Basis of Presentation - Dividends Declared (Details)	May 19, 2020 $ / shares
Real Estate Properties [Line Items]
Common stock, dividends, per share, declared	$ 0.02
7.375% Series B Cumulative Redeemable Perpetual Preferred Shares
Real Estate Properties [Line Items]
Dividends payable, date declared	May 19, 2020
Preferred stock, dividends per share, declared	$ 0.4609375
Dividends payable, date to be Paid	Jun. 15, 2020
Dividends payable, date of record	Jun. 01, 2020
7.20% Series C Preferred Shares
Real Estate Properties [Line Items]
Dividends payable, date declared	May 19, 2020
Preferred stock, dividends per share, declared	$ 0.450000
Dividends payable, date to be Paid	Jun. 15, 2020
Dividends payable, date of record	Jun. 01, 2020
6.875% Series D Preferred Shares
Real Estate Properties [Line Items]
Dividends payable, date declared	May 19, 2020
Preferred stock, dividends per share, declared	$ 0.4296875
Dividends payable, date to be Paid	Jun. 15, 2020
Dividends payable, date of record	Jun. 01, 2020
Shares of Beneficial Interest, $1.00 Par
Real Estate Properties [Line Items]
Dividends payable, date declared	May 19, 2020
Dividends payable, date to be Paid	Jun. 15, 2020
Dividends payable, date of record	Jun. 01, 2020