Disclosure About Fair Value of Financial Instruments - Additional Information (Detail)	6 Months Ended
Jun. 30, 2019
Fair Value Disclosures [Abstract]
Turnover rate of loan portfolio	1.2

The annual turnover of the finance receivables in the portfolio.

No definition available.

Name:	rm_FinanceReceivablePortfolioTurnoverRate
Namespace Prefix:	rm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration