Acquisition and Investments Other Equity Investments (Details) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017 USD ($) members	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Schedule of Equity Method Investments [Line Items]
Total special items		$ 28.1	$ (2,522.4)	$ 346.7
BRI [Member]
Schedule of Equity Method Investments [Line Items]
Investment in joint venture		2.8	(9.5)
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, Voting Control Percentage		50.00%
Equity Method Investment, Number of Members in Distribution Operation | members		2
Investment in joint venture		$ 33.2	29.2
Equity Method Investment, Administrative Fees Related to Agreements		$ 37.3	34.3	$ 36.4
ABI [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Voting Control Percentage		50.00%
Revolving Credit Facility [Member]
Schedule of Equity Method Investments [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 1,500.0
Debt Instrument, Term	5 years
Other Current Liabilities [Member] | BRI [Member]
Schedule of Equity Method Investments [Line Items]
Guarantees, Fair Value Disclosure		$ 38.1	$ 31.7
Grolsch [Member]
Schedule of Equity Method Investments [Line Items]
MCBC economic Interest (as a percent)		49.00%