Allowance for doubtful accounts (Aging Analysis) (Details) (USD $) In Millions, unless otherwise specified	Jan. 31, 2012	Oct. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 2,594	$ 2,843
30-90 days past due	38	90
Over 90 days past due	15	14
Total finance receivables	2,647	2,947
Retail Portfolio [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,336	1,515
30-90 days past due	32	85
Over 90 days past due	14	13
Total finance receivables	1,382	1,613
Wholesale Portfolio [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,258	1,328
30-90 days past due	6	5
Over 90 days past due	1	1
Total finance receivables	$ 1,265	$ 1,334