Goodwill and Intangible Assets Amortization Expense (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($) event	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014
Estimated amortization expense of finite-lived intangible assets
2015 - remaining	$ 10.0		$ 10.0
2016	39.9		39.9
2017	29.2		29.2
2018	27.7		27.7
2019	27.7		27.7
Amortization expense of intangible assets	$ 6.4	$ 10.1	20.1	$ 31.1
Number of events triggering potential impairment | event	0
Brands [Member]
Estimated amortization expense of finite-lived intangible assets
Intangible Assets, Reclassified, Fair Value	$ 700.2		700.2
Brands [Member] | Minimum [Member]
Estimated amortization expense of finite-lived intangible assets
Finite-Lived Intangible Asset, Useful Life	30 years
Brands [Member] | Maximum [Member]
Estimated amortization expense of finite-lived intangible assets
Finite-Lived Intangible Asset, Useful Life	50 years
Canada [Member]
Estimated amortization expense of finite-lived intangible assets
Percentage Of Fair Value Exceeding Carrying Value					11.00%
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	$ 2,280.4		$ 2,280.4