Mortgages on Operating Properties (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended			3 Months Ended		3 Months Ended			1 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 Principal balance [Member] Loans	Mar. 31, 2014 Principal amortization [Member]	Mar. 31, 2014 Citadel Mall [Member]	Jan. 31, 2014 Citadel Mall [Member]	Mar. 31, 2014 Columbia Place [Member] Loans	Mar. 31, 2014 Columbia Place [Member] Principal balance [Member]	Mar. 31, 2014 Operating property loan [Member] Loans	Jan. 31, 2014 St. Clair Square [Member]
Mortgages on Operating Properties [Abstract]
Interest Rate at Repayment Date											3.25%
Principal Balance Repaid											$ 122,375
Gain (loss) on extinguishment of debt	(42,660)	0				(43,909)					1,249
Mortgage loan, carrying amount						68,563	68,169	27,265
Debt instrument, maturity date								Sep. 01, 2013
Number of debt instruments				2				1		1
Weighted average maturity of mortgage and other indebtedness (in years)	4 years 9 months 14 days		4 years 8 months 1 day
Schedule of principal repayments [Abstract]
2014	194,885			164,040	3,580				27,265	113,400
2015	752,147
2016	846,937
2017	488,826
2018	671,936
Thereafter	1,840,019
Total payments	4,794,750									50,640
Net unamortized premiums	5,067
Mortgage and other indebtedness	$ 4,799,817		$ 4,857,523