Intangible Assets and Below Market Lease Liabilities - Scheduled Future Amortization (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Scheduled future amortization of intangible assets [Abstract]
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 194,848	$ 195,273
Scheduled future amortization of below market lease liabilities [Abstract]
Total scheduled future amortization of acquisition-related below market lease liabilities	(23,995)	$ (25,648)
Deferred Leasing Costs and Acquisition-Related Intangible Assets (in Depreciation and Amortization) [Member]
Scheduled future amortization of intangible assets [Abstract]
April 1 through December 31, 2019	28,419
2020	32,940
2021	28,377
2022	24,053
2023	20,650
Thereafter	46,416
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 180,855
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 1 month
Lease Incentives (in Rental and Other Revenues) [Member]
Scheduled future amortization of intangible assets [Abstract]
April 1 through December 31, 2019	$ 1,222
2020	1,300
2021	1,060
2022	836
2023	763
Thereafter	3,521
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 8,702
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 2 months
Acquisition-Related Intangible Assets (in Rental and Other Revenues) [Member]
Scheduled future amortization of intangible assets [Abstract]
April 1 through December 31, 2019	$ 903
2020	957
2021	631
2022	462
2023	308
Thereafter	1,100
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 4,361
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]
April 1 through December 31, 2019	$ 416
2020	514
2021	0
2022	0
2023	0
Thereafter	0
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 930
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 8 months
Acquisition-Related Below Market Lease Liabilities (in Rental and Other Revenues) [Member]
Scheduled future amortization of below market lease liabilities [Abstract]
April 1 through December 31, 2019	$ (4,649)
2020	(5,005)
2021	(4,204)
2022	(3,133)
2023	(2,753)
Thereafter	(4,251)
Total scheduled future amortization of acquisition-related below market lease liabilities	$ (23,995)
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 6 months