CAPITAL STOCK - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 07, 2018	Jan. 31, 2018	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2019
Class of Stock [Line Items]
Authorized amount of stock available for repurchase						$ 1,500,000,000
Shares repurchased (in shares)			26,200,000
Shares repurchased (in shares)			$ 223,200,000
Options exercised under incentive plans (in shares)				11,300,000.0	11,300,000.0
Preferred stock, par value (in dollars per share)			$ 0.01	$ 0.01	$ 0.01
Preferred stock, redemption price (in dollars per share)			$ 25.00	$ 25.00
Preferred stock, shares issued (in shares)			81,900,000	81,900,000	73,400,000
7.625% Series C Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption price (in dollars per share)			$ 25.00	$ 25.00
Preferred stock redeemed (in shares)				7,000,000.0	5,000,000.0
Preferred stock dividend rate, percentage				7.625%
Redemption of preferred stock				$ 175,000,000.0	$ 125,000,000.0
Preferred stock, shares issued (in shares)			0	0	7,000,000
8.125% Series H Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption price (in dollars per share)			$ 25.00	$ 25.00
Preferred stock redeemed (in shares)				2,200,000
Preferred stock dividend rate, percentage				8.125%
Redemption of preferred stock				$ 55,000,000.0
Preferred stock, shares issued (in shares)			0	0	2,200,000
Series I Preferred Stock
Class of Stock [Line Items]
Preferred stock dividend rate, percentage				6.75%
Preferred stock, shares issued (in shares)			17,700,000	17,700,000	0
Proceeds from issuance of redeemable preferred stock				$ 442,500,000
6.50% Series G Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Preferred stock dividend rate, percentage				6.50%	6.50%
Preferred stock, shares issued (in shares)			17,000,000	17,000,000	17,000,000.0
Proceeds from issuance of redeemable preferred stock					$ 425,000,000.0
7.625% Series E Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Preferred stock redeemed (in shares)					11,500,000
Preferred stock dividend rate, percentage					7.625%
Redemption of preferred stock					$ 287,500,000
Public Offering
Class of Stock [Line Items]
Sale of stock, shares issued (in shares)				75,000,000.0	75,000,000.0
Proceeds from sale of stock				$ 730,500,000	$ 762,800,000
Public Offering, Additional Share Purchase Option
Class of Stock [Line Items]
Sale of stock, shares issued (in shares)				11,300,000	11,300,000
Proceeds from sale of stock				$ 109,600,000	$ 114,400,000
Option to purchase additional shares, period				30 days	30 days
At-the-market Sale Program
Class of Stock [Line Items]
Sale of stock, shares issued (in shares)				56,000,000.0	24,000,000.0
Proceeds from sale of stock				$ 569,100,000	$ 251,100,000
Aggregate stock offering price		$ 1,500,000,000
Mountain Merger Sub Corporation
Class of Stock [Line Items]
Shares issued as part of the consideration for asset acquisition (in shares)	43,600,000				43,600,000
Mountain Merger Sub Corporation | 8.125% Series H Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)	$ 0.01