Earnings per Share Basic and Diluted (Details) (USD $) In Millions, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 24, 2011	Sep. 25, 2010	Sep. 24, 2011	Sep. 25, 2010
Amounts attributable to MCBC
Net income (loss) from continuing operations	$ 194.7	$ 257.0	$ 501.6	$ 556.8
Income (loss) from discontinued operations, net of tax	2.7	(0.9)	1.5	41.1
Net income (loss) attributable to Molson Coors Brewing Company	$ 197.4	$ 256.1	$ 503.1	$ 597.9
Weighted average shares for basic EPS (in shares)	185.0	186.0	186.3	185.7
Effect of dilutive securities:
Weighted average shares for diluted EPS (in shares)	186.2	187.4	187.8	187.1
Basic net income (loss) per share:
Continuing operations attributable to MCBC (in dollars per share)	$ 1.05	$ 1.39	$ 2.69	$ 3.00
Discontinued operations attributable to MCBC (in dollars per share)	$ 0.01	$ (0.01)	$ 0.01	$ 0.22
Net income attributable to MCBC (in dollars per share)	$ 1.06	$ 1.38	$ 2.70	$ 3.22
Diluted net income (loss) per share:
Continuing operations attributable to MCBC (in dollars per share)	$ 1.05	$ 1.38	$ 2.67	$ 2.98
Discontinued operations attributable to MCBC (in dollars per share)	$ 0.01	$ (0.01)	$ 0.01	$ 0.22
Net income attributable to MCBC (in dollars per share)	$ 1.06	$ 1.37	$ 2.68	$ 3.20
Dividends declared per share (in dollars per share)	$ 0.32	$ 0.28	$ 0.92	$ 0.80
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	0.9	0.9	0.9
RSU PU DSU [Member]
Effect of dilutive securities:
Effect of dilutive securities of Options, SOSAR's, RSU's, PU's, and DSU's	0.4	0.5	0.6	0.5