Commitments and Contingencies Loss Contingency (Details) CAD in Millions, $ in Millions		1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Dec. 12, 2014 CAD	Dec. 31, 2009 CAD	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 1990 USD ($)	Dec. 31, 2014 USD ($)
Loss Contingencies [Line Items]
Loss contingency, possible loss, maximum			$ 106.0			$ 106.0
Guarantees
Letter of credit provided to entity | CAD		CAD 10
Litigation and Other Disputes
Accrued liabilities, litigations and disputes			14.1			14.1			$ 16.6
Loss contingency, possible loss, portion not accrued			78.0			78.0
Loss contingency, possible loss, minimum			0.0			0.0
Gain on litigation, favorable outcome					$ 13.0
Income tax benefit, litigation settlement					$ (18.5)
Kaiser purchased tax credits indemnity reserve, category two
Loss Contingencies [Line Items]
Loss contingency, possible loss, maximum			88.6			$ 88.6
Kaiser Tax, Civil and Labor Indemnity Reserve [Member]
Loss Contingencies [Line Items]
Equity interest sold (as a percent)						68.00%
Loss contingency, possible loss, maximum			68.0			$ 68.0
Environmental matters Lowry [Member]
Environmental
Environmental remediation expense, pretax charge								$ 30.0
Environmental remediation threshold, assumed remediation cost			$ 120.0			$ 120.0
Inflation rate assumption, future costs (as a percent)			2.50%			2.50%
Risk free rate of return assumption (as a percent)			2.47%			2.47%
Site contingency, accrual, present value			$ 3.3			$ 3.3
Site contingency, accrual, undiscounted amount			6.2			6.2
David Hughes and 631992 Ontario Inc [Member]
Litigation and Other Disputes
Loss contingency, damages sought | CAD	CAD 1,400
Cervejarias Kaiser Brasil S.A. [Member]
Loss Contingencies [Line Items]
Gain (loss) discontinued operations			2.9	$ 1.3		4.5	$ (0.4)
Other Current Liabilities [Member] | Brewers' Retail Inc. (BRI) [Member]
Loss Contingencies [Line Items]
Guarantor Obligations, Current Carrying Value			12.4			12.4
Other Noncurrent Liabilities [Member] | Canada [Member]
Loss Contingencies [Line Items]
Guarantor Obligations, Current Carrying Value			$ 4.6			$ 4.6			$ 5.3