Document and Entity Information Document	3 Months Ended
	Mar. 31, 2015	May 01, 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	Mar. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
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		2,559,794
Common Class B [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		162,818,993
Class A Exchangeable Shares [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		2,894,040
Class B Exchangeable Shares [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		17,367,524