Cash, Cash Equivalents, and Marketable Securities Available for Sale Securities (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds	$ 1,300,000,000	$ 0	$ 2,600,000,000	$ 69,000,000
Available-for-sale Securities, Gross Realized Gains	2,000,000	0	3,000,000	1,000,000
Available-for-sale Securities, Gross Realized Losses	6,000,000	$ 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	8,928,000,000		8,928,000,000		$ 6,533,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	6,000,000		6,000,000		3,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(18,000,000)		(18,000,000)		(27,000,000)
Available-for-sale Securities	8,916,000,000		8,916,000,000		6,509,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	2,205,000,000		2,205,000,000		1,906,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	6,614,000,000		6,614,000,000		4,415,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	97,000,000		97,000,000		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	5,824,000,000		5,824,000,000		2,872,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(18,000,000)		(18,000,000)		(27,000,000)
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	5,824,000,000		5,824,000,000		2,872,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(18,000,000)		(18,000,000)		(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	2,587,000,000		2,587,000,000		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	(7,000,000)		(7,000,000)		(14,000,000)
Available-for-sale Securities	2,580,000,000		2,580,000,000		3,691,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	524,000,000		524,000,000		727,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	2,056,000,000		2,056,000,000		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	2,580,000,000		2,580,000,000		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	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	2,580,000,000		2,580,000,000		1,474,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(7,000,000)		(7,000,000)		(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	1,982,000,000		1,982,000,000		308,000,000
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	(4,000,000)		(4,000,000)		(2,000,000)
Available-for-sale Securities	1,979,000,000		1,979,000,000		306,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	677,000,000		677,000,000		0
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	1,237,000,000		1,237,000,000		306,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	65,000,000		65,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,172,000,000		1,172,000,000		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	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	1,172,000,000		1,172,000,000		261,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(4,000,000)		(4,000,000)		(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	2,961,000,000		2,961,000,000		1,443,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	5,000,000		5,000,000		1,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(5,000,000)		(5,000,000)		(11,000,000)
Available-for-sale Securities	2,961,000,000		2,961,000,000		1,433,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	248,000,000		248,000,000		148,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	2,688,000,000		2,688,000,000		1,285,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	25,000,000		25,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,555,000,000		1,555,000,000		1,137,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(5,000,000)		(5,000,000)		(11,000,000)
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	1,555,000,000		1,555,000,000		1,137,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(5,000,000)		(5,000,000)		(11,000,000)
Operating Segments [Member] | Automotive | Corporate debt
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,398,000,000		1,398,000,000		1,079,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0		0		0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(2,000,000)		(2,000,000)		0
Available-for-sale Securities	1,396,000,000		1,396,000,000		1,079,000,000
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	756,000,000		756,000,000		1,031,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	633,000,000		633,000,000		48,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	7,000,000		7,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	517,000,000		517,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(2,000,000)		(2,000,000)		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	517,000,000		517,000,000		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (2,000,000)		$ (2,000,000)		$ 0