Document and Entity Information	3 Months Ended
	Mar. 31, 2018 shares
Document and Entity Information
Entity Registrant Name	CITIGROUP INC
Entity Central Index Key	0000831001
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	2,549,933,493
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1