Manager and Other Related Parties - Summary of Organization and Offering Expenses (Details) - USD ($)		3 Months Ended	102 Months Ended
		Mar. 31, 2018	Mar. 31, 2018
Related Party Transactions [Abstract]
Balance, beginning of period		$ 2,335,325
O&O expenses reimbursed to RMC		143,694	$ 3,038,308
Early withdrawal penalties applied	[1]	(696)	(19,211)
O&O expenses allocated	[2]	(70,208)	(452,365)
O&O expenses reimbursed by RMC	[3]	(12,193)	(170,810)
Balance, end of period	[4]	$ 2,395,922	$ 2,395,922

[1] Early withdrawal penalties collected are applied to the next installment of principal due under the formation loan and to reduce the amount owed to RMC for O&O expenses. The amounts credited will be determined by the ratio between the amount of the formation loan and the amount of offering costs incurred by the company.

[2] Beginning in 2016, O&O expenses reimbursed to RMC by RMI IX are allocated to members’ capital accounts over 40 quarters

[3] RMC reimburses the company for any unallocated O&O expenses on units redeemed

[4] Proceeds from investors admitted to RMI IX were $67,106,564 through March 31, 2018. O&O expenses incurred by RMC and remaining to be reimbursed to RMC by RMI IX were $3,210,028.