Represents amounts drawn under the securitization transaction as of the balance sheet date.

No definition available.

Name:	omf_AmountOutstandingUnderSecuritizationTransaction
Namespace Prefix:	omf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

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=124435984&loc=d3e28551-108399

Reference 3: 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

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

+ Details

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

- Definition

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

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types: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

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

- 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.

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3291-108585

+ Details

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

- Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesSecuritizedLoansAndReceivablesMember
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:	dei_LegalEntityAxis=omf_OneMainFinanceCorporationMember
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_SevenPointSevenFiveSeniorNotesDueTwentyTwentyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

Long-term Debt - Narrative (Details) - USD ($)			1 Months Ended	3 Months Ended	12 Months Ended
Long-term Debt - Narrative (Details) - USD ($)	Nov. 10, 2021	Jan. 08, 2021	Jan. 31, 2007	Dec. 31, 2021	Dec. 31, 2021	Aug. 11, 2021	Jun. 22, 2021	Dec. 09, 2020
Debt Instrument [Line Items]
Amounts drawn				$ 600,000,000	$ 600,000,000
Revolver \| Securitizations
Debt Instrument [Line Items]
Amounts drawn				$ 0	$ 0
Junior Subordinated Debt
Debt Instrument [Line Items]
Interest rate				1.87%	1.87%
OMFC \| Revolver \| Securitizations
Debt Instrument [Line Items]
Total borrowing capacity				$ 1,000,000,000	$ 1,000,000,000
Debt instrument, term					5 years
OMFC \| Senior Debt \| 7.75% Senior Notes Due 2021
Debt Instrument [Line Items]
Interest rate				7.75%	7.75%			7.75%
Repayments of debt		$ 681,000,000
Loss on repurchase and repayments of debt					$ 47,000,000
OMFC \| Senior Debt \| 3.5% Senior Notes Due 2027
Debt Instrument [Line Items]
Interest rate							3.50%
Debt instrument, principal amount							$ 750,000,000
OMFC \| Senior Debt \| 3.875% Senior Notes Due 2028
Debt Instrument [Line Items]
Interest rate						3.875%
Debt instrument, principal amount						$ 600,000,000
OMFC \| Senior Debt \| 6.125% Senior Notes Due 2022
Debt Instrument [Line Items]
Interest rate	6.125%
Repayments of debt	$ 1,000,000,000
Loss on repurchase and repayments of debt				$ 23,000,000
OMFC \| Junior Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, principal amount			$ 350,000,000
Debt instrument, term			60 years
Tangible equity to tangible managed assets (ratio) (less than)				5.50%	5.50%
Average fixed charge ratio (not more than)				1.10	1.10
OMFC \| Junior Subordinated Debt \| LIBOR \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate					1.75%
OMFC \| Junior Subordinated Debt \| LIBOR \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate					1.87%