    <SEC-DOCUMENT>0001628280-24-002175-index.html : 20240125
    <SEC-HEADER>0001628280-24-002175.hdr.sgml : 20240125
    <ACCEPTANCE-DATETIME>20240125093331
    ACCESSION NUMBER:		0001628280-24-002175
    CONFORMED SUBMISSION TYPE:	424B2
    PUBLIC DOCUMENT COUNT:		14
    FILED AS OF DATE:		20240125
    DATE AS OF CHANGE:		20240125

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			New Mountain Finance Corp
    		CENTRAL INDEX KEY:			0001496099
    		ORGANIZATION NAME:
    		IRS NUMBER:				272978010
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		424B2
    		SEC ACT:		1933 Act
    		SEC FILE NUMBER:	333-272060
    		FILM NUMBER:		24559175

    	BUSINESS ADDRESS:
    		STREET 1:		1633 BROADWAY
    		STREET 2:		48TH FLOOR
    		CITY:			NEW YORK
    		STATE:			NY
    		ZIP:			10019
    		BUSINESS PHONE:		2127300200

    	MAIL ADDRESS:
    		STREET 1:		1633 BROADWAY
    		STREET 2:		48TH FLOOR
    		CITY:			NEW YORK
    		STATE:			NY
    		ZIP:			10019

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	New Mountain Guardian Corp
    		DATE OF NAME CHANGE:	20100706
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>424B2
    <SEQUENCE>1
    <FILENAME>nmfc-20240125.htm
    <DESCRIPTION>424B2
    <TEXT>
    Document 1 - file: nmfc-20240125.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>2
    <FILENAME>nmfc-20240125.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 2 - file: nmfc-20240125.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.DEF
    <SEQUENCE>3
    <FILENAME>nmfc-20240125_def.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION DEFINITION LINKBASE DOCUMENT
    <TEXT>
    Document 3 - file: nmfc-20240125_def.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>4
    <FILENAME>nmfc-20240125_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT
    <TEXT>
    Document 4 - file: nmfc-20240125_lab.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>5
    <FILENAME>nmfc-20240125_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
    <TEXT>
    Document 5 - file: nmfc-20240125_pre.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>6
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 6 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>7
    <FILENAME>R2.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 7 - file: R2.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>8
    <FILENAME>nmfc-20240125_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 8 - file: nmfc-20240125_htm.html

    Document 8 - RAW XML: nmfc-20240125_htm.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>9
    <FILENAME>Financial_Report.xlsx
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 9 - file: Financial_Report.xlsx

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>10
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 10 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>11
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 11 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>12
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 12 - file: FilingSummary.html

    Document 12 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>14
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 14 - file: MetaLinks.json

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>15
    <FILENAME>0001628280-24-002175-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 15 - file: 0001628280-24-002175-xbrl.zip

    </DOCUMENT>
    </SEC-DOCUMENT>