Intangible Assets and Below Market Lease Liabilities - Scheduled Future Amortization (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Scheduled future amortization of intangible assets [Abstract]
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 196,048	$ 195,273
Scheduled future amortization of below market lease liabilities [Abstract]
Total scheduled future amortization of acquisition-related below market lease liabilities	(20,576)	$ (25,648)
Deferred Leasing Costs and Acquisition-Related Intangible Assets (in Depreciation and Amortization) [Member]
Scheduled future amortization of intangible assets [Abstract]
October 1 through December 31, 2019	9,538
2020	34,968
2021	30,100
2022	25,689
2023	22,180
Thereafter	58,995
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 181,470
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	7 years 3 months 18 days
Lease Incentives (in Rental and Other Revenues) [Member]
Scheduled future amortization of intangible assets [Abstract]
October 1 through December 31, 2019	$ 428
2020	1,584
2021	1,338
2022	1,104
2023	1,025
Thereafter	4,735
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 10,214
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	9 years 3 months 18 days
Acquisition-Related Intangible Assets (in Rental and Other Revenues) [Member]
Scheduled future amortization of intangible assets [Abstract]
October 1 through December 31, 2019	$ 258
2020	954
2021	631
2022	462
2023	308
Thereafter	1,100
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 3,713
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	6 years 6 months
Acquisition-Related Intangible Assets (in Rental Property and Other Expenses) [Member]
Scheduled future amortization of intangible assets [Abstract]
October 1 through December 31, 2019	$ 137
2020	514
2021	0
2022	0
2023	0
Thereafter	0
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 651
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	1 year 2 months 12 days
Acquisition-Related Below Market Lease Liabilities (in Rental and Other Revenues) [Member]
Scheduled future amortization of below market lease liabilities [Abstract]
October 1 through December 31, 2019	$ (1,349)
2020	(5,107)
2021	(4,152)
2022	(3,086)
2023	(2,707)
Thereafter	(4,175)
Total scheduled future amortization of acquisition-related below market lease liabilities	$ (20,576)
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Finite-lived below market lease liabilities, average useful life (in years)	5 years 2 months 12 days