Intangible Assets (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Annual amortization of intangible assets and liabilities
Intangible Assets, net	$ 132,329,000	$ 70,620,000
Assets [Member]
Annual amortization of intangible assets and liabilities
2014	27,043,000
2015	23,314,000
2016	18,573,000
2017	16,573,000
2018	12,161,000
Thereafter	34,665,000
Intangible Assets, net	132,329,000
Liabilities [Member]
Annual amortization of intangible assets and liabilities
2014	7,614,000
2015	5,455,000
2016	3,486,000
2017	2,890,000
2018	2,353,000
Thereafter	12,646,000
Intangible Assets, net	34,444,000
Tenant Move-Outs Prior to End of the Lease Term [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible Assets Written Off Through Accelerated Amortization	1,600,000	1,400,000	7,400,000
Intangible Liabilities Written Off Through Accelerated Amortization			$ 200,000