Acquired Intangible Assets and Liabilities (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Mar. 09, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Amortization of customer relationship value, acquired in-place lease value and deferred leasing costs				$ 178,682	$ 192,686
Customer Relationship Value
Finite-Lived Intangible Assets [Line Items]
Expected average remaining lives (in years)	15 years
Amortization of customer relationship value, acquired in-place lease value and deferred leasing costs		$ 49,700	$ 30,700	$ 78,800	68,700
Weighted average remaining contractual life for acquired leases excluding renewals or extensions (in years)				13 years 3 months 18 days
Acquired in-place lease value
Finite-Lived Intangible Assets [Line Items]
Expected average remaining lives (in years)				5 years 9 months 18 days
Amortization of customer relationship value, acquired in-place lease value and deferred leasing costs		29,800	37,400	$ 57,000	82,400
Weighted average remaining contractual life for acquired leases excluding renewals or extensions (in years)				5 years 7 months 6 days
Below-Market Leases, Net of Above-Market Leases
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired leases		$ 3,100	$ 6,200	$ 6,400	$ 10,200
Expected average remaining lives of acquired below market leases (in years)				7 years 6 months
Expected average remaining lives (in years)				2 years 1 month 6 days