EARNINGS PER COMMON SHARE AND DIVIDEND PER SHARE - Dividend Per Share (Details)					2 Months Ended			3 Months Ended	9 Months Ended
	Sep. 01, 2019 $ / shares	Jun. 01, 2019 $ / shares	Mar. 01, 2019 $ / shares	Mar. 01, 2019 $ / shares	May 31, 2019 $ / shares	Feb. 28, 2019 $ / shares	Feb. 28, 2019 $ / shares	Aug. 31, 2019 $ / shares	Sep. 30, 2019 $ / shares	Sep. 30, 2019 $ / shares
Common shares
Dividends Payable [Line Items]
Common stock, dividends, per share, declared (in dollars per share)									$ 0.73800
Preference Shares, Series A | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.34375
Preference Shares, Series B | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.21340
Preference Shares, Series C | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)		$ 0.25647	$ 0.25395		$ 0.25395	$ 0.25459			0.25243
Preference Shares, Series D | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.27875
Preference Shares, Series F | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.29306
Preference Shares, Series H | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.27350
Preference Shares, Series J | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)										$ 0.30540
Preference Shares, Series L | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)										0.30993
Preference Shares, Series N | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.31788
Preference Shares, Series P | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)			0.27369			0.25000			0.27369
Preference Shares, Series R | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)		$ 0.25456			$ 0.25000				0.25456
Preference Shares, Series 1 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)										0.37182
Preference Shares, Series 34 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)	$ 0.23356							$ 0.25000	0.23356
Preference Shares, Series 5 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)				$ 0.33596			$ 0.27500			$ 0.33596
Preference Shares, Series 7 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)			$ 0.27806			$ 0.27500			0.27806
Preference Shares, Series 9 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.27500
Preference Shares, Series 11 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.27500
Preference Shares, Series 13 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.27500
Preference Shares, Series 15 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.27500
Preference Shares, Series 17 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									0.32188
Preference Shares, Series 19 | Preferred share investment
Dividends Payable [Line Items]
Dividend per share (in dollars per share)									$ 0.30625