Intangible Assets and Below Market Lease Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Intangible assets and below market lease liabilities, net [Abstract]
Deferred financing and leasing costs, accumulated amortization	$ (123,463)		$ (123,463)		$ (112,804)
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	255,849		255,849		228,768
Amortization of intangible assets and below market lease liabilities [Abstract]
Acquired intangible assets (amortized in rental and other revenue)	3,051		3,051
Acquired intangible assets (amortized in depreciation and amortization)	35,534		35,534
Assumed below market lease liabilities (amortized in rental and other revenue)	(10,733)		(10,733)
Deferred Financing Costs [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred financing and leasing costs, gross	19,935		19,935		19,478
Deferred financing and leasing costs, accumulated amortization	(8,906)		(8,906)		(7,953)
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	11,029		11,029		11,525
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of intangible assets	873	$ 819	2,501	$ 2,270
Deferred Leasing Costs [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred financing and leasing costs, gross	359,377		359,377		322,094
Deferred financing and leasing costs, accumulated amortization	(114,557)		(114,557)		(104,851)
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	244,820		244,820		217,243
Deferred Leasing Costs and Acquisition-Related Intangible Assets [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	219,923		219,923
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of intangible assets	11,176	9,465	31,638	29,443
Lease Incentives [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	7,682		7,682
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of intangible assets	378	327	1,162	1,077
Acquisition-Related Intangible Assets (in Rental and Other Revenues) [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	14,338		14,338
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of intangible assets	1,414	1,080	3,769	3,310
Acquisition-Related Intangible Assets (in Rental Property and Other Expenses) [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	2,877		2,877
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of intangible assets	140	140	416	416
Acquisition-Related Below Market Lease Liabilities [Member]
Intangible assets and below market lease liabilities, net [Abstract]
Acquisition-related below market lease liabilities, gross	65,002		65,002		55,783
Acquisition-related below market lease liabilities, accumulated amortization	(17,166)		(17,166)		(13,548)
Acquisition-related below market lease liabilities, net	47,836		47,836		$ 42,235
Amortization of intangible assets and below market lease liabilities [Abstract]
Amortization of acquisition-related below market lease liabilities	$ (1,727)	$ (1,532)	$ (5,133)	$ (4,554)