Loans - Additional Information (Details)	1 Months Ended		3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Jul. 31, 2019 USD ($) Loan	Aug. 31, 2018	Sep. 30, 2019 USD ($) MortgageLoan		Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($) MortgageLoan		Dec. 31, 2018 USD ($) Loan MortgageLoan	Sep. 30, 2019	Sep. 30, 2019 Loan	Sep. 30, 2019 Interest	Sep. 30, 2019 MortgageLoan	Oct. 21, 2011
Loans Details [Line Items]
Loans Receivable, Term						5 years
Loans Receivable Number of Loans | Loan								56		47
Loans Receivable, Percent								100.00%	100.00%
Loans Receivable, Number of Interest Only Loans | Interest											15
Loans Receivable, Amortization Term						30 years
Number of loans sold to an unaffiliated third party | Loan	3
Aggregate principal amount of loans sold to unaffiliated third party	$ 7,740,000
Mortgage Loans on Real Estate, Number of Loans Renewed | MortgageLoan			1			5
Loans - principal renewed (in Dollars)			$ 650,000			$ 5,658,000
Loans Receivable Largest Loan (in Dollars)			10,200,000			$ 10,200,000		$ 10,900,000
Matured as of September 30, 2019, Loan										4		1
Number of secured loans | MortgageLoan						47		56
Principal			86,190,000	[1]	$ 96,132,000	$ 86,190,000	[1]	$ 97,438,000
Mortgage Loans on Real Estate, Number of Loans matured										4		1
Number of secured loans | MortgageLoan						47		56
Allowance for loan losses			0			$ 0		$ 0
Loans, Principal			86,190,000	[1]	$ 96,132,000	86,190,000	[1]	97,438,000
Percentage of membership interest equal to distributions of profit and return of invested capital													25.00%
Percentage of claim of profit and amount to be distributed to developer		25.00%
Past Due 90 Days Or More [Member]
Loans Details [Line Items]
Mortgage Loan balance			3,896,000			3,896,000		3,300,000
Revenue, loans						$ 273,000		$ 88,000
Loans Receivable, Interest Accrual, Period						90 days		90 days
Number of secured loans | MortgageLoan						4
Principal			10,851,000,000			$ 10,851,000,000
Number of secured loans | MortgageLoan						4
Mortgage Loan balance			3,896,000			$ 3,896,000		$ 3,300,000
Number of loan designated impaired and non-accrual substantially paid off | MortgageLoan						1		1
Loans, Principal			10,851,000,000			$ 10,851,000,000
Workout Agreements [Member]
Loans Details [Line Items]
Principal			1,612,500,000,000			1,612,500,000,000
Loans, Principal			1,612,500,000,000			1,612,500,000,000
Non-accrual [Member]
Loans Details [Line Items]
Matured as of September 30, 2019, Loan | Loan										4
Mortgage Loan balance			3,896,000			3,896,000
Number of secured loans | MortgageLoan								0
Mortgage Loans on Real Estate, Number of Loans matured | Loan										4
Mortgage Loan balance			7,550,000			7,550,000
Number of secured loans | MortgageLoan								0
Mortgage Loan balance			3,896,000			3,896,000
Non-accrual [Member] | Past Due 153 Days [Member]
Loans Details [Line Items]
Principal			594,900,000			594,900,000
Loans, Principal			594,900,000			594,900,000
Loan Past Maturity [Member]
Loans Details [Line Items]
Matured as of September 30, 2019, Loan | Loan										3
Mortgage Loan balance			6,955,000			6,955,000
Mortgage Loans on Real Estate, Number of Loans matured | Loan										3
Mortgage Loan balance			6,955,000			$ 6,955,000
Modifications of Secured Loan [Member]
Loans Details [Line Items]
Number of secured loans | MortgageLoan						0		0
Number of secured loans | MortgageLoan						0		0
Workout Agreements [Member]
Loans Details [Line Items]
Number of secured loans | MortgageLoan						0		0
Number of secured loans | MortgageLoan						0		0
Troubled Debt Restructuring [Member]
Loans Details [Line Items]
Number of secured loans | MortgageLoan						0		0
Number of secured loans | MortgageLoan						0		0
Minimum [Member]
Loans Details [Line Items]
Loans Receivable, Remaining Term						5 years
Five Year Term or Less [Member]
Loans Details [Line Items]
Loans Receivable Number of Loans | Loan										37
Loans Receivable, Percent									79.00%
Loans Receivable, Percent of Aggregate Principal									96.00%
Interest Only [Member]
Loans Details [Line Items]
Loans Receivable, Percent									32.00%
Loans Receivable, Percent of Aggregate Principal									63.00%
Largest Loan [Member]
Loans Details [Line Items]
Loans Receivable, Yield of Loan Acquired									9.50%
Loans Receivable Maturity Date					Sep. 01, 2020
Construction Loans [Member]
Loans Details [Line Items]
Loans outstanding			0			$ 0
Rehabilitation Loans [Member]
Loans Details [Line Items]
Loans outstanding			$ 0			$ 0

[1] Borrower payments are deposited into an independent bank trust account established and administered by RMC, pursuant to California regulations, and are disbursed to the partnership after an appropriate holding period to ensure the funds are collected. Borrower payments deposited into the trust account are not included in the consolidated financial statements until disbursed to the partnership. At September 30, 2019, there was $69,325 in borrower payments held in the RMC trust account, all of which was disbursed to the partnership by October 22, 2019.