Manager and Other Related Parties - Summary of Organization and Offering Expenses (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Related Party Transactions [Abstract]
Balance, January 1		$ 1,458	$ 1,858
O&O expenses allocated		(73)	(77)
O&O expenses repaid to Members' Capital by RMC	[1]	(34)	(18)
Early withdrawal penalties applied	[2]	0	(4)
Balance, March 31		$ 1,351	$ 1,759

[1] RMC is obligated per the Operating Agreement to repay RMI IX for the amount of unallocated O&O expenses attributed to a member’s capital account if the member redeems prior to the 40 quarterly allocations. RMC estimated its future obligation to repay unallocated O&O expenses on scheduled redemptions as of March 31, 2022, to be approximately $21,000.

[2] Beginning in 2022, RMC discontinued the specific allocation of early withdrawal penalties it received to the formation loan and to the amount owed for unallocated O&O expenses on redeeming-members’ accounts. Prior to 2022, the O&O expenses component of early withdrawal penalties were applied as a reduction to O&O expenses to be repaid by RMC to members’ capital on scheduled redemptions. The amounts credited were determined by the ratio between the amount of the formation loan and the amount of offering costs incurred by the company. The change in 2022 has no net effect on the amounts paid by RMC to RMI IX.