INTERIM FINANCIAL INFORMATION (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information [Line Items]
Total revenue	$ 2,474,549	$ 2,438,662	$ 2,451,081	$ 2,396,567	$ 2,454,940	$ 2,417,801	$ 2,364,153	$ 2,329,714		$ 9,760,859	$ 9,566,608	$ 9,306,950
Operating expenses		(1,967,147)	(1,968,538)	(1,954,089)	(1,926,216)	(1,912,243)	(2,029,094)	(2,016,676)		(7,937,048)	(7,884,229)	(8,465,942)
Operating income	427,275	471,515	482,543	442,478	528,724	505,558	335,059	313,038		1,823,811	1,682,379	841,008
Net income	1,331	77,396	86,410	(25,198)	213,808	33,739	(98,004)	(128,949)		139,939	20,594	1,494,764
Net loss (income) attributable to noncontrolling interests	(1,002)	(157)	(43)	199	(722)	(1,186)	149	(2)		(1,003)	(1,761)	(1,587)
Net income attributable to Altice USA, Inc. stockholders	$ 329	$ 77,239	$ 86,367	$ (24,999)	$ 213,086	$ 32,553	$ (97,855)	$ (128,951)		$ 138,936	$ 18,833	1,493,177
Basic and diluted income (loss) per share attributable to Altice USA Inc.'s stockholders (in dollars per share)	$ 0	$ 0.12	$ 0.13	$ (0.04)	$ 0.30	$ 0.04	$ (0.13)	$ (0.17)		$ 0.21	$ 0.03
Impact from changes in tax rates										$ (1,046)	$ (52,915)	(12,896)
Payments of dividends									$ 79,617	0	1,499,935	919,317	$ 365,559
Operating Income (Loss)	$ 427,275	$ 471,515	$ 482,543	$ 442,478	$ 528,724	$ 505,558	$ 335,059	$ 313,038		1,823,811	1,682,379	841,008
Net Income (Loss) Attributable to Noncontrolling Interest	1,002	157	43	(199)	722	1,186	(149)	2		1,003	1,761	1,587
Net income (loss) attributable to members	329	77,239	86,367	(24,999)	213,086	32,553	(97,855)	(128,951)		138,936	18,833	1,493,177
Changes in the state rates used to measure deferred taxes, net of federal impact										(1,046)	(52,915)	(12,896)
CSC Holdings
Quarterly Financial Information [Line Items]
Total revenue	2,474,549	2,438,662	2,451,081	2,396,567	2,454,940	2,417,801	2,364,153	2,329,714		9,760,859	9,566,608	9,306,950
Operating expenses	(2,047,274)	(1,967,147)	(1,968,538)	(1,954,089)	(1,926,216)	(1,912,243)	(2,029,094)	(2,016,676)		(7,937,048)	(7,884,229)	(8,465,824)
Operating income	427,275	471,515	482,543	442,478	528,724	505,558	335,059	313,038		1,823,811	1,682,379	841,126
Net income	21,022	95,517	104,142	(7,864)	242,020	86,747	21,527	(89,968)		212,817	260,326	2,577,876
Net loss (income) attributable to noncontrolling interests	(1,002)	(157)	(43)	199	(722)	(1,186)	149	(2)		(1,003)	(1,761)	(1,587)
Net income attributable to Altice USA, Inc. stockholders	20,020	95,360	104,099	(7,665)	241,298	85,561	21,676	(89,970)		211,814	258,565	2,576,289
Impact from changes in tax rates										6,532	(53,493)	(12,999)
Payments of dividends										2,279,472	3,058,750	2,777,497
Operating Income (Loss)	427,275	471,515	482,543	442,478	528,724	505,558	335,059	313,038		1,823,811	1,682,379	841,126
Net Income (Loss) Attributable to Noncontrolling Interest	1,002	157	43	(199)	722	1,186	(149)	2		1,003	1,761	1,587
Net income (loss) attributable to members	20,020	95,360	104,099	(7,665)	241,298	85,561	21,676	(89,970)		211,814	258,565	2,576,289
Changes in the state rates used to measure deferred taxes, net of federal impact										6,532	(53,493)	(12,999)
Video
Quarterly Financial Information [Line Items]
Total revenue		993,158	1,018,426	1,017,330	1,033,649	1,054,667	1,034,404	1,033,708		3,997,873	4,156,428	4,274,122
Video | CSC Holdings
Quarterly Financial Information [Line Items]
Total revenue	968,959	993,158	1,018,426	1,017,330	1,033,649	1,054,667	1,034,404	1,033,708		3,997,873	4,156,428	4,274,122
Broadband
Quarterly Financial Information [Line Items]
Total revenue		814,328	806,250	775,573	743,725	729,907	712,202	701,621		3,222,605	2,887,455	2,608,595
Broadband | CSC Holdings
Quarterly Financial Information [Line Items]
Total revenue	826,454	814,328	806,250	775,573	743,725	729,907	712,202	701,621		3,222,605	2,887,455	2,608,595
Telephony
Quarterly Financial Information [Line Items]
Total revenue		148,231	150,232	154,464	162,007	161,351	163,499	166,038		598,694	652,895	700,765
Telephony | CSC Holdings
Quarterly Financial Information [Line Items]
Total revenue	145,767	148,231	150,232	154,464	162,007	161,351	163,499	166,038		598,694	652,895	700,765
Business services and wholesale
Quarterly Financial Information [Line Items]
Total revenue		357,628	357,806	350,689	348,087	344,193	337,388	333,090		1,428,532	1,362,758	1,298,213
Business services and wholesale | CSC Holdings
Quarterly Financial Information [Line Items]
Total revenue	362,409	357,628	357,806	350,689	348,087	344,193	337,388	333,090		1,428,532	1,362,758	1,298,213
News and advertising (a) | CSC Holdings
Quarterly Financial Information [Line Items]
Total revenue												396,187
Other (a)
Quarterly Financial Information [Line Items]
Total revenue		4,076	3,917	3,773	4,200	3,770	5,318	6,520		15,987	19,808	29,068
Other (a) | CSC Holdings
Quarterly Financial Information [Line Items]
Total revenue	4,221	4,076	3,917	3,773	4,200	3,770	5,318	6,520		15,987	19,808	29,068
Mobile [Member]
Quarterly Financial Information [Line Items]
Total revenue		3,174	0	0						21,264	0	0
Mobile [Member] | CSC Holdings
Quarterly Financial Information [Line Items]
Total revenue	18,090	3,174	0	0						21,264
Advertising and News [Member]
Quarterly Financial Information [Line Items]
Total revenue		118,067	114,450	94,738	163,272	123,913	111,342	88,737		475,904	487,264	$ 396,187
Advertising and News [Member] | CSC Holdings
Quarterly Financial Information [Line Items]
Total revenue	$ 148,649	$ 118,067	$ 114,450	$ 94,738	$ 163,272	$ 123,913	$ 111,342	$ 88,737		$ 475,904	$ 487,264