Name:	kw_FairValueMeasurementsWithUnobservableInputsReconciliationRecurringBasisAssetIncreaseDecreaseInForeignExchange
Namespace Prefix:	kw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Fair Value, Measurements with Unobservable Inputs Reconciliation Recurring Basis, Asset, Other

No definition available.

Name:	kw_FairValueMeasurementsWithUnobservableInputsReconciliationRecurringBasisAssetOther
Namespace Prefix:	kw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Fair Value, Measurements with Unobservable Inputs Reconciliation Recurring Basis, Asset, Unrealized and Realized Gains

No definition available.

Name:	kw_FairValueMeasurementsWithUnobservableInputsReconciliationRecurringBasisAssetUnrealizedAndRealizedGains
Namespace Prefix:	kw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Fair Value, Measurements with Unobservable Inputs Reconciliation Recurring Basis, Asset, Unrealized and Realized Losses

No definition available.

Name:	kw_FairValueMeasurementsWithUnobservableInputsReconciliationRecurringBasisAssetUnrealizedAndRealizedLosses
Namespace Prefix:	kw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-SubTopic 10
-Topic 820
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2