Allowance for Credit Losses - Allowance for Credit Losses on Finance Receivables and Investments in Operating Leases (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Allowance for Credit Losses on Finance Receivables and Investments in Operating Leases
Allowance for credit losses at beginning of period	$ 485	$ 454
Provision for credit losses	45	38
Charge-offs, net of recoveries	(63)	(45)
Allowance for credit losses at end of period	$ 467	$ 447