Consolidated Statements of Assets, Liabilities and Members' Capital (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Investments, cost	$ 569,247	$ 123,436	[1]
Deferred financing costs, accumulated amortization	$ 413	$ 11
Common units, units issued (in shares)		7,525,831
Common units, units outstanding (in shares)	26,941,956	7,525,831

[1] New Mountain Guardian IV BDC, L.L.C. (the "Company") generally acquires its investments in private transactions exempt from registration under the Securities Act of 1933, as amended (the "Securities Act"). These investments are generally subject to certain limitations on resale, and may be deemed to be "restricted securities" under the Securities Act.