Summary of Significant Accounting Policies Schedule of Variable Interest Entities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) retail_shopping_center	Dec. 31, 2018 USD ($)
Variable Interest Entity [Line Items]
Noncontrolling Interest in Variable Interest Entity	$ 30,655	$ 30,280
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	17,740	18,432
Real Estate [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	325,464	112,085
Cash and Cash Equivalents [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 57,269	$ 7,309
Minimum [Member]
Variable Interest Entity [Line Items]
Expected useful lives of the properties and other intangible assets	10 years
Maximum [Member]
Variable Interest Entity [Line Items]
Expected useful lives of the properties and other intangible assets	40 years
Partially Owned Properties [Member]
Variable Interest Entity [Line Items]
Number of real estate properties | retail_shopping_center	127
Consolidated Properties [Member]
Variable Interest Entity [Line Items]
Number of real estate properties | retail_shopping_center	11