Cash, Cash Equivalents, and Marketable Securities Available for Sale Securities (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 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	1,142,000,000	1,339,000,000
Available-for-sale Securities, Gross Realized Gains	2,000,000	0
Available-for-sale Securities, Gross Realized Losses	5,000,000	$ 6,000,000
Operating Segments [Member] | Automotive
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	13,891,000,000		$ 12,911,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	38,000,000		12,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	41,000,000		98,000,000
Available-for-sale Securities	13,888,000,000		12,825,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	5,552,000,000		3,854,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	8,240,000,000		8,879,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	96,000,000		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	694,000,000		2,674,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,000,000)		(19,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	5,538,000,000		6,534,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(40,000,000)		(79,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	6,232,000,000		9,208,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(41,000,000)		(98,000,000)
Operating Segments [Member] | Automotive | U.S. government
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	2,914,000,000		2,933,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	7,000,000		5,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5,000,000		10,000,000
Available-for-sale Securities	2,916,000,000		2,928,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	1,884,000,000		1,714,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	1,027,000,000		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		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	324,000,000		199,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		(1,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	685,000,000		1,637,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(5,000,000)		(9,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,009,000,000		1,836,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(5,000,000)		(10,000,000)
Operating Segments [Member] | Automotive | U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,972,000,000		1,920,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,000,000		0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	10,000,000		18,000,000
Available-for-sale Securities	1,963,000,000		1,902,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	1,106,000,000		797,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	851,000,000		1,087,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	6,000,000		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	90,000,000		193,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		(1,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,524,000,000		1,596,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(10,000,000)		(17,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,614,000,000		1,789,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(10,000,000)		(18,000,000)
Operating Segments [Member] | Automotive | Non-U.S. government and agencies
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	3,639,000,000		3,841,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	8,000,000		4,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	17,000,000		37,000,000
Available-for-sale Securities	3,630,000,000		3,808,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	362,000,000		194,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	3,263,000,000		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		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	25,000,000		341,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		(1,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2,171,000,000		2,445,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(17,000,000)		(36,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,196,000,000		2,786,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(17,000,000)		(37,000,000)
Operating Segments [Member] | Automotive | Corporate debt
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	5,154,000,000		4,010,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	21,000,000		3,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	9,000,000		33,000,000
Available-for-sale Securities	5,166,000,000		3,980,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	2,199,000,000		1,148,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	2,964,000,000		2,830,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	3,000,000		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	233,000,000		1,816,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,000,000)		(16,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,110,000,000		856,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(8,000,000)		(17,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,343,000,000		2,672,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(9,000,000)		(33,000,000)
Operating Segments [Member] | Automotive | Other marketable securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	212,000,000		207,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,000,000		0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0		0
Available-for-sale Securities	213,000,000		207,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value	1,000,000		1,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value	135,000,000		134,000,000
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value	77,000,000		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	22,000,000		125,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	48,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	70,000,000		125,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 0		$ 0