Summary of Significant Accounting Policies and Procedures and Recent Accounting Pronouncements - Provision For Impairment (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) property	Dec. 31, 2015 USD ($) property	Dec. 31, 2014 USD ($) property
Impairment Provisions
Total Provisions for impairment | $	$ 20,700,000	$ 10,600,000	$ 4,600,000
Number of impaired properties held-for-sale	6		1
Number of impaired properties held-for-investment	2	3
Number of impaired properties sold	31	11	10
Number of impaired properties disposed from other than sale		1
Provision for impairment, amount included in income from continuing operations | $			$ 4,100,000
Provisions for impairment | $			$ 510,000
Automotive parts
Impairment Provisions
Number of properties impaired	1
Automotive services
Impairment Provisions
Number of properties impaired	2
Automotive tire services
Impairment Provisions
Number of properties impaired	1
Convenience stores
Impairment Provisions
Number of properties impaired	1	1	1
Financial services
Impairment Provisions
Number of properties impaired	1
General merchandise
Impairment Provisions
Number of properties impaired	1
Health and fitness
Impairment Provisions
Number of properties impaired	1	1
Home furnishings
Impairment Provisions
Number of properties impaired	2		1
Pet supplies and services
Impairment Provisions
Number of properties impaired		1
Restaurant-casual dining industry
Impairment Provisions
Number of properties impaired	24	11	6
Restaurant-quick service
Impairment Provisions
Number of properties impaired	2
Consumer electronics
Impairment Provisions
Number of properties impaired			1
Home improvement
Impairment Provisions
Number of properties impaired			2
Other
Impairment Provisions
Number of properties impaired	3	1