Supplemental Cash Flow Information (Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Supplemental Cash Flow Elements [Abstract]
Additions to property, plant and equipment per the consolidated statements of cash flows				$ 1,910	$ 2,419
Decrease in capital accruals				(421)	(281)
Capital expenditures	[1]	$ 593	$ 1,132	$ 1,489	$ 2,138

[1] Includes changes in capital expenditure accruals. See Note 19 for a reconciliation of total capital expenditures to additions to property, plant and equipment for the six months ended June 30, 2020 and 2019 as reported in the consolidated statements of cash flows.