Investments in Unconsolidated Real Estate Joint Ventures Summary Balance Sheets for Unconsolidated Joint Ventures (Details) (Partnership Interest [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Partnership Interest [Member]
Summary Balance Sheets of Unconsolidated Joint Ventures [Line Items]
Real Estate Investment Property, at Cost	$ 487,293		$ 390,343
Real Estate Investment Property, Accumulated Depreciation	(57,067)		(46,245)
Real Estate Investment Property, Net	430,226		344,098
Land	78,531		77,864
Investment Building and Building Improvements	295,593		288,934
Construction in Progress, Gross	113,169		23,545
Assets Held-for-sale, at Carrying Value	1,821	[1]	0
Cash and Cash Equivalents, at Carrying Value	10,778		7,582
Deferred Costs, Leasing, Net	13,586		14,815
Deferred Finance Costs, Net	5,773		7,566
Prepaid Expense and Other Assets	21,396		11,687
Equity Method Investment, Summarized Financial Information, Assets	483,580		385,748
Mortgage Loans on Real Estate	288,978		303,230
Construction Payable	14,506		2,669
Accounts Payable and Other Accrued Liabilities	26,125		27,246
Equity Method Investment, Summarized Financial Information, Liabilities	329,609		333,145
Equity Method Investment Summarized Financial Information, Equity	153,971		52,603
Equity Method Investment, Summarized Financial Information, Liabilities and Equity	$ 483,580		$ 385,748

[1] (1) Assets related to our Deer Park Warehouse joint venture, which is currently under contract to be sold.