Real Estate Activities - Dispositions of Assets for Discontinued Operations (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	3 Months Ended	9 Months Ended			3 Months Ended	9 Months Ended
	Sep. 30, 2013 Phillipsburg Mall [Member] 2013 Activity [Member] Mall [Member]	Mar. 31, 2013 Paxton Towne Centre [Member]	Sep. 30, 2013 Paxton Towne Centre [Member] 2013 Activity [Member] Power center [Member]	Sep. 30, 2013 Orlando Fashion Square, Orlando, Florida (4) 2013 Activity [Member] Mall [Member]	Sep. 30, 2013 Commons at Magnolia, Florence, South Carolina (5) 2013 Activity [Member] Power center [Member]	Sep. 30, 2013 Christiana Center [Member]	Sep. 30, 2013 Christiana Center [Member] 2013 Activity [Member] Power center [Member]
Disposals [Line Items]
Goodwill, Written off Related to Sale of Business Unit		$ 0.7				$ 0.8
Capitalization Rate	9.80%		6.90%	9.80%	8.90%		6.50%
Sale Price (in millions of dollars)	11.5		76.8	35.0	12.3		75.0
Gain (in millions of dollars)			$ 32.7	$ 0.6	$ 4.2		$ 40.9