Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, net (Details) - USD ($) $ in Thousands		Mar. 31, 2016		Dec. 31, 2015
Deferred Leasing Costs and Acquisition-related Intangible Assets, Net
Finite-lived intangible assets, net		$ 186,271		$ 176,683
Acquisition-related Intangible Liabilities, Net
Finite lived intangible liabilities, net	[1]	30,303		32,324
Deferred Leasing Costs [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets, Net
Finite-lived intangible assets, gross		223,224		205,888
Finite-lived intangible assets accumulated amortization		(77,211)		(72,745)
Finite-lived intangible assets, net		146,013		133,143
Above-Market Leases [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets, Net
Finite-lived intangible assets, gross		10,688		10,989
Finite-lived intangible assets accumulated amortization		(6,830)		(6,739)
Finite-lived intangible assets, net		3,858	[2]	4,250
In-Place Leases [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets, Net
Finite-lived intangible assets, gross		70,644		72,639
Finite-lived intangible assets accumulated amortization		(34,703)		(33,810)
Finite-lived intangible assets, net		35,941		38,829
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		(31)		(29)
Finite-lived intangible assets, net		459	[3]	461
Below Market Lease [Member]
Acquisition-related Intangible Liabilities, Net
Finite lived intangible liabilities, gross	[1]	52,733		53,502
Finite lived intangible liabilities accumulated amortization	[1]	(28,300)		(27,074)
Finite lived intangible liabilities, net	[1]	24,433	[4]	26,428
Above-Market Ground Lease Obligation [Member]
Acquisition-related Intangible Liabilities, Net
Finite lived intangible liabilities, gross	[1]	6,320		6,320
Finite lived intangible liabilities accumulated amortization	[1]	(450)		(424)
Finite lived intangible liabilities, net	[1]	$ 5,870	[5]	$ 5,896

[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.