Revenue - Disaggregation of Sales by Product (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Net sales	$ 20,275	$ 9,741	$ 12,937
Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	138	96	316
Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	6,485	2,066	3,501
Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	4,759	2,266	2,795
Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	6,516	3,894	3,999
Tubular products
Disaggregation of Revenue [Line Items]
Net sales	839	661	1,206
All Other (b)
Disaggregation of Revenue [Line Items]
Net sales	1,538	758	1,120
Flat-Rolled
Disaggregation of Revenue [Line Items]
Net sales	12,180	7,071	9,279
Flat-Rolled | Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	12	94	305
Flat-Rolled | Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	2,592	1,273	2,504
Flat-Rolled | Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	3,785	2,102	2,512
Flat-Rolled | Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	4,408	2,990	2,993
Flat-Rolled | Tubular products
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Flat-Rolled | All Other (b)
Disaggregation of Revenue [Line Items]
Net sales	1,383	612	965
Mini Mill (a)
Disaggregation of Revenue [Line Items]
Net sales	3,008
Mini Mill (a) | Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	0
Mini Mill (a) | Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	1,744
Mini Mill (a) | Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	526
Mini Mill (a) | Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	732
Mini Mill (a) | Tubular products
Disaggregation of Revenue [Line Items]
Net sales	0
Mini Mill (a) | All Other (b)
Disaggregation of Revenue [Line Items]
Net sales	6
USSE
Disaggregation of Revenue [Line Items]
Net sales	4,262	1,967	2,417
USSE | Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	126	2	11
USSE | Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	2,149	793	997
USSE | Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	448	164	283
USSE | Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	1,376	904	1,006
USSE | Tubular products
Disaggregation of Revenue [Line Items]
Net sales	58	40	40
USSE | All Other (b)
Disaggregation of Revenue [Line Items]
Net sales	105	64	80
Tubular
Disaggregation of Revenue [Line Items]
Net sales	789	639	1,188
Tubular | Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Tubular | Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Tubular | Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Tubular | Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Tubular | Tubular products
Disaggregation of Revenue [Line Items]
Net sales	781	621	1,166
Tubular | All Other (b)
Disaggregation of Revenue [Line Items]
Net sales	8	18	22
Other
Disaggregation of Revenue [Line Items]
Net sales	36	64	53
Other | Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other | Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other | Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other | Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other | Tubular products
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other | All Other (b)
Disaggregation of Revenue [Line Items]
Net sales	$ 36	$ 64	$ 53