Acquired Lease Intangibles (Schedule Net Amortization Or Accretion) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Accretion of above and below market leases	$ 18,198	$ 19,100	$ 16,084
Operating Lease Revenue [Member] | Tenant Lease [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Accretion of above and below market leases	18,165	12,467	13,752
Office Parking And Other Income [Member] | Above Market Ground Leases [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Accretion of above and below market leases	(17)	(17)	(17)
Office Expense [Member] | Above Market Ground Leases [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Accretion of above and below market leases	50	50	50
Other Income [Member] | Above Market Ground Leases [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Accretion of above and below market leases	$ 0	$ 6,600	$ 2,299