Mortgages on Operating Properties (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Mortgages on Operating Properties [Abstract]
Retirement of debt, number of instruments		2
Extinguishment of debt		$ 77,099
Stated interest rate percentage				7.00%
Loss on extinguishment of debt	0		(178)		9,108	(178)
Payments of Debt Extinguishment Costs					8,708	0
Debt Instrument, Maturity Date				May 31, 2015
Weighted average maturity of mortgage and other indebtedness (in years)	4.02				4.02		4.9
Basis Spread On Variable Rate Debt	140				140
Schedule of principal repayments [Abstract]
2013	45,898				45,898
2014	219,148				219,148
2015	1,108,496				1,108,496
2016	943,779				943,779
2017	550,777				550,777
Thereafter	1,988,573				1,988,573
Total payments	4,856,671				4,856,671
Net unamortized premiums	11,046				11,046
Mortgage and other indebtedness	4,867,717				4,867,717		4,745,683
Forum at Grandview [Member]
Mortgages on Operating Properties [Abstract]
Extinguishment of debt					10,200
Alamance Crossing West [Member]
Mortgages on Operating Properties [Abstract]
Extinguishment of debt					16,000
Statesboro Crossing [Member]
Mortgages on Operating Properties [Abstract]
Mortgage Loans on Real Estate, New Mortgage Loans					11,400
Mortgage Loans Terms In Years					3
Extinguishment of debt		13,460
Debt Instrument, Maturity Date					Jun. 28, 2016
Number of Extension Options Available	2				2
Debt Instrument, Maturity Date Range, End					Jun. 28, 2018
Debt Instrument, Description of Variable Rate Basis					LIBOR plus
Basis Spread On Variable Rate Debt	180				180
Mid Rivers and South County [Member]
Mortgages on Operating Properties [Abstract]
Retirement of debt, number of instruments					2
Extinguishment of debt					160,150
Citadel Mall [Member]
Mortgages on Operating Properties [Abstract]
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	68,282				68,282
Debt Instrument, Maturity Date					Apr. 30, 2017
Columbia Place [Member]
Mortgages on Operating Properties [Abstract]
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	27,265				27,265
Debt Instrument, Maturity Date					Sep. 01, 2013
Debt Instrument, Number of Instruments	1				1
Westmoreland Mall [Member]
Mortgages on Operating Properties [Abstract]
Extinguishment of debt		63,639
South Country Center [Member]
Mortgages on Operating Properties [Abstract]
Extinguishment of debt					71,740
Loss on extinguishment of debt					172
Mid Rivers Mall [Member]
Mortgages on Operating Properties [Abstract]
Extinguishment of debt					88,410
Stated interest rate percentage	5.88%				5.88%
Loss on extinguishment of debt					8,936
Payments of Debt Extinguishment Costs					8,708
Unamortized Debt Issuance Expense	228				228
Louisville Outlet Shoppes [Member]
Mortgages on Operating Properties [Abstract]
Number of Extension Options Available	2				2
Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases	$ 60,200				$ 60,200
Interest rate terms					LIBOR plus 200 basis points
Debt Instrument, Percentage of Debt Guaranteed					100.00%