Summary of Significant Accounting Policies (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
In-Place Lease and Customer Relationship [Member]
Net amortization expense related to deferred leasing intangibles
2012	$ 6,519
2013	5,457
2014	4,417
2015	3,750
2016	2,394
Above Market Lease and Below Market Lease [Member]
Net amortization expense related to deferred leasing intangibles
2012	763
2013	531
2014	380
2015	371
2016	$ 884