Fair Value (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Fair Value
Total	$ (11,484,000)	$ (470,000)
Interest rate swap
Fair Value
Interest rate swap asset	2,765,000
Interest rate swap liability	(14,200,000)	(500,000)
Level 3
Fair Value
Investment in collateralized loans	13,100,000	23,000,000
Fixed rate mortgage notes payable	178,900,000	745,300,000
Carrying value of fixed rate mortgage notes payable	184,300,000	770,700,000
Recurring | Level 2 | Interest rate swap
Fair Value
Interest rate swap asset	2,765,000
Interest rate swap liability	(14,249,000)
Total	(11,484,000)
Recurring | Total | Interest rate swap
Fair Value
Interest rate swap asset	2,765,000
Interest rate swap liability	(14,249,000)
Total	$ (11,484,000)