Cash, Cash Equivalents, and Marketable Securities Available for Sale Securities (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities			$ 0	$ 0
Proceeds from Sale of Debt Securities, Available-for-sale	$ 1,858,000,000	$ 1,507,000,000	3,000,000,000	2,846,000,000
Available-for-sale Securities, Gross Realized Gains	3,000,000	1,000,000	5,000,000	1,000,000
Available-for-sale Securities, Gross Realized Losses	5,000,000	$ 5,000,000	10,000,000	$ 11,000,000
Operating Segments | Automotive
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	12,792,000,000		12,792,000,000		$ 12,911,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	81,000,000		81,000,000		12,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(8,000,000)		(8,000,000)		(98,000,000)
Available-for-sale Securities	12,865,000,000		12,865,000,000		12,825,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	4,967,000,000		4,967,000,000		3,854,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	7,779,000,000		7,779,000,000		8,879,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	119,000,000		119,000,000		92,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	387,000,000		387,000,000		2,674,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		0		(19,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2,683,000,000		2,683,000,000		6,534,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(8,000,000)		(8,000,000)		(79,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,070,000,000		3,070,000,000		9,208,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(8,000,000)		(8,000,000)		(98,000,000)
Operating Segments | Automotive | U.S. government
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	2,360,000,000		2,360,000,000		2,933,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	13,000,000		13,000,000		5,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		(10,000,000)
Available-for-sale Securities	2,373,000,000		2,373,000,000		2,928,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	1,423,000,000		1,423,000,000		1,714,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	945,000,000		945,000,000		1,214,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	5,000,000		5,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	183,000,000		183,000,000		199,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		0		(1,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	249,000,000		249,000,000		1,637,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0		0		(9,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	432,000,000		432,000,000		1,836,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0		0		(10,000,000)
Operating Segments | Automotive | U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,660,000,000		1,660,000,000		1,920,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2,000,000		2,000,000		0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(3,000,000)		(3,000,000)		(18,000,000)
Available-for-sale Securities	1,659,000,000		1,659,000,000		1,902,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	963,000,000		963,000,000		797,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	687,000,000		687,000,000		1,087,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	9,000,000		9,000,000		18,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	85,000,000		85,000,000		193,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		0		(1,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	959,000,000		959,000,000		1,596,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(3,000,000)		(3,000,000)		(17,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,044,000,000		1,044,000,000		1,789,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(3,000,000)		(3,000,000)		(18,000,000)
Operating Segments | Automotive | Non-U.S. government and agencies
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	3,736,000,000		3,736,000,000		3,841,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	19,000,000		19,000,000		4,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(3,000,000)		(3,000,000)		(37,000,000)
Available-for-sale Securities	3,752,000,000		3,752,000,000		3,808,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	882,000,000		882,000,000		194,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	2,865,000,000		2,865,000,000		3,614,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	5,000,000		5,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	27,000,000		27,000,000		341,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		0		(1,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,076,000,000		1,076,000,000		2,445,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(3,000,000)		(3,000,000)		(36,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,103,000,000		1,103,000,000		2,786,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(3,000,000)		(3,000,000)		(37,000,000)
Operating Segments | Automotive | Corporate debt
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	4,850,000,000		4,850,000,000		4,010,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	45,000,000		45,000,000		3,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(1,000,000)		(1,000,000)		(33,000,000)
Available-for-sale Securities	4,894,000,000		4,894,000,000		3,980,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	1,699,000,000		1,699,000,000		1,148,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	3,177,000,000		3,177,000,000		2,830,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	18,000,000		18,000,000		2,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	82,000,000		82,000,000		1,816,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		0		(16,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	379,000,000		379,000,000		856,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,000,000)		(1,000,000)		(17,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	461,000,000		461,000,000		2,672,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(1,000,000)		(1,000,000)		(33,000,000)
Operating Segments | Automotive | Other marketable securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	186,000,000		186,000,000		207,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2,000,000		2,000,000		0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(1,000,000)		(1,000,000)		0
Available-for-sale Securities	187,000,000		187,000,000		207,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	0		0		1,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	105,000,000		105,000,000		134,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	82,000,000		82,000,000		72,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	10,000,000		10,000,000		125,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	20,000,000		20,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,000,000)		(1,000,000)		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	30,000,000		30,000,000		125,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (1,000,000)		$ (1,000,000)		$ 0