Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net - Deferred Leasing Costs and Acquisition-related Intangible Assets and Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, Net
Total deferred leasing costs and acquisition-related intangible assets, net	$ 210,949	$ 212,805
Acquisition-related Intangible Liabilities, Net [Abstract]
Total acquisitions-related intangible liabilities, net	13,345	24,092
Deferred leasing costs [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, Net
Finite-lived intangible assets/liabilities, gross	300,556	286,026
Accumulated amortization	(104,277)	(100,145)
Finite-lived intangible assets	196,279	185,881
Above market leases [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, Net
Finite-lived intangible assets/liabilities, gross	0	611
Accumulated amortization	0	(116)
Finite-lived intangible assets	0	495
In-place leases [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, Net
Finite-lived intangible assets/liabilities, gross	40,323	58,076
Accumulated amortization	(25,653)	(31,647)
Finite-lived intangible assets	14,670	26,429
Below-market operating leases [Member]
Acquisition-related Intangible Liabilities, Net [Abstract]
Acquisition-related intangible liabilities, gross	26,405	51,263
Accumulated amortization	(13,060)	(27,171)
Acquisition-related intangible liabilities, net	$ 13,345	$ 24,092