SUBSEQUENT EVENTS - Additional Information (Details) - $ / shares		9 Months Ended	12 Months Ended
	Oct. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
6.45% Series D Preferred Stock
Subsequent events
Preferred stock, dividend rate		6.45%	6.45%
6.45% Series D Preferred Stock | Subsequent Event
Subsequent events
Cash dividends declared, preferred stock (in dollars per share)	$ 0.403125
Preferred stock, dividend rate	6.45%
6.25% Series E Preferred Stock
Subsequent events
Preferred stock, dividend rate		6.25%	6.25%
6.25% Series E Preferred Stock | Subsequent Event
Subsequent events
Cash dividends declared, preferred stock (in dollars per share)	$ 0.390625
Preferred stock, dividend rate	6.25%