Acquired in-Place Leases and Above/Below Market Leases (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of acquired lease intangibles, included in other assets and other liabilities
Acquired lease intangible assets	$ 48,843	$ 45,659
Acquired lease intangible liabilities	54,793	48,617
Net of accumulated amortization of other intangible assets	4,208	3,885
In-place leases [Member]
Schedule of acquired lease intangibles, included in other assets and other liabilities
Acquired lease intangible assets	72,853	59,812
Net of accumulated amortization of other intangible assets	(36,806)	(30,924)
Above market leases [Member]
Schedule of acquired lease intangibles, included in other assets and other liabilities
Acquired lease intangible assets	32,910	42,428
Net of accumulated amortization of other intangible assets	(20,114)	(25,657)
Below market leases [Member]
Schedule of acquired lease intangibles, included in other assets and other liabilities
Acquired lease intangible liabilities	80,263	70,332
Accumulated accretion	$ (25,470)	$ (21,715)