Indebtedness (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended				12 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended		1 Months Ended	12 Months Ended								12 Months Ended	0 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended									12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Standby letters of credit	Dec. 31, 2013 Standby letters of credit HCP item	Dec. 31, 2013 Senior Living Communities property	Jun. 30, 2014 SNH SNF Subsequent event property	Dec. 31, 2013 SNH Rehabilitation hospitals property	Aug. 31, 2013 SNH Senior Living Communities property	May 31, 2011 SNH Senior Living Communities property	Jan. 31, 2014 SNH Senior Living Communities Subsequent event property	Dec. 31, 2013 Credit Agreement	Dec. 31, 2012 Credit Agreement	Dec. 31, 2011 Credit Agreement	Dec. 31, 2013 Credit Agreement LIBOR	Dec. 31, 2013 Credit Facility item	Dec. 31, 2012 Credit Facility	Sep. 08, 2014 Credit Facility Subsequent event	Dec. 31, 2013 Credit Facility Senior Living Communities unit item	Dec. 31, 2013 Credit Facility LIBOR	Jul. 08, 2013 Notes	Oct. 31, 2006 Notes	Sep. 30, 2013 Notes	Dec. 31, 2013 Notes	Dec. 31, 2012 Notes	Dec. 31, 2011 Notes	Dec. 31, 2013 Mortgage notes	Dec. 31, 2012 Mortgage notes	Dec. 31, 2011 Mortgage notes	Dec. 31, 2013 Mortgage notes FNMA item	Dec. 31, 2013 Mortgage notes FMCC item	Dec. 31, 2013 Mortgage notes Senior Living Communities item	Dec. 31, 2012 Bridge Loan	Dec. 31, 2011 Bridge Loan	Dec. 31, 2013 Bridge Loan SNH	Dec. 31, 2012 Bridge Loan SNH	Dec. 31, 2011 Bridge Loan SNH	May 31, 2011 Bridge Loan SNH
Indebtedness
Maximum borrowing capacity				$ 950								$ 25,000	$ 35,000			$ 150,000
Number of real estate properties sold							2	2	1		1
Variable rate basis															LIBOR					LIBOR
Basis spread (as a percent)												2.50%				2.50%
Interest rate at period end (as a percent)												2.67%				2.67%
Quarterly commitment fee on the unused part of borrowing availability (as a percent)												0.35%				0.35%
Amount borrowed during the period	85,000	62,500	12,000									0
Amount outstanding under credit facility												0				35,000		20,000
Interest expense and other associated costs incurred												386	676	726		1,985	1,746							511	1,124	1,470	3,010	2,843	1,588				314	593	0	314	593
Number of extensions to maturity date																2
Extension period available																1 year
Number of real estate properties mortgaged																														1	3	4
Number of real estate properties securing borrowings on the new credit facility																			15
Number of units in real estate properties securing borrowings on the new credit facility																			1,549
Proceeds from issue of notes																						122,600
Interest rate (as a percent)																						3.75%
Conversion ratio, number of common shares per $1,000 principal amount																						76.9231
Initial conversion price of shares (in dollars per share)																						$ 13.00
Percentage of principal amount at which notes may be required to be repurchased in event of fundamental change																						100.00%
Amount of notes outstanding redeemed																					24,872
Outstanding notes purchased and retired																									12,410	623
Gain, net of related unamortized costs, on early extinguishment of debt	(599)	45	1																				(599)		45	1
Mortgage notes, total																																37,620
Weighted average interest rate (as a percent)													6.25%	6.25%		3.05%	2.98%
Loan amount																						126,500															80,000	80,000
Number of properties operated						255				6
Repayments of borrowing		$ 38,000	$ 42,000																																		$ 42,000
Number of irrevocable standby letters of credit					6