Shareholders' Equity (Details 3) (USD $)			0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Feb. 07, 2014 RMR	Jan. 28, 2014 Common Shares Trustees Subsequent Event trustee
Shareholders' Equity
Common shares issued			12,187
Shares of beneficial interest granted				2,000
Par value of shares of beneficial interest (in dollars per share)	$ 0.01	$ 0.01		$ 0.01
Price per common share (in dollars per share)				$ 23.46
Number of recently appointed trustees to whom common shares granted				2