CORPORATE LOANS AND ALLOWANCE FOR LOAN LOSSES (Details 3) - Successor Company $ in Millions	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($) issuer loan
Recorded investment in impaired loans and related allowances for credit losses
Number of loans in default \| loan	0	1
Estimated fair value of corporate loans in default		$ 113.6
Number of issuers in default \| issuer		1
Corporate Loan Portfolio Segment \| Corporate loans, at estimated fair value
Recorded investment in impaired loans and related allowances for credit losses
Par amount of non-accrual loans	$ 114.1	$ 435.2
Estimated fair value of non-accrual loans	26.0	127.5
Par amount of non-accrual and past due loans	$ 0.0	374.7
Estimated fair value of past due loans		$ 118.2

Represents the par value of non-accrual and past due loans.

No definition available.

Name:	kfn_FinancingReceivableNonAccrualAndPastDueLoansParAmount
Namespace Prefix:	kfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the par value of non-accrual loans.

+ References

No definition available.

+ Details

Name:	kfn_FinancingReceivableNonAccrualLoansParAmount
Namespace Prefix:	kfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the estimated fair value of past due loans.

+ References

No definition available.

+ Details

Name:	kfn_FinancingReceivablePastDueLoansAtFairValue
Namespace Prefix:	kfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Estimated fair value of financing receivables that are in default at the balance sheet date.

+ References

No definition available.

+ Details

Name:	kfn_FinancingReceivablesEstimatedFairValueInDefault
Namespace Prefix:	kfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The number of issuers of loans receivable that are in default.

+ References

No definition available.

+ Details

Name:	kfn_LoanReceivableInDefaultNumberOfIssuers
Namespace Prefix:	kfn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of loans receivable that are in default.

+ References

No definition available.

+ Details

Name:	kfn_LoanReceivableInDefaultNumberOfLoans
Namespace Prefix:	kfn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

This item represents the aggregate fair value of loans held as assets that are in nonaccrual status for which the fair value option has been elected, if the entity's policy is to recognize interest income separately from other changes in fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (e)(2)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

+ Details

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

- 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.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_SuccessorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=kfn_CorporateLoansAtEstimatedFairValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: