CAPITAL STOCK - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2019
Class of Stock [Line Items]
Option to purchase additional shares, period			30 days
Options exercised under incentive plans (in shares)			11,300,000
Authorized amount of stock available for repurchase		$ 1,500,000,000		$ 1,500,000,000
Shares repurchased (in shares)		32,400,000	26,200,000
Shares repurchased (in shares)		$ 208,900,000	$ 223,200,000
Preferred Stock, par value (in dollars per share)		$ 0.01	$ 0.01
Preferred stock, redemption price (in dollars per share)		$ 25.00
Preferred Stock, shares issued (in shares)		63,500,000	81,900,000
7.50% Series D Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption price (in dollars per share)		$ 25.00
Preferred stock redeemed (in shares)		18,400,000
Preferred stock dividend rate, percentage		7.50%
Redemption of preferred stock		$ 460,000,000.0
Preferred Stock, shares issued (in shares)		0	18,400,000
7.625% Series C Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption price (in dollars per share)			$ 25.00
Preferred stock redeemed (in shares)			7,000,000.0
Preferred stock dividend rate, percentage			7.625%
Redemption of preferred stock			$ 175,000,000.0
8.125% Series H Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption price (in dollars per share)			$ 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
Series I Preferred Stock
Class of Stock [Line Items]
Preferred stock dividend rate, percentage		6.75%	6.75%
Preferred Stock, shares issued (in shares)		17,700,000	17,700,000
Proceeds from issuance of redeemable preferred stock			$ 442,500,000
Public Offering
Class of Stock [Line Items]
Sale of stock, shares issued (in shares)			75,000,000.0
Proceeds from sale of stock			$ 730,500,000
Public Offering, Additional Share Purchase Option
Class of Stock [Line Items]
Sale of stock, shares issued (in shares)			11,300,000
Proceeds from sale of stock			$ 109,600,000
At-the-market Sale Program
Class of Stock [Line Items]
Sale of stock, shares issued (in shares)		0	56,000,000.0
Proceeds from sale of stock			$ 569,100,000
Aggregate stock offering price	$ 1,500,000,000