Acquisition and Investments Transactions with MillerCoors (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Oct. 10, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Millercoors [Member]
Schedule of Equity Method Investments [Line Items]
Beer sales to MillerCoors	$ 7.5	$ 0.0		$ 11.7
Beer purchases from MillerCoors	32.0	0.0		43.2
Service agreement costs and other charges to MillerCoors	1.9	0.0		2.6
Service agreement costs and other charges from MillerCoors	$ 0.9	0.0		0.9
BRI [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Administrative Fees Related to Agreements		93.5	$ 85.8	88.8
BDL [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Administrative Fees Related to Agreements		$ 37.3	$ 34.3	$ 36.4