| **Allowance for doubtful accounts (Aging Analysis) (Details) (USD $)In Millions, unless otherwise specified** | Apr. 30, 2012 | Oct. 31, 2011 |
|---------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Financing Receivable, Recorded Investment, Past Due [Line Items]**                                          |          |          |
| Current                                                                                                       | $ 2,588       | $ 2,843       |
| 30-90 days past due                                                                                           | 67            | 90            |
| Over 90 days past due                                                                                         | 13            | 14            |
| Total finance receivables                                                                                     | 2,668         | 2,947         |
| Retail Portfolio [Member]                                                                                     |          |          |
| **Financing Receivable, Recorded Investment, Past Due [Line Items]**                                          |          |          |
| Current                                                                                                       | 1,307         | 1,515         |
| 30-90 days past due                                                                                           | 65            | 85            |
| Over 90 days past due                                                                                         | 12            | 13            |
| Total finance receivables                                                                                     | 1,384         | 1,613         |
| Wholesale Portfolio [Member]                                                                                  |          |          |
| **Financing Receivable, Recorded Investment, Past Due [Line Items]**                                          |          |          |
| Current                                                                                                       | 1,281         | 1,328         |
| 30-90 days past due                                                                                           | 2             | 5             |
| Over 90 days past due                                                                                         | 1             | 1             |
| Total finance receivables                                                                                     | $ 1,284       | $ 1,334       |

| X                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Financing Receivables Recorded Investment 30 To 90 Days Past Due
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Financing receivables that are current.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=6965416&loc=SL6953401-111524
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Financing receivables that are equal to or greater than 90 days past due.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=6965416&loc=SL6953401-111524
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| X                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reflects the aggregate gross carrying amount of all categories of loans and leases held in portfolio, prior to deducting deferred income and the allowance for losses on loans and leases.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 01-6 -Paragraph 13 -Subparagraph e -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 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522
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