Variable Interest Entities (Summary Of Consolidated Variable Interest Entities) (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($) item	Dec. 31, 2019 USD ($) item
Variable Interest Entity [Line Items]
Assets	$ 3,910,147	$ 3,937,934
Assets Held as Collateral for Debt	3,910,147	3,937,934
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	230,133	228,954
Assets Held as Collateral for Debt	230,133	228,954
Maximum Risk of Loss	$ 29,784	$ 29,784
Number of VIE real estate joint ventures guaranteed by company | item	1	1
Asset Pledged as Collateral [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	$ 40,638	$ 39,782
Assets Held as Collateral for Debt	$ 40,638	$ 39,782