v3.22.4

Document and Entity Information	Mar. 07, 2023
Document And Entity Information [Line Items]
Amendment Flag	false
Entity Central Index Key	0001464963
Current Fiscal Year End Date	--12-31
Document Type	8-K
Document Period End Date	Mar. 07, 2023
Entity Registrant Name	FIRST EAGLE ALTERNATIVE CAPITAL BDC, INC.
Entity Incorporation State Country Code	DE
Entity File Number	814-00789
Entity Tax Identification Number	27-0344947
Entity Address, Address Line One	500 Boylston St.
Entity Address, Address Line Two	Suite 1200
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02116
City Area Code	(800)
Local Phone Number	450-4424
Written Communications	false
Soliciting Material	false
Pre Commencement Tender Offer	false
Pre Commencement Issuer Tender Offer	false
Entity Emerging Growth Company	false
Common Stock [Member]
Document And Entity Information [Line Items]
Security 12b Title	Common stock, par value of $0.001 per share
Trading Symbol	FCRD
Security Exchange Name	NASDAQ
Deferrable Notes [Member]
Document And Entity Information [Line Items]
Security 12b Title	5.00% Notes due 2026
Trading Symbol	FCRX
Security Exchange Name	NYSE

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

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No definition available.

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- Definition

Area code of city

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No definition available.

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- Definition

End date of current fiscal year in the format --MM-DD.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

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'.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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Data Type:	xbrli:normalizedStringItemType
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- Definition

Address Line 2 such as Street or Suite number

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No definition available.

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Name of the City or Town

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No definition available.

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Data Type:	xbrli:normalizedStringItemType
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- Definition

Code for the postal or zip code

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No definition available.

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- Definition

Name of the state or province.

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No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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- Definition

Indicate if registrant meets the emerging growth company criteria.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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- Definition

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.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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- Definition

Local phone number for entity.

+ References

No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
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- Definition

Title of a 12(b) registered security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

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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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Section 14a
-Number 240
-Subsection 12

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- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Securities Act
-Number 230
-Section 425

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Balance Type:	na
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- References

No definition available.

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- Details

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First Eagle Alternative Capital BDC, Inc. 8-K