Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Adoption of Accounting Standard Update	Common Stock Voting Common Stock	Paid-in Capital	Accumulated Deficit	Accumulated Deficit Adoption of Accounting Standard Update	Accumulated Other Comprehensive Loss, net of tax
Balance at Dec. 31, 2018	$ 659	$ (8)	$ 1	$ 1,788	$ (1,100)	$ (8)	$ (30)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201802Member
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	$ 13			13
Pension and OPEB liability adjustment	0
Foreign currency translation adjustment	(3)						(3)
Available-for-sale securities and interest rate swaps	(19)						(19)
Issuance of common stock	1			1
Repurchase of common stock	(393)				(393)
Dividends on common stock	(73)				(73)
Net income	604				604
Balance at Dec. 31, 2019	781		1	1,802	(970)		(52)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	17			17
Pension and OPEB liability adjustment	(27)						(27)
Foreign currency translation adjustment	10						10
Available-for-sale securities and interest rate swaps	(20)						(20)
Issuance of common stock	(1)			(1)
Repurchase of common stock	(225)				(225)
Dividends on common stock	(78)				(78)
Net income	299				299
Balance at Dec. 31, 2020	756		1	1,818	(974)		(89)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	14			14
Pension and OPEB liability adjustment	2						2
Foreign currency translation adjustment	(8)						(8)
Available-for-sale securities and interest rate swaps	22						22
Repurchase of common stock	(513)				(513)
Dividends on common stock	(81)				(81)
Net income	442				442
Balance at Dec. 31, 2021	$ 634		$ 1	$ 1,832	$ (1,126)		$ (73)