Finance Receivables - Delinquency (Details) - Retail Finance Receivables [Member] - Automobile Loan [Member] - USD ($) $ in Millions	Jun. 30, 2019	Jun. 30, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable past due	$ 1,581	$ 1,640
Financing receivable past due (percent)	3.70%	4.60%
In repossession	$ 48	$ 57
In repossession (percent)	0.10%	0.10%
Total finance receivables more than 30 days delinquent or in repossession	$ 1,629	$ 1,697
Total finance receivables more than 30 days delinquent or in repossession (percent)	3.80%	4.70%
31 to 60 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable past due	$ 1,083	$ 1,178
Financing receivable past due (percent)	2.50%	3.30%
Greater Than 60 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable past due	$ 498	$ 462
Financing receivable past due (percent)	1.20%	1.30%