Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, net (Details 1) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2015		Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014	Dec. 31, 2014
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization Of Intangible Liabilities		$ (8,240)		$ (10,642)	$ (25,717)		$ (31,879)
Deferred Leasing Costs [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization of Intangible Assets	[1]	6,932		7,132	20,847		20,683
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014		6,740			6,740
2015		25,662			25,662
2016		22,661			22,661
2017		19,023			19,023
2018		15,150			15,150
Thereafter		37,372			37,372
Finite-lived intangible assets, net		126,608			126,608			$ 141,198
Above-Market Leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization of Intangible Assets	[2]	487		1,305	2,135		4,230
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	[3]	399			399
2015	[3]	1,499			1,499
2016	[3]	1,241			1,241
2017	[3]	831			831
2018	[3]	643			643
Thereafter	[3]	33			33
Finite-lived intangible assets, net		4,646	[3]		4,646	[3]		6,782
In-Place Leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization of Intangible Assets	[1]	3,073		5,169	11,710		17,090
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014		2,800			2,800
2015		10,449			10,449
2016		9,113			9,113
2017		6,373			6,373
2018		4,714			4,714
Thereafter		8,291			8,291
Finite-lived intangible assets, net		41,740			41,740			53,477
Below Market Ground Lease Obligation [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization of Intangible Assets	[4]	2		2	6		6
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	[5]	2			2
2015	[5]	8			8
2016	[5]	8			8
2017	[5]	8			8
2018	[5]	8			8
Thereafter	[5]	429			429
Finite-lived intangible assets, net		463	[5]		463	[5]		469
Below Market Leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization Of Intangible Liabilities	[6]	(2,228)		(2,940)	(8,905)		(10,054)
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	[7]	(2,044)			(2,044)
2015	[7]	(7,638)			(7,638)
2016	[7]	(7,017)			(7,017)
2017	[7]	(5,735)			(5,735)
2018	[7]	(3,597)			(3,597)
Thereafter	[7]	(2,473)			(2,473)
Acquisition-related Intangible Liabilities, net		(28,504)	[7]		(28,504)	[7]		(37,431)
Above-Market Ground Lease Obligation [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization Of Intangible Liabilities	[8]	(26)		$ (26)	(76)		$ (76)
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	[9]	(25)			(25)
2015	[9]	(101)			(101)
2016	[9]	(101)			(101)
2017	[9]	(101)			(101)
2018	[9]	(101)			(101)
Thereafter	[9]	(5,492)			(5,492)
Acquisition-related Intangible Liabilities, net		$ (5,921)	[9]		$ (5,921)	[9]		$ (5,996)

[1] The amortization of deferred leasing costs related to lease incentives is recorded to rental income and other deferred leasing costs and in-place leases is recorded to depreciation and amortization expense in the consolidated statements of operations for the periods presented.

[2] The amortization of above-market operating leases is recorded as a decrease to rental income in the consolidated statements of operations for the periods presented.

[3] Represents estimated annual amortization related to above-market operating leases. Amounts will be recorded as a decrease to rental income in the consolidated statements of operations.

[4] The amortization of the below-market ground lease obligation is recorded as an increase to ground lease expense in the consolidated statements of operations for the periods presented.

[5] Represents estimated annual amortization related to below-market ground lease obligations. Amounts will be recorded as an increase to ground lease expense in the consolidated statements of operations.

[6] The amortization of below-market operating leases is recorded as an increase to rental income in the consolidated statements of operations for the periods presented.

[7] Represents estimated annual amortization related to below-market operating leases. Amounts will be recorded as an increase to rental income in the consolidated statements of operations.

[8] The amortization of the above-market ground lease obligation is recorded as a decrease to ground lease expense in the consolidated statements of operations for the periods presented.

[9] Represents estimated annual amortization related to above-market ground lease obligations. Amounts will be recorded as a decrease to ground lease expense in the consolidated statements of operations.