Summary of Significant Accounting Policies (Schedule of Fixed and Variable Lease Payments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accounting Policies [Abstract]
Fixed payments	$ 108,071	$ 105,207	$ 329,281	$ 311,503
Variable payments	20,209	25,372	62,400	70,710
Total Rental and Tenant Reimbursement Revenue	$ 128,280	$ 130,579	$ 391,681	$ 382,213