REDEEMABLE PREFERRED STOCK - Dividends Narrative (Details) - USD ($)		9 Months Ended
	Dec. 22, 2020	Sep. 30, 2021	Sep. 30, 2020
Class of Stock [Line Items]
Initial dividend on common stock	$ 4,448,223
Initial dividend, common stock, paid		$ 3,979,000	$ 3,319,000
Payments on preferred stock dividends		$ 15,440,000	14,464,000
Series A Preferred Stock
Class of Stock [Line Items]
Cumulative dividend rate		5.50%
Preferred dividend per share per quarter (in usd per share)		$ 0.34375
Payments on preferred stock dividends		$ 7,000,000	6,100,000
Series D Preferred Stock
Class of Stock [Line Items]
Cumulative dividend rate		5.65%
Preferred dividend per share per quarter (in usd per share)		$ 0.35313
Payments on preferred stock dividends		$ 26,000	4,000
Series L Preferred Stock
Class of Stock [Line Items]
Cumulative dividend rate		5.50%
Preferred dividend per share per quarter (in usd per share)		$ 1.56035
Dividend increase per year for failure to timely declare or pay dividends		1.00%
Dividend increase per year for failure to timely declare or pay dividends, maximum increase		8.50%
Payments on preferred stock dividends		$ 8,400,000	$ 8,400,000