Deferred Costs (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Components of Deferred Costs Net [Abstract]
Leasing Costs, Total Cost	$ 150,331	$ 140,772
Financing Costs, Total Cost	40,246	38,929
Total Cost	190,577	179,701
Leasing Costs, Accumulated Amortization	(58,343)	(50,990)
Financing Costs, Accumulated Amortization	(9,991)	(13,349)
Total, Accumulated Amortization	(68,334)	(64,339)
Leasing Costs, Deferred Costs, net	91,988	89,782
Financing Costs, Deferred Costs, net	30,255	25,580
Deferred Costs	$ 122,243	$ 115,362