Derivatives - Classification of Gross Fair Values of Derivative Instruments, Excluding Cash Collateral (Detail) - Commodity derivatives - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Other current assets
Derivatives, Fair Value [Line Items]
Asset		$ 786	$ 63
Liability		629	106
Other current liabilities(a)
Derivatives, Fair Value [Line Items]
Asset		0	0
Liability	[1]	2	5
Deferred credits and other liabilities
Derivatives, Fair Value [Line Items]
Asset		0	0
Liability	[1]	$ 43	$ 55

[1] Includes embedded derivatives.