Schedule of Common and Preferred Subsequent Events Dividends (Details) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Jun. 30, 2015
Subsequent Event [Line Items]
Common Dividend per Share/Unit	$ 0.38	[1]	$ 0.28
For the Quarter Ended	Dec. 31, 2014
Record Date	Dec. 31, 2014
Payable Date	Jan. 15, 2015
7 1/2% Series H Preferred Shares [Member]
Subsequent Event [Line Items]
Preferred Dividend per Share/Unit	$ 0.47	[2]
For the Quarter Ended	Dec. 31, 2014
Record Date	Jan. 01, 2015
Payable Date	Jan. 15, 2015
6 3/8% Series I Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred Dividend per Share/Unit	$ 0.40	[2]
For the Quarter Ended	Dec. 31, 2014
Record Date	Jan. 01, 2015
Payable Date	Jan. 15, 2015
Subsequent Event [Member] | Common Shares of Beneficial Interest [Member]
Subsequent Event [Line Items]
Common Dividend per Share/Unit				$ 0.38	[2]
For the Quarter Ended				Mar. 31, 2015
Record Date				Mar. 31, 2015
Payable Date				Apr. 15, 2015
Subsequent Event [Member] | 7 1/2% Series H Preferred Shares [Member]
Subsequent Event [Line Items]
Preferred Dividend per Share/Unit				$ 0.47	[2]
For the Quarter Ended				Mar. 31, 2015
Record Date				Apr. 01, 2015
Payable Date				Apr. 15, 2015
Subsequent Event [Member] | 6 3/8% Series I Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred Dividend per Share/Unit				$ 0.40	[2]
For the Quarter Ended				Mar. 31, 2015
Record Date				Apr. 01, 2015
Payable Date				Apr. 15, 2015

[1] Amount is rounded to the nearest whole cent for presentation purposes.

[2] Amounts are rounded to the nearest whole cent for presentation purposes.