CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	[1]
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ (3,112)	$ 891	$ 537
Change in value of pension and other postretirement liabilities:
Amortization of prior service cost and net loss, including loss on settlements and curtailments included in net periodic pension cost	[2]	3	8	10
Net actuarial loss incurred in period	[3]	(8)	(5)	(2)
Total change in value of pension and postretirement liabilities		(5)	3	8
Comprehensive income (loss)		$ (3,117)	$ 894	$ 545

[1] In 2018, deferred tax activity incurred in other comprehensive income was offset by a valuation allowance.

[2] Net of $1 million and $2 million in taxes for the years ended December 31, 2020 and 2019, respectively.

[3] Net of ($2) million and ($1) million in taxes for the year ended December 31, 2020 and 2019, respectively.