Consolidated Statements of Shareholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Dividends declared on Common Shares of beneficial interest	$ 0.65	$ 0.65	$ 0.65
Series C [Member]
Dividends declared on Series C Preferred Share			$ 1.43
Series D Preferred Shares of Beneficial Interest [Member]
Dividends declared on Series C Preferred Share	$ 2.3125	$ 1.92628	$ 0.212
Accumulated Distributions in Excess of Net Income [Member]
Dividends declared on Common Shares of beneficial interest	$ 0.65	$ 0.65	$ 0.65
Accumulated Distributions in Excess of Net Income [Member] | Series C [Member]
Dividends declared on Series C Preferred Share			$ 1.43
Accumulated Distributions in Excess of Net Income [Member] | Series D Preferred Shares of Beneficial Interest [Member]
Dividends declared on Series C Preferred Share	$ 2.3125	$ 1.92628	$ 0.212