Quarterly report pursuant to Section 13 or 15(d)

VIEs - Narrative (Details)

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VIEs - Narrative (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Sep. 30, 2015
Jun. 30, 2018
Trust 2016 Unconsolidated [Member]    
Variable Interest Entity [Line Items]    
Total of automobile loans transferred in securitization transactions   $ 1,500
2015-1 Automobile Trust    
Variable Interest Entity [Line Items]    
Total of automobile loans transferred in securitization transactions $ 750