EQUITY AND LONG-TERM INCENTIVE PLANS, Cablevision's Equity Plans (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended			3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2012
Cablevision's Equity Plans [Abstract]
Annual vesting percentage (in hundredths)	100.00%
Share-based compensation expense	$ 43,984	$ 52,715	$ 60,705
Share-based compensation expense related to equity classified awards	43,984	52,715	60,646
Income tax benefit recognized in continuing operations resulting from share-based compensation expense	17,801	21,682	24,747
Excess tax benefit on share-based awards	336	1,280	0
Cash received from option exercises	55,355	18,120	18,722
CSC Holdings, LLC
Cablevision's Equity Plans [Abstract]
Share-based compensation expense related to equity classified awards	43,984	52,715	60,646
Excess tax benefit on share-based awards	4,978	46,164	61,434
Stock Options
Cablevision's Equity Plans [Abstract]
Share-based compensation expense	7,573	17,560	29,849
Restricted Stock
Cablevision's Equity Plans [Abstract]
Share-based compensation expense	36,411	35,155	30,797
Stock Appreciation Rights
Cablevision's Equity Plans [Abstract]
Share-based compensation expense	0	0	59
Cablevision Systems Corporation Employee Stock Plan | Stock Options
Cablevision's Equity Plans [Abstract]
Maximum expiration period from date of grant (in years)	10 years			10 years
Additional expiration period from date of grant in case of holder's death (in years)	1 year
Vesting period (in years)	3 years			3 years
Annual vesting percentage (in hundredths)	33.33%
Cablevision Systems Corporation Employee Stock Plan | Restricted Stock | Minimum
Cablevision's Equity Plans [Abstract]
Vesting period (in years)	3 years
Cablevision Systems Corporation Employee Stock Plan | Restricted Stock | Maximum
Cablevision's Equity Plans [Abstract]
Vesting period (in years)	4 years
Cablevision Systems Corporation Employee Stock Plan | Stock Appreciation Rights
Cablevision's Equity Plans [Abstract]
Maximum expiration period from date of grant (in years)	10 years				10 years
Additional expiration period from date of grant in case of holder's death (in years)	1 year
Vesting period (in years)	3 years				3 years
Annual vesting percentage (in hundredths)	33.33%
Cablevision Systems Corporation Employee Stock Plan | Performance Based Vesting Options
Cablevision's Equity Plans [Abstract]
Maximum expiration period from date of grant (in years)						10 years
Additional expiration period from date of grant in case of holder's death (in years)	1 year
Vesting period (in years)						2 years
Annual vesting percentage (in hundredths)						50.00%
Cablevision Systems Corporation Employee Stock Plan | Performance Based Restricted Stock
Cablevision's Equity Plans [Abstract]
Vesting period (in years)	3 years
Cablevision Systems Corporation Employee Stock Plan | CNYG Class A Common Stock
Cablevision's Equity Plans [Abstract]
Shares of common stock available for grant, subject to certain adjustments (in shares)	46,000,000
Cablevision Systems Corporation Stock Plan for Non-Employee Directors | Stock Options
Cablevision's Equity Plans [Abstract]
Maximum expiration period from date of grant (in years)	10 years
Additional expiration period from date of grant in case of holder's death (in years)	1 year
Cablevision Systems Corporation Stock Plan for Non-Employee Directors | Restricted Stock
Cablevision's Equity Plans [Abstract]
Value of restricted stock units awarded to each non-employee director on the date of each annual meeting of Cablevision's stockholders	$ 150
Number of restricted stock units granted to non-employee directors (in shares)	66,421	71,200
Vested award balance outstanding (in shares)	434,596
Cablevision Systems Corporation Stock Plan for Non-Employee Directors | CNYG Class A Common Stock
Cablevision's Equity Plans [Abstract]
Shares of common stock available for grant, subject to certain adjustments (in shares)	1,000,000