Finance Receivables and Loans, Net (Schedule of Financing Receivables, Non Accrual Status) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	$ 987	$ 1,092
Consumer portfolio segment | Consumer loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	718	743
Consumer portfolio segment | Automobile loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	643	664
Consumer portfolio segment | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	75	79
Consumer portfolio segment | Mortgage Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	13	9
Consumer portfolio segment | Mortgage - Legacy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	62	70
Commercial portfolio segment | Commercial loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	269	349
Commercial portfolio segment | Commercial and industrial automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	138	203
Commercial portfolio segment | Commercial and industrial other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	125	142
Commercial portfolio segment | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	$ 6	$ 4