Cover - shares	9 Months Ended
	Jun. 30, 2020	Jul. 31, 2020
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	1-278
Entity Registrant Name	EMERSON ELECTRIC CO.
Entity Central Index Key	0000032604
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Incorporation, State or Country Code	MO
Entity Tax Identification Number	43-0259330
Entity Address, Address Line One	8000 W. Florissant Ave.
Entity Address, Address Line Two	P.O. Box 4100
Entity Address, City or Town	St. Louis,
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63136
City Area Code	314
Local Phone Number	553-2000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		597,591,921
Amendment Flag	false
NEW YORK STOCK EXCHANGE, INC. [Member] | Common Stock of $0.50 par value per share [Member]
Entity Information [Line Items]
Title of 12(b) Security	Common Stock of $0.50 par value per share
Trading Symbol	EMR
Security Exchange Name	NYSE
NEW YORK STOCK EXCHANGE, INC. [Member] | 0.375% Notes due 2024 [Member]
Entity Information [Line Items]
Title of 12(b) Security	0.375% Notes due 2024
Trading Symbol	EMR 24
Security Exchange Name	NYSE
NEW YORK STOCK EXCHANGE, INC. [Member] | 1.250% Notes due 2025 [Member]
Entity Information [Line Items]
Title of 12(b) Security	1.250% Notes due 2025
Trading Symbol	EMR 25A
Security Exchange Name	NYSE
NEW YORK STOCK EXCHANGE, INC. [Member] | 2.000% Notes due 2029 [Member]
Entity Information [Line Items]
Title of 12(b) Security	2.000% Notes due 2029
Trading Symbol	EMR 29
Security Exchange Name	NYSE
CHICAGO STOCK EXCHANGE, INC [Member] | Common Stock of $0.50 par value per share [Member]
Entity Information [Line Items]
Title of 12(b) Security	Common Stock of $0.50 par value per share
Trading Symbol	EMR
Security Exchange Name	CHX