Special Items Severance and Other Employee Related (Details) $ in Millions	9 Months Ended		12 Months Ended		24 Months Ended
	Sep. 30, 2017 USD ($) employee	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($) employee	Dec. 31, 2014 employee	Dec. 31, 2015 USD ($) employee
Severance and other employee-related costs [Member]
Changes in restructuring accruals [Roll Forward]
Beginning balance of restructuring accruals	$ 14.7	$ 9.2
Charges incurred	2.1
Payments made	(9.2)	(2.1)
Changes in estimates		(2.2)
Foreign currency and other adjustments	0.6	(0.4)
Ending balance of restructuring accruals	8.2	4.5	$ 9.2		$ 9.2
Severance and other employee-related costs [Member] | UNITED STATES
Changes in restructuring accruals [Roll Forward]
Beginning balance of restructuring accruals	5.1	0.0
Charges incurred	0.7
Payments made	(5.1)	0.0
Changes in estimates		0.0
Foreign currency and other adjustments	0.0	0.0
Ending balance of restructuring accruals	0.7	0.0	0.0		0.0
Severance and other employee-related costs [Member] | Canada [Member]
Changes in restructuring accruals [Roll Forward]
Beginning balance of restructuring accruals	5.9	2.3
Charges incurred	(0.3)
Payments made	(1.4)	(0.1)
Changes in estimates		0.0
Foreign currency and other adjustments	0.4	0.0
Ending balance of restructuring accruals	4.6	2.2	2.3		2.3
Severance and other employee-related costs [Member] | Europe [Member]
Changes in restructuring accruals [Roll Forward]
Beginning balance of restructuring accruals	2.8	5.6
Charges incurred	0.1
Payments made	(1.2)	(0.7)
Changes in estimates		(2.2)
Foreign currency and other adjustments	0.2	(0.4)
Ending balance of restructuring accruals	1.9	2.3	5.6		5.6
Severance and other employee-related costs [Member] | International [Member]
Changes in restructuring accruals [Roll Forward]
Beginning balance of restructuring accruals	0.2	1.3
Charges incurred	1.5
Payments made	(0.8)	(1.3)
Changes in estimates		0.0
Foreign currency and other adjustments	0.0	0.0
Ending balance of restructuring accruals	0.9	0.0	1.3		1.3
Severance and other employee-related costs [Member] | Corporate [Member]
Changes in restructuring accruals [Roll Forward]
Beginning balance of restructuring accruals	0.7	0.0
Charges incurred	0.1
Payments made	(0.7)	0.0
Changes in estimates		0.0
Foreign currency and other adjustments	0.0	0.0
Ending balance of restructuring accruals	$ 0.1	$ 0.0	$ 0.0		$ 0.0
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | employee			332	72	404
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Payment of severance obligations, term	12 months
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Payment of severance obligations, term	15 months
MillerCoors
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | employee	84