Earnings per Share ("EPS") Basic and Diluted (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Sep. 24, 2011	Sep. 29, 2012	Sep. 24, 2011
Amounts attributable to MCBC
Net income (loss) from continuing operations	$ 197.7	$ 194.7	$ 381.4	$ 501.6
Income (loss) from discontinued operations, net of tax	0.7	2.7	1.6	1.5
Net income (loss) attributable to Molson Coors Brewing Company	$ 198.4	$ 197.4	$ 383.0	$ 503.1
Weighted average shares for basic EPS (in shares)	181.0	185.0	180.7	186.3
Effect of dilutive securities:
Weighted average shares for diluted EPS (in shares)	182.0	186.2	181.7	187.8
Basic net income (loss) per share:
Continuing operations attributable to MCBC (in dollars per share)	$ 1.09	$ 1.05	$ 2.11	$ 2.69
Discontinued operations attributable to MCBC (in dollars per share)	$ 0.00	$ 0.01	$ 0.01	$ 0.01
Net income attributable to MCBC (in dollars per share)	$ 1.09	$ 1.06	$ 2.12	$ 2.70
Diluted net income (loss) per share:
Continuing operations attributable to MCBC (in dollars per share)	$ 1.09	$ 1.05	$ 2.10	$ 2.67
Discontinued operations attributable to MCBC (in dollars per share)	$ 0.00	$ 0.01	$ 0.01	$ 0.01
Net income attributable to MCBC (in dollars per share)	$ 1.09	$ 1.06	$ 2.11	$ 2.68
Dividends declared per share (in dollars per share)	$ 0.32	$ 0.32	$ 0.96	$ 0.92
Options and Sosars [Member]
Effect of dilutive securities:
Effect of dilutive securities of Options, SOSAR's, RSU's, PU's, and DSU's	0.6	0.8	0.5	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	0.4	0.5	0.6