Loan Receivable (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		1 Months Ended		1 Months Ended				3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Apr. 30, 2012 Five Star	May 31, 2011 Five Star Maximum	Apr. 30, 2012 Five Star Senior living communities item	Dec. 31, 2011 Five Star Senior living communities	Sep. 30, 2011 Five Star Senior living communities	May 31, 2011 Five Star Senior living communities item	Mar. 31, 2012 Five Star Senior living communities
Loans Receivable
Amount agreed to be lent under Bridge Loan Agreement				$ 80,000
Number of properties funded under Bridge Loan								6
Amount borrowed under the Bridge Loan							80,000
Amount repaid by borrower			38,000		38,000	42,000
Number of properties mortgaged, acquired by borrower					3
Number of properties mortgaged, owned by borrower					4
Spread over annual rates of interest applicable to borrowings under revolving credit facility (as a percent)					1.00%
Interest income recognized	$ 173	$ 482							$ 275