Allowance for doubtful accounts (Impaired Finance Receivables) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Oct. 31, 2011
Financing Receivable, Impaired [Line Items]
Specific loss reserves on impaired finance receivables	$ 10		$ 10
Finance receivables on non-accrual status	12		14
Impaired financing receivable without specific loss reserves [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	1		2
Impaired finance receivables with specific loss reserves [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	17		15
Retail Portfolio [Member]
Financing Receivable, Impaired [Line Items]
Specific loss reserves on impaired finance receivables	10		10
Finance receivables on non-accrual status	12		14
Average balance of impaired finance receivables	13	44
Retail Portfolio [Member] | Impaired financing receivable without specific loss reserves [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	1		2
Retail Portfolio [Member] | Impaired finance receivables with specific loss reserves [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	17		15
Wholesale Portfolio [Member]
Financing Receivable, Impaired [Line Items]
Specific loss reserves on impaired finance receivables	0		0
Finance receivables on non-accrual status	0		0
Wholesale Portfolio [Member] | Impaired financing receivable without specific loss reserves [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	0		0
Wholesale Portfolio [Member] | Impaired finance receivables with specific loss reserves [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 0		$ 0