Summary of Significant Accounting Policies - Real Estate Assets (Details)	12 Months Ended
	Dec. 31, 2016 store
Property, Plant and Equipment [Line Items]
Number of properties whereby leases cannot be classified as ground or building leases	3
Number of properties whereby leases have been assumed at rates lower than the current market rates	8
Building and Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Building and Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	39 years