OTHER ASSETS - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Nov. 18, 2020	Aug. 29, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Loss from equity method investments			$ (36.0)	$ (35.0)	$ (61.0)
Fair value adjustments associated with equity securities			24.0	0.1
Equity investments without readily determinable fair value			26.0	28.0
Cumulative impairments			7.0
Impairment to carrying amount				7.0
Unfunded commitments related to private equity investment funds			98.0	32.0
Level 1 | Carrying Value
Schedule of Equity Method Investments [Line Items]
Investments in common stock			68.0	2.0
Level 1 | Other Investments
Schedule of Equity Method Investments [Line Items]
Investments in common stock			68.0	2.0
Level 3 | Options and Warrants | Carrying Value
Schedule of Equity Method Investments [Line Items]
Variable payment obligations			332.0	0.0
YES Network
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments		$ 346.0
Loss from equity method investments			6.0	$ 16.0
Bally's
Schedule of Equity Method Investments [Line Items]
Penny warrants acquirable (up to) (in shares)	8,200,000
Warrants available for purchase (up to) (in shares)	3,300,000
Option available for purchase (up to) (in shares)	1,600,000
Option purchase price, starting at	$ 30
Option purchase price, maximum	$ 45
Vesting period	4 years
Bally's | Options and Warrants
Schedule of Equity Method Investments [Line Items]
Initial value related to equity interests	$ 199.0
Measurement adjustments			$ 133.0