Commitments and contingencies (Details)	1 Months Ended	3 Months Ended		0 Months Ended	3 Months Ended	0 Months Ended		12 Months Ended					3 Months Ended		9 Months Ended	3 Months Ended		3 Months Ended
	Jan. 31, 2012 USD ($)	Apr. 30, 2010	Jul. 31, 2012 USD ($) site	Jan. 31, 2012 Pending Litigation [Member] FATMA Notice, Trial [Member] Penalties [Member] USD ($)	Jul. 31, 2012 Pending Litigation [Member] FATMA Notice, Trial [Member] Penalties [Member] BRL	Jan. 31, 2012 Pending Litigation [Member] Lis Franco vs. Syntex and MWM, Trial [Member] USD ($)	Oct. 25, 2011 Pending Litigation [Member] Lis Franco vs. Syntex and MWM, Trial [Member] BRL	Dec. 31, 1999 Pending Litigation [Member] Lis Franco vs. Syntex and MWM, Trial [Member] Royalties [Member] BRL	Jul. 31, 2012 Pending Litigation [Member] Lis Franco vs. Syntex and MWM, Trial [Member] Royalties [Member] USD ($)	May 30, 2010 Pending Litigation [Member] Lis Franco vs. Syntex and MWM, Trial [Member] Royalties [Member] BRL	Dec. 31, 2009 Pending Litigation [Member] Lis Franco vs. Syntex and MWM, Trial [Member] Royalties [Member] BRL	Jul. 31, 2012 Damages from Product Defects [Member] USD ($)	Jul. 31, 2012 Damages from Product Defects [Member] Kruse Technology vs. Ford Motor Company [Member] patents	Jul. 31, 2012 Damages from Product Defects [Member] Non-conformance Penalties [Member] Penalties [Member] USD ($)	Jul. 31, 2012 Damages from Product Defects [Member] Non-conformance Penalties [Member] Penalties [Member] USD ($)	Jul. 31, 2012 G E Operating Agreement [Member] USD ($)	Oct. 31, 2011 G E Operating Agreement [Member] USD ($)	Jul. 31, 2012 Minimum [Member]	Jul. 31, 2012 Maximum [Member]
Loss Contingencies [Line Items]
Length of Agreement		3
Length Of Potential Automatic Extension Years		1
Operating Agreement Excess Loss Percentage																10.00%
Outstanding finance receivables, off-balance sheet																$ 1,100,000,000	$ 723,000,000
Related originations of outstanding finance receivables, off-balance sheet																1,400,000,000	818,000,000
Historical losses on finance receivables, measured as percentage of average balance of related finance receivable																		0.30%	2.10%
Available stand-by letters of credit and surety bonds			65,000,000
Unused credit commitments outstanding			36,000,000
Purchase commitments	99,000,000
Long Term Purchase Commitment Cancellation Fees	40,000,000
Number of Contaminated Sites			2
Accrual for environmental loss contingencies			21,000,000
Damages sought, value				1,000,000	2,000,000	0	10,850,000	42,000,000						10,000,000	20,000,000
Notive of Violation, number												7,600
Potential patent infringement, number of patents													3
Estimate of possible loss								16,000,000	$ 36,000,000	74,000,000	70,000,000