Real Estate Properties (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				3 Months Ended		1 Months Ended		1 Months Ended
	Mar. 31, 2014 item building property state	Mar. 31, 2013	Mar. 31, 2014 MOB item sqft building property	Dec. 31, 2013 MOB property building sqft	Mar. 31, 2014 Senior living communities item	Dec. 31, 2013 Senior living communities item	Aug. 31, 2013 Senior living communities Five Star property item	Mar. 31, 2014 Senior living communities Five Star item	Apr. 30, 2014 Sale MOB Subsequent event property building	Jan. 31, 2014 Sale Senior living communities Five Star property item	Aug. 31, 2013 Sale Senior living communities Five Star item	Apr. 30, 2014 Acquisition MOB Subsequent event building property sqft	Feb. 28, 2014 MA Agreement to acquire MOB property building sqft	Jan. 31, 2014 Texas Sale Senior living communities Five Star item
Real Estate Properties
Number of properties owned	374
Number of buildings owned	400
Number of states in which properties are located	40
Real Estate Properties
Number of properties acquired or agreed to be acquired												1	1
Number of buildings acquired												1	2
Number of living units					708	744				36	112
Cash Paid plus Assumed Debt, excluding closing costs												$ 32,658	$ 1,125,420
Mortgage debt assumed in connection with real estate acquisitions		12,266										15,630
Area of real estate properties acquired (in square feet)												125,240	1,651,037
Impairment of asset charges recorded		1,304	721		721
Number of properties classified as held for sale	13		4	4	9	10	10	9
Number of buildings classified as held for sale			7	7
Property held for sale (in square feet)			831,499	831,499
Number of properties impaired	1		2		2
Real estate properties, held for sale					25,644	27,888
Number of properties to be sold							1		1	1				36
Sale price of property sold and agreed to be sold									5,000	2,400	2,550			2,400
Gain on the sale of property	$ 156													$ 156
Number of buildings sold									1