Earnings and Dividends Per Common Share - Computations for Basic and Diluted Income (Loss) Per Common Share from Continuing Operations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net earnings (loss) attributable to United States Steel Corporation stockholders	$ 4,174	$ (1,165)	$ (630)
Weighted-average shares outstanding (in thousands):
Basic	264,667	196,721	171,418
Effect of convertible notes	11,126	0	0
Effect of stock options, restricted stock units and performance awards	4,651	0	0
Adjusted weighted-average shares outstanding, diluted	280,444	196,721	171,418
Basic earnings (loss) per common share	$ 15.77	$ (5.92)	$ (3.67)
Diluted earnings (loss) per common share	$ 14.88	$ (5.92)	$ (3.67)