The percentage points (also referred to as 'margin') added to the reference rate as stated in the loan agreement and used to compute the variable rate on the loans. For instance, the loan agreement might state that the interest rate the borrower is obligated to pay is the London Interbank Offered Rate (LIBOR) plus a 150 basis point spread adjusted quarterly (each three months). LIBOR in this example is the index or reference rate, 150 basis points are the margin, the reference rate plus the margin is the fully indexed rate. This element would be used to report separately the margin.

No definition available.

Mortgages on Operating Properties (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended				3 Months Ended		6 Months Ended			3 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jul. 31, 2013	Dec. 31, 2012	Jun. 30, 2013 Statesboro Crossing [Member]	Mar. 31, 2013 Statesboro Crossing [Member]	Jun. 30, 2013 Statesboro Crossing [Member]	Jun. 30, 2013 Citadel Mall [Member]	Jun. 30, 2013 Columbia Place [Member]	Mar. 31, 2013 Westmoreland Mall [Member]	May 10, 2013 South Country Center [Member]	Jun. 30, 2013 South Country Center [Member]	Jun. 30, 2013 Mid Rivers Mall [Member]	Mar. 31, 2013 Mid Rivers Mall [Member]	Jun. 30, 2013 Property Loans Maturing [Member]	Jun. 30, 2013 Principal Amortization [Member]
Mortgages on Operating Properties [Abstract]
Retirement of debt, number of instruments		2
Mortgage Loans on Real Estate, New Mortgage Loans										$ 11,400
Mortgage Loans Terms In Years										3
Mortgage Loans on Real Estate, Carrying Amount of Mortgages											68,282	27,265
Debt maturing in current year with extension available	26,200			26,200
Debt Maturing In Current Year Without Extension Options Available	27,266			27,266
Extinguishment of Debt, Amount		77,099							13,460				63,639	16,000	71,740	88,410
Debt Instrument, Interest Rate, Stated Percentage	7.00%			7.00%													5.88%
Loss on extinguishment of debt	(9,108)		0	(9,108)	0										(172)	8,936
Payments of Debt Extinguishment Costs				8,708	0											8,708
Unamortized Debt Issuance Expense																228
Debt Instrument, Maturity Date				May 31, 2015						Jun. 28, 2016	Apr. 30, 2017	Sep. 01, 2013
Debt Instrument, Maturity Date Range, End										Jun. 28, 2018
Weighted average maturity of mortgage and other indebtedness (in years)	4.63			4.63			4.9
Debt Instrument, Description of Variable Rate Basis								LIBOR plus
Basis Spread On Variable Rate Debt	140			140		150		180		180
Schedule of principal repayments [Abstract]
2013	89,731			89,731														53,466	36,265
2014	219,168			219,168
2015	890,611			890,611
2016	1,271,515			1,271,515
2017	550,368			550,368
Thereafter	1,589,235			1,589,235
Total payments	4,610,628			4,610,628
Net unamortized premiums	11,767			11,767
Mortgage and other indebtedness	$ 4,622,395			$ 4,622,395			$ 4,745,683