Intangible Assets and Below Market Lease Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Assets:
Deferred leasing costs (including lease incentives and above market lease and in-place lease acquisition-related intangible assets)	$ 339,623		$ 339,623		$ 344,191
Deferred leasing costs, accumulated amortization	(144,555)		(144,555)		(143,512)
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	195,068		195,068		200,679
Liabilities (in accounts payable, accrued expenses and other liabilities):
Acquisition-related below market lease liabilities, gross	58,847		58,847		59,947
Acquisition-related below market lease liabilities, accumulated amortization	(30,133)		(30,133)		(28,214)
Acquisition-related below market lease liabilities, net	28,714		28,714		$ 31,733
Deferred Leasing Costs and Acquisition-Related Intangible Assets (in Depreciation and Amortization) [Member]
Assets:
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	177,582		177,582
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of intangible assets	9,207	$ 10,133	18,702	$ 20,752
Lease Incentives (in Rental and Other Revenues) [Member]
Assets:
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	10,620		10,620
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of intangible assets	476	443	905	840
Acquisition-Related Intangible Assets (in Rental and Other Revenues) [Member]
Assets:
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	5,518		5,518
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of intangible assets	429	675	877	1,711
Acquisition-Related Intangible Assets (in Rental Property and Other Expenses) [Member]
Assets:
Deferred leasing costs, net/Total scheduled future amortization of intangible assets	1,348		1,348
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of intangible assets	139	139	276	276
Acquisition-Related Below Market Lease Liabilities (in Rental and Other Revenues) [Member]
Liabilities (in accounts payable, accrued expenses and other liabilities):
Acquisition-related below market lease liabilities, net	28,714		28,714
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of acquisition-related below market lease liabilities	$ (1,495)	$ (1,592)	$ (3,018)	$ (3,172)