Real Estate Activities Real Estate Activities - Impairment of Assets (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Impairment of assets and expensed project costs	$ 6,332,000us-gaap_ImpairmentOfRealEstate	$ 1,341,000us-gaap_ImpairmentOfRealEstate
Uniontown Mall [Member]
Impairment Of Assets	$ 6,200,000

The charge against earnings in the period to reduce the carrying amount of real property to fair value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2921-110230

Name:	us-gaap_ImpairmentOfRealEstate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration