Goodwill and Intangible Assets Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Oct. 11, 2016
Goodwill activity:
Balance at beginning of year	$ 8,250.1	$ 1,983.3
Purchase price adjustment	(92.1)
Goodwill, Acquired During Period	13.8	6,415.0
Goodwill, Impairment Loss		(15.7)
Foreign currency translation	233.7	(132.5)
Balance at end of year	$ 8,405.5	8,250.1
Europe [Member]
Goodwill [Line Items]
Percentage Of Fair Value Exceeding Carrying Value	18.00%
Goodwill activity:
Balance at beginning of year	$ 1,260.5	1,408.7
Purchase price adjustment	100.0
Goodwill, Acquired During Period	0.0	0.0
Goodwill, Impairment Loss		0.0
Foreign currency translation	177.5	(148.2)
Balance at end of year	$ 1,538.0	1,260.5
U.S.
Goodwill [Line Items]
Percentage Of Fair Value Exceeding Carrying Value	28.00%
Goodwill activity:
Balance at beginning of year	$ 6,415.6	0.0
Purchase price adjustment	(487.1)
Goodwill, Acquired During Period	0.0	6,415.6
Goodwill, Impairment Loss		0.0
Foreign currency translation	0.0	0.0
Balance at end of year	$ 5,928.5	6,415.6
Canada
Goodwill [Line Items]
Percentage Of Fair Value Exceeding Carrying Value	26.00%
Goodwill activity:
Balance at beginning of year	$ 567.6	551.4
Purchase price adjustment	295.0
Goodwill, Acquired During Period	13.8	0.0
Goodwill, Impairment Loss		0.0
Foreign currency translation	55.7	16.2
Balance at end of year	932.1	567.6
International
Goodwill activity:
Balance at beginning of year	6.4	23.2
Purchase price adjustment	0.0
Goodwill, Acquired During Period	0.0	(0.6)
Goodwill, Impairment Loss		(15.7)
Foreign currency translation	0.5	(0.5)
Balance at end of year	$ 6.9	$ 6.4
Millercoors [Member]
Goodwill [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			$ 9,875.0