Employee Benefit Plans (Changes in Projected Benefit Obligations, Plan Assets and Funded Status) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance	$ 2,618
Company contributions		$ 75
End balance	2,965	2,618
Amounts recognized in the Consolidated Balance Sheet:
Accounts payable and accrued liabilities	(85)	(80)
Other postretirement benefits	(661)	(629)
Accrued pensions	(745)	(645)
Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, Beginning of year	3,100	3,462
Service cost	23	28	$ 33
Interest cost	105	97	98
Actuarial losses (gains) - net	449	(246)
Benefits paid	(144)	(125)
Plan transfers	0	8
Foreign currency translation adjustments	34	(88)
Settlements and curtailments	(4)	(24)
Other	(2)	4
Projected benefit obligation, End of year	3,561	3,100	3,462
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance	2,618	2,883
Actual return on plan assets	409	(135)
Company contributions	13	99
Benefits paid	(111)	(102)
Plan settlements	(4)	(24)
Foreign currency translation adjustments	42	(95)
Other	(2)	(8)
End balance	2,965	2,618	2,883
Funded Status	(596)	(482)
Amounts recognized in the Consolidated Balance Sheet:
Other assets (long-term)	183	189
Accounts payable and accrued liabilities	(34)	(26)
Accrued pensions	(745)	(645)
Net liability recognized	(596)	(482)
Other Postretirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, Beginning of year	681	753
Service cost	8	10	10
Interest cost	26	24	24
Plan amendments	(17)	0
Actuarial losses (gains) - net	60	(47)
Benefits paid	(49)	(49)
Foreign currency translation adjustments	4	(8)
Other	(1)	(2)
Projected benefit obligation, End of year	712	681	753
Amounts recognized in the Consolidated Balance Sheet:
Accounts payable and accrued liabilities	(51)	(52)
Other postretirement benefits	(661)	(629)
Net liability recognized	(712)	(681)
United States
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Company contributions	0	75	54
United States | Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, Beginning of year	1,582	1,706
Service cost	13	17
Interest cost	64	57
Actuarial losses (gains) - net	263	(129)
Benefits paid	(80)	(70)
Plan transfers	0	0
Foreign currency translation adjustments	0	0
Settlements and curtailments	0	0
Other	0	1
Projected benefit obligation, End of year	1,842	1,582	1,706
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance	1,140	1,196
Actual return on plan assets	219	(82)
Company contributions	0	75
Benefits paid	(55)	(49)
Plan settlements	0	0
Foreign currency translation adjustments	0	0
Other	0	0
End balance	1,304	1,140	1,196
Funded Status	(538)	(442)
Amounts recognized in the Consolidated Balance Sheet:
Other assets (long-term)	0	0
Accounts payable and accrued liabilities	(26)	(18)
Accrued pensions	(512)	(424)
Net liability recognized	(538)	(442)
United States | Other Postretirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, Beginning of year	587	641
Service cost	8	9
Interest cost	23	21
Plan amendments	(17)	0
Actuarial losses (gains) - net	59	(38)
Benefits paid	(44)	(45)
Foreign currency translation adjustments	0	0
Other	0	(1)
Projected benefit obligation, End of year	616	587	641
Amounts recognized in the Consolidated Balance Sheet:
Accounts payable and accrued liabilities	(46)	(48)
Other postretirement benefits	(570)	(539)
Net liability recognized	(616)	(587)
International
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Company contributions	13	24	33
International | Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, Beginning of year	1,518	1,756
Service cost	10	11
Interest cost	41	40
Actuarial losses (gains) - net	186	(117)
Benefits paid	(64)	(55)
Plan transfers	0	(8)
Foreign currency translation adjustments	34	(88)
Settlements and curtailments	(4)	(24)
Other	(2)	3
Projected benefit obligation, End of year	1,719	1,518	1,756
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance	1,478	1,687
Actual return on plan assets	190	(53)
Company contributions	13	24
Benefits paid	(56)	(53)
Plan settlements	(4)	(24)
Foreign currency translation adjustments	42	(95)
Other	(2)	(8)
End balance	1,661	1,478	1,687
Funded Status	(58)	(40)
Amounts recognized in the Consolidated Balance Sheet:
Other assets (long-term)	183	189
Accounts payable and accrued liabilities	(8)	(8)
Accrued pensions	(233)	(221)
Net liability recognized	(58)	(40)
International | Other Postretirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, Beginning of year	94	112
Service cost	0	1
Interest cost	3	3
Plan amendments	0	0
Actuarial losses (gains) - net	1	(9)
Benefits paid	(5)	(4)
Foreign currency translation adjustments	4	(8)
Other	(1)	(1)
Projected benefit obligation, End of year	96	94	$ 112
Amounts recognized in the Consolidated Balance Sheet:
Accounts payable and accrued liabilities	(5)	(4)
Other postretirement benefits	(91)	(90)
Net liability recognized	$ (96)	$ (94)