Future Minimum Lease Receipts (Schedule Of Future Minimum Base Rentals On Non-Cancelable Office And Ground Operating Leases) (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Operating Leases, Future Minimum Payments Receivable [Abstract]
2017	$ 487,764
2018	420,983
2019	359,650
2020	298,096
2021	220,484
Thereafter	595,806
Total future minimum base rentals(1)	$ 2,382,783