Related Person Transactions (Details) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended	1 Months Ended	3 Months Ended		9 Months Ended		1 Months Ended		3 Months Ended		9 Months Ended		0 Months Ended	9 Months Ended	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 27, 2013	Jul. 31, 2013 item	Sep. 30, 2013 item	Sep. 30, 2012	Sep. 30, 2013 item	Sep. 30, 2012	Jul. 31, 2013 RMR	Mar. 31, 2013 RMR	Sep. 30, 2013 RMR agreement	Sep. 30, 2012 RMR	Sep. 30, 2013 RMR agreement	Sep. 30, 2012 RMR	Mar. 15, 2013 CWH	Sep. 30, 2013 CWH	Jun. 30, 2013 AIC	Sep. 30, 2013 AIC item	Sep. 30, 2012 AIC	Sep. 30, 2013 AIC item	Sep. 30, 2012 AIC	Dec. 31, 2012 AIC
Related Party Transaction
Number of employees			0		0
Number of agreements to avail management and administrative services									2		2
Percentage of interest in subsidiaries														100.00%
Expenses incurred pursuant to our business management agreement									$ 1,942	$ 2,742	$ 6,924	$ 7,001
Number of shares issued for the incentive fee for services rendered	20,230							20,230
Property management and construction supervision fees incurred									2,179	1,829	5,794	5,034
Base business management fee payable in common shares (as a percent)									10.00%		10.00%
Number of other companies owning interest in equity method investment																5		5
Shares sold by former parent company													9,950,000
Common shares registration and sale expenses paid by related party													310
Amount invested in equity investee																5,194		5,194
Investment at carrying value																5,900		5,900		5,747
Recognized income (loss) related to investment in AIC			64	115	219	236										64	115	219	236
Coverage of purchased property insurance																		500,000
Aggregate coverage of separate directors' and officers' liability insurance policy purchased							5,000
Premium for property insurance																		1,161
Premium paid for combined directors' and officers' liability insurance policy							333
Percentage of interest																12.50%		12.50%
Program extension term															1 year
Number of other companies to whom management services were provided by related party		4
Aggregate coverage of combined directors' and officers' liability insurance policy purchased by the related party							10,000
Aggregate coverage of property insurance		$ 10,000