Pension and Postretirement Plans (Reconciliation of Projected Benefit Obligations and Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits \| United States
Change in Benefit Obligations
Benefit obligations at January 1	$ 2,730	$ 3,043
Service cost	127	136	$ 132
Interest cost	109	104	108
Plan participant contributions	0	0
Plan amendments	0	0
Net actuarial loss (gain)	380	(167)
Benefits paid	(198)	(386)
Curtailment gain	0	0
Foreign currency exchange rate change	0	0
Benefit obligations at December 31	3,148	2,730	3,043
Change in Fair Value of Plan Assets
Fair value of plan assets at January 1	2,377	2,751
Actual return on plan assets	478	(122)
Company contributions	45	134
Plan participant contributions	0	0
Benefits paid	(198)	(386)
Foreign currency exchange rate change	0	0
Fair value of plan assets at December 31	2,702	2,377	2,751
Funded Status at December 31	(446)	(353)
Pension Benefits \| Int’l.
Change in Benefit Obligations
Benefit obligations at January 1	1,007	1,209
Service cost	23	29	32
Interest cost	26	28	27
Plan participant contributions	2	2
Plan amendments	0	0
Net actuarial loss (gain)	186	(165)
Benefits paid	(31)	(27)
Curtailment gain	0	(5)
Foreign currency exchange rate change	15	(64)
Benefit obligations at December 31	1,228	1,007	1,209
Change in Fair Value of Plan Assets
Fair value of plan assets at January 1	902	972
Actual return on plan assets	121	(29)
Company contributions	28	34
Plan participant contributions	2	2
Benefits paid	(31)	(27)
Foreign currency exchange rate change	24	(50)
Fair value of plan assets at December 31	1,046	902	972
Funded Status at December 31	(182)	(105)
Other Benefits
Change in Benefit Obligations
Benefit obligations at January 1	220	232
Service cost	5	6	6
Interest cost	9	7	8
Plan participant contributions	5	4
Plan amendments	(2)	0
Net actuarial loss (gain)	6	(9)
Benefits paid	(17)	(20)
Curtailment gain	0	0
Foreign currency exchange rate change	0	0
Benefit obligations at December 31	226	220	232
Change in Fair Value of Plan Assets
Fair value of plan assets at January 1	0	0
Actual return on plan assets	0	0
Company contributions	12	16
Plan participant contributions	5	4
Benefits paid	(17)	(20)
Foreign currency exchange rate change	0	0
Fair value of plan assets at December 31		0	$ 0
Funded Status at December 31	$ (226)	$ (220)

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of contributions received by defined benefit plan from participant which increase benefit obligation.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Amount of (increase) decrease in benefit obligation of defined benefit plan from event reducing expected years of future service of present employees or eliminating accrual of benefits for some or all future services of present employees.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of contributions received by defined benefit plan from participant which increases plan assets.

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Amount of foreign currency translation gain (loss) which increases (decreases) plan assets of defined benefit plan.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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