Goodwill and Intangible Assets Amortization Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 30, 2013 event	Mar. 31, 2012	Dec. 29, 2012
Estimated amortization expense of finite-lived intangible assets
2012 - remaining	$ 34.9
2013	38.7
2014	36.2
2015	36.2
2016	22.3
Amortization expense of intangible assets	11.9	9.3
Indefinite-lived Intangible Assets, Impairment Losses			0
Goodwill	2,365.7		2,453.1
Number of events triggering potential impairment	0
Licensing Agreements [Member]
Estimated amortization expense of finite-lived intangible assets
Finite-Lived Intangible Assets, Net	66.4
U.K. [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage of fair value exceeding carrying value	7.00%
Goodwill	818.1
Canada [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage of fair value exceeding carrying value	15.00%
Goodwill	750.0		764.0
Central Europe
Estimated amortization expense of finite-lived intangible assets
Goodwill	789.4
Acquired Indefinite-lived Intangible Asset, Amount	2,332.1
Molson Core Brands [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage of fair value exceeding carrying value	14.00%
Indefinite-lived intangible assets	3,002.3
Carling [Member] | U.K. [Member]
Estimated amortization expense of finite-lived intangible assets
Indefinite-lived intangible assets	$ 304.6