Goodwill and Intangible Assets Amortization Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 event		Mar. 31, 2014		Dec. 31, 2014
Estimated amortization expense of finite-lived intangible assets
2015 - remaining	$ 17.0
2016	22.7
2017	11.5
2018	10.0
2019	10.0
Amortization expense of intangible assets	7.8		15.5
Goodwill	2,021.1				2,191.6
Number of events triggering potential impairment	0
Canada [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage Of Fair Value Exceeding Carrying Value	11.00%
Goodwill	601.4				656.5
Canada [Member] | Licensing Agreements [Member]
Estimated amortization expense of finite-lived intangible assets
Amortization expense of intangible assets	0	[1]	4.9	[1]
Finite-Lived Intangible Assets, Net			4.9
Brands [Member]
Estimated amortization expense of finite-lived intangible assets
Indefinite-lived intangible assets	4,175.0				4,590.2
Finite-Lived Intangible Assets, Net	226.6				254.4
Molson Core Brands [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage Of Fair Value Exceeding Carrying Value	9.00%
Indefinite-lived intangible assets	2,393.1
Jelen Ozujsko Branik [Member] [Member]
Estimated amortization expense of finite-lived intangible assets
Indefinite-lived intangible assets	$ 728.1

[1] Upon termination of our MMI operations in the first quarter of 2014, we recognized termination fee income and charges associated with the write-off of the definite-lived intangible asset associated with the joint venture. See Note 4, "Investments" for further discussion.