Summary Of Significant Accounting Policies (Recent Accounting Pronouncements) (Details) $ in Millions		12 Months Ended
	Jan. 01, 2019 USD ($)	Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of Properties Subject to Ground Leases | property		14
Cumulative Effect on Retained Earnings, Tax	$ 7.1
Capitalized internal leasing and external legal leasing costs		$ 2.2	$ 7.5