Fair Value of Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value of Financial Instruments
Mortgage notes payable	$ 91,343	$ 93,127
5.73% Mortgage notes due in 2015
Fair Value of Financial Instruments
Mortgage notes payable	48,607	49,274
Interest rate (as a percent)	5.73%	5.73%
Unamortized fair value premium included in mortgage notes	463
6.21% Mortgage notes due in 2016
Fair Value of Financial Instruments
Mortgage notes payable	24,223	24,441
Interest rate (as a percent)	6.21%	6.21%
7% Mortgage notes due in 2019
Fair Value of Financial Instruments
Mortgage notes payable	10,003	10,247
Interest rate (as a percent)	7.00%	7.00%
Unamortized fair value premium included in mortgage notes	782
8.15% Mortgage notes due in 2021
Fair Value of Financial Instruments
Mortgage notes payable	8,510	9,165
Interest rate (as a percent)	8.15%	8.15%
Unamortized fair value premium included in mortgage notes	556
Carrying Amount
Fair Value of Financial Instruments
Mortgage notes payable	91,343
Carrying Amount | 5.73% Mortgage notes due in 2015
Fair Value of Financial Instruments
Mortgage notes payable	48,607
Carrying Amount | 6.21% Mortgage notes due in 2016
Fair Value of Financial Instruments
Mortgage notes payable	24,223
Carrying Amount | 7% Mortgage notes due in 2019
Fair Value of Financial Instruments
Mortgage notes payable	10,003
Carrying Amount | 8.15% Mortgage notes due in 2021
Fair Value of Financial Instruments
Mortgage notes payable	8,510
Fair Value
Fair Value of Financial Instruments
Mortgage notes payable	96,438
Fair Value | 5.73% Mortgage notes due in 2015
Fair Value of Financial Instruments
Mortgage notes payable	50,095
Fair Value | 6.21% Mortgage notes due in 2016
Fair Value of Financial Instruments
Mortgage notes payable	26,361
Fair Value | 7% Mortgage notes due in 2019
Fair Value of Financial Instruments
Mortgage notes payable	10,578
Fair Value | 8.15% Mortgage notes due in 2021
Fair Value of Financial Instruments
Mortgage notes payable	$ 9,404