Real Estate and In-Place Lease Value - Schedule of Acquisitions (Details) $ in Millions	9 Months Ended
Sep. 30, 2017 USD ($) property
Business Acquisition [Line Items]
Land	$ 65.1
Building	228.2
Acquired in place lease values	22.7
Investment debt	170.2
NCI	8.7
KWH Shareholders' Equity	138.4
Retail Centers and Commercial Property Acquired in the Western U.S. [Member]
Business Acquisition [Line Items]
Land	54.1
Building	228.2
Acquired in place lease values	22.7
Investment debt	170.2
NCI	3.8
KWH Shareholders' Equity	$ 131.0
Retail Centers and Commercial Property Acquired in the Western U.S. [Member] \| Retail [Member]
Business Acquisition [Line Items]
Number of properties acquired \| property	2
Retail Centers and Commercial Property Acquired in the Western U.S. [Member] \| Multifamily [Member]
Business Acquisition [Line Items]
Number of properties acquired \| property	3
Retail Centers and Commercial Property Acquired in the Western U.S. [Member] \| Commercial [Member]
Business Acquisition [Line Items]
Number of properties acquired \| property	1
Retail Centers and Commercial Property Acquired in the Western U.S. [Member] \| Development Project [Member]
Business Acquisition [Line Items]
Number of properties acquired \| property	1
Development Project Acquired in Ireland [Member]
Business Acquisition [Line Items]
Land	$ 11.0
Building	0.0
Acquired in place lease values	0.0
Investment debt	0.0
NCI	4.9
KWH Shareholders' Equity	$ 7.4

Business Combination, Equity Interest in Acquiree

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- Definition

Number of Properties Acquired

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- Definition

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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This element represents the fair value of the noncontrolling interest in the acquiree at the acquisition date.

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Amount of facility held for productive use including, but not limited to, office, production, storage and distribution facilities, acquired at the acquisition date.

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The amount of financial liabilities assumed (as defined) which have been recognized as of the acquisition date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
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-URI http://asc.fasb.org/extlink&oid=84160947&loc=d3e2207-128464

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The amount of identifiable intangible assets recognized as of the acquisition date.

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Amount of real estate acquired, at the acquisition date.

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