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Summary of Significant Accounting Policies - Summary of Properties (Details) - New Mountain Net Lease Corporation ft² in Thousands, $ in Thousands	Sep. 30, 2023 USD ($) ft²
Property, Plant and Equipment [Line Items]
Fair Value	$ 118,074
NM NL Holdings LP / NM GP Holdco LLC
Property, Plant and Equipment [Line Items]
Fair Value	$ 96,933
NM CLFX LP
Property, Plant and Equipment [Line Items]
Total Square Feet | ft²	423
Fair Value	$ 11,692
NM YI, LLC
Property, Plant and Equipment [Line Items]
Total Square Feet | ft²	212
Fair Value	$ 9,449
NM APP Canada Corp
Property, Plant and Equipment [Line Items]
Fair Value	$ 7

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- Definition

Area of a real estate property.

+ References

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- Definition

Fair value portion of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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