INCOME TAXES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2014
Income Taxes [Line Items]
Minimum ownership percentage for subsidiaries to be included in consolidated federal income tax return (in hundredths)	80.00%
Reversal of noncurrent liability relating to uncertain tax position				$ 53,132
Current expense (benefit) [Abstract]
Federal	6,122	(144)	(3,493)
State	2,788	(3,510)	19,800
Total current expense (benefit)	8,910	(3,654)	16,307
Deferred expense (benefit) [Abstract]
Federal	135,873	69,258	48,441
State	23,906	198	(6,111)
Total deferred expense (benefit)	159,779	69,456	42,330
Tax benefit relating to uncertain tax positions, including accrued interest	(52,921)	(167)	(6,643)
Income tax expense	115,768	65,635	51,994
Income Tax Expense Attributable to Discontinued Operations [Abstract]
Total income tax expense, discontinued operations	2,206	232,807	110,581
Current income tax expense, discontinued operations	108	18,120	5,340
Deferred income tax (benefit) expense, discontinued operations	2,098	214,687	105,241
Reconciliation of the statuory federal income tax to the effective income tax [Abstract]
Federal tax expense at statutory rate	148,803	67,536	44,212
State income taxes, net of federal benefit	19,059	3,607	4,763
Changes in the valuation allowance	(344)	5,631	5,480
Changes in the state apportionment rates used to measure deferred taxes, net of federal benefit	(322)	(11,228)	2,273
Tax expense (benefit) relating to uncertain tax positions, including accrued interest, net of deferred tax benefits	(52,914)	(124)	(2,659)
Impact of New York State tax reform enacted on March 31, 2014	(2,050)	0	0
Impact of non-deductible officers' compensation	1,532	796	470
Other non-deductible expenses	3,697	3,628	3,363
Increase in the deferred tax asset for certain state tax loss carry forwards pursuant to LLC conversions of certain subsidiaries	0	0	(3,935)
Research credit	(2,634)	(3,739)	0
Tax expense (benefit) from exclusion of pretax loss (income) of an entity that is not consolidated for income tax purposes	0	0	(2,605)
Other, net	941	(472)	632
Income tax expense	115,768	65,635	51,994
Deferred Tax Asset (Liability), Current [Abstract]
NOLs and tax credit carry forwards	144,833	224,968
Compensation and benefit plans	74,220	44,629
Allowance for doubtful accounts	4,557	5,502
Other liabilities	4,909	13,389
Deferred tax asset	228,519	288,488
Valuation allowance	(3,496)	(6,988)
Net deferred tax asset, current	225,023	281,500
Investments	(159,475)	(97,565)
Prepaid expenses	(27,605)	(24,111)
Deferred tax liability, current	(187,080)	(121,676)
Net deferred tax asset, current	37,943	159,824
Deferred Tax Asset (Liability), Noncurrent [Abstract]
NOLs and tax credit carry forwards	25,427	65,322
Compensation and benefit plans	99,076	106,595
Newsday Holdings and other partnership investments	123,243	132,384
Investments	22,294	0
Other	7,345	4,896
Deferred tax asset	277,385	309,197
Valuation allowance	(3,901)	(7,488)
Net deferred tax asset, noncurrent	273,484	301,709
Fixed assets and intangibles	(884,120)	(840,375)
Investments	0	(29,563)
Other	(452)	(1,827)
Deferred tax liability, noncurrent	(884,572)	(871,765)
Net deferred tax liability, noncurrent	(611,088)	(570,056)
Total net deferred tax liability	(573,145)	(410,232)
Operating Loss and Tax Credit Carryforwards [Abstract]
NOL for which a deferred tax asset has been recorded	241,005
NOL for which a deferred tax asset has not been recorded	378,950
Excess tax benefit on share-based awards	336	1,280	0
Reconciliation of unrecognized tax benefits associated with uncertain tax positions, excluding associated deferred tax benefits and accrued interest [Roll Forward]
Balance, beginning of period	57,407
Increases related to prior year tax positions	58
Decreases related to prior year tax positions	(53,460)
Increases related to current year tax positions	6
Balance, end of period	4,011	57,407
Decrease in income tax expense if all uncertain tax positions were sustained	2,608
Interest expense (income) included in income tax expense attributable to continuing operations	284	107	(377)
Accrued interest on uncertain tax positions included in accrued liabilities	268
Accrued interest on uncertain tax positions included in other noncurrent liabilities	2,975
Research tax credit carryforward
Operating Loss and Tax Credit Carryforwards [Abstract]
Research tax credit carryforward, amount	14,818
Internal Revenue Service (IRS)
Operating Loss and Tax Credit Carryforwards [Abstract]
Consolidated federal net operating loss carryforwards	619,955
Federal alternative minimum tax credit carryforwards which do not expire	39,919
Internal Revenue Service (IRS) | Minimum
Operating Loss and Tax Credit Carryforwards [Abstract]
Operating loss carryforward, expiration date	Dec. 31, 2024
Internal Revenue Service (IRS) | Maximum
Operating Loss and Tax Credit Carryforwards [Abstract]
Operating loss carryforward, expiration date	Dec. 31, 2031
CSC Holdings, LLC
Income Taxes [Line Items]
Minimum ownership percentage for subsidiaries to be included in consolidated federal income tax return (in hundredths)	80.00%
Current expense (benefit) [Abstract]
Federal	189,609	66,800	47,250
State	46,573	21,579	39,561
Total current expense (benefit)	236,182	88,379	86,811
Deferred expense (benefit) [Abstract]
Federal	35,445	89,832	79,731
State	17,744	10,035	(7,352)
Total deferred expense (benefit)	53,189	99,867	72,379
Tax benefit relating to uncertain tax positions, including accrued interest	(52,921)	(167)	(6,643)
Income tax expense	236,450	188,079	152,547
Income Tax Expense Attributable to Discontinued Operations [Abstract]
Total income tax expense, discontinued operations	2,206	240,412	110,581
Current income tax expense, discontinued operations	2,479	299,353	28,242
Deferred income tax (benefit) expense, discontinued operations	(273)	(58,941)	82,339
Reconciliation of the statuory federal income tax to the effective income tax [Abstract]
Federal tax expense at statutory rate	243,740	167,098	132,864
State income taxes, net of federal benefit	42,769	27,177	22,542
Changes in the valuation allowance	(382)	(101)	1,038
Changes in the state apportionment rates used to measure deferred taxes, net of federal benefit	379	(6,484)	1,188
Tax expense (benefit) relating to uncertain tax positions, including accrued interest, net of deferred tax benefits	(52,914)	(124)	(2,659)
Impact of New York State tax reform enacted on March 31, 2014	(1,502)	0	0
Impact of non-deductible officers' compensation	1,532	796	470
Other non-deductible expenses	3,697	3,628	3,363
Increase in the deferred tax asset for certain state tax loss carry forwards pursuant to LLC conversions of certain subsidiaries	0	0	(3,935)
Research credit	(2,634)	(3,739)	0
Tax expense (benefit) from exclusion of pretax loss (income) of an entity that is not consolidated for income tax purposes	0	0	(2,605)
Other, net	1,765	(172)	281
Income tax expense	236,450	188,079	152,547
Deferred Tax Asset (Liability), Current [Abstract]
Compensation and benefit plans	74,220	44,629
Allowance for doubtful accounts	4,557	5,502
Other liabilities	4,909	13,389
Deferred tax asset	83,686	63,520
Valuation allowance	(1,891)	(2,426)
Net deferred tax asset, current	81,795	61,094
Investments	(159,475)	(97,565)
Prepaid expenses	(27,605)	(24,111)
Deferred tax liability, current	(187,080)	(121,676)
Net deferred tax liability, current	(105,285)	(60,582)
Deferred Tax Asset (Liability), Noncurrent [Abstract]
Tax credit carry forwards	11,702	20,137
Compensation and benefit plans	99,076	106,595
Newsday Holdings and other partnership investments	123,243	132,384
Investments	22,294	0
Other	7,345	4,896
Deferred tax asset	263,660	264,012
Valuation allowance	(5,454)	(10,084)
Net deferred tax asset, noncurrent	258,206	253,928
Fixed assets and intangibles	(884,120)	(840,375)
Investments	0	(29,563)
Other	(453)	(1,827)
Deferred tax liability, noncurrent	(884,573)	(871,765)
Net deferred tax liability, noncurrent	(626,367)	(617,837)
Total net deferred tax liability	(731,652)	(678,419)
Operating Loss and Tax Credit Carryforwards [Abstract]
Estimated federal income tax liability of CSC Holdings as determined on a standalone basis due to Cablevision	230,786
Excess tax benefit on share-based awards	4,978	46,164	61,434
Accrued income taxes, current	$ 2,897