Impairments (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) item	Jun. 30, 2014 USD ($) item	Jun. 30, 2015 USD ($) item	Jun. 30, 2014 USD ($) item
Impairments
Provisions for impairment | $	$ 3,200,000	$ 499,000	$ 5,300,000	$ 2,200,000
Number of impaired properties sold		2	1	6
Number of impaired properties held-for-sale	3		3
Number of impaired properties held-for-investment	2		3
Number of impaired properties disposed from other than sale			1
Restaurants - casual dining industry
Impairments
Number of impaired properties sold		1		3
Number of impaired properties held-for-sale	3		6
Consumer electronics
Impairments
Number of impaired properties sold				1
Home furnishings
Impairments
Number of impaired properties sold				1
Home improvement
Impairments
Number of impaired properties sold		1		1
Health and fitness
Impairments
Number of impaired properties held-for-sale	1		1
Other non-reportable segments
Impairments
Number of impaired properties held-for-sale	1		1