Document and Entity Information Document	9 Months Ended
	Dec. 31, 2012
Document And Entity Information [Abstract]
Entity Registrant Name	MCKESSON CORP
Entity Central Index Key	0000927653
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Dec. 31, 2012
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding	232,889,372