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, 2017	Jun. 30, 2016
Allowance for Credit Losses on Finance Receivables and Investments in Operating Leases
Allowance for credit losses at beginning of period	$ 622	$ 535
Provision for credit losses	85	52
Charge-offs, net of recoveries	(96)	(98)
Allowance for credit losses at end of period	$ 611	$ 489