SUBSEQUENT EVENTS (Details) - USD ($) $ / shares in Units, $ in Millions						12 Months Ended
	Jul. 15, 2021	Jun. 15, 2021	May 17, 2021	Mar. 05, 2021	Jan. 21, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Series A Preferred Stock
Subsequent Event [Line Items]
Preferred dividends, per share amount (in usd per share)						$ 1.719	$ 1.375	$ 1.375
Series D Preferred Stock
Subsequent Event [Line Items]
Preferred dividends, per share amount (in usd per share)						$ 1.648
Forecast | Series A Preferred Stock
Subsequent Event [Line Items]
Preferred dividends, per share amount (in usd per share)	$ 0.114583	$ 0.114583	$ 0.114583
Forecast | Series D Preferred Stock
Subsequent Event [Line Items]
Preferred dividends, per share amount (in usd per share)	$ 0.117708	$ 0.117708	$ 0.117708
Subsequent event
Subsequent Event [Line Items]
Dividends declared, common (in usd per share)				$ 0.075
Subsequent event | Series A Preferred Stock
Subsequent Event [Line Items]
Stock issued in lieu of cash for asset management fees (in shares)					96,740
Equity-based payment for asset management fees					$ 2.4
Preferred stock, dividends per share, declared (in usd per share)				0.34375
Subsequent event | Series D Preferred Stock
Subsequent Event [Line Items]
Preferred stock, dividends per share, declared (in usd per share)				$ 0.353125