Derivative Instruments and Hedging Activities Derivative Valuation Activity (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended				3 Months Ended			3 Months Ended
	Sep. 29, 2012 Minimum [Member]		Sep. 29, 2012 Maximum [Member]		Sep. 29, 2012 Significant unobservable inputs (Level 3) [Member]		Dec. 31, 2011 Significant unobservable inputs (Level 3) [Member]	Sep. 29, 2012 Significant unobservable inputs (Level 3) [Member] Included in Earnings (or Change in Net Assets) [Member]	Sep. 29, 2012 Significant unobservable inputs (Level 3) [Member] Issuances [Member]		Sep. 29, 2012 Significant unobservable inputs (Level 3) [Member] Equity conversion feature of debt	Sep. 29, 2012 Zero Coupon Senior Unsecured Note [Member] Convertible Debt [Member] Equity conversion feature of debt Molson Coors Central Europe (MCCE)
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, Sales, Issuances, Settlements									$ (15.2)	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings					(13.8)	[1]		(13.8)
Derivative financial instruments, liabilities, fair value disclosure					$ (29.0)		$ 0				$ (29.0)	$ (29.0)
Sensitivitiy of Fair Value Changes, Unobservable Imputs, Implied Volatility Percentage	23.00%	[2]	25.00%	[2]

[1] At issuance, we recorded a liability of $15.2 million related to the Convertible Note's embedded conversion feature.

[2] (1)Significant increase (decrease) in the unobservable input in isolation would result in a significantly higher (lower) fair value measurement.