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:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	rm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	rm_CurrentPercentageOfAdvancesOnEligibleSecuredFinanceReceivables
Namespace Prefix:	rm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The current period percentage of eligible unsecured finance receivables that is available to be advanced from credit facility.

+ References

No definition available.

+ Details

Name:	rm_CurrentPercentageOfAdvancesOnEligibleUnsecuredFinanceReceivables
Namespace Prefix:	rm_
Data Type:	num: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

The amount by which the borrowing capacity of the line of credit facility may be expanded.

+ References

No definition available.

+ Details

Name:	rm_LineOfCreditFacilityAccordionFeature
Namespace Prefix:	rm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The servicing fee percentage paid by the VIE to the servicer.

+ References

No definition available.

+ Details

Name:	rm_PercentageOfServiceFeeOnLoan
Namespace Prefix:	rm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5074-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.4)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_AllowanceForDoubtfulAccountsReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ 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/presentationRef
-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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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

- Definition

Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

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

- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

+ Details

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
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:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

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

- 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_LineOfCreditFacilityLineItems
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

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5074-111524

+ Details

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

- Definition

The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element.

+ References

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

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=rm_ContractualPriorityPaymentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_AutomobileLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
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Balance Type:
Period Type:

- Details

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- Details

Name:	us-gaap_VariableRateAxis=rm_MarginRateMember
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Long-Term Debt - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Aug. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Line of Credit Facility [Line Items]
Finance receivables		$ 717,775,000	$ 628,444,000	$ 546,192,000
Allowance for credit losses		41,250,000	37,452,000	40,511,000	$ 30,089,000
Cash deposited to restricted cash reserve account		8,297,000	10,506,000
Waterfall [Member]
Line of Credit Facility [Line Items]
Cash deposited to restricted cash reserve account		2,700,000	3,900,000
Variable Interest Entity, Primary Beneficiary [Member]
Line of Credit Facility [Line Items]
Finance receivables		41,244,000	80,309,000
Allowance for credit losses		2,337,000	2,588,000
Cash deposited to restricted cash reserve account		$ 4,426,000	7,605,000
Servicing fee		4.00%
Asset Backed Loans [Member]
Line of Credit Facility [Line Items]
Amortizing loan, amount			$ 75,700,000
Amortizing loan, maturity date			2022-12
Senior Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Secured line of credit	$ 585,000,000
Debt agreement expiration date	Aug. 31, 2016
Line of credit facility, accordion feature	$ 650,000,000
Current percentage of advances on eligible secured finance receivables		85.00%
Current percentage of advances on eligible unsecured finance receivables		70.00%
Percentage of advances on debt agreement eligible secured finance receivables		83.00%
Percentage of advances on debt agreement eligible unsecured finance receivables		68.00%
Credit facility, eligible capacity		$ 58,200,000
Senior Revolving Credit Facility [Member] \| Senior Revolving Credit Facility Prior to August 26, 2016 [Member]
Line of Credit Facility [Line Items]
Secured line of credit	$ 538,000,000
Debt agreement expiration date	Sep. 18, 2018
Credit Agreement [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Line of Credit Facility [Line Items]
Allowance for credit losses			$ 2,600,000
Cash deposited to restricted cash reserve account			$ 1,700,000
Credit agreement, Interest rate			3.00%
Terms related to loan prepayment		The credit agreement allows RMR to prepay the loan when the outstanding balance falls below 20% of the original loan amount.
Automobile Loans [Member]
Line of Credit Facility [Line Items]
Finance receivables		$ 90,432,000	$ 116,109,000	154,382,000
Allowance for credit losses		$ 5,910,000	8,828,000	$ 11,776,000	$ 10,827,000
Automobile Loans [Member] \| Credit Agreement [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Line of Credit Facility [Line Items]
Finance receivables			$ 86,100,000
London Interbank Offered Rate (LIBOR) [Member] \| Senior Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Senior Secured Revolving Credit Facility, Description of Variable Rate Basis		The Company elects between one and six months, with a LIBOR floor of 1.00%, plus a 3.00% margin.
Interest rate, basis spread		3.00%
Interest rate		0.88%	0.50%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Senior Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Effective interest rate on line of credit		1.00%
Base Rate [Member] \| Senior Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Senior Secured Revolving Credit Facility, Description of Variable Rate Basis		The Company may pay interest at prime rate plus a 2.00% margin.
Margin Rate [Member] \| Senior Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Interest rate, basis spread		2.00%
Prime Rate [Member] \| Senior Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Interest rate		3.75%	3.50%