Goodwill and Intangible Assets Amortization Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended				12 Months Ended
	Jun. 30, 2014 event		Jun. 29, 2013		Jun. 30, 2014		Jun. 29, 2013		Dec. 31, 2013
Estimated amortization expense of finite-lived intangible assets
2014 - remaining	$ 21.3				$ 21.3
2015	40.2				40.2
2016	40.2				40.2
2017	14.1				14.1
2018	12.3				12.3
Amortization expense of intangible assets	10.4		11.7		21.0		23.6
Indefinite-lived Intangible Assets, Impairment Losses									0
Goodwill	2,440.7				2,440.7				2,418.7
Number of events triggering potential impairment	0
Licensing Agreements [Member]
Estimated amortization expense of finite-lived intangible assets
Finite-Lived Intangible Assets, Net	32.0				32.0
Canada [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage Of Fair Value Exceeding Carrying Value	16.00%				16.00%
Goodwill	715.0				715.0				718.2
Canada [Member] | Licensing Agreements [Member]
Estimated amortization expense of finite-lived intangible assets
Amortization expense of intangible assets	0	[1]	0	[1]	4.9	[1]	0	[1]
Finite-Lived Intangible Assets, Net									4.9
Brands [Member]
Estimated amortization expense of finite-lived intangible assets
Indefinite-lived intangible assets	5,462.2				5,462.2				5,482.3
Molson Core Brands [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage Of Fair Value Exceeding Carrying Value	10.00%				10.00%
Indefinite-lived intangible assets	2,845.0				2,845.0
Jelen Ozujsko Branik [Member] [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage Of Fair Value Exceeding Carrying Value	1.00%				1.00%
Indefinite-lived intangible assets	$ 1,302.5				$ 1,302.5

[1] See Note 4, "Investments" for further discussion related to the termination of MMI operations and related intangible asset charge.