Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2015	Jul. 31, 2015
Entity Information [Line Items]
Entity Registrant Name	MOLSON COORS BREWING CO
Trading Symbol	tap
Entity Central Index Key	0000024545
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Filer Category	Large Accelerated Filer
Common Class A [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		2,562,594
Common Class B [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		162,773,925
Class A Exchangeable Shares [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		2,891,240
Class B Exchangeable Shares [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		16,819,014