Pension and Other Postretirement Employee Benefit Plans - Defined Benefit Pension Plans (Details) - USD ($)			12 Months Ended
	Nov. 30, 2018	Dec. 21, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Health care cost trend rate:
Assumed for next year			5.00%	5.00%
Ultimate			5.00%	5.00%	5.00%
Year when rate will reach ultimate			2019	2018
Overfunded Plan
Change in plan assets
Net funded status			$ 5,100,000,000	$ 5,600,000,000
Underfunded Plan
Change in plan assets
Net funded status			$ 547,000,000	$ 612,000,000
Minimum
Weighted-average actuarial assumptions used to determine benefit obligations
Rate of compensation increase			2.25%	2.25%
Interest crediting rate			1.81%	1.81%
Maximum
Weighted-average actuarial assumptions used to determine benefit obligations
Rate of compensation increase			3.00%	3.00%
Interest crediting rate			4.90%	4.90%
Non-U.S.
Change in plan assets
Fair value of plan assets, beginning of year			$ 3,900,000,000
Fair value of plan assets, end of year			3,500,000,000	$ 3,900,000,000
Accumulated benefit obligation, end of year			(3,300,000,000)	(3,800,000,000)
Defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Increase to pension expense representing immediate recognition of prior service cost			(21,000,000)	0	$ 0
Change in benefit obligation
Benefit obligation, beginning of year			(16,700,000,000)	(15,594,000,000)
Benefits earned during the year			(354,000,000)	(330,000,000)	(332,000,000)
Interest cost on benefit obligations			(556,000,000)	(598,000,000)	(629,000,000)
Plan amendments			(29,000,000)	0
Plan curtailment			123,000,000	0
Employee contributions			(7,000,000)	(7,000,000)
Net gain/(loss)			938,000,000	(721,000,000)
Benefits paid			873,000,000	841,000,000
Plan settlements			15,000,000	30,000,000
Foreign exchange impact and other			185,000,000	(321,000,000)
Benefit obligation, end of year			(15,512,000,000)	(16,700,000,000)	(15,594,000,000)
Change in plan assets
Fair value of plan assets, beginning of year			19,603,000,000	17,703,000,000
Actual return on plan assets			(548,000,000)	2,356,000,000
Firm contributions			75,000,000	78,000,000
Employee contributions			7,000,000	7,000,000
Benefits paid			(873,000,000)	(841,000,000)
Plan settlements			(15,000,000)	(30,000,000)
Foreign exchange impact and other			(197,000,000)	330,000,000
Fair value of plan assets, end of year			18,052,000,000	19,603,000,000	17,703,000,000
Net funded status			2,540,000,000	2,903,000,000
Accumulated benefit obligation, end of year			(15,494,000,000)	(16,530,000,000)
Pretax pension and OPEB amounts recorded in AOCI
Net gain/(loss)			(3,134,000,000)	(2,800,000,000)
Prior service credit/(cost)			(23,000,000)	6,000,000
Accumulated other comprehensive income/(loss), pretax, end of year			(3,157,000,000)	(2,794,000,000)
Funded status of plan - supplemental information
Plans with projected benefit obligation exceeding plan assets, projected benefit obligation			1,300,000,000	762,000,000
Plans with projected benefit obligation exceeding plan assets, fair value of plan assets			1,400,000,000	811,000,000
Plans with accumulated benefit obligation exceeding plan assets, accumulated benefit obligation			1,300,000,000	762,000,000
Plans with accumulated benefit obligation exceeding plan assets, fair value of plan assets			$ 1,400,000,000	$ 811,000,000
Defined benefit pension plans | Minimum
Weighted-average actuarial assumptions used to determine benefit obligations
Discount rate			0.60%	0.60%
Defined benefit pension plans | Maximum
Weighted-average actuarial assumptions used to determine benefit obligations
Discount rate			4.30%	3.70%
Defined benefit pension plans | U.S.
Defined Benefit Plan Disclosure [Line Items]
Increase to pension expense representing immediate recognition of prior service cost	$ 21,000,000
Weighted-average actuarial assumptions used to determine benefit obligations
Discount rate			4.30%	3.70%
Rate of compensation increase			2.30%	2.30%
Interest crediting rate			4.90%	4.90%
Defined benefit pension plans | U.S. | Participation rights under participating annuity contracts
Change in plan assets
Fair value of plan assets, beginning of year			$ 302,000,000
Fair value of plan assets, end of year			302,000,000	$ 302,000,000
Defined benefit pension plans | U.S. | Accrued receivables
Funded status of plan - supplemental information
Defined benefit plans, amounts not measured at fair value			340,000,000	377,000,000
Defined benefit pension plans | U.S. | Accrued liabilities
Funded status of plan - supplemental information
Defined benefit plans, amounts not measured at fair value			503,000,000	587,000,000
Defined benefit pension plans | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Defined benefit pension plan, estimated future employer contributions in next fiscal year			45,000,000
Defined benefit plan, contractually required future employer contributions in next fiscal year			30,000,000
OPEB plans
Defined Benefit Plan Disclosure [Line Items]
Increase to pension expense representing immediate recognition of prior service cost			0	0	0
Cash contributed to the trust by the Firm		$ 600,000,000
Change in benefit obligation
Benefit obligation, beginning of year			(684,000,000)	(708,000,000)
Benefits earned during the year			0	0	0
Interest cost on benefit obligations			(24,000,000)	(28,000,000)	(31,000,000)
Plan amendments			0	0
Plan curtailment			0	0
Employee contributions			(15,000,000)	(16,000,000)
Net gain/(loss)			40,000,000	(4,000,000)
Benefits paid			69,000,000	76,000,000
Plan settlements			0	0
Expected Medicare Part D subsidy receipts			0	(1,000,000)
Foreign exchange impact and other			2,000,000	(3,000,000)
Benefit obligation, end of year			(612,000,000)	(684,000,000)	(708,000,000)
Change in plan assets
Fair value of plan assets, beginning of year			2,757,000,000	1,956,000,000
Actual return on plan assets			(28,000,000)	233,000,000
Firm contributions			2,000,000	602,000,000
Employee contributions			15,000,000	0
Benefits paid			(113,000,000)	(34,000,000)
Plan settlements			0	0
Foreign exchange impact and other			0	0
Fair value of plan assets, end of year			2,633,000,000	2,757,000,000	$ 1,956,000,000
Net funded status			2,021,000,000	2,073,000,000
Pretax pension and OPEB amounts recorded in AOCI
Net gain/(loss)			184,000,000	271,000,000
Prior service credit/(cost)			0	0
Accumulated other comprehensive income/(loss), pretax, end of year			$ 184,000,000	$ 271,000,000
Weighted-average actuarial assumptions used to determine benefit obligations
Discount rate			4.20%	3.70%
Funded status of plan - supplemental information
Plans with projected benefit obligation exceeding plan assets, projected benefit obligation			$ 26,000,000	$ 32,000,000
Plans with projected benefit obligation exceeding plan assets, fair value of plan assets			0	0
OPEB plans | U.K.
Change in plan assets
Net funded status			$ 26,000,000	$ 32,000,000