SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, CSC Holdings Membership Interests (Details) (CSC Holdings, LLC, USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CSC Holdings, LLC
CSC Holdings Membership Interests [Abstract]
Membership units issued (in shares)		17,631,479	17,631,479
Membership units outstanding (in shares)		17,631,479	17,631,479
Membership interests issued (in shares)	3,198,729
Capital contributions from Cablevision	$ 735,000	$ 0	$ 0	$ 735,000