Finance Receivables - Delinquency (Details) - Retail Finance Receivables [Member] - Automobile Loan [Member] - USD ($) $ in Millions	Jun. 30, 2017	Jun. 30, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
In repossession	$ 43	$ 47
In repossession (percent)	0.20%	0.20%
Total finance receivables more than 30 days delinquent or in repossession	$ 1,583	$ 1,556
Total finance receivables more than 30 days delinquent or in repossession (percent)	5.10%	6.40%
31 to 60 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable past due	$ 1,076	$ 1,055
Financing receivable past due (percent)	3.40%	4.30%
Greater Than 60 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable past due	$ 464	$ 454
Financing receivable past due (percent)	1.50%	1.90%
Thirty or More Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable past due	$ 1,540	$ 1,509
Financing receivable past due (percent)	4.90%	6.20%