Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Allowance for doubtful accounts receivable, current	$ 8	$ 11
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 25	$ 25
Preferred stock, shares authorized (in shares)	10	10
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	2,400	2,400
Common stock, shares issued (in shares)	1,741	1,741
Treasury stock (in shares)	817	821