Retirement Plans - Change in Benefit Obligation, Fair Value of Plan Assets, and Funded Status of Pension Plans and Postretirement Medical Plan (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in Fair Value of Plan Assets
Beginning balance	$ 2,568
Ending balance	2,732	$ 2,568
Funded Pension Plans
Change in Benefit Obligation
Beginning balance	2,492	2,765
Service cost	33	30
Interest cost	82	84
Actuarial (gains) loss	401	(237)
Single premium annuity contract payment	(249)	0
Benefit payments	(113)	(110)
Plan curtailments	0	(10)
Plan amendments	0	4
Foreign currency exchange rate changes	21	(34)
Ending balance	2,667	2,492	$ 2,765
Change in Fair Value of Plan Assets
Beginning balance	2,568	2,732
Actual return on plan assets	462	(77)
Employer contributions	40	59
Single premium annuity contract payment	(249)	0
Benefit payments	(113)	(110)
Foreign currency exchange rate changes	24	(36)
Ending balance	2,732	2,568	2,732
Funded Status (Plan assets greater (less) than benefit obligations) at December 31,	65	76
Unrecognized Net Actuarial (Gains) Losses	756	778
Postretirement Medical Plan
Change in Benefit Obligation
Beginning balance	59	87
Service cost	2	2	4
Interest cost	2	3	3
Actuarial (gains) loss	19	(24)
Single premium annuity contract payment	0	0
Benefit payments	(7)	(7)
Plan curtailments	0	(2)
Plan amendments	0	0
Foreign currency exchange rate changes	0	0
Ending balance	75	59	87
Change in Fair Value of Plan Assets
Beginning balance	0	0
Actual return on plan assets	0	0
Employer contributions	7	7
Single premium annuity contract payment	0	0
Benefit payments	(7)	(7)
Foreign currency exchange rate changes	0	0
Ending balance	0	0	0
Funded Status (Plan assets greater (less) than benefit obligations) at December 31,	(75)	(59)
Unrecognized Net Actuarial (Gains) Losses	(12)	(32)
Unfunded Pension Plan
Change in Benefit Obligation
Beginning balance	216	249
Service cost	11	12
Interest cost	7	7
Actuarial (gains) loss	22	(29)
Single premium annuity contract payment	0	0
Benefit payments	(14)	(19)
Plan curtailments	0	(4)
Plan amendments	0	0
Foreign currency exchange rate changes	0	0
Ending balance	242	216	249
Change in Fair Value of Plan Assets
Beginning balance	0	0
Actual return on plan assets	0	0
Employer contributions	14	19
Single premium annuity contract payment	0	0
Benefit payments	(14)	(19)
Foreign currency exchange rate changes	0	0
Ending balance	0	0	$ 0
Funded Status (Plan assets greater (less) than benefit obligations) at December 31,	(242)	(216)
Unrecognized Net Actuarial (Gains) Losses	$ 65	$ 47

Defined benefit plan plan assets single premium annuity contract payment.

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Defined benefit plan single premium annuity contract payment.

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Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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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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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 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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