Acquisition and Investments Investment in MillerCoors (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Oct. 10, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 11, 2016
Schedule of Equity Method Investments [Line Items]
Special items, net		$ 28.1	$ (2,522.4)	$ 346.7
Accelerated depreciation		20.5	12.4	49.4
Restructuring Charges		$ 2.6	$ 9.4	$ 9.5
Millercoors [Member]
Schedule of Equity Method Investments [Line Items]
MCBC economic Interest (as a percent)	42.00%		42.00%	42.00%	100.00%
Special items, net	$ 85.6
Accelerated depreciation	103.2			$ 61.3
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	25.7
Restructuring Charges				6.4
Defined Benefit Plan, Settlements, Benefit Obligation				42.4
Condensed balance sheets
Current assets	977.9
Non-current assets	9,247.8
Total assets	10,225.7
Current liabilities	1,140.8
Non-current liabilities	1,244.7
Total liabilities	2,385.5
Noncontrolling interests	17.9
Owners' equity	7,822.3
Total liabilities and equity	10,225.7
Results Of Operations
Net sales	6,125.4			7,725.5
Cost of goods sold	(3,457.4)			(4,547.5)
Gross profit	2,668.0			3,178.0
Operating income	1,169.2			1,239.2
Net income attributable to MillerCoors	$ 1,157.2			$ 1,217.8
SAB Miller [Member]
Schedule of Equity Method Investments [Line Items]
MCBC economic Interest (as a percent)			58.00%		58.00%