Finance Receivables and Loans, Net (Financing Receivable Credit Quality Indicators - Performing and Nonperforming) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 114,959	$ 111,600	$ 107,990
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	75,673	74,065
Consumer Portfolio Segment [Member] | Consumer Loan [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	75,031	73,462
Consumer Portfolio Segment [Member] | Consumer Loan [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	642	603
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	64,816	64,292	63,610
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	64,274	63,817
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	542	475
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	10,857	9,773	$ 9,769
Consumer Portfolio Segment [Member] | Residential Mortgage [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	10,757	9,645
Consumer Portfolio Segment [Member] | Residential Mortgage [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	100	128
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	7,931	6,413
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	7,922	6,398
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	9	15
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,926	3,360
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,835	3,247
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 91	$ 113