Equity (Details 1) - $ / shares	3 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Series A Preferred Stock [Member]
Dividends on preferred shares/units
Dividend per Share (usd per share)				$ 0.31
Record Date				Mar. 31, 2016
Payable Date				Apr. 15, 2016
8.00% Series B [Member]
Dividends on preferred shares/units
Dividend per Share (usd per share)		$ 0.38	$ 0.50	$ 0.50
Record Date		Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Payable Date		Oct. 17, 2016	Jul. 15, 2016	Apr. 15, 2016
6.50% Series C [Member]
Dividends on preferred shares/units
Dividend per Share (usd per share)	$ 0.41	$ 0.41	$ 0.41	$ 0.41
Record Date	Dec. 30, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Payable Date	Jan. 17, 2017	Oct. 17, 2016	Jul. 15, 2016	Apr. 15, 2016
6.375% Series D [Member]
Dividends on preferred shares/units
Dividend per Share (usd per share)	$ 0.40	$ 0.40	$ 0.16
Record Date	Dec. 30, 2016	Sep. 30, 2016	Jun. 30, 2016
Payable Date	Jan. 17, 2017	Oct. 17, 2016	Jul. 15, 2016