodwill					$ (23,101,000)
Common Class A
Business Acquisition [Line Items]
Common stock, shares outstanding (in shares) | shares				446,749,307				446,749,307	496,064,027	246,982,292	446,749,307
Shares repurchased (in shares) | shares									28,028,680
Common Class B
Business Acquisition [Line Items]
Common stock conversion ratio				1				1			1
Common stock, shares outstanding (in shares) | shares				186,245,832				186,245,832	212,976,259	490,086,674	186,245,832
Shares repurchased (in shares) | shares									0
IPO
Business Acquisition [Line Items]
Percentage of ownership							98.20%
IPO | Common Class A
Business Acquisition [Line Items]
Number of shares issued (in shares) | shares							71,724,139
Price per share (in dollars per share) | $ / shares							$ 30.00
Percentage of ownership							70.20%
Proceeds form issuance of shares							$ 362,069,000
Underwriting discount and expenses							$ 12,998,000
Consideration received on transaction, used to repay long term debt						$ 350,120,000
Over-Allotment Option | Common Class A
Business Acquisition [Line Items]
Number of shares issued (in shares) | shares							7,781,110
Neptune Holdings LP Acquisition [Member] | Common Class A
Business Acquisition [Line Items]
Number of shares issued (in shares) | shares				6,290,292
Altice USA | IPO | Common Class A
Business Acquisition [Line Items]
Number of shares issued (in shares) | shares							12,068,966
Existing Shareholders | IPO | Common Class A
Business Acquisition [Line Items]
Number of shares issued (in shares) | shares							59,655,173
Co-investor
Business Acquisition [Line Items]
Conversion of debt			$ 525,000,000
Subsidiary of Common Parent
Business Acquisition [Line Items]
Conversion of debt			$ 1,225,000,000
Notes payable and supply chain financing | Cablevision Systems Corp.
Business Acquisition [Line Items]
Principal Amount														$ 1,750,000,000
2019 Share Repurchase Authorization [Member]
Business Acquisition [Line Items]
Share repurchase authorized												$ 5,000,000,000.0
10.875% Notes due October 15, 2025 | Senior Notes
Business Acquisition [Line Items]
Outstanding debt				$ 1,665,237,000		315,779,000		$ 1,665,237,000	$ 1,663,027,000		$ 1,665,237,000
Stated interest rate				10.875%				10.875%			10.875%
Gain (loss) on extinguishment of debt						$ (34,341,000)
Principal Amount				$ 1,684,221,000				$ 1,684,221,000	1,684,221,000		$ 1,684,221,000
10.125% Notes due January 15, 2023 | Senior Notes
Business Acquisition [Line Items]
Outstanding debt				$ 0				$ 0	1,781,424,000		$ 0
Stated interest rate				10.125%				10.125%			10.125%
Principal Amount				$ 0				$ 0	1,800,000,000		$ 0
6.625% Notes due October 15, 2025 | Secured Debt [Member]
Business Acquisition [Line Items]
Outstanding debt				$ 989,483,000				$ 989,483,000	988,052,000		$ 989,483,000
Stated interest rate				6.625%				6.625%			6.625%
Principal Amount				$ 1,000,000,000				$ 1,000,000,000	1,000,000,000		$ 1,000,000,000
Notes Payable at 10.75% | Notes payable and supply chain financing | Cablevision Systems Corp.
Business Acquisition [Line Items]
Stated interest rate														10.75%
Principal Amount														$ 875,000,000
Notes Payable at 11% | Notes payable and supply chain financing | Cablevision Systems Corp.
Business Acquisition [Line Items]
Stated interest rate														11.00%
Principal Amount														$ 875,000,000
Debt issued by Cablevision [Member] | Secured Debt [Member]
Business Acquisition [Line Items]
Outstanding debt				1,095,193,000				1,095,193,000			1,095,193,000
Altice N.V. Distribution | Altice N.V.
Business Acquisition [Line Items]
Controlling interest percent													67.20%
Common stock conversion ratio													0.4163
Altice N.V. Distribution | Altice N.V. | Common Class A
Business Acquisition [Line Items]
Common stock, shares outstanding (in shares) | shares													489,384,523
Altice N.V. Distribution | Altice N.V. | Common Class B
Business Acquisition [Line Items]
Common stock, shares outstanding (in shares) | shares													247,684,443
CSC Holdings
Business Acquisition [Line Items]
Goodwill				$ 8,142,309,000				8,142,309,000	8,012,416,000		$ 8,142,309,000
Distribution Made to Limited Liability Company (LLC) Member, Non-cash Distributions Paid								2,279,472,000	(3,058,747,000)
Retained Earnings (Accumulated Deficit)
Business Acquisition [Line Items]
Decrease in connection with dividends paid	536,224,000
Retained Earnings (Accumulated Deficit) | CSC Holdings
Business Acquisition [Line Items]
Distribution Made to Limited Liability Company (LLC) Member, Non-cash Distributions Paid								747,990,000
Additional Paid-in Capital [Member]
Business Acquisition [Line Items]
Stock Issued During Period Relating to Acquisition								163,862,000
Decrease in connection with dividends paid	$ 963,711,000
Value of shares repurchased								1,686,146,000	$ 499,720,000
Additional Paid-in Capital [Member] | CSC Holdings
Business Acquisition [Line Items]
Distribution Made to Limited Liability Company (LLC) Member, Non-cash Distributions Paid								$ 1,531,482,000