EQUITY AND LONG-TERM INCENTIVE PLANS, Stock Option Award Activity (Details) (Cablevision Systems Corporation Employee Stock Plan, USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Stock Options
Stock Options Outstanding, Weighted Average Exercise Price [Roll Forward]
Balance at beginning of period, weighted average exercise price per share (in dollars per share)	$ 13.20
Granted, weighted average exercise price per share (in dollars per share)	$ 17.64
Exercised, weighted average exercise price per share (in dollars per share)	$ 11.74
Balance at end of period, weighted average exercise price per share (in dollars per share)	$ 14.41	$ 13.20
Options exercisable at end of period, weighted average exercise price per share (in dollars per share)	$ 13.76
Options expected to vest in the future, weighted average exercise price per share (in dollars per share)	$ 15.81
Stock Options Outstanding, Additional Disclosures [Abstract]
Balance at beginning of period, weighted average remaining contractual term (in years)	7 years 2 months 2 days	7 years 2 months 14 days
Balance at end of period, weighted average remaining contractual term (in years)	7 years 2 months 2 days	7 years 2 months 14 days
Options exercisable at end of period, weighted average remaining contractual term (in years)	6 years 5 months 23 days
Options expected to vest in the future, weighted average remaining contractual term (in years)	8 years 8 months 5 days
Balance at beginning of period, aggregate intrinsic value	$ 71,823
Balance at end of period, aggregate intrinsic value	79,347	71,823
Options exercisable at end of period, aggregate intrinsic value	60,027
Options expected to vest in the future, aggregate intrinsic value	19,320
Aggregate intrinsic value of options exercised	$ 34,409
Stock Options | AMC Networks Inc. and Madison Square Garden
Stock Options Outstanding [Roll Forward]
Balance at end of period (in shares)	143,666
Time Vesting Options
Stock Options Outstanding [Roll Forward]
Balance at beginning of period (in shares)	4,514,479
Granted (in shares)	2,000,000
Exercised (in shares)	(1,416,813)
Balance at end of period (in shares)	5,097,666
Options exercisable at end of period (in shares)	1,097,666
Options expected to vest in the future (in shares)	4,000,000
Performance Based Vesting Options
Stock Options Outstanding [Roll Forward]
Balance at beginning of period (in shares)	10,639,125
Granted (in shares)	0
Exercised (in shares)	(3,005,625)
Balance at end of period (in shares)	7,633,500
Options exercisable at end of period (in shares)	7,633,500
Options expected to vest in the future (in shares)	0