Label	Element	Value
BNY Mellon Small/Mid Cap Growth Fund
Risk/Return:	rr_RiskReturnAbstract
Supplement to Prospectus [Text Block]	rr_SupplementToProspectusTextBlock	BNY MELLON INVESTMENT FUNDS I BNY Mellon Small/Mid Cap Growth Fund Supplement to Current Summary Prospectus and Prospectus IMPORTANT NOTICE REGARDING CHANGE IN INVESTMENT POLICY
Risk/Return [Heading]	rr_RiskReturnHeading	BNY Mellon Small/Mid Cap Growth Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Effective May 1, 2024, the following information will supersede and replace the information in the second and third sentence in the first paragraph in the sections "Principal Investment Strategy" in the summary prospectus and "Fund Summary – Principal Investment Strategy" in the prospectus: The fund considers small-cap and mid-cap companies to be those companies with total market capitalizations that are equal to or less than the total market capitalization of the largest company included in the Russell Midcap^® Index (the "Index"). As of January 31, 2024, the market capitalization of the largest company in the Index was approximately $76.588 billion.

No definition available.

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- Definition

Risk/Return Summary Investment Objectives/Goals Include the following information, in plain English under rule 421(d) under the Securities Act, in the order and subject matter indicated

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 2

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- Definition

Principal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 4
-Subsection a

+ Details

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- Definition

This element contains the text of a prospectus supplement (submission type 497) not already contained in an element containing amended text or other data from a previous submission.

+ References

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

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