Special items Summary Special Items (Details) £ in Millions, $ in Millions		3 Months Ended						9 Months Ended			12 Months Ended
	Apr. 30, 2015 GBP (£)	Sep. 30, 2015 GBP (£)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	[1]	Sep. 30, 2015 GBP (£)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 GBP (£)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Restructuring Cost and Reserve [Line Items]
Special items			$ 293.5		$ 367.6				$ 335.8	$ 317.8
Intangible asset write-off			6.4		10.1				20.1	31.1
Accelerated depreciation expense			21.8
Heineken [Member]
Restructuring Cost and Reserve [Line Items]
Proceeds from early contract termination | £	£ 8.0	£ 13.0									£ 5.0
Modelo [Member]
Restructuring Cost and Reserve [Line Items]
Termination fee (income) expense			0.0		0.0	$ (63.2)			0.0	(63.2)
Canada [Member]
Restructuring Cost and Reserve [Line Items]
Accelerated depreciation expense			15.4	$ 7.9
Canada [Member] | Licensing Agreements [Member]
Restructuring Cost and Reserve [Line Items]
Intangible asset write-off			0.0		8.9				0.0	13.8
Canada [Member] | Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Special items			0.0		2.2				0.0	7.6
Canada [Member] | Asset Abandonment [Member]
Restructuring Cost and Reserve [Line Items]
Special items			15.7	$ 8.2	0.0				23.9	0.0
Europe [Member]
Restructuring Cost and Reserve [Line Items]
Termination fee (income) expense			0.0		0.0				10.0	0.0
Accelerated depreciation expense			2.0						21.8
Loss on contract termination								£ 19.0	29.4
Unusual or Infrequent Item, Loss, Gross					0.4							$ 2.2
Europe [Member] | Heineken [Member]
Restructuring Cost and Reserve [Line Items]
Termination fee (income) expense									(19.4)
Europe [Member] | Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Special items			0.5		0.0				(0.5)	1.0
Europe [Member] | Asset Abandonment [Member]
Restructuring Cost and Reserve [Line Items]
Special items			2.3		0.0				23.4	0.0
Europe [Member] | Brand Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Special items			275.0		360.0				275.0	360.0		$ 360.0	$ 150.9
Europe [Member] | Flood loss [Member]
Restructuring Cost and Reserve [Line Items]
Unusual or Infrequent Item, Net of Insurance Proceeds			0.0		(3.5)				(2.4)	(1.7)
Restructuring, Settlement and Impairment Provisions - Gain									2.4
Unusual or Infrequent Item, Insurance Proceeds										3.9
MCI [Member]
Restructuring Cost and Reserve [Line Items]
Accelerated depreciation expense									0.7
MCI [Member] | Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Special items			0.0		0.0				3.2	0.0
MCI [Member] | China Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Special items			0.0		0.0				3.2	0.0
Corporate [Member] | Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Special items			$ 0.0		$ 0.0				$ 0.0	$ 0.3

[1] During the second quarter of 2015, we announced our decision to substantially restructure our business in China and consequently, recognized employee-related and asset write-off charges, including $0.7 million of accelerated depreciation.