Derivative Instruments and Hedging Activities Derivative Valuation Activity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 30, 2013	Dec. 29, 2012
Significant unobservable inputs (Level 3) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	$ (29.5)
Derivative financial instruments, liabilities, fair value disclosure	(37.4)	(7.9)
Significant unobservable inputs (Level 3) [Member] | Included in Earnings (or Change in Net Assets) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	(29.5)
Significant unobservable inputs (Level 3) [Member] | Issuances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, Sales, Issuances, Settlements	0
Significant unobservable inputs (Level 3) [Member] | Equity conversion feature of debt
Derivative Instruments, Gain (Loss) [Line Items]
Derivative financial instruments, liabilities, fair value disclosure	(37.4)
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]
Derivative financial instruments, liabilities, fair value disclosure	$ 37.4