Revenue - Disaggregation of Revenue from Contract with Customer by Products and Services (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	$ 36,451	$ 115,450
Vehicles, parts, and accessories
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	32,401	103,143
Used vehicles
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	606	2,187
Extended service contracts
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	314	921
Other revenue (a)
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	255	789
Revenues from sales and services
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	33,576	107,040
Leasing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	1,523	4,502
Financing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	1,314	3,788
Insurance income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	38	120
Operating Segments [Member] | Automotive
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	33,646	107,234
Operating Segments [Member] | Automotive | Vehicles, parts, and accessories
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	32,401	103,143
Operating Segments [Member] | Automotive | Used vehicles
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	606	2,187
Operating Segments [Member] | Automotive | Extended service contracts
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	314	921
Operating Segments [Member] | Automotive | Other revenue (a)
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	197	623
Operating Segments [Member] | Automotive | Revenues from sales and services
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	33,518	106,874
Operating Segments [Member] | Automotive | Leasing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	128	360
Operating Segments [Member] | Automotive | Financing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | Automotive | Insurance income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | Financial Services
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	2,802	8,209
Operating Segments [Member] | Financial Services | Vehicles, parts, and accessories
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | Financial Services | Used vehicles
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | Financial Services | Extended service contracts
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | Financial Services | Other revenue (a)
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	55	159
Operating Segments [Member] | Financial Services | Revenues from sales and services
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	55	159
Operating Segments [Member] | Financial Services | Leasing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	1,395	4,142
Operating Segments [Member] | Financial Services | Financing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	1,314	3,788
Operating Segments [Member] | Financial Services | Insurance income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	38	120
Operating Segments [Member] | All Other
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	3	7
Operating Segments [Member] | All Other | Vehicles, parts, and accessories
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | All Other | Used vehicles
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | All Other | Extended service contracts
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | All Other | Other revenue (a)
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	3	7
Operating Segments [Member] | All Other | Revenues from sales and services
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	3	7
Operating Segments [Member] | All Other | Leasing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | All Other | Financing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	0	0
Operating Segments [Member] | All Other | Insurance income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	$ 0	$ 0
Minimum [Member] | Operating Segments [Member] | Automotive | Vehicles, parts, and accessories
Disaggregation of Revenue [Line Items]
Revenue Performance Obligation Payment Terms		30 days