Selected Quarterly Financial Data (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Selected Quarterly Financial Data (Unaudited) [Abstract]
Total financing revenues	$ 1,811	$ 1,870	$ 3,608	$ 3,790
Depreciation on operating leases	(880)	(829)	(1,735)	(1,654)
Interest expense	(283)	(149)	(341)	(606)
Net financing revenues	648	892	1,532	1,530
Provision for credit losses	(3)	(11)	(19)	192
Income before income taxes	526	730	1,282	1,478
Provision for income taxes	200	279	479	562
Net income	$ 326	$ 451	$ 803	$ 916