Finance Receivables - Delinquency (Details) - Consumer Finance Receivables [Member] - USD ($) $ in Millions	Sep. 30, 2015	Sep. 30, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	$ 1,137	$ 979
Greater than 60 days	454	425
Greater than 30 days past due	1,591	1,404
In repossession	53	49
Past Due	$ 1,644	$ 1,453
31 - 60 days, Percent of contractual amount due	4.00%	3.90%
Greater than 60 days, Percent of contractual amount due	1.60%	1.70%
Greater than 30 days past due, Percent of contractual amount due	5.60%	5.60%
In repossession, Percent of contractual amount due	0.20%	0.20%
Percent of contractual amount due	5.80%	5.80%
North America Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	$ 1,039	$ 865
Greater than 60 days	362	305
Greater than 30 days past due	1,401	1,170
In repossession	47	44
Past Due	1,448	1,214
International Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	98	114
Greater than 60 days	92	120
Greater than 30 days past due	190	234
In repossession	6	5
Past Due	$ 196	$ 239