Represents the average fixed charge ratio covenant under the debt agreements.

No definition available.

Name:	omf_DebtInstrumentCovenantAverageFixedChargeRatio
Namespace Prefix:	omf_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the percentage of tangible equity to tangible managed assets covenant under the debt agreements.

+ References

No definition available.

+ Details

Name:	omf_DebtInstrumentCovenantPercentageOfTangibleEquityToTangibleManagedAssets
Namespace Prefix:	omf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Number Of Redemptions

+ References

No definition available.

+ Details

Name:	omf_DebtInstrumentNumberOfRedemptions
Namespace Prefix:	omf_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of gain (loss) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase, excluding deferred cost write-offs and premiums paid.

+ References

No definition available.

+ Details

Name:	omf_GainLossOnRepurchaseAndRepaymentOfDebtInstrument
Namespace Prefix:	omf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Repayments Of Senior Debt, Including Interest And Premiums

+ References

No definition available.

+ Details

Name:	omf_RepaymentsOfSeniorDebtIncludingInterestAndPremiums
Namespace Prefix:	omf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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

Percentage of principal amount of debt redeemed.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=omf_SpringleafFinanceCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=omf_SeniorNotes6.125PercentDue2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=omf_SeniorNotes5.25PercentDue2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=omf_SeniorNotes6.00PercentDue2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=omf_SeniorNotes6.625PercentDue2028Member
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_DebtInstrumentAxis=omf_SeniorNotes5375PercentDue2029Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
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Data Type:	na
Balance Type:
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- Details

Name:	dei_LegalEntityAxis=omf_OneMainFinancialHoldingsLLCMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=omf_OMFHNotes2019Member
Namespace Prefix:
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- Details

Name:	us-gaap_DebtInstrumentAxis=omf_OMFHNotes2021Member
Namespace Prefix:
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Long-term Debt - Narrative (Details)			1 Months Ended	12 Months Ended
Long-term Debt - Narrative (Details)	Apr. 15, 2019 USD ($)	Mar. 25, 2019 USD ($)	Jan. 31, 2007 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) redemption	Dec. 31, 2017 USD ($)	Nov. 07, 2019 USD ($)	Jul. 02, 2019 USD ($)	May 09, 2019 USD ($)	Mar. 15, 2019	Feb. 22, 2019 USD ($)
Debt Instrument [Line Items]
Net loss on repurchases and repayments of debt				$ 35,000,000	$ 9,000,000	$ 29,000,000
SFC
Debt Instrument [Line Items]
Net loss on repurchases and repayments of debt				35,000,000	$ 9,000,000	$ 29,000,000
SFC \| Senior Debt \| 6.125% SFC Notes due 2024
Debt Instrument [Line Items]
Interest rate											6.125%
Debt instrument, face amount								$ 300,000,000			$ 1,000,000,000.0
SFC \| Senior Debt \| 5.25% Senior Notes due 2019
Debt Instrument [Line Items]
Interest rate		5.25%
Aggregate amount paid, inclusive of accrued interest and premiums		$ 706,000,000
Net loss on repurchases and repayments of debt				21,000,000
SFC \| Senior Debt \| 6.00% Senior Notes due 2020
Debt Instrument [Line Items]
Interest rate										6.00%
Aggregate amount paid, inclusive of accrued interest and premiums	$ 317,000,000
Net loss on repurchases and repayments of debt				$ 11,000,000
SFC \| Senior Debt \| 6.625% SFC Notes due 2028
Debt Instrument [Line Items]
Interest rate									6.625%
Debt instrument, face amount									$ 800,000,000
SFC \| Senior Debt \| 5.375% SFC Notes due 2029
Debt Instrument [Line Items]
Interest rate							5.375%
Debt instrument, face amount							$ 750,000,000
SFC \| Junior Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, face amount			$ 350,000,000
Debt instrument, term			60 years
Effective interest rate				3.74%
Tangible equity to tangible managed assets (ratio) (less than)				5.50%
Average fixed charge ratio (not more than)				1.10
SFC \| Junior Subordinated Debt \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate				1.75%
OMFH
Debt Instrument [Line Items]
Debt Instrument, Number Of Redemptions \| redemption					2
OMFH \| Senior Debt
Debt Instrument [Line Items]
Net loss on repurchases and repayments of debt					$ 8,000,000
OMFH \| Senior Debt \| OMFH Notes due 2019
Debt Instrument [Line Items]
Debt instrument, face amount					$ 700,000,000
Redemption price (as a percent)					103.375%
OMFH \| Senior Debt \| OMFH Notes due 2021
Debt Instrument [Line Items]
Debt instrument, face amount					$ 800,000,000
Redemption price (as a percent)					103.625%