Special items Summary Special Items (Details) (USD $)	3 Months Ended				12 Months Ended
	Mar. 31, 2012		Mar. 26, 2011		Dec. 26, 2009
Restructuring Cost and Reserve [Line Items]
Total special items	$ 1,500,000		$ 0
Non-income-related Tax Reserves					10,400,000
Gain (Loss) Related to Restructuring Reserve Low End of Range	0
Gain (Loss) Related to Restructuring Reserve High End of Range	22,300,000
Canada | Restructuring, exit and other related costs associated with the Edmonton and Montreal breweries
Restructuring Cost and Reserve [Line Items]
Total special items	1,600,000		0
Canada | Special termination benefits
Restructuring Cost and Reserve [Line Items]
Total special items	500,000	[1]	2,800,000	[1]
Canada | Flood insurance reimbursement
Restructuring Cost and Reserve [Line Items]
Total special items	0	[2]	(600,000)	[2]
U.K. | Restructuring charge
Restructuring Cost and Reserve [Line Items]
Total special items	1,800,000		300,000
U.K. | Release of non-income-related tax reserve
Restructuring Cost and Reserve [Line Items]
Total special items	(3,500,000)	[3]	(2,500,000)	[3]
Corporate [Member] | Restructuring charge
Restructuring Cost and Reserve [Line Items]
Total special items	$ 1,100,000		$ 0

[1] During the first quarters of 2012 and 2011, we recognized charges related to special termination benefits as eligible employees elected early retirement offered as a result of the Montreal Brewery and Distribution group's ratification of a Collective Bargaining Agreement with MCC in the first quarter of 2011.

[2] During 2011, we incurred expenses related to flood damages at our Toronto offices, which was partially offset by insurance proceeds.

[3] During 2009, we established a non-income-related tax reserve of $10.4 million that was recorded as a Special item. Our estimates indicated a range of possible loss relative to this reserve of zero to $22.3 million, inclusive of potential penalties and interest. The amounts recorded in 2012 and 2011 represent a release of a portion of this reserve as a result of a change in estimate.