Allowance for Credit Losses (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Allowance for Credit Losses on Finance Receivables and Investments in Operating Leases
Allowance for credit losses at	$ 501	$ 606	$ 527	$ 619
Provision for credit losses	28	3	39	19
Charge-offs, net of recoveries	(62)	(60)	(99)	(89)
Allowance for credit losses at	467	549	467	549
Recoveries from credit loss charge-offs	$ 21	$ 18	$ 45	$ 41