Finance Receivables and Loans, Net (Schedule of Accounts, Notes, Loans and Financing Receivables) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derivative, Amount of Hedged Item	$ 481	$ 331
Loans and Leases Receivable, Gross	114,959	111,600	$ 107,990
Loans and Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	310	110
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	75,673	74,065
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	64,816	64,292	63,610
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derivative, Amount of Hedged Item	66	66
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	10,857	9,773	9,769
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	7,931	6,413
Held For Investment Mortgage Finance Receivables Interest Only Mortgage Loans	$ 32	44
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Three months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	0.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | One year and three months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	3.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Two years and three months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	0.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Three years three months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	39.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Four years and three months, or greater [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	39.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 2,926	3,360
Held For Investment Mortgage Finance Receivables Interest Only Mortgage Loans	$ 771	941
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Three months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	8.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | One year and three months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	23.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Two years and three months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	2.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Three years three months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	0.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Four years and three months, or greater [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	1.00%
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 39,286	37,535	$ 34,611
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	32,260	31,469
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	3,250	2,640
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 3,776	$ 3,426