Earnings per Share ("EPS") Basic and Diluted (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 26, 2011
Amounts attributable to MCBC
Net income (loss) from continuing operations	$ 79.4	$ 82.6
Income (loss) from discontinued operations, net of tax	0.1	0.3
Net income (loss) attributable to Molson Coors Brewing Company	$ 79.5	$ 82.9
Weighted average shares for basic EPS (in shares)	180.3	186.9
Effect of dilutive securities:
Weighted average shares for diluted EPS (in shares)	181.7	188.7
Basic net income (loss) per share:
Continuing operations attributable to MCBC (in dollars per share)	$ 0.44	$ 0.44
Discontinued operations attributable to MCBC (in dollars per share)	$ 0.00	$ 0.00
Net income attributable to MCBC (in dollars per share)	$ 0.44	$ 0.44
Diluted net income (loss) per share:
Continuing operations attributable to MCBC (in dollars per share)	$ 0.44	$ 0.44
Discontinued operations attributable to MCBC (in dollars per share)	$ 0.00	$ 0.00
Net income attributable to MCBC (in dollars per share)	$ 0.44	$ 0.44
Dividends declared per share (in dollars per share)	$ 0.32	$ 0.28
Options and Sosars [Member]
Effect of dilutive securities:
Effect of dilutive securities of Options, SOSAR's, RSU's, PU's, and DSU's	0.8	1.0
RSU PU DSU [Member]
Effect of dilutive securities:
Effect of dilutive securities of Options, SOSAR's, RSU's, PU's, and DSU's	0.6	0.8