DEBT OBLIGATIONS AND CREDIT FACILITIES - Additional Information (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Fair value of debt obligations		$ 4,127,994
Consolidated Funds
Debt Instrument [Line Items]
Fair value of debt obligations	$ 4,312,023
Total remaining principal	4,355,553
Securities owned and pledged as collateral	4,900,000	4,700,000
Oaktree Capital Group Excluding Consolidated Funds
Debt Instrument [Line Items]
Total remaining principal	750,000	750,000
Oaktree Capital Group Excluding Consolidated Funds \| Level III
Debt Instrument [Line Items]
Fair value of debt obligations	$ 790,000	$ 720,300
Weighted average interest rate	3.10%	4.40%
Percentage increase in average borrowing rate assumption that would decrease fair value of debt obligation	10.00%
Fair value of debt obligation decrease in value due to increase in average borrowing rate	$ 770,500
Percentage decrease in average borrowing rate assumption that would increase fair value of debt obligation	10.00%
Fair value of debt obligation increase in value due to decrease in average borrowing rate	$ 809,500
Credit Agreement \| Senior secured notes
Debt Instrument [Line Items]
Weighted average interest rate	3.73%
Total remaining principal	$ 914,499	$ 870,098
Credit Agreement \| Consolidated Funds
Debt Instrument [Line Items]
Total remaining principal	914,500	914,600
Credit Agreement \| Consolidated Funds \| Level III
Debt Instrument [Line Items]
Fair value of debt	$ 914,400	$ 871,300
Credit Agreement \| Maximum \| Consolidated Funds \| Senior secured notes
Debt Instrument [Line Items]
Term (in years)	10 years

Fair value of debt obligation, decrease in value due to increase in average borrowing rate.

No definition available.

Name:	oak_FairValueOfDebtObligationDecreaseInValueDueToIncreaseInAverageBorrowingRate
Namespace Prefix:	oak_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of debt obligation, increase in value due to decrease in average borrowing rate.

+ References

No definition available.

+ Details

Name:	oak_FairValueOfDebtObligationIncreaseInValueDueToDecreaseInAverageBorrowingRate
Namespace Prefix:	oak_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage decrease in average borrowing rate assumption that would increase fair value of debt obligation.

+ References

No definition available.

+ Details

Name:	oak_PercentageDecreaseInAverageBorrowingRateAssumptionThatWouldIncreaseFairValueOfDebtObligation
Namespace Prefix:	oak_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage increase in average borrowing rate assumption that would lower fair value of debt obligation.

+ References

No definition available.

+ Details

Name:	oak_PercentageIncreaseInAverageBorrowingRateAssumptionThatWouldLowerFairValueOfDebtObligation
Namespace Prefix:	oak_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Senior Notes, Term

+ References

No definition available.

+ Details

Name:	oak_SeniorNotesTerm
Namespace Prefix:	oak_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

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(16))
-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(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: 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(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611

+ Details

Name:	us-gaap_DebtInstrumentFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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

- Definition

Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

+ Details

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

- Details

Name:	us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_ConsolidatedEntityExcludingVariableInterestEntitiesVIEMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: