DERIVATIVE CONTRACTS AND COLLATERALIZED INDEBTEDNESS - Statement of Operations, Derivative Instrument Data (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gain (loss) on derivative contracts (related to change in the value of equity derivative contracts related to Comcast common stock)	$ (77,333)	$ (79,628)	$ (303,986)	$ 130,883
Change in fair value of Comcast common stock included in gain (loss) on investments	120,277	111,684	473,796	(199,312)
Loss on interest rate swap contracts	$ (11,163)	$ (19,554)	$ (61,735)	$ (64,405)

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Amount of gain (loss) included in earnings for the period from the increase (decrease) in fair value of interest rate derivatives not designated as hedging instruments.

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Amount of realized and unrealized gain (loss) on investment.

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