Organization and Significant Accounting Policies - Organization and Principles of Consolidation (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020 USD ($) retail_shopping_center	Jun. 30, 2020 USD ($) retail_shopping_center Rent_Agreement
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Unsecured public and private notes | $	$ 500.0	$ 500.0
Operating Partnership [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Ownership percentage of outstanding common partnership units		99.60%
COVID-19 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percentage of base rent collected from tenants	72.00%
Number of mutually accepted agreements | Rent_Agreement		600
Pro-rata base rent | $		$ 16.4
Percentage of annual base rent		1.80%
Wholly Owned Properties [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of real estate properties | retail_shopping_center	300	300
Unconsolidated Properties [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of real estate properties | retail_shopping_center	115	115