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