Finance Receivables, Net (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	$ 61,672		$ 58,611
Allowance for credit losses	(549)	(606)	(619)	(623)	(667)	(879)
Finance receivables, net	61,090		58,042
Finance Receivables, Net [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	61,672		58,611	56,203
Deferred origination costs	637		639
Unearned income	(759)		(684)
Allowance for credit losses	(460)	(515)	(524)	(510)	(528)	(754)
Finance receivables, net	61,090		58,042
Finance Receivables, Net [Member] | Retail receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	37,371		35,020
Finance Receivables, Net [Member] | Pledged retail receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	10,345		10,726
Finance Receivables, Net [Member] | Dealer financing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	13,956		12,865
Allowance for credit losses	(122)		(119)
Finance Receivables, Net [Member] | Retail and Pledged Retail Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses	(338)		(405)
Investments In Operating Leases, Net [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses	$ (89)		$ (95)