Shareholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified			1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 RMR	Dec. 31, 2011 RMR	Mar. 29, 2012 RMR
Common Share Issuances
Common shares issued for services rendered by RMR			33,132
Common shares, par value (in dollars per share)	$ 0.01	$ 0.01			$ 0.01
Incentive fee earned by RMR				$ 741