Intangible Assets and Below Market Lease Liabilities - Scheduled Future Amortization (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Scheduled future amortization of intangible assets [Abstract]
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 195,068	$ 200,679
Scheduled future amortization of below market lease liabilities [Abstract]
Total scheduled future amortization of acquisition-related below market lease liabilities	(28,714)	$ (31,733)
Deferred Leasing Costs and Acquisition-Related Intangible Assets (in Depreciation and Amortization) [Member]
Scheduled future amortization of intangible assets [Abstract]
July 1 through December 31, 2018	18,504
2019	32,788
2020	28,231
2021	23,756
2022	19,520
Thereafter	54,783
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 177,582
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 6 months
Lease Incentives (in Rental and Other Revenues) [Member]
Scheduled future amortization of intangible assets [Abstract]
July 1 through December 31, 2018	$ 866
2019	1,578
2020	1,311
2021	1,086
2022	872
Thereafter	4,907
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 10,620
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	10 years
Acquisition-Related Intangible Assets (in Rental and Other Revenues) [Member]
Scheduled future amortization of intangible assets [Abstract]
July 1 through December 31, 2018	$ 784
2019	1,273
2020	959
2021	632
2022	462
Thereafter	1,408
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 5,518
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]
July 1 through December 31, 2018	$ 277
2019	553
2020	518
2021	0
2022	0
Thereafter	0
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	$ 1,348
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	2 years 6 months
Acquisition-Related Below Market Lease Liabilities (in Rental and Other Revenues) [Member]
Scheduled future amortization of below market lease liabilities [Abstract]
July 1 through December 31, 2018	$ (2,918)
2019	(5,446)
2020	(5,186)
2021	(4,377)
2022	(3,264)
Thereafter	(7,523)
Total scheduled future amortization of acquisition-related below market lease liabilities	$ (28,714)
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)	6 years 2 months 12 days