Summary Of Significant Accounting Policies (Real Estate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation Expense Real Estate	$ 227.9	$ 215.4	$ 216.0
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