Real Estate (Classification of Investment Property Leases) (Details)	3 Months Ended
	Mar. 31, 2018 property option
Lease classification:
Weighted average remaining lease term (years)	11 years 5 months
Number of renewal options, or more | option	1
Operating
Lease classification:
Operating	2,830
Direct financing
Lease classification:
Direct financing	7
Building portion – direct financing/land portion – operating
Lease classification:
Building portion – direct financing/land portion – operating	2