NOTES PAYABLE AND COMMERCIAL BANK FINANCING - Senior Unsecured Notes, Debt of Variable Interest Entities and Other Non-Media Subsidiaries (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Debt and capital lease obligations	$ 3,892.5
Debt of variable interest entities
Debt Instrument [Line Items]
Weighted average effective interest rate (as a percent)	4.87%	3.59%
Debt of other non-media related subsidiaries
Debt Instrument [Line Items]
Weighted average effective interest rate (as a percent)	3.94%	4.31%
Fixed interest rate (as a percent)	3.88%
LIBOR \| Debt of variable interest entities
Debt Instrument [Line Items]
Interest rate margin (as a percent)	2.50%
Debt Instrument, Redemption, Period One \| Senior Notes
Debt Instrument [Line Items]
Percent redeemable	35.00%
Debt Instrument, Redemption, Period Two \| Senior Notes
Debt Instrument [Line Items]
Percent redeemable	100.00%
Guarantee Obligations
Debt Instrument [Line Items]
Unconditional and irrevocably guaranteed debt	$ 76.5	$ 74.0
Consolidated VIEs, aggregated
Debt Instrument [Line Items]
Debt and capital lease obligations	$ 24.4	$ 29.3

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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