Distribution from cost method investment.

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Joint venture interest percentage.

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Number of joint ventures.

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Undivided interest in property percentage.

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Area of a real estate property.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments.

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No definition available.

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For investments in debt and equity securities accounted for at cost, the excess of the carrying amount over net sale proceeds of investments disposed of during the period and any losses recognized thereon for impairments of other than a temporary nature.

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Amount before tax of gain (loss) recognized on the sale or disposal of a disposal group. Excludes discontinued operations.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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The number of businesses acquired by the entity during the period.

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The number of real estate properties owned as of the balance sheet date.

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Cash received from the sale of real estate that is held for investment, that is, it is part of an investing activity during the period.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Investments in and Advances to Unconsolidated Affiliates - Fund Investments - Additional Information (Details)									3 Months Ended			12 Months Ended
	Aug. 21, 2019 USD ($) ft²	Jun. 29, 2019 USD ($)	Apr. 30, 2019 USD ($) ft²	Mar. 19, 2019 USD ($) ft²	Aug. 29, 2018 USD ($) property	Jun. 29, 2018 USD ($) property	May 15, 2018 USD ($)	Jan. 18, 2018 USD ($) property	Dec. 31, 2019 USD ($) property	Sep. 30, 2019 USD ($) property	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2014 property JointVenture	Oct. 31, 2018 segment
Schedule of Equity Method Investments [Line Items]
Purchase Price												$ 324,339,000	$ 186,463,000
Number of retail properties \| property									186			186
Proceeds from the disposition of properties, net												$ 88,738,000	$ 63,866,000	$ 260,711,000
Disposed of by sale
Schedule of Equity Method Investments [Line Items]
Number of retail properties \| property										2
Gain (loss) on disposal									$ 16,300,000	$ 12,100,000	$ 5,100,000
Fund V Family Center at Riverdale
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage									89.42%			89.42%
Tri City Plaza
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage									90.00%			90.00%
Fund III's Storage Post venture
Schedule of Equity Method Investments [Line Items]
Distribution from cost method investment		$ 1,600,000					$ 3,200,000
Cost method investments		0
Fund III's Storage Post venture \| Partnership Interest
Schedule of Equity Method Investments [Line Items]
Distribution from cost method investment		$ 400,000					$ 800,000
BSP I and BSP II
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage															50.00%
Number of Joint Ventures \| JointVenture															2
Broughton St. Portfolio Savannah, GA
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage									50.00%			50.00%
Number of businesses acquired \| property															23
Number of retail properties \| property									13			13
Fund I Vs Broughton Street Portfolio Venture
Schedule of Equity Method Investments [Line Items]
Number of retail properties \| property						2									8
Losses on cost method investments						$ 1,000,000.0
Fund I Vs Broughton Street Portfolio Venture \| Partnership Interest \| Maximum
Schedule of Equity Method Investments [Line Items]
Losses on cost method investments						$ 100,000
Fund IV \| Disposed of by sale \| Broughton St. Portfolio Savannah, GA
Schedule of Equity Method Investments [Line Items]
Number of retail properties \| property					1			2							2
Proceeds from the disposition of properties, net					$ 2,000,000.0			$ 8,000,000.0
Gain (loss) on disposal					(300,000)			(400,000)
Fund IV \| Partnership Interest \| Disposed of by sale \| Broughton St. Portfolio Savannah, GA
Schedule of Equity Method Investments [Line Items]
Gain (loss) on disposal								$ 0
Fund IV \| Partnership Interest \| Disposed of by sale \| Broughton St. Portfolio Savannah, GA \| Maximum
Schedule of Equity Method Investments [Line Items]
Gain (loss) on disposal					$ (100,000)
BSP I
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage																100.00%
BSP I \| Consolidated Entity
Schedule of Equity Method Investments [Line Items]
Number of retail properties \| segment																11
BSP II \| Unconsolidated Affiliates
Schedule of Equity Method Investments [Line Items]
Number of retail properties \| property									2			2
Riverdale, Utah \| Fund V Family Center at Riverdale
Schedule of Equity Method Investments [Line Items]
Joint venture interest percentage				99.35%
Undivided interest in property percentage				90.00%
Square footage of real estate property (in square feet) \| ft²				428,000
Purchase Price				$ 48,500,000
Vernon, Connecticut \| Tri City Plaza
Schedule of Equity Method Investments [Line Items]
Joint venture interest percentage			90.00%
Square footage of real estate property (in square feet) \| ft²			300,000
Purchase Price			$ 36,700,000
Frederick County, Maryland \| 225,000 Square Foot Property
Schedule of Equity Method Investments [Line Items]
Joint venture interest percentage	90.00%
Square footage of real estate property (in square feet) \| ft²	225,000
Purchase Price	$ 21,800,000
Frederick County, Maryland \| 300,00 Square Foot Property
Schedule of Equity Method Investments [Line Items]
Joint venture interest percentage	90.00%
Square footage of real estate property (in square feet) \| ft²	300,000
Purchase Price	$ 33,100,000