Intangible Assets and Below Market Lease Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Intangible assets and below market lease liabilities, net [Abstract]
Deferred leasing costs, gross	$ 344,548	$ 344,191
Deferred leasing costs, accumulated amortization	(149,275)	(143,512)
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	195,273	200,679
Acquisition-related below market lease liabilities, gross	57,955	59,947
Acquisition-related below market lease liabilities, accumulated amortization	(32,307)	(28,214)
Acquisition-related below market lease liabilities, net	25,648	31,733
Deferred Leasing Costs and Acquisition-Related Intangible Assets [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	178,360
Amortization of intangible assets and below market lease liabilities
Amortization of intangible assets	36,486	41,187	$ 44,968
Lease Incentives [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	11,127
Amortization of intangible assets and below market lease liabilities
Amortization of intangible assets	1,908	1,765	1,779
Acquisition-Related Intangible Assets (in Rental and Other Revenue) [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	4,719
Amortization of intangible assets and below market lease liabilities
Amortization of intangible assets	1,677	2,921	3,851
Acquisition-Related Intangible Assets (in Rental Property and Other Expenses) [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	1,067
Amortization of intangible assets and below market lease liabilities
Amortization of intangible assets	557	557	557
Acquisition-Related Below Market Lease Liabilities [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Acquisition-related below market lease liabilities, net	25,648
Amortization of intangible assets and below market lease liabilities
Amortization of acquisition-related below market lease liabilities	$ (6,085)	$ (6,415)	$ (8,183)