Summary Of Significant Accounting Policies (Real Estate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Real estate depreciation expense	$ 193.3	$ 173.2	$ 156.5
Building and Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	35 years
Building and Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	50 years
Minor Improvements, Furniture and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Minor Improvements, Furniture and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years