EQUITY PLANS, Stock Option Award Activity (Details) - Cablevision Systems Corporation Employee Stock Plan - USD ($) $ / shares in Units, $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2015	Dec. 31, 2014
Stock Options Outstanding, Weighted Average Exercise Price [Roll Forward]
Balance at beginning of period, weighted average exercise price per share (in dollars per share)		$ 14.41
Granted, weighted average exercise price per share (in dollars per share)		19.17
Exercised, weighted average exercise price per share (in dollars per share)		12.74
Balance at end of period, weighted average exercise price per share (in dollars per share)		15.23	$ 14.41
Options exercisable at end of period, weighted average exercise price per share (in dollars per share)		13.90
Options expected to vest in the future, weighted average exercise price per share (in dollars per share)		$ 16.93
Stock Options Outstanding, Additional Disclosures [Abstract]
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2		7 years 2 months 35 days	7 years 2 months
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2		7 years 2 months 35 days	7 years 2 months
Options exercisable at end of period, weighted average remaining contractual term		6 years 1 month 25 days
Options expected to vest in the future, weighted average remaining contractual term		8 years 6 months 65 days
Balance at beginning of period, aggregate intrinsic value	[1]	$ 79,347
Balance at end of period, aggregate intrinsic value	[1]	119,267	$ 79,347
Options exercisable at end of period, aggregate intrinsic value	[1]	77,207
Options expected to vest in the future, aggregate intrinsic value	[1]	$ 42,060
Time Vesting Options
Stock Options Outstanding [Roll Forward]
Balance at beginning of period (in shares)		5,097,666
Granted (in shares)		2,000,000
Exercised (in shares)		(302,500)
Balance at end of period (in shares)		6,795,166	5,097,666
Options exercisable at end of period (in shares)		795,166
Options expected to vest in the future (in shares)		6,000,000
Performance Based Vesting Options
Stock Options Outstanding [Roll Forward]
Balance at beginning of period (in shares)		7,633,500
Granted (in shares)		0
Exercised (in shares)		(736,383)
Balance at end of period (in shares)		6,897,117	7,633,500
Options exercisable at end of period (in shares)		6,897,117
Options expected to vest in the future (in shares)		0
Stock Options | AMC Networks Inc. and Madison Square Garden
Stock Options Outstanding [Roll Forward]
Balance at end of period (in shares)		108,066

[1] The aggregate intrinsic value is calculated as the difference between (i) the exercise price of the underlying award and (ii) the quoted price of CNYG Class A common stock on June 30, 2015 or December 31, 2014, as indicated, and June 30, 2015 in the case of options exercisable and options expected to vest in the future.