Loans - Secured Loans by Property Type (Parenthetical) (Details)	9 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($) MortgageLoan		Dec. 31, 2018 USD ($) MortgageLoan	Jun. 30, 2019 USD ($)
Loans Details [Line Items]
Number of secured loans | MortgageLoan	47		56
Secured loans, principal | $	$ 86,190,000	[1]	$ 97,438,000	$ 96,132,000
Single Family Property-Owner Occupied [Member]
Loans Details [Line Items]
Number of secured loans | MortgageLoan	14		16
Secured loans, principal | $	$ 8,571,000		$ 12,839,000
Single Family Property-NonOwner Occupied [Member]
Loans Details [Line Items]
Number of secured loans | MortgageLoan	19		16
Secured loans, principal | $	$ 23,030,000		$ 23,054,000

[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.