Document and Entity Information	6 Months Ended
	Jun. 30, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	ARCELORMITTAL
Entity Central Index Key	0001243429
Current Fiscal Year End Date	--12-31
Document Type	6-K
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false