Goodwill and Intangible Assets Intangible Assets (Details) (USD $)	6 Months Ended		12 Months Ended
	Jun. 30, 2012 years		Dec. 31, 2011 years
Details of intangible assets, other than goodwill:
Total Gross	$ 7,589,000,000		$ 5,028,700,000
Total Net	7,125,300,000		4,586,000,000
Intangible assets subject to amortization:
Accumulated amortization	(463,700,000)		(442,700,000)
Intangible assets not subject to amortization:
Impairment charge associated with Molson brands intangible asset	0
Goodwill, Impaired, Accumulated Impairment Loss	0
Brands [Member]
Intangible assets subject to amortization:
Useful life - minimum (in years)	3		3
Useful life - maximum (in years)	40		40
Gross	456,300,000	[1]	316,900,000
Accumulated amortization	(189,600,000)	[1]	(179,000,000)
Net	266,700,000	[1]	137,900,000
Intangible assets not subject to amortization:
Indefinite-lived intangible assets	5,725,800,000	[1]	3,322,400,000
Brands [Member] | Molson Coors Central Europe (MCCE) [Member]
Details of intangible assets, other than goodwill:
Finite-Lived Intangible Assets, Useful Life	30
Intangible assets subject to amortization:
Gross	135,600,000
Intangible assets not subject to amortization:
Indefinite-lived intangible assets	2,377,500,000
Distribution rights
Intangible assets subject to amortization:
Useful life - minimum (in years)	2		2
Useful life - maximum (in years)	23		23
Gross	343,700,000		342,000,000
Accumulated amortization	(242,500,000)		(234,000,000)
Net	101,200,000		108,000,000
Patents and technology and distribution channels
Intangible assets subject to amortization:
Useful life - minimum (in years)	3		3
Useful life - maximum (in years)	10		10
Gross	34,300,000		34,900,000
Accumulated amortization	(30,400,000)		(28,900,000)
Net	3,900,000		6,000,000
Land use rights and other
Intangible assets subject to amortization:
Useful life - minimum (in years)	2		2
Useful life - maximum (in years)	42		42
Gross	18,300,000	[1]	6,500,000
Accumulated amortization	(1,200,000)	[1]	(800,000)
Net	17,100,000	[1]	5,700,000
Land use rights and other | Molson Coors Central Europe (MCCE) [Member]
Details of intangible assets, other than goodwill:
Finite-Lived Intangible Assets, Useful Life	2
Intangible assets subject to amortization:
Gross	12,000,000
Distribution networks
Intangible assets not subject to amortization:
Indefinite-lived intangible assets	995,100,000		990,500,000
Other, intangible
Intangible assets not subject to amortization:
Indefinite-lived intangible assets	$ 15,500,000		$ 15,500,000

[1] Includes the preliminary fair values of $135.6 million for brand intangibles with a 30 year useful life, $2,377.5 million for brand intangibles with an indefinite-life and a preliminary fair value of a favorable supply contract and other intangibles of $12.0 million with a 2 year useful life as a result of the Acquisition. See Note 3, "Acquisition of StarBev" for total allocation of consideration.