Real Estate Activities Real Estate Activities - Impairment of assets (Details) - USD ($) $ in Millions	1 Months Ended
	Sep. 30, 2017	Jun. 30, 2017
Property, Plant and Equipment [Line Items]
Fair Value Input Terminal Capitalization Rate		12.00%
Gainesville Land [Member]
Property, Plant and Equipment [Line Items]
Impairment Of Assets	$ 1.3
Sunrise Plaza Land [Member]
Property, Plant and Equipment [Line Items]
Impairment Of Assets	$ 0.2
Logan Valley Mall [Member]
Property, Plant and Equipment [Line Items]
Impairment Of Assets		$ 38.7
Valley View Mall [Member]
Property, Plant and Equipment [Line Items]
Impairment Of Assets		$ 15.5