Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ (14,831)	$ (522)	$ 4,131
Other comprehensive income (loss) items:
Losses on derivatives	[1]	(2)	(129)	(6)
Pension and postretirement gains (losses)	[2]	(71)	78	137
Reclassification of realized losses on derivatives	[3]	6	2	13
Other comprehensive income (loss), net of tax		(67)	(49)	144
Comprehensive income (loss)		(14,898)	(571)	4,275
Less: Comprehensive income attributable to noncontrolling interests		0	(145)	0
Comprehensive income (loss) attributable to preferred and common stockholders		$ (14,898)	$ (716)	$ 4,275

[1] Net of tax of $1, $36 and $2 in 2020, 2019 and 2018, respectively.

[2] Net of tax of $24, $(25) and $(38) in 2020, 2019 and 2018, respectively. See Note 15 - Retirement and Postretirement Benefit Plans in the Notes to Consolidated Financial Statements in Part II Item 8 of this Form 10-K for additional information.

[3] Net of tax of $(2), $0 and $(4) in 2020, 2019 and 2018, respectively.