Selected Quarterly Financial Data (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Selected Quarterly Financial Data (Unaudited) [Abstract]
Total financing revenues	$ 1,815	$ 1,835	$ 5,423	$ 5,625
Depreciation on operating leases	(901)	(844)	(2,636)	(2,498)
Interest expense	(284)	(163)	(625)	(769)
Net financing revenues	630	828	2,162	2,358
Provision for credit losses	(88)	(56)	(107)	136
Income before income taxes	439	698	1,721	2,176
Provision for income taxes	156	266	635	828
Net income	$ 283	$ 432	$ 1,086	$ 1,348