Intangible Assets and Below Market Lease Liabilities - Scheduled Future Amortization (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Scheduled future amortization of intangible assets [Abstract]
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	$ 255,849	$ 228,768
Deferred Financing Costs [Member]
Scheduled future amortization of intangible assets [Abstract]
October 1, 2015 through December 31, 2015	1,049
2016	3,252
2017	2,711
2018	1,531
2019	1,123
Thereafter	1,363
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	$ 11,029	11,525
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	4 years
Deferred Leasing Costs and Acquisition-Related Intangible Assets [Member]
Scheduled future amortization of intangible assets [Abstract]
October 1, 2015 through December 31, 2015	$ 12,976
2016	45,955
2017	38,353
2018	31,244
2019	25,530
Thereafter	65,865
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	$ 219,923
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 8 months
Lease Incentives [Member]
Scheduled future amortization of intangible assets [Abstract]
October 1, 2015 through December 31, 2015	$ 353
2016	1,298
2017	1,197
2018	1,091
2019	898
Thereafter	2,845
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	$ 7,682
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 11 months
Acquisition-Related Intangible Assets (in Rental and Other Revenues) [Member]
Scheduled future amortization of intangible assets [Abstract]
October 1, 2015 through December 31, 2015	$ 1,111
2016	3,884
2017	2,731
2018	1,752
2019	1,307
Thereafter	3,553
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	$ 14,338
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 1 month
Acquired finite-lived intangible assets, weighted average useful life (in years)	4 years 11 months
Acquisition-Related Intangible Assets (amortized in Depreciation and Amortization) [Member]
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Acquired finite-lived intangible assets, weighted average useful life (in years)	5 years 6 months
Acquisition-Related Intangible Assets (in Rental Property and Other Expenses) [Member]
Scheduled future amortization of intangible assets [Abstract]
October 1, 2015 through December 31, 2015	$ 132
2016	553
2017	553
2018	553
2019	553
Thereafter	533
Deferred financing and leasing costs, net/Total scheduled future amortization of intangible assets	$ 2,877
Weighted average remaining amortization periods for intangible assets and below market lease liabilities [Abstract]
Finite-lived intangible assets, average useful life (in years)	5 years 2 months
Acquisition-Related Below Market Lease Liabilities [Member]
Scheduled future amortization of below market lease liabilities [Abstract]
October 1, 2015 through December 31, 2015	$ (1,888)
2016	(6,997)
2017	(6,653)
2018	(6,216)
2019	(5,740)
Thereafter	(20,342)
Total scheduled future amortization of acquisition-related below market lease liabilities	$ (47,836)	$ (42,235)
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)	8 years 1 month
Assumed finite-lived below market lease liabilities, weighted average useful life (in years)	9 years 8 months