EQUITY PLANS EQUITY PLANS, Performance Based Restricted Stock Units (Details) - 6 months ended Jun. 30, 2015 - Cablevision Systems Corporation Employee Stock Plan - Performance Based Restricted Stock Units, Performance Criteria Not Yet Satisfied (PSUs) - shares	Total
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	1,816,660
Vesting period	3 years
Purchase price of common stock, percent	150.00%