v3.25.2

Document And Entity Information	Oct. 10, 2025
Document Information [Line Items]
Document Type	8-K
Amendment Flag	false
Document Period End Date	Oct. 10, 2025
Entity Registrant Name	Runway Growth Finance Corp.
Entity Central Index Key	0001653384
Entity Emerging Growth Company	true
Entity File Number	814-01180
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	47-5049745
Entity Address, Address Line One	205 N. Michigan Ave.
Entity Address, Address Line Two	Suite 4200
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60601
City Area Code	(312)
Local Phone Number	698-6902
Entity Information, Former Legal or Registered Name	Not Applicable
Written Communications	true
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Entity Ex Transition Period	false
Sec 7.50 Notes Due 2027 [Member]
Document Information [Line Items]
Title of 12(b) Security	7.50% Notes due 2027
Trading Symbol	RWAYL
Security Exchange Name	NASDAQ
Common Stock Par Value 0.01 Per Share [Member]
Document Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	RWAY
Security Exchange Name	NASDAQ
Notes 8.00 Due 2027 [Member]
Document Information [Line Items]
Title of 12(b) Security	8.00% Notes due 2027
Trading Symbol	RWAYZ
Security Exchange Name	NASDAQ

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

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Area code of city

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

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The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

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Address Line 1 such as Attn, Building Name, Street Name

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Address Line 2 such as Street or Suite number

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Name of the City or Town

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Code for the postal or zip code

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Name of the state or province.

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A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Indicate if an emerging growth company has elected not to use the extended transition period for complying with any new or revised financial accounting standards.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

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Two-character EDGAR code representing the state or country of incorporation.

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Former Legal or Registered Name of an entity

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The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Local phone number for entity.

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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Name of the Exchange on which a security is registered.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Trading symbol of an instrument as listed on an exchange.

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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Runway Growth Finance Corp. 8-K