Document and Entity Information	Mar. 19, 2020
Prospectus:
Document Type	497
Document Period End Date	Mar. 19, 2020
Registrant Name	BNY Mellon Investment Funds I
Entity Central Index Key	0000799295
Entity Inv Company Type	N-1A
Amendment Flag	false
Document Creation Date	Mar. 19, 2020
Document Effective Date	Mar. 19, 2020
Prospectus Date	Jan. 31, 2020
BNY Mellon Natural Resources Fund \| Class Y \| BNY Mellon Opportunity Funds
Prospectus:
Trading Symbol	DLDYX
BNY Mellon Natural Resources Fund \| Class I \| BNY Mellon Opportunity Funds
Prospectus:
Trading Symbol	DLDRX
BNY Mellon Natural Resources Fund \| Class C \| BNY Mellon Opportunity Funds
Prospectus:
Trading Symbol	DLDCX
BNY Mellon Natural Resources Fund \| Class A \| BNY Mellon Opportunity Funds
Prospectus:
Trading Symbol	DNLAX
BNY Mellon International Core Equity Fund \| Class Y \| BNY Mellon Stock Funds
Prospectus:
Trading Symbol	DIEYX
BNY Mellon International Core Equity Fund \| Class I \| BNY Mellon Stock Funds
Prospectus:
Trading Symbol	DIERX
BNY Mellon International Core Equity Fund \| Class C \| BNY Mellon Stock Funds
Prospectus:
Trading Symbol	DIECX
BNY Mellon International Core Equity Fund \| Class A \| BNY Mellon Stock Funds
Prospectus:
Trading Symbol	DIEAX
BNY Mellon Diversified Emerging Markets Fund \| Class Y \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	SBYEX
BNY Mellon Diversified Emerging Markets Fund \| Class C \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	DBECX
BNY Mellon Diversified Emerging Markets Fund \| Class A \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	DBEAX
BNY Mellon Diversified Emerging Markets Fund \| Class I \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	SBCEX
BNY Mellon Tax Sensitive Total Return Bond Fund \| Class Y \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	SDYTX
BNY Mellon Tax Sensitive Total Return Bond Fund \| Class C \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	DSDCX
BNY Mellon Tax Sensitive Total Return Bond Fund \| Class A \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	DSDAX
BNY Mellon Tax Sensitive Total Return Bond Fund \| Class I \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	SDITX
BNY Mellon Small Cap Growth Fund \| Class Y \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	SSYGX
BNY Mellon Small Cap Growth Fund \| Class I \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	SSETX
BNY Mellon Small Cap Value Fund \| Class Y \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	BOSYX
BNY Mellon Small Cap Value Fund \| Class C \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	BOSCX
BNY Mellon Small Cap Value Fund \| Class A \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	RUDAX
BNY Mellon Small Cap Value Fund \| Class I \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	STSVX
BNY Mellon Small/Mid Cap Growth Fund \| Class Z \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	DBMZX
BNY Mellon Small/Mid Cap Growth Fund \| Class Y \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	DBMYX
BNY Mellon Small/Mid Cap Growth Fund \| Class C \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	DBMCX
BNY Mellon Small/Mid Cap Growth Fund \| Class A \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	DBMAX
BNY Mellon Small/Mid Cap Growth Fund \| Class I \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	SDSCX
BNY Mellon International Equity Fund \| Class Y \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	NIEYX
BNY Mellon International Equity Fund \| Class C \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	NIECX
BNY Mellon International Equity Fund \| Class A \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	NIEAX
BNY Mellon International Equity Fund \| Class I \| BNY Mellon Investment Funds I
Prospectus:
Trading Symbol	SNIEX

If the value is true, then the document is an amendment to previously-filed/accepted document.

No definition available.

Name:	dei_AmendmentFlag
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

The date the document was made available and submitted, in CCYY-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

Name:	dei_DocumentCreationDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-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

Name:	dei_DocumentEffectiveDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

+ References

No definition available.

+ Details

Name:	dei_DocumentPeriodEndDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	dei_DocumentType
Namespace Prefix:	dei_
Data Type:	dei:submissionTypeItemType
Balance Type:	na
Period Type:	duration

- 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 Regulation 12B
-Number 240
-Section 12
-Subsection b-2

+ Details

Name:	dei_EntityCentralIndexKey
Namespace Prefix:	dei_
Data Type:	dei:centralIndexKeyItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	dei_EntityInvCompanyType
Namespace Prefix:	dei_
Data Type:	dei:invCompanyType
Balance Type:	na
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 Regulation 12B
-Number 240
-Section 12
-Subsection b-2

+ Details

Name:	dei_EntityRegistrantName
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:	dei_TradingSymbol
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

The date of the prospectus.

+ References

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

+ Details

Name:	rr_ProspectusDate
Namespace Prefix:	rr_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Prospectus Table.

+ References

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

+ Details

Name:	rr_ProspectusTable
Namespace Prefix:	rr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration