Revenue - Disaggregation of Revenue from Contract with Customer by Products and Services (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	$ 39,853	$ 78,999
Vehicles, parts, and accessories
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	35,746	70,742
Sale of used vehicles
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	708	1,581
Extended service contracts
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	332	607
Other (a)
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	259	534
Revenues from sales and services
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	37,045	73,464
Leasing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	1,506	2,979
Financing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	1,260	2,474
Insurance income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	42	82
Operating Segments [Member] | Automotive
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	37,113	73,588
Operating Segments [Member] | Automotive | Vehicles, parts, and accessories
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	35,746	70,742
Operating Segments [Member] | Automotive | Sale of used vehicles
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	708	1,581
Operating Segments [Member] | Automotive | Extended service contracts
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	332	607
Operating Segments [Member] | Automotive | Other (a)
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	202	426
Operating Segments [Member] | Automotive | Revenues from sales and services
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	36,988	73,356
Operating Segments [Member] | Automotive | Leasing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	125	232
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	2,738	5,407
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 | Sale of 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 (a)
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	55	104
Operating Segments [Member] | Financial Services | Revenues from sales and services
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	55	104
Operating Segments [Member] | Financial Services | Leasing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	1,381	2,747
Operating Segments [Member] | Financial Services | Financing income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	1,260	2,474
Operating Segments [Member] | Financial Services | Insurance income
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	42	82
Operating Segments [Member] | All Other
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	2	4
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 | Sale of 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 (a)
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	2	4
Operating Segments [Member] | All Other | Revenues from sales and services
Disaggregation of Revenue [Line Items]
Revenue, excluding assessed tax	2	4
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