Special Items Summary Special Items (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
	Oct. 11, 2016	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Special items		$ 36.6		$ 4.1		$ (267.7)	$ 27.3
Accounts and Other Receivables, Net, Current				8.2			8.2
Other Employee-Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Special items		28.7		0.8		33.6	2.1
Purchase Price Adjustment [Member]
Restructuring Cost and Reserve [Line Items]
Unusual or Infrequent Item, or Both, Gain, Gross		0.0	$ (328.0)	0.0		(328.0)	0.0
UNITED STATES | Asset Abandonment [Member]
Restructuring Cost and Reserve [Line Items]
Special items		1.4		0.1		4.2	14.5
Canada [Member] | Asset Abandonment [Member]
Restructuring Cost and Reserve [Line Items]
Special items		5.9		6.1		18.0	8.4
Europe [Member]
Restructuring Cost and Reserve [Line Items]
Europe - Gain on sale of asset		0.0		(4.8)		0.0	(4.8)
Europe [Member] | Plovdiv Brewery [Member]
Restructuring Cost and Reserve [Line Items]
Europe - Gain on sale of asset				(4.8)
Europe [Member] | Asset Abandonment [Member]
Restructuring Cost and Reserve [Line Items]
Special items		0.5		1.9		3.2	7.1
International [Member] | China Business [Member]
Restructuring Cost and Reserve [Line Items]
Special items		$ 0.1		$ 0.0		$ 1.3	$ 0.0
MillerCoors
Restructuring Cost and Reserve [Line Items]
Payments to Acquire Businesses, Gross	$ 12,000.0
Finite-Lived Intangible Assets, Purchase Accounting Adjustments					$ 70.0
CashReceivedforAdjustmentAmount			330.0
AdjustmentAmount			$ 328.0