EQUITY PLANS, Stock Option Award Activity (Details) - Cablevision Systems Corporation Employee Stock Plan - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2016	Dec. 31, 2015
Stock Options Outstanding, Weighted Average Exercise Price [Roll Forward]
Balance at beginning of period, weighted average exercise price per share (in dollars per share)		$ 15.28
Granted, weighted average exercise price per share (in dollars per share)		0.00
Exercised, weighted average exercise price per share (in dollars per share)		14.86
Balance at end of period, weighted average exercise price per share (in dollars per share)		15.31	$ 15.28
Options exercisable at end of period, weighted average exercise price per share (in dollars per share)		14.24
Options expected to vest in the future, weighted average exercise price per share (in dollars per share)		$ 18.25
Stock Options Outstanding, Additional Disclosures [Abstract]
Balance at beginning of period, weighted average remaining contractual term (years)		6 years 7 months 24 days	6 years 9 months 18 days
Balance at end of period, weighted average remaining contractual term (years)		6 years 7 months 24 days	6 years 9 months 18 days
Options exercisable at end of period, weighted average remaining contractual term (years)		6 years 11 days
Options expected to vest in the future, weighted average remaining contractual term (years)		8 years 3 months 29 days
Balance at beginning of period, aggregate intrinsic value	[1]	$ 221,900
Balance at end of period, aggregate intrinsic value	[1]	219,925	$ 221,900
Options exercisable at end of period, aggregate intrinsic value	[1]	170,765
Options expected to vest in the future, aggregate intrinsic value	[1]	$ 49,160
Time Vesting Options
Stock Options Outstanding [Roll Forward]
Balance at beginning of period (in shares)		6,744,000
Granted (in shares)		0
Exercised (in shares)		(200,000)
Balance at end of period (in shares)		6,544,000	6,744,000
Options exercisable at end of period (in shares)		3,210,666
Options expected to vest in the future (in shares)		3,333,334
Performance Based Vesting Options
Stock Options Outstanding [Roll Forward]
Balance at beginning of period (in shares)		6,609,217
Granted (in shares)		0
Exercised (in shares)		(718,517)
Balance at end of period (in shares)		5,890,700	6,609,217
Options exercisable at end of period (in shares)		5,890,700
Options expected to vest in the future (in shares)		0

[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 March 31, 2016 or December 31, 2015, as indicated, and March 31, 2016 in the case of options exercisable and options expected to vest in the future.