Employee Benefit Plans and Postretirement Benefits - Defined Benefit Pension, Healthcare and Other Plans (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Beginning benefit obligation
Plan amendments	$ 527
Change in the fair value of plan assets:
Beginning plan assets	2,422
Ending plan assets	2,248	$ 2,422
Pension
Beginning benefit obligation
Beginning benefit obligation	3,029	3,365
Service cost	23	25	$ 30
Interest cost	74	71	74
Plan participants’ contributions	3	3
Actuarial loss (gain)	377	(140)
Gross benefits paid	(156)	(207)
Plan amendments	(2)	22
Currency translation adjustments and other	(410)	(110)
Ending benefit obligation	2,938	3,029	3,365
Change in the fair value of plan assets:
Beginning plan assets	2,281	2,517
Actual return on plan assets	305	(46)
Employer contributions	53	55
Plan participants’ contributions	3	3
Gross benefits paid	(130)	(179)
Currency translation adjustments and other	(416)	(69)
Ending plan assets	2,096	2,281	2,517
Funded status	(842)	(748)
Healthcare
Beginning benefit obligation
Beginning benefit obligation	434	1,120
Service cost	5	6	6
Interest cost	14	24	36
Plan participants’ contributions	10	9
Actuarial loss (gain)	45	(129)
Gross benefits paid	(42)	(63)
Plan amendments	(47)	(530)
Currency translation adjustments and other	(7)	(3)
Ending benefit obligation	412	434	1,120
Change in the fair value of plan assets:
Beginning plan assets	141	184
Actual return on plan assets	27	(6)
Employer contributions	0	0
Plan participants’ contributions	0	0
Gross benefits paid	(16)	(37)
Currency translation adjustments and other	0	0
Ending plan assets	152	141	184
Funded status	(260)	(293)
Other
Beginning benefit obligation
Beginning benefit obligation	422	470
Service cost	13	15	15
Interest cost	3	3	3
Plan participants’ contributions	0	0
Actuarial loss (gain)	37	(8)
Gross benefits paid	(37)	(37)
Plan amendments	0	0
Currency translation adjustments and other	(7)	(21)
Ending benefit obligation	431	422	470
Change in the fair value of plan assets:
Beginning plan assets	0	0
Actual return on plan assets	0	0
Employer contributions	0	0
Plan participants’ contributions	0	0
Gross benefits paid	0	0
Currency translation adjustments and other	0	0
Ending plan assets	0	0	$ 0
Funded status	$ (431)	$ (422)

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 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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