Recently Adopted Accounting Standards - Narrative (Details)	Dec. 31, 2021 pool
Accounting Changes and Error Corrections [Abstract]
Number of receivable pools	2
Percent of receivables balance covered by credit insurance	79.00%

Credit Risk, Percent Of Receivables Covered By Credit Insurance

No definition available.

Name:	x_CreditRiskPercentOfReceivablesCoveredByCreditInsurance
Namespace Prefix:	x_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant