EQUITY AND LONG-TERM INCENTIVE PLANS, Cablevision's Equity Plans (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended			12 Months Ended
		Mar. 31, 2015	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cablevision's Equity Plans [Abstract]
Annual vesting percentage (in hundredths)						100.00%
Share-based compensation expense						$ 65,286	$ 43,984	$ 52,715
Share-based compensation expense related to equity classified awards						60,321	43,984	52,715
Income tax benefit recognized in continuing operations resulting from share-based compensation expense						26,718	17,801	21,682
Excess tax benefit on share-based awards						5,694	336	1,280
Cash received from option exercises						18,727	55,355	18,120
CSC Holdings, LLC
Cablevision's Equity Plans [Abstract]
Share-based compensation expense related to equity classified awards						60,321	43,984	52,715
Excess tax benefit on share-based awards						14,170	4,978	46,164
Stock Options
Cablevision's Equity Plans [Abstract]
Share-based compensation expense						9,159	7,573	17,560
Restricted Stock
Cablevision's Equity Plans [Abstract]
Share-based compensation expense						51,162	36,411	35,155
Stock Appreciation Rights
Cablevision's Equity Plans [Abstract]
Share-based compensation expense						$ 4,965	$ 0	$ 0
Cablevision Systems Corporation 2015 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) (up to)		25,000,000	25,000,000
Maximum expiration period from date of grant (in years) (no later than)		10 years
Additional expiration period from date of grant in case of holders death (years)		1 year
Granted (in shares)						79,780
Cablevision Systems Corporation Employee Stock Plan | Performance Shares
Cablevision's Equity Plans [Abstract]
Granted (in shares)	[1]					1,851,700
Award vesting period (years)						3 years
Cablevision Systems Corporation Employee Stock Plan | Stock Options
Cablevision's Equity Plans [Abstract]
Maximum expiration period from date of grant (in years) (no later than)		10 years	10 years		10 years	10 years
Additional expiration period from date of grant in case of holders death (years)		1 year
Award vesting period (years)			3 years		3 years	3 years
Annual vesting percentage (in hundredths)						33.33%
Cablevision Systems Corporation Employee Stock Plan | Restricted Stock
Cablevision's Equity Plans [Abstract]
Granted (in shares)						1,747,870
Cablevision Systems Corporation Employee Stock Plan | Restricted Stock | Minimum
Cablevision's Equity Plans [Abstract]
Award vesting period (years)						3 years
Cablevision Systems Corporation Employee Stock Plan | Restricted Stock | Maximum
Cablevision's Equity Plans [Abstract]
Award vesting period (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) (no later than)				10 years		10 years
Award vesting period (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) (no later than)									10 years
Award vesting period (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]
Granted (in shares)						584,400
Award vesting period (years)						3 years
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) (no later than)						10 years
Additional expiration period from date of grant in case of holders death (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)						73,056	66,421
Non-option equity instruments, outstanding (shares)						466,283
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) (up to)						1,000,000

[1] The PSUs entitle the employee to shares of CNYG common stock up to 150% of the number of PSUs granted depending on the level of achievement of the specified performance criteria. If the minimum performance threshold is not met, no shares will be issued. Accrued dividends are paid to the extent that a PSU vests and the related stock is issued.