Finance Receivables and Loans, Net (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 128,231	$ 129,926
Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	128,220
Consumer portfolio segment
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	89,924	87,240
Consumer portfolio segment | Fair value | Finance receivables and Loans, net
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Fair Value Disclosure	11
Consumer portfolio segment | Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	89,913
Consumer portfolio segment | Performing Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		86,497
Consumer portfolio segment | Performing Financial Instruments | Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	89,092
Consumer portfolio segment | Nonperforming Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		743
Consumer portfolio segment | Nonperforming Financial Instruments | Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	821
Consumer portfolio segment | Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	72,390	70,539
Consumer portfolio segment | Automotive loan | Performing Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	71,628	69,875
Consumer portfolio segment | Automotive loan | Nonperforming Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	762	664
Consumer portfolio segment | Real estate-backed loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	17,322	16,701
Consumer portfolio segment | Real estate-backed loan | Performing Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	17,265	16,622
Consumer portfolio segment | Real estate-backed loan | Nonperforming Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	57	79
Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	16,181	15,155
Consumer portfolio segment | Mortgage Finance operations | Performing Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	16,164	15,146
Consumer portfolio segment | Mortgage Finance operations | Nonperforming Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	17	9
Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	1,141	1,546
Consumer portfolio segment | Mortgage - Legacy | Performing Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	1,101	1,476
Consumer portfolio segment | Mortgage - Legacy | Nonperforming Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	40	70
Consumer portfolio segment | Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	212	0
Consumer portfolio segment | Other loan | Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	201
Consumer portfolio segment | Other loan | Performing Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		0
Consumer portfolio segment | Other loan | Performing Financial Instruments | Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	199
Consumer portfolio segment | Other loan | Nonperforming Financial Instruments
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		$ 0
Consumer portfolio segment | Other loan | Nonperforming Financial Instruments | Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 2