EQUITY AND EARNINGS PER SHARE - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands										1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 23, 2020	May 27, 2020	May 19, 2020	Feb. 14, 2020	Aug. 20, 2019	Aug. 15, 2019	Aug. 01, 2019	Jul. 02, 2019	Jul. 30, 2018	Feb. 29, 2020	Aug. 31, 2019	Jul. 31, 2019	Feb. 28, 2019	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Issuance of stock (in shares)													46,000,000.0
Shares issued, price per share (in dollars per share)													$ 16.50
Issuance of common stock													$ 751,700			$ 1,734	$ 752,217
Options granted (in shares)																1,619,739
Common stock, par value (in dollars per share)			$ 0.01											$ 0.01		$ 0.01		$ 0.01
Number of shares issued (in shares)																33,610,000
Preferred stock, par values (in dollars per share)														$ 0.01		$ 0.01		$ 0.01
Common stock, shares outstanding (in shares)														415,744,518		415,744,518		415,520,780
Authorized repurchase amount					$ 200,000
Share repurchases (in shares)					0
Fair value			$ 53,500
Share price (in dollars per share)														$ 7.95		$ 7.95
Fortress-managed funds
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Common stock, shares outstanding (in shares)														2,400,000		2,400,000
Share-based Payment Arrangement, Nonemployee
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted (in shares)													4,600,000
Options granted, fair value													$ 3,800
Risk free interest rate													2.40%
Expected dividend rate													9.30%
Expected volatility rate													19.26%
Expected term (in years)													10 years
Share-based Payment Arrangement, Nonemployee | Common stock purchase warrants
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted (in shares)		43,400,000														43,400,000
Risk free interest rate			0.24%
Expected volatility rate			35.00%
Expected term (in years)			3 years
Exercise price range, lower range limit (in dollars per share)			$ 6.11
Exercise price range, upper range limit (in dollars per share)			$ 7.94
Share-based Payment Arrangement, Nonemployee | Common stock purchase warrants | Exercise Price One
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Shares exercisable (in shares)			24,600,000
Exercise price (in dollars per share)			$ 6.11
Share-based Payment Arrangement, Nonemployee | Common stock purchase warrants | Exercise Price Two
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Shares exercisable (in shares)			18,900,000
Exercise price (in dollars per share)			$ 7.94
7.50% Series A Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Risk free interest rate								1.91%
Expected dividend rate								9.73%
Expected volatility rate								17.95%
Expected term (in years)								10 years
Net proceeds from liquidation								$ 150,000
Number of shares issued (in shares)								6,200,000				6,210,000
Interest rate								7.50%				7.50%				7.50%		7.50%
Preferred stock, par values (in dollars per share)								$ 0.01						$ 0.01		$ 0.01		$ 0.01
Liquidation preference per share (in dollars per share)								$ 25.00
Dividends declared on preferred stock (in dollars per share)	$ 0.47													0.47		$ 1,410
Preferred dividends	$ 2,900
7.50% Series A Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock | Share-based Payment Arrangement, Nonemployee
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Fair value of options granted to Manager								$ 500
7.125% Series B Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Risk free interest rate						1.56%
Expected dividend rate						11.20%
Expected volatility rate						18.23%
Expected term (in years)						10 years
Net proceeds from liquidation						$ 273,400
Number of shares issued (in shares)						11,300,000					11,300,000
Interest rate						7.125%					7.125%				7.125%	7.125%
Preferred stock, par values (in dollars per share)						$ 0.01								0.01		$ 0.01		0.01
Liquidation preference per share (in dollars per share)						$ 25.00
Dividends declared on preferred stock (in dollars per share)	$ 0.45													0.45		$ 1,340
Preferred dividends	$ 5,000
7.125% Series B Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock | Share-based Payment Arrangement, Nonemployee
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Fair value of options granted to Manager						$ 700
6.375% Series C Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Risk free interest rate				1.55%
Expected dividend rate				9.00%
Expected volatility rate				17.39%
Expected term (in years)				10 years
Net proceeds from liquidation				$ 389,500
Number of shares issued (in shares)				16,100,000						16,100,000
Interest rate				6.375%						6.375%					6.375%	6.375%
Preferred stock, par values (in dollars per share)				$ 0.01										0.01		$ 0.01		$ 0.01
Liquidation preference per share (in dollars per share)				$ 25.00
Dividends declared on preferred stock (in dollars per share)	$ 0.40													$ 0.40		$ 1,200
Preferred dividends	$ 6,400
6.375% Series C Preferred Stock | Share-based Payment Arrangement, Nonemployee
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Fair value of options granted to Manager				$ 1,000
Distribution Agreement
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Common stock, par value (in dollars per share)									$ 0.01
Over-Allotment Option | 7.50% Series A Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of shares issued (in shares)								600,000
Over-Allotment Option | 7.125% Series B Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of shares issued (in shares)						1,100,000
Over-Allotment Option | 6.375% Series C Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of shares issued (in shares)				1,600,000
Common Stock | Distribution Agreement
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Net proceeds from liquidation							$ 500,000		$ 500,000