INCOME TAXES - Characterization of Distributions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock
Class of Stock [Line Items]
Ordinary income (in dollars per share)	$ 0.6132	$ 0.7200	$ 0.6725
Ordinary Income Distribution, Percent	85.16%	100.00%	100.00%
Capital gain distributions (in dollars per share)	$ 0.1068	$ 0	$ 0
Capital Gain Distribution, Percent	14.84%	0.00%	0.00%
Distribution Per Share (in dollars per share)	$ 0.7200	$ 0.7200	$ 0.6725
Distribution Paid, Percent	100.00%	100.00%	100.00%
Preferred Stock - Series B
Class of Stock [Line Items]
Ordinary income (in dollars per share)	$ 0	$ 0	$ 2.0234
Ordinary Income Distribution, Percent	0.00%	0.00%	100.00%
Capital gain distributions (in dollars per share)	$ 0	$ 0	$ 0
Capital Gain Distribution, Percent	0.00%	0.00%	0.00%
Distribution Per Share (in dollars per share)	$ 0	$ 0	$ 2.0234
Distribution Paid, Percent	0.00%	0.00%	100.00%
Preferred Stock - Series C
Class of Stock [Line Items]
Ordinary income (in dollars per share)	$ 0	$ 0.5393	$ 1.7813
Ordinary Income Distribution, Percent	0.00%	100.00%	100.00%
Capital gain distributions (in dollars per share)	$ 0	$ 0	$ 0
Capital Gain Distribution, Percent	0.00%	0.00%	0.00%
Distribution Per Share (in dollars per share)	$ 0	$ 0.5393	$ 1.7813
Distribution Paid, Percent	0.00%	100.00%	100.00%
Preferred Stock - Series D
Class of Stock [Line Items]
Ordinary income (in dollars per share)	$ 1.3732	$ 1.6125	$ 1.6125
Ordinary Income Distribution, Percent	85.16%	100.00%	100.00%
Capital gain distributions (in dollars per share)	$ 0.2393	$ 0	$ 0
Capital Gain Distribution, Percent	14.84%	0.00%	0.00%
Distribution Per Share (in dollars per share)	$ 1.6125	$ 1.6125	$ 1.6125
Distribution Paid, Percent	100.00%	100.00%	100.00%
Preferred Stock - Series E
Class of Stock [Line Items]
Ordinary income (in dollars per share)	$ 1.3307	$ 1.5625	$ 0.0694
Ordinary Income Distribution, Percent	85.16%	100.00%	100.00%
Capital gain distributions (in dollars per share)	$ 0.2318	$ 0	$ 0
Capital Gain Distribution, Percent	14.84%	0.00%	0.00%
Distribution Per Share (in dollars per share)	$ 1.5625	$ 1.5625	$ 0.0694
Distribution Paid, Percent	100.00%	100.00%	100.00%