DERIVATIVE CONTRACTS AND COLLATERALIZED INDEBTEDNESS - Statement of Operations, Derivative Instrument Data (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 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)	$ (49,624)	$ 42,159	$ (226,653)	$ 210,511
Gain (loss) on investments (primarily related to change in fair value Comcast common stock)	98,794	(58,420)	353,519	(310,996)
Loss on interest rate swap contracts	$ (26,900)	$ (12,929)	$ (50,572)	$ (44,851)

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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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