Cash, Cash Equivalents, and Marketable Securities Available for Sale Securities (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds	$ 491,000,000	$ 0	$ 3,100,000,000	$ 69,000,000
Available-for-sale Securities, Gross Realized Gains	0	0	3,000,000	1,000,000
Available-for-sale Securities, Gross Realized Losses	0	$ 0	8,000,000	0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities			0	$ 0
Operating Segments [Member] | Automotive
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	9,957,000,000		9,957,000,000		$ 6,533,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	7,000,000		7,000,000		3,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(21,000,000)		(21,000,000)		(27,000,000)
Available-for-sale Securities	9,943,000,000		9,943,000,000		6,509,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	2,125,000,000		2,125,000,000		1,906,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	7,753,000,000		7,753,000,000		4,415,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	65,000,000		65,000,000		188,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	6,781,000,000		6,781,000,000		2,872,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(19,000,000)		(19,000,000)		(27,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	137,000,000		137,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,000,000)		(2,000,000)		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	6,918,000,000		6,918,000,000		2,872,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(21,000,000)		(21,000,000)		(27,000,000)
Operating Segments [Member] | Automotive | U.S. government
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	3,228,000,000		3,228,000,000		3,703,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0		0		2,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(8,000,000)		(8,000,000)		(14,000,000)
Available-for-sale Securities	3,220,000,000		3,220,000,000		3,691,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	1,268,000,000		1,268,000,000		727,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	1,952,000,000		1,952,000,000		2,776,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	0		0		188,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	2,674,000,000		2,674,000,000		1,474,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(7,000,000)		(7,000,000)		(14,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	49,000,000		49,000,000		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	2,723,000,000		2,723,000,000		1,474,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(8,000,000)		(8,000,000)		(14,000,000)
Operating Segments [Member] | Automotive | U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,795,000,000		1,795,000,000		308,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0		0		0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(5,000,000)		(5,000,000)		(2,000,000)
Available-for-sale Securities	1,790,000,000		1,790,000,000		306,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	228,000,000		228,000,000		0
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	1,547,000,000		1,547,000,000		306,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	15,000,000		15,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,608,000,000		1,608,000,000		261,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(4,000,000)		(4,000,000)		(2,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	49,000,000		49,000,000		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	1,657,000,000		1,657,000,000		261,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(5,000,000)		(5,000,000)		(2,000,000)
Operating Segments [Member] | Automotive | Non-U.S. government and agencies
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	3,392,000,000		3,392,000,000		1,443,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	6,000,000		6,000,000		1,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(7,000,000)		(7,000,000)		(11,000,000)
Available-for-sale Securities	3,391,000,000		3,391,000,000		1,433,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	99,000,000		99,000,000		148,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	3,242,000,000		3,242,000,000		1,285,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	50,000,000		50,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,956,000,000		1,956,000,000		1,137,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(7,000,000)		(7,000,000)		(11,000,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	39,000,000		39,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,995,000,000		1,995,000,000		1,137,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(7,000,000)		(7,000,000)		(11,000,000)
Operating Segments [Member] | Automotive | Corporate debt
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,542,000,000		1,542,000,000		1,079,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,000,000		1,000,000		0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(1,000,000)		(1,000,000)		0
Available-for-sale Securities	1,542,000,000		1,542,000,000		1,079,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	530,000,000		530,000,000		1,031,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	1,012,000,000		1,012,000,000		48,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	543,000,000		543,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,000,000)		(1,000,000)		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	543,000,000		543,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (1,000,000)		$ (1,000,000)		$ 0