Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 210	$ 173
Non-cash investing and financing activities:
Net transfers of property, plant and equipment from (to) materials and supplies inventories	$ (1)	$ 1