Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, net (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Deferred Leasing Costs and Acquisition-related Intangible Assets, Net
Total deferred leasing costs and acquisition-related intangible assets, net	$ 188,466		$ 186,622
Acquisition-related Intangible Liabilities, Net
Total acquisitions-related intangible liabilities, net	51,278	[1]	49,776	[1]
Deferred Leasing Costs [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets, Net
Finite-lived intangible assets, gross	183,813		178,720
Finite-lived intangible assets accumulated amortization	(68,152)		(63,246)
Finite-lived intangible assets, net	115,661		115,474
Above-Market Leases [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets, Net
Finite-lived intangible assets, gross	27,351		27,635
Finite-lived intangible assets accumulated amortization	(15,489)		(14,283)
Finite-lived intangible assets, net	11,862	[2]	13,352
In-Place Leases [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets, Net
Finite-lived intangible assets, gross	104,643		100,318
Finite-lived intangible assets accumulated amortization	(44,175)		(42,999)
Finite-lived intangible assets, net	60,468		57,319
Below Market Ground Lease Obligation [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets, Net
Finite-lived intangible assets, gross	490		490
Finite-lived intangible assets accumulated amortization	(15)		(13)
Finite-lived intangible assets, net	475	[3]	477
Below Market Lease [Member]
Acquisition-related Intangible Liabilities, Net
FiniteLivedIntangibleLiabilitiesGross	73,522		69,385
Accumulated amortization	(28,316)		(25,706)
Acquisition-related Intangible Liabilities, net	45,206	[1],[4]	43,679	[1]
Above-Market Ground Lease Obligation [Member]
Acquisition-related Intangible Liabilities, Net
FiniteLivedIntangibleLiabilitiesGross	6,320		6,320
Accumulated amortization	(248)		(223)
Acquisition-related Intangible Liabilities, net	$ 6,072	[1],[5]	$ 6,097	[1]

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

[2] 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.

[3] 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.

[4] 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.

[5] 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.