The standard percentage of eligible secured finance receivables that is available to be advanced from credit facility.

No definition available.

Name:	rm_AdvancesOnDebtAgreementEligibleSecuredFinanceReceivables
Namespace Prefix:	rm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The maturity date of the amortizing loan credit agreement, in CCYY-MM format.

+ References

No definition available.

+ Details

Name:	rm_DebtInstrumentMaturityDateOne
Namespace Prefix:	rm_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument revolving period end date, in CCYY-MM format.

+ References

No definition available.

+ Details

Name:	rm_DebtInstrumentRevolvingPeriodEndDateMonthAndYear
Namespace Prefix:	rm_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
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:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the declared dividend will be paid, in YYYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=126999549&loc=d3e4304-108586

+ Details

Name:	us-gaap_DividendPayableDateToBePaidDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

+ References

+ Details

Name:	us-gaap_DividendsPayableAmountPerShare
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The month and year (YYYY-MM) that the dividend to be paid was declared.

+ References

+ Details

Name:	us-gaap_DividendsPayableDateDeclaredMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	instant

- Definition

Date the holder must own the stock to be entitled to the dividend, in YYYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_DividendsPayableDateOfRecordDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the terms of a credit facility arrangement. Terms typically include interest rate, collateral required, guarantees required, repayment requirements, and restrictions on use of assets and activities of the entity.

+ 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 https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

The effective interest rate at the end of the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of interest rate for borrowing under credit facility. Includes, but is not limited to, terms and method for determining interest rate.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Proceeds from securitizations of receivables treated as collateralized borrowings, which are classified as financing transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromAccountsReceivableSecuritization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DividendsAxis=rm_QuarterlyCashDividendMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
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- Details

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Subsequent Events - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended
	May 31, 2023	Apr. 30, 2023	Mar. 31, 2023	Mar. 31, 2022
Subsequent Event [Line Items]
Advances on securitizations			$ 0	$ 250,000,000
Subsequent Event \| Quarterly Cash Dividend
Subsequent Event [Line Items]
Cash dividend per share	$ 0.30
Dividends payable, date to be paid	Jun. 14, 2023
Dividend date of record	May 24, 2023
Dividend date of declaration	2023-05
Subsequent Event \| RMR VII revolving warehouse credit facility
Subsequent Event [Line Items]
Debt revolving period end date		2024-10
Percentage of advances on debt agreement eligible secured finance receivables		80.00%
Secured line of credit		$ 75,000,000
Line of credit facility, description		The facility converts to an amortizing loan in October 2024 and terminates in October 2025. The debt will be secured by finance receivables and other related assets that the Company will purchase from its affiliates, which the Company will sell and transfer to RMR VII. Advances on the facility are capped at 80% of eligible finance receivables.
Line of credit facility, interest rate description		Borrowings under the facility bear interest, payable monthly, at a rate equal to one-month SOFR, plus (i) 0.10% per annum, (ii) a margin of 3.00%, and (iii) the applicable step-up margin (0.00% during the revolving period). RMR VII pays a monthly unused commitment fee ranging between 0.45% and 0.65%.
Debt maturity date		2025-10
Subsequent Event \| RMR IV Revolving Warehouse Credit Facility Amendment
Subsequent Event [Line Items]
Debt revolving period end date		2023-05
Line of credit facility, description		In April 2023, the Company and its wholly-owned SPE, RMR IV, entered into an amendment that extends the date at which the facility converts to an amortizing loan from April 2023 to May 2023.
Subsequent Event \| Secured Overnight Financing Rate (“SOFR”) \| RMR VII revolving warehouse credit facility
Subsequent Event [Line Items]
Interest rate, basis spread		3.00%
Interest rate		0.10%
Subsequent Event \| Maximum \| RMR VII revolving warehouse credit facility
Subsequent Event [Line Items]
Unused line fee		0.65%
Subsequent Event \| Minimum \| RMR VII revolving warehouse credit facility
Subsequent Event [Line Items]
Unused line fee		0.45%