Summary of Significant Accounting Policies - Properties in Development (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2013
Development in Process	$ 186,450	$ 192,067
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	(688,058)
Other Cost and Expense, Operating	528	1,500	241
Impairment of Real Estate	6,000	74,816	15,883
Impairment Losses Related to Real Estate Partnerships	(5,880)	(5,880)
Deferred Costs, Leasing, Net	59,027	55,485
Deferred Finance Costs, Net	10,936	14,021
Deferred costs, less accumulated amortization of $73,231 and $69,224 at December 31, 2013 and 2012, respectively	69,963	69,506
Discontinued operations
Property, Plant and Equipment [Line Items]
Impairment of Real Estate	0	54,500	3,417
Properties in Development [Member]
Property, Plant and Equipment [Line Items]
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	3,500	3,500
Refundable deposits - development
Property, Plant and Equipment [Line Items]
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	700	2,300
Construction in Progress
Property, Plant and Equipment [Line Items]
Development in Process	158,002	129,628
Land Held for Future Development
Property, Plant and Equipment [Line Items]
Development in Process	24,953	58,914
Subsidiaries [Member]
Property, Plant and Equipment [Line Items]
Impairment Losses Related to Real Estate Partnerships	$ 0	$ 0	$ 4,580
Minimum [Member] | Construction in Progress
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Development in Process, Percentage Leased	90.00%
Time Period In Which Anchor Has Been Open But Still Considered Construction In Process	1 year
Maximum [Member] | Construction in Progress
Property, Plant and Equipment [Line Items]
Percentage Of Expected Costs	90.00%
Property, Plant and Equipment, Development in Process, Percentage Leased	95.00%
Time Period In Which Anchor Has Been Open But Still Considered Construction In Process	2 years
Property, Plant and Equipment, Development in Process, Period Since Start of Construction	3 years