Business Combination, Equity Interest in Acquiree

No definition available.

Name:	kw_BusinessCombinationEquityInterestinAcquiree
Namespace Prefix:	kw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedBuildings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 55
-Paragraph 37
-URI http://asc.fasb.org/extlink&oid=84160947&loc=d3e2207-128464

+ Details

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

- Definition

The amount of identifiable intangible assets 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 10
-Section 55
-Paragraph 37
-URI http://asc.fasb.org/extlink&oid=84160947&loc=d3e2207-128464

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

+ Details

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of real estate acquired, at the acquisition date.

+ References

+ Details

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLand
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

In a business combination achieved in stages, this element represents the amount of gain recognized by the entity as a result of remeasuring to fair value the equity interest in the acquiree it held before the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)(2)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

Name:	us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

Name:	us-gaap_GainLossOnSaleOfProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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- Details

Name:	us-gaap_BusinessAcquisitionAxis=kw_RetailCentersAndCommercialPropertyAcquiredInWesternU.S.Member
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=kw_DevelopmentProjectOfficeAndMultifamilyPropertyAcquiredInIrelandMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_BusinessAcquisitionAxis=kw_RetailMultiFamilyandResidentialAcquiredinWesternU.S.Member
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- Details

Name:	us-gaap_BusinessAcquisitionAxis=kw_CommercialAndDevelopmentPropertiesAcquiredInIrelandMember
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- Details

Name:	us-gaap_BusinessAcquisitionAxis=kw_DevelopmentProjectAndSupermarketAcquiredInSpainMember
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- Details

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- Details

Name:	us-gaap_BusinessAcquisitionAxis=kw_OfficeAndCommercialPropertiesAcquiredInUnitedKingdomMember
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REAL ESTATE AND ACQUIRED IN PLACE LEASE VALUE - Schedule of Acquisitions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Land	$ 128.0	$ 195.8
Building	486.7	550.6
Acquired in place lease values	24.1	32.8
Investment debt	312.3	295.8
NCI	8.7	227.0
KWH Shareholders' Equity	318.9	256.4
Gain on sale of real estate properties	258.0	137.9	$ 73.5
Acquisition-related gains	0.0	$ 16.2	$ 108.1
KWE [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Ownership percentage by parent		23.60%
Retail Centers And Commercial Property Acquired In Western U.S. [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Land	99.3
Building	427.9
Acquired in place lease values	24.1
Investment debt	312.3
NCI	3.8
KWH Shareholders' Equity	235.1
Development Project, Office And Multifamily Property Acquired In Ireland [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Land	28.7
Building	58.8
Acquired in place lease values	0.0
Investment debt	0.0
NCI	4.9
KWH Shareholders' Equity	$ 83.8
Retail, Multi-Family and Residential Acquired in Western U.S. [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Land		$ 124.6
Building		360.2
Acquired in place lease values		8.7
Investment debt		295.8
NCI		2.0
KWH Shareholders' Equity		195.7
Gain on sale of real estate properties		8.6
Acquisition-related gains		7.6
Commercial And Development Properties Acquired In Ireland [Member] \| KWE [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Land		25.3
Building		84.9
Acquired in place lease values		5.8
Investment debt		0.0
NCI		91.6
KWH Shareholders' Equity		24.4
Development Project And Supermarket Acquired In Spain [Member] \| KWE [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Land		1.9
Building		17.1
Acquired in place lease values		0.3
Investment debt		0.0
NCI		15.3
KWH Shareholders' Equity		$ 4.0
KWE [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Ownership percentage by parent		23.60%
KWE [Member] \| Office And Commercial Properties Acquired In United Kingdom [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Land		$ 44.0
Building		88.4
Acquired in place lease values		18.0
Investment debt		0.0
NCI		118.1
KWH Shareholders' Equity		$ 32.3