Segment Reporting (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Segment Sales	$ 5,441	$ 5,677
Segment Earnings	691	873
Net sales	5,309	5,535
Earnings before income taxes	553	713
Charge for the elimination of post-65 supplemental retiree medical benefits	19
Acquisition-related costs	17
Interest expense	58	61
Approximate number of active employees affected by elimination of post-65 supplemental retiree medical benefits	8,000
Process Management [Member]
Segment Reporting Information [Line Items]
Segment Sales	1,527	1,542
Segment Earnings	190	290
Industrial Automation [Member]
Segment Reporting Information [Line Items]
Segment Sales	1,229	1,210
Segment Earnings	182	185
Intersegment sales	110	126
Network Power [Member]
Segment Reporting Information [Line Items]
Segment Sales	1,495	1,669
Segment Earnings	122	182
Climate Technologies [Member]
Segment Reporting Information [Line Items]
Segment Sales	733	810
Segment Earnings	100	123
Tools And Storage [Member]
Segment Reporting Information [Line Items]
Segment Sales	457	446
Segment Earnings	97	93
Differences In Accounting Methods [Member]
Segment Reporting Information [Line Items]
Differences in accounting methods	49	53
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Segment Earnings	(129)	(152)
Change in stock compensation expense	33
Eliminations/Interest [Member]
Segment Reporting Information [Line Items]
Segment Sales	(132)	(142)
Interest expense	$ (58)	$ (61)

Increase (decrease) in stock compensation expense compared to prior period.

No definition available.

Name:	emr_ChangeInStockCompensationExpense
Namespace Prefix:	emr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Charge for the elimination of post-65 supplemental retiree medical benefits for a small group of active employees.

+ References

No definition available.

+ Details

Name:	emr_ChargeForEliminationOfPostSixtyFiveSupplementalRetireeMedicalBenefits
Namespace Prefix:	emr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Differences in accounting methods

+ References

No definition available.

+ Details

Name:	emr_DifferencesInAccountingMethods
Namespace Prefix:	emr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Approximate number of active employees affected by elimination of post-65 supplemental retiree medical benefits.

+ References

No definition available.

+ Details

Name:	emr_NumberOfEmployeesAffectedByEliminationOfPostSupplementRetireeMedicalBenefits
Namespace Prefix:	emr_
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	duration

- Definition

Purchase accounting adjustments.

+ References

No definition available.

+ Details

Name:	emr_PurchaseAccountingAdjustments
Namespace Prefix:	emr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 5

-Section 03

-Paragraph 10

+ Details

Name:	us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 4

-Section 08

-Paragraph h

-Subparagraph 1(i)

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h)(1)(i))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

+ Details

Name:	us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The net amount of nonoperating interest income (expense).

+ References

No definition available.

+ Details

Name:	us-gaap_InterestIncomeExpenseNonoperatingNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue from transactions with other operating segments of the same entity.

+ References

+ Details

Name:	us-gaap_RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 5

-Section 03

-Paragraph 1

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

+ Details

Name:	us-gaap_SalesRevenueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_SegmentReportingInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of total revenue for the reportable segments, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph a, b, c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 22

-Subparagraph (a),(b),(c)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8736-108599

+ Details

Name:	us-gaap_SegmentReportingInformationRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration