Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net - Amortization of Deferred Leasing Costs and Acquisition-related Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	$ 35,130	$ 45,188	$ 40,415
Deferred leasing costs [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	33,624	35,779	34,341
Estimated annual amortization related to acquisition-related intangible assets
Finite-lived intangible assets, 2021	31,048
Finite-lived intangible assets, 2022	28,334
Finite-lived intangible assets, 2023	24,470
Finite-lived intangible assets, 2024	21,545
Finite-lived intangible assets, 2025	19,726
Finite-lived intangible assets, thereafter	71,156
Finite-lived intangible assets	196,279	185,881
Above market leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	495	192	444
Estimated annual amortization related to acquisition-related intangible assets
Finite-lived intangible assets	0	495
In-place leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	11,759	18,615	15,915
Estimated annual amortization related to acquisition-related intangible assets
Finite-lived intangible assets, 2021	6,531
Finite-lived intangible assets, 2022	3,885
Finite-lived intangible assets, 2023	1,534
Finite-lived intangible assets, 2024	584
Finite-lived intangible assets, 2025	473
Finite-lived intangible assets, thereafter	1,663
Finite-lived intangible assets	14,670	26,429
Below-market ground lease obligation [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	0	0	8
Below-market operating leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization of intangible liabilities	(10,748)	(9,398)	(10,192)
Estimated annual amortization related to acquisition-related intangible liabilities
Acquisition-related intangible liabilities, 2021	(4,152)
Acquisition-related intangible liabilities, 2022	(3,167)
Acquisition-related intangible liabilities, 2023	(1,486)
Acquisition-related intangible liabilities, 2024	(812)
Acquisition-related intangible liabilities, 2025	(710)
Acquisition-related intangible liabilities, thereafter	(3,018)
Acquisition-related intangible liabilities	(13,345)	(24,092)
Above-market ground lease obligation [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization of intangible liabilities	$ 0	$ 0	$ (101)