Allowance for doubtful accounts (Rollforward) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Apr. 30, 2012 segments		Apr. 30, 2011		Apr. 30, 2012		Apr. 30, 2011
Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Start of Period	$ 47		$ 94		$ 50		$ 96
Provision for doubtful accounts, net of recoveries	0		(2)		0		(2)
Charge-off of accounts	(2)	[1]	(16)	[1]	(5)	[1]	(18)	[1]
Financing Receivable, Allowance for Credit Losses, End of Period	45		76		45		76
Number of portfolio segments of finance receivables	2
Losses recognized at time of repossession	2		12		3		15
Retail [Member]
Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Start of Period	28		54		31		58
Provision for doubtful accounts, net of recoveries	0		1		(2)		(1)
Charge-off of accounts	(2)	[1]	(15)	[1]	(3)	[1]	(17)	[1]
Financing Receivable, Allowance for Credit Losses, End of Period	26		40		26		40
Number of classes of receivables in each portfolio	1
Wholesale [Member]
Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Start of Period	3		2		3		2
Provision for doubtful accounts, net of recoveries	(1)		0		(1)		0
Charge-off of accounts	0	[1]	0	[1]	0	[1]	0	[1]
Financing Receivable, Allowance for Credit Losses, End of Period	2		2		2		2
Number of classes of receivables in each portfolio	1
Trade and Other Receivables [Member]
Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Start of Period	16		38		16		36
Provision for doubtful accounts, net of recoveries	1		(3)		3		(1)
Charge-off of accounts	0	[1]	(1)	[1]	(2)	[1]	(1)	[1]
Financing Receivable, Allowance for Credit Losses, End of Period	$ 17		$ 34		$ 17		$ 34

[1] We repossess sold and leased vehicles on defaulted finance receivables and leases, and place them into Inventories. Losses recognized at the time of repossession and charged against the allowance for doubtful accounts were $2 million and $3 million for the three and six months ended April 30, 2012, respectively, and $12 million and $15 million for the three and six months ended April 30, 2011, respectively.