Selected Quarterly Financial Data (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Selected Quarterly Financial Data (Unaudited) [Abstract]
Total financing revenues	$ 2,112	$ 1,876	$ 6,129	$ 5,516
Depreciation on operating leases	1,248	1,033	3,544	2,950
Interest expense	161	386	506	1,236
Net financing revenues	703	457	2,079	1,330
Provision for credit losses	103	63	220	102
Income before income taxes	492	306	1,536	843
Provision for income taxes	185	113	574	315
Net income	$ 307	$ 193	$ 962	$ 528