Commitments And Contingencies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) item
Commitments And Contingencies [Abstract]
Deductible for general liability	$ 2,000,000.0
Deductible for property	25,000,000.0
Reduced deductible for property	5,000,000.0
Aggregate maximum losses for property	35,000,000.0
Aggregate per occurance property coverage	5,000,000.0
Aggregate limit for property coverage	75,000,000.0
Aggregate limit for general liability coverage	102,000,000.0
Tenant insurance program against claims, maximum amount	5,000
Third-party insurance coverage for claims paid exceeding amount for individual event	15,000,000.0
Third-party limit for insurance coverage claims paid for individual event	$ 5,000,000.0
Tenant certificate holders participating in insurance program, approximate | item	935,000
Aggregate coverage of tenants participating in insurance program	$ 3,200,000,000
Construction commitments	77,200,000
Construction commitments 2020	69,700,000
Construction commitments 2021	$ 7,500,000