Net Interest and Other Financial Costs (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Other Income and Expenses [Abstract]
Interest income		$ (2)	$ (2)	$ (3)	$ (8)
Interest expense		337	371	688	726
Interest capitalized		(19)	(34)	(36)	(71)
Pension and other postretirement non-service costs	[1]	56	(1)	56	(4)
Other financial costs		0	7	20	30
Net interest and other financial costs		$ 372	$ 341	$ 725	$ 673

[1] See Note 23.