EQUITY AND LONG-TERM INCENTIVE PLANS, Valuation Assumptions (Details) - Cablevision Systems Corporation Employee Stock Plan - $ / shares	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
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (years)		3 years		3 years	3 years
Maximum expiration period from date of grant (in years) (no later than)	10 years	10 years		10 years	10 years
Assumptions Used to Calculate the Fair Value of Stock Option Awards Granted [Abstract]
Risk-free interest rate (in hundredths)					1.82%	2.12%	1.25%
Expected life (in years)					8 years	6 years 6 months	6 years 6 months
Dividend yield (in hundredths)					3.63%	3.79%	3.86%
Volatility (in hundredths)					39.98%	42.80%	42.31%
Grant date fair value (in dollars per share)					$ 5.45	$ 5.27	$ 3.96
Stock Appreciation Rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (years)			3 years		3 years
Maximum expiration period from date of grant (in years) (no later than)			10 years		10 years