Property (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($) property Center	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Property, Plant and Equipment [Line Items]
Number of centers sold | property	2
Proceeds from sale and disposition of property	$ 33,500
Gain on sale of property	$ 21,474	$ 69,848
Number of real estate properties | property	1
Acquisition of real estate property	$ 43,000
Investment in new development	$ 49,200
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Property, Plant and Equipment [Line Items]
Number of properties held-for-sale | Center	1
Real Estate Held-for-sale	$ 25,900		$ 0