Goodwill and Intangible Assets Amortization Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 29, 2013 event	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012	Dec. 29, 2012
Estimated amortization expense of finite-lived intangible assets
2013 - remaining	$ 22.9		$ 22.9
2014	37.9		37.9
2015	35.4		35.4
2016	35.4		35.4
2017	22.0		22.0
Amortization expense of intangible assets	11.7	9.3	23.6	18.6
Indefinite-lived Intangible Assets, Impairment Losses					0
Goodwill	2,325.5		2,325.5		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	61.9		61.9
U.K. [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage of fair value exceeding carrying value	7.00%		7.00%
Canada [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage of fair value exceeding carrying value	15.00%		15.00%
Goodwill	725.3		725.3		764.0
Central Europe
Estimated amortization expense of finite-lived intangible assets
Acquired Indefinite-lived Intangible Asset, Amount	2,702.1		2,702.1
Molson Core Brands [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage of fair value exceeding carrying value	14.00%		14.00%
Indefinite-lived intangible assets	$ 2,903.9		$ 2,903.9