Derecognition Of Financing Liability

No definition available.

Name:	onit_DerecognitionOfFinancingLiability
Namespace Prefix:	onit_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This represents the amount of liability arose in connection with sales proceeds received in 2012 and 2013 as part of the Rights to MSRs transactions with NRZ/HLSS and has no contractual maturity or repayment schedule. The balance of the liability is adjusted each reporting period to its fair value based on the present value of the estimated future cash flows underlying the related MSRs.

+ References

No definition available.

+ Details

Name:	onit_FinancingLiabilityAtFairValue
Namespace Prefix:	onit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This represents the decrease in the value of financing liability due to portfolio runoff, settlements and other.

+ References

No definition available.

+ Details

Name:	onit_RunoffSettlementsAndOtherFinancingLiability
Namespace Prefix:	onit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Servicing asset at fair value sales.

+ References

No definition available.

+ Details

Name:	onit_ServicingAssetAtFairValueSales
Namespace Prefix:	onit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Servicing Liability at Fair Value, Changes in Fair Value Resulting from Changes in Valuation Inputs or Changes in Assumptions, Net of Adjustments

+ References

No definition available.

+ Details

Name:	onit_ServicingLiabilityAtFairValueChangesInFairValueResultingFromChangesInValuationInputsOrChangesInAssumptionsNetOfAdjustments
Namespace Prefix:	onit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Servicing Liability, At Fair Value, Settlements

+ References

No definition available.

+ Details

Name:	onit_ServicingLiabilityAtFairValueSettlements
Namespace Prefix:	onit_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Total Fair Value Changes In Servicing Liability At Fair Value, Net Of Adjustments

+ References

No definition available.

+ Details

Name:	onit_TotalFairValueChangesInServicingLiabilityAtFairValueNetOfAdjustments
Namespace Prefix:	onit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Unpaid Principal Balance, Mortgage Servicing Rights Sold, Subservicing Retained

+ References

No definition available.

+ Details

Name:	onit_UnpaidPrincipalBalanceMortgageServicingRightsSoldSubservicingRetained
Namespace Prefix:	onit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Unpaid Principal Balance Of Servicing Asset, Transferred

+ References

No definition available.

+ Details

Name:	onit_UnpaidPrincipalBalanceOfServicingAssetTransferred
Namespace Prefix:	onit_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

The value of new servicing liabilities, that are subsequently measured at fair value, acquired or created during the current period through assumptions of servicing obligations and servicing obligations that result from transfers of financial assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481229/860-50-50-3

+ Details

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

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=onit_FinancingLiabilityExcessServicingSpreadMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=onit_FinancingLiabilityMortgageServicingRightsPledgedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=onit_OtherMSRCapitalPartnersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=onit_FairValueNonAgencyMortgageServicingRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=onit_MSRAssetVehicleLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=onit_MAVAssetVehicleLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=onit_RithmCapitalCorpMember
Namespace Prefix:
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MSR Related Financing Liabilities, at Fair Value - Schedule of Activity Related to Financing Liability - MSRs Pledged (Details) - USD ($) $ in Millions			3 Months Ended				9 Months Ended
	Jun. 30, 2026	Jan. 05, 2026	Sep. 30, 2026	Jun. 30, 2026	Mar. 31, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Servicing Asset at Fair Value, Amount [Roll Forward]
MSR transfers			$ 136.7				$ 157.2
Financing Liability Excess Servicing Spread [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
ESS issuances			0.0			$ 12.7	8.6	$ 12.7
Financing Liability Mortgage Servicing Rights Pledged [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance			729.0		$ 842.0	818.1	842.0	846.9
MSR transfers			9.8			7.9	(25.2)	(22.1)
ESS settlement			0.0			0.0	(20.8)	0.0
Derecognition of financing liability			(126.6)			0.0	(249.7)	(12.2)
Changes in fair value due to inputs and assumptions			15.3			1.2	59.0	5.3
Realization of cash flows			(14.4)			(18.0)	(51.2)	(52.8)
Total fair value (gain) loss			0.9			(16.8)	7.8	(47.5)
Ending balance	$ 729.0		613.1	$ 729.0		$ 822.0	613.1	$ 822.0
Unpaid Principal Balance, Mortgage Servicing Rights Sold, Subservicing Retained		$ 1,300.0
Other MSR Capital Partners
Servicing Asset at Fair Value, Amount [Roll Forward]
RMSR							5,900.0
Other MSR Capital Partners \| Fair Value Non-Agency Mortgage Servicing Rights
Servicing Asset at Fair Value, Amount [Roll Forward]
Derecognition of financing liability	(126.6)
Other MSR Capital Partners \| Financing Liability Mortgage Servicing Rights Pledged [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Derecognition of financing liability	$ (105.9)
MSR Asset Vehicle LLC \| Financing Liability Mortgage Servicing Rights Pledged [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Derecognition of financing liability			(85.1)				(85.1)
MAV Asset Vehicle LLC
Servicing Asset at Fair Value, Amount [Roll Forward]
RMSR			5,100.0				5,100.0
Rithm Capital Corp
Servicing Asset at Fair Value, Amount [Roll Forward]
RMSR			3,400.0				4,600.0
Rithm Capital Corp \| Fair Value Non-Agency Mortgage Servicing Rights
Servicing Asset at Fair Value, Amount [Roll Forward]
RMSR			3,400.0	$ 0.0	$ 1,200.0		4,600.0
Rithm Capital Corp \| Financing Liability Mortgage Servicing Rights Pledged [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Derecognition of financing liability			$ (41.5)				$ (58.7)