Selected Quarterly Financial Data (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Selected Quarterly Financial Data (Unaudited) [Abstract]
Total financing revenues	$ 2,057	$ 1,845	$ 4,017	$ 3,640
Depreciation on operating leases	1,196	966	2,296	1,917
Interest expense	215	314	345	850
Net financing revenues	646	565	1,376	873
Provision for credit losses	79	28	117	39
Income before income taxes	467	393	1,044	537
Provision for income taxes	176	149	389	202
Net income	$ 291	$ 244	$ 655	$ 335