Summary of Significant Accounting Policies - Organization and Principles of Consolidation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) retail_shopping_center TenantAccount ShoppingCenter shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)	Mar. 27, 2020 USD ($)
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Unsecured public and private notes	$ 200,000
General Partners' Capital Account, Units Outstanding | shares	169,680,000	167,571,000
Partners' Capital Account, Units | shares	170,445,184	168,317,000
Tax Basis of Investments, Unrealized Appreciation (Depreciation), Net	$ 2,700,000	$ 2,800,000
Restricted Cash and Cash Equivalent	$ 2,377	2,542
Cash and cash equivalents and restricted original maturity	90 days or less
Concentration risk, percentage	20.00%
Number of tenant | TenantAccount	0
Number of shopping center. | ShoppingCenter	0
COVID-19 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Estimated stimulate package under CARES Act				$ 2,200,000,000
Parent Company [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Restricted Cash and Cash Equivalent	$ 2,400	$ 2,500
Maximum [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Concentration risk, percentage	5.00%
Land Improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property, Plant and Equipment, Useful Life	15 years
Building and Improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Tenant Improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Furniture and Equipment [Member] | Minimum [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Equipment [Member] | Maximum [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property, Plant and Equipment, Useful Life	7 years
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%
General Partners' Capital Account, Units Outstanding | shares	169,680,138
Parent Company, Ownership Percentage of Outstanding Common Partnership Units of Operating Partnership	99.60%	99.60%
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	297
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	114
Development And Redevelopment
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Interest costs capitalized	$ 4,400	$ 4,200	$ 7,000
Maximum Period Of Time In Which Company Capitalizes Interest Costs	12 months
Development [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Interest costs capitalized	$ 10,200	$ 20,400	$ 17,100