Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, net (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangible assets	$ 11,288		$ 13,232
Deferred Leasing Costs [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangible assets	6,780	[1]	7,844	[1]
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	20,006
2015	22,162
2016	19,351
2017	16,742
2018	13,416
Thereafter	23,984
Finite-lived intangible assets, net	115,661				115,474
Above-Market Leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangible assets	1,490	[2]	1,438	[2]
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	3,830	[3]
2015	2,918	[3]
2016	1,891	[3]
2017	1,573	[3]
2018	973	[3]
Thereafter	677	[3]
Finite-lived intangible assets, net	11,862	[3]			13,352
In-Place Leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangible assets	6,136	[1]	7,458	[1]
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	15,274
2015	13,562
2016	10,475
2017	8,774
2018	5,689
Thereafter	6,694
Finite-lived intangible assets, net	60,468				57,319
Below Market Ground Lease Obligation [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangible assets	0	[4]	2	[4]
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	6	[5]
2015	8	[5]
2016	8	[5]
2017	8	[5]
2018	8	[5]
Thereafter	437	[5]
Finite-lived intangible assets, net	475	[5]			477
Below Market Leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to acquistion-related liabilities	(3,093)	[6]	(3,485)	[6]
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	(9,802)	[7]
2015	(9,577)	[7]
2016	(7,847)	[7]
2017	(6,780)	[7]
2018	(5,177)	[7]
Thereafter	(6,023)	[7]
Acquisition-related Intangible Liabilities, net	(45,206)	[7],[8]			(43,679)	[8]
Above-Market Ground Lease Obligation [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to acquistion-related liabilities	(25)	[9]	(25)	[9]
Estimated annual amortization related to acquisition-related intangibles
Remaining 2014	(76)	[10]
2015	(101)	[10]
2016	(101)	[10]
2017	(101)	[10]
2018	(101)	[10]
Thereafter	(5,592)	[10]
Acquisition-related Intangible Liabilities, net	$ (6,072)	[10],[8]			$ (6,097)	[8]

[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] Included in deferred revenue and acquisition-related intangible liabilities, net in the consolidated balance sheets.

[9] 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.

[10] 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.