Estimated earnings allocated to limited partners.

No definition available.

Name:	ck0001448038_EstimatedEarningsAllocatedToLimitedPartners
Namespace Prefix:	ck0001448038_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Limited liability company percentage of profit to be allocated to manager.

+ References

No definition available.

+ Details

Name:	ck0001448038_LimitedLiabilityCompanyPercentageOfProfitToBeAllocatedToManager
Namespace Prefix:	ck0001448038_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Limited liability company percentage of profit to be allocated to members.

+ References

No definition available.

+ Details

Name:	ck0001448038_LimitedLiabilityCompanyPercentageOfProfitToBeAllocatedToMembers
Namespace Prefix:	ck0001448038_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Limited partners capital account sales per unit from gross proceeds of units sales.

+ References

No definition available.

+ Details

Name:	ck0001448038_LimitedPartnersCapitalAccountSalesPerUnitFromGrossProceedsOfUnitsSales
Namespace Prefix:	ck0001448038_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Limited partners capital account units issued value.

+ References

No definition available.

+ Details

Name:	ck0001448038_LimitedPartnersCapitalAccountUnitsIssuedValue
Namespace Prefix:	ck0001448038_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum capital units for redemption per quarter per individual.

+ References

No definition available.

+ Details

Name:	ck0001448038_MaximumCapitalUnitsForRedemptionPerQuarterPerIndividual
Namespace Prefix:	ck0001448038_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum percentage of members outstanding units for redemption per quarter per individual.

+ References

No definition available.

+ Details

Name:	ck0001448038_MaximumPercentageOfMembersOutstandingUnitsForRedemptionPerQuarterPerIndividual
Namespace Prefix:	ck0001448038_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum percentage of weighted average number of members outstanding units during twelve months.

+ References

No definition available.

+ Details

Name:	ck0001448038_MaximumPercentageOfWeightedAverageNumberOfMembersOutstandingUnitsDuringTwelveMonthsForRedemption
Namespace Prefix:	ck0001448038_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Organization and general details.

+ References

No definition available.

+ Details

Name:	ck0001448038_OrganizationAndGeneralDetailsLineItems
Namespace Prefix:	ck0001448038_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of net offering proceeds.

+ References

No definition available.

+ Details

Name:	ck0001448038_PercentageOfNetOfferingProceeds
Namespace Prefix:	ck0001448038_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of proceeds from sale of units used for funding loan to related party.

+ References

No definition available.

+ Details

Name:	ck0001448038_PercentageOfProceedsFromSaleOfUnitsUsedForFundingLoanToRelatedParty
Namespace Prefix:	ck0001448038_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of proceeds from sale of units used to pay for organization and offering expenses.

+ References

No definition available.

+ Details

Name:	ck0001448038_PercentageOfProceedsFromSaleOfUnitsUsedToPayForOrganizationAndOfferingExpenses
Namespace Prefix:	ck0001448038_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Redemption value percentage of purchase price or capital account balance.

+ References

No definition available.

+ Details

Name:	ck0001448038_RedemptionValuePercentageOfPurchasePriceOrCapitalAccountBalance
Namespace Prefix:	ck0001448038_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Required holding period by the investor before redemption is allowed.

+ References

No definition available.

+ Details

Name:	ck0001448038_UnitRedemptionProgramTermAfterPurchase
Namespace Prefix:	ck0001448038_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash eligible for distribution to members or limited partners of limited liability company (LLC) or limited partnership (LP), subject to reserves to be maintained as defined in operating or partnership agreement, or in a credit facility agreement.

+ References

No definition available.

+ Details

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

- Definition

Distribution/dividend policy defined in the operating or partnership agreement of the LLC or LP, which governs the distributions of cash or stock or units to members or limited partners. Policy may include minimum amount of cash or stock or units, allocation method among unit holders, timing of payment, and reinvestment procedures.

+ References

No definition available.

+ Details

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

- Definition

Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

+ Details

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

- Definition

The number of limited partner units issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

+ Details

Name:	us-gaap_LimitedPartnersCapitalAccountUnitsIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate amount of net income allocated to limited partners.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

+ Details

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

- Definition

Amount of an agreement for an unconditional promise by an owner to pay limited liability company (LLC) a definite sum of money at a future date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

+ Details

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

- Definition

The cash outflow for a loan, supported by a promissory note, granted to related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

+ Details

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

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_MemberUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CapitalUnitsByClassAxis=ck0001448038_CapitalUnitsIssuedUnderPreviousRegistrationStatementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ck0001448038_FormationLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=ck0001448038_RedemptionBetweenOneToTwoYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=ck0001448038_RedemptionBetweenTwoToThreeYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=ck0001448038_RedemptionBetweenThreeToFourYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=ck0001448038_RedemptionBetweenFourToFiveYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=ck0001448038_RedemptionAfterFiveYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ck0001448038_RedwoodMortgageCorpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Organization and General - Additional Information (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) Unit $ / shares shares	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Organization and General (Details) [Line Items]
Ownership interest held by the manager	1.00%	1.00%
Members or partners capital, description	Cash available for distribution at the end of each calendar month is allocated ninety-nine percent (99%) to the members and one percent (1%) to the manager.
Percentage of distribution allocated to members	99.00%
Estimated earnings allocated to members accounts	$ 1,160,555
Net income available to members	1,131,064	$ 808,652
Cash available for distribution	$ 29,491
Unit Redemption Program, Years After Purchase	1 year
Maximum Capital Units for Redemption Per Quarter Per Individual \| Unit	100,000
Maximum Percentage of Members Outstanding Units for Redemption Per Quarter Per Individual	25.00%
Maximum Percentage of Weighted Average Number of Members Outstanding Units During Twelve Months for Redemption	5.00%
Formation loan, advances	$ 357,794	$ 315,951
Receivable from affiliate (formation loan)	$ 4,133,831		$ 3,777,088
Member Units [Member]
Organization and General (Details) [Line Items]
Capital Unit Sold in Public Offering, Shares \| shares	34,827,000
Capital Unit Sold in Public Offering, Value	$ 34,827,000
Limited partners capital account sales per unit from gross proceeds of unit sales \| $ / shares	$ 1
Maximum [Member]
Organization and General (Details) [Line Items]
Percentage of offering proceeds	7.00%
Maximum [Member] \| Member Units [Member] \| Capital Units Issued Under Previous Registration Statements [Member]
Organization and General (Details) [Line Items]
Capital Unit Sold in Public Offering, Shares \| shares	74,234,000
Minimum [Member] \| Member Units [Member] \| Capital Units Issued Under Previous Registration Statements [Member]
Organization and General (Details) [Line Items]
Capital Unit Sold in Public Offering, Shares \| shares	39,407,000
Capital Unit Sold in Public Offering, Value	$ 39,407,000
Formation Loan [Member]
Organization and General (Details) [Line Items]
Formation loan, advances	5,017,741
Receivable from affiliate (formation loan)	$ 4,133,831
Redemption Between One to Two Years [Member]
Organization and General (Details) [Line Items]
Redemption Value Percentage of Purchase Price or Capital Account Balance	92.00%
Redemption Between Two to Three Years [Member]
Organization and General (Details) [Line Items]
Redemption Value Percentage of Purchase Price or Capital Account Balance	94.00%
Redemption Between Three to Four Years [Member]
Organization and General (Details) [Line Items]
Redemption Value Percentage of Purchase Price or Capital Account Balance	96.00%
Redemption Between Four to Five Years [Member]
Organization and General (Details) [Line Items]
Redemption Value Percentage of Purchase Price or Capital Account Balance	98.00%
Redemption After Five Years [Member]
Organization and General (Details) [Line Items]
Redemption Value Percentage of Purchase Price or Capital Account Balance	100.00%
RMC [Member]
Organization and General (Details) [Line Items]
Percentage of profits and losses allocated to manager	1.00%
Ownership interest held by the manager	0.10%
RMC [Member] \| Maximum [Member]
Organization and General (Details) [Line Items]
Percentage of proceeds from sale of units used to pay for organization and offering expenses	4.50%
Percentage of proceeds from sale of units used for funding formation loan to related party	7.00%