Commitments and Contingencies (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 50.0
Letters of Credit Outstanding, Amount	12.5	$ 9.4
Purchase Commitment, Remaining Minimum Amount Committed	$ 17.1
Maximum [Member] \| Operating Shopping Center [Member]
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	81.63%
Minimum [Member] \| Operating Shopping Center [Member]
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	16.63%

Minimum amount to be expended to satisfy the terms of arrangements in which the entity has agreed to expend funds to procure goods or services, excluding long-term purchase commitments or unconditional purchase obligations.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(17))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(19))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(25))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant