Label	Element	Value
Risk/Return:	oef_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Sep. 30, 2025
Registrant Name	dei_EntityRegistrantName	BNY Mellon Investment Funds I
Entity Central Index Key	dei_EntityCentralIndexKey	0000799295
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jan. 27, 2026
Document Effective Date	dei_DocumentEffectiveDate	Jan. 30, 2026
Entity Investment Company Type	dei_EntityInvCompanyType	N-1A
Prospectus Date	oef_ProspectusDate	Jan. 30, 2026
BNY Mellon International Equity Fund \| A
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	NIEAX
BNY Mellon International Equity Fund \| C
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	NIECX
BNY Mellon International Equity Fund \| I
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	SNIEX
BNY Mellon International Equity Fund \| Y
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	NIEYX
BNY Mellon Small Cap Value Fund \| A
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RUDAX
BNY Mellon Small Cap Value Fund \| C
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	BOSCX
BNY Mellon Small Cap Value Fund \| I
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	STSVX
BNY Mellon Small Cap Value Fund \| Y
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	BOSYX
BNY Mellon Small/Mid Cap Growth Fund \| A
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	DBMAX
BNY Mellon Small/Mid Cap Growth Fund \| C
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	DBMCX
BNY Mellon Small/Mid Cap Growth Fund \| I
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	SDSCX
BNY Mellon Small/Mid Cap Growth Fund \| Y
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	DBMYX
BNY Mellon Small/Mid Cap Growth Fund \| Z
Risk/Return:	oef_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	DBMZX

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

No definition available.

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- Definition

The date the document was made available and submitted, in YYYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.

+ References

No definition available.

+ Details

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- Definition

The date when a document, upon receipt and acceptance, becomes officially effective, in YYYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.

+ References

No definition available.

+ Details

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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.

+ Details

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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.

+ Details

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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

+ Details

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- Definition

One of: N-1A (Mutual Fund), N-1 (Open-End Separate Account with No Variable Annuities), N-2 (Closed-End Investment Company), N-3 (Separate Account Registered as Open-End Management Investment Company), N-4 (Variable Annuity UIT Separate Account), N-5 (Small Business Investment Company), N-6 (Variable Life UIT Separate Account), S-1 or S-3 (Face Amount Certificate Company), S-6 (UIT, Non-Insurance Product).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-T
-Number 232
-Section 313

+ Details

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Period Type:	duration

- 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

+ Details

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- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

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- References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 1
-Subsection a
-Paragraph 3

+ Details

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Namespace Prefix:	oef_
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Period Type:	duration

- References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 1

+ Details

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