Selected Quarterly Financial Data (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Selected Quarterly Financial Data (Unaudited) [Abstract]
Total financing revenues	$ 7,429	$ 8,064	$ 8,163
Depreciation on operating leases	(3,339)	(3,353)	(3,564)
Interest expense	(1,300)	(1,614)	(2,023)
Net financing revenues	2,790	3,097	2,576
Provision for credit losses	98	433	(604)
Income before income taxes	2,423	3,003	1,679
Provision for income taxes	937	1,150	616
Net income	$ 1,486	$ 1,853	$ 1,063