Employee Benefits, Defined Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Postretirement Medical Obligations
Accrued annual VEBA contribution	$ 13.7		$ 16.0
Benefit Obligations and Funded Status Additional Disclosure
Net asset In respect of VEBAs	340.1		406.0
Net liability of VEBA	17.2		0
Estimated future benefit payments
Expected future benefit payments, 2015	30.6
Expected future benefit payments, 2016	30.4
Expected future benefit payments, 2017	30.2
Expected future benefit payments, 2018	29.8
Expected future benefit payments, 2019	29.5
Expected future benefit payments, 2020-2023	139.5
Components of Net Periodic Benefit Cost (Income)
Net periodic benefit cost (income)	(23.5)		(22.0)		(11.5)
Canadian pension plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	6.2		5.8
Assumptions used to determine benefit obligations
Discount rate	4.00%		4.90%
Rate of compensation increase	3.00%		3.00%
Assumptions used to determine net periodic benefit cost (income)
Discount rate	4.90%		4.40%		5.60%
Expected long-term return on plan assets	4.75%		4.50%		4.60%
Rate of compensation increase	3.00%		3.00%		3.00%
Change in benefit obligation:
Obligation at beginning of year	6.6		7.0
Foreign currency translation adjustment	(0.5)		(0.5)
Service cost	0.2		0.3		0.2
Interest cost	0.3		0.3		0.3
Actuarial (gain) loss	0.7		(0.2)
Plan participant contributions	0		0
Benefits paid by Company	(0.3)		(0.3)
Obligation at end of year	7.0		6.6		7.0
Change in plan assets:
Fair market value of plan assets at beginning of year	6.2		5.7
Foreign currency translation adjustment	(0.5)		(0.4)
Actual return on assets	0.6		0.7
Plan participant contributions	0		0
Employer/Company contributions	0.3		0.5
Benefits paid by Company	(0.3)		(0.3)
Fair market value of plan assets at end of year	6.3		6.2		5.7
Net funded status	(0.7)		(0.4)
Net Funded Status
Accumulated plan benefit obligation	(7.0)		(6.6)		(7.0)
Plan assets	6.3		6.2		5.7
Net funded status	(0.7)		(0.4)
Net benefits expected to be contributed in 2014	0.3
Estimated future benefit payments
Expected future benefit payments, 2015	0.3
Expected future benefit payments, 2016	0.3
Expected future benefit payments, 2017	0.3
Expected future benefit payments, 2018	0.3
Expected future benefit payments, 2019	0.3
Expected future benefit payments, 2020-2023	1.6
Accumulated other comprehensive (loss) income
Accumulated net actuarial (losses) gains	(1.9)		(1.8)
Transition assets	0.2		0.2
Loss recognized in Accumulated other comprehensive income (loss)	(1.7)		(1.6)
Amounts in Accumulated other comprehensive (loss) income expected to be recognized in 2014
Future amortization of prior service cost	0.1
Components of Net Periodic Benefit Cost (Income)
Service cost	0.2		0.3		0.2
Interest cost	0.3		0.3		0.3
Expected return on plan assets	(0.3)		(0.3)		(0.2)
Amortization of prior service cost	0		0		0
Amortization of net actuarial loss (gain)	0.1		0.2		0.1
Canadian pension plan | London, Ontario Facility | Equity Securities
Defined Benefit Plan at the London, Ontario Facility, Information About Plan Assets
Actual plan asset allocations	66.00%
Asset mix target allocation on long-term investments	66.00%
Canadian pension plan | London, Ontario Facility | Fixed Income Securities
Defined Benefit Plan at the London, Ontario Facility, Information About Plan Assets
Actual plan asset allocations	31.00%
Asset mix target allocation on long-term investments	30.00%
VEBAs
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Amendments	90.4		84.6	[1]
Postretirement Medical Obligations
Cash flow in determining VEBA obligation	20.0
Change in benefit obligation:
Obligation at beginning of year	374.7	[1]	384.1	[1]
Foreign currency translation adjustment	0		0	[1]
Service cost	2.2		2.5	[1]	3.4
Interest cost	16.7		14.6	[1]	17.9
Actuarial (gain) loss	10.2	[2]	(91.9)	[1],[2]
Plan participant contributions	0		0	[1]
Benefits paid by VEBAs	(24.7)		(21.5)	[1]
Reimbursement from Retiree Drug Subsidy	1.4	[3]	2.3	[1],[3]
Obligation at end of year	470.9		374.7	[1]	384.1	[1]
Change in plan assets:
Fair market value of plan assets at beginning of year	780.7	[1]	744.7	[1]
Foreign currency translation adjustment	0		0	[1]
Actual return on assets	22.7		39.2	[1]
Plan participant contributions	0		0	[1]
Employer/Company contributions	13.7	[4]	16.0	[1],[4]
Benefits paid by VEBAs	(24.7)		(21.5)	[1]
Reimbursement from Retiree Drug Subsidy	1.4	[3]	2.3	[1],[3]
Fair market value of plan assets at end of year	793.8		780.7	[1]	744.7	[1]
Net funded status	322.9	[5]	406.0	[1],[5]
Benefit Obligations and Funded Status Additional Disclosure
Actuarial gain due to a decrease in discount rate	(45.0)		(30.5)
Actuarial gain due to higher than expected mortality rate	(37.2)
Actuarial loss resulting from an increase in existing benefits reimbursement rates			20.8
Actuarial (gain) loss due to projected lower benefit utilization	53.6
Net Funded Status
Accumulated plan benefit obligation	(470.9)		(374.7)	[1]	(384.1)	[1]
Plan assets	793.8		780.7	[1]	744.7	[1]
Net funded status	322.9	[5]	406.0	[1],[5]
Estimated future benefit payments
Expected future benefit payments, 2015	30.3	[6]
Expected future benefit payments, 2016	30.1	[6]
Expected future benefit payments, 2017	29.9	[6]
Expected future benefit payments, 2018	29.5	[6]
Expected future benefit payments, 2019	29.2	[6]
Expected future benefit payments, 2020-2023	137.9	[6]
Accumulated other comprehensive (loss) income
Accumulated net actuarial (losses) gains	43.6		84.3
Prior service cost	(197.4)		(117.5)
Loss recognized in Accumulated other comprehensive income (loss)	(153.8)		(33.2)
Amounts in Accumulated other comprehensive (loss) income expected to be recognized in 2014
Amounts in Accumulated other comprehensive (loss) income expected to be recognized in 2014	18.3
Future amortization of prior service cost	17.3
Future amortization of actuarial gain (loss)	1.0
Components of Net Periodic Benefit Cost (Income)
Service cost	2.2		2.5	[1]	3.4
Interest cost	16.7		14.6	[1]	17.9
Expected return on plan assets	(51.4)		(45.1)		(40.4)
Amortization of prior service cost	10.6	[7]	4.2	[7]	4.2	[7]
Amortization of net actuarial loss (gain)	(1.8)		1.3		3.0
VEBAs | Maximum
Postretirement Medical Obligations
Variable cash contribution obligation to VEBAs	20.0
VEBAs | Annual Cash Flows up to $20 Million
Postretirement Medical Obligations
Postretirement medical plan contribution obligation percentage	10.00%
VEBAs | Annual Cash Flows in Excess of $20 Million
Postretirement Medical Obligations
Postretirement medical plan contribution obligation percentage	20.00%
Union VEBA
Postretirement Medical Obligations
Number of trustees	4
Percent allocation of total contribution between VEBAs	85.50%
Accrued annual VEBA contribution	11.7
Assumptions used to determine benefit obligations
Discount rate	3.80%		4.70%
Initial medical trend rate	7.00%	[8]	7.50%	[8]
Ultimate medical trend rate	5.00%	[8],[9]	5.00%	[8],[9]	5.00%	[9]
Year that rate reaches ultimate trend rate	2019		2019		2019
Effect of one-percentage-point increase in medical trend rate on accumulated postretirement benefit obligation	37.7		27.8
Effect of one-percentage-point decrease in medical trend rate on accumulated postretirement benefit obligation	29.9		22.7
Assumptions used to determine net periodic benefit cost (income)
Discount rate	4.70%		4.00%		4.20%
Expected long-term return on plan assets	6.75%	[10]	6.25%	[10]	7.25%	[10]
Initial medical trend rate	7.50%	[9]	8.00%	[9]	8.50%	[9]
Ultimate medical trend rate	5.00%	[8],[9]	5.00%	[8],[9]	5.00%	[9]
Year that rate reaches ultimate trend rate	2019		2019		2019
Effect of one-percentage-point increase on service and interest cost components	2.6		2.0		2.5
Effect of one-percentage-point decrease on service and interest cost components	2.0		1.5		2.0
Change in benefit obligation:
Obligation at beginning of year	312.7
Obligation at end of year	391.5		312.7
Change in plan assets:
Fair market value of plan assets at beginning of year	717.5
Sale of Company's common stock by Union VEBA	0		0	[1]
Fair market value of plan assets at end of year	731.6		717.5
Net funded status	340.1		404.8
Benefit Obligations and Funded Status Additional Disclosure
Actuarial gain due to lower than expected drug claim costs	18.0		54.9
Actuarial gain due to higher than expected mortality rate			(8.0)
Actuarial loss due to the addition of a new healthcare premium reimbursement benefit starting in 2014	60.5
Prior Service Cost Due to a New Death Benefit	15.9
Prior Service Cost Due to Increase in the Annual Healthcare Reimbursement			63.8
Actuarial loss due to changes in administrative costs	0.4		2.7
Net Funded Status
Accumulated plan benefit obligation	(391.5)		(312.7)
Plan assets	731.6		717.5
Net funded status	340.1		404.8
Union VEBA | Company Appointed
Postretirement Medical Obligations
Number of trustees	2
Union VEBA | USW Appointed
Postretirement Medical Obligations
Number of trustees	2
Salaried VEBA
Postretirement Medical Obligations
Percent allocation of total contribution between VEBAs	14.50%
Accrued annual VEBA contribution	2.0
Assumptions used to determine benefit obligations
Discount rate	3.60%		4.20%
Assumptions used to determine net periodic benefit cost (income)
Discount rate	4.20%		3.40%		3.75%
Expected long-term return on plan assets	7.75%	[10]	7.25%	[10]	7.25%	[10]
Change in benefit obligation:
Obligation at beginning of year	62.0
Obligation at end of year	79.4		62.0
Change in plan assets:
Fair market value of plan assets at beginning of year	63.2
Fair market value of plan assets at end of year	62.2		63.2
Net funded status	(17.2)		1.2
Benefit Obligations and Funded Status Additional Disclosure
Prior Service Cost Due to Increase in the Annual Healthcare Reimbursement	14.0
Net Funded Status
Accumulated plan benefit obligation	(79.4)		(62.0)
Plan assets	62.2		63.2
Net funded status	(17.2)		1.2
Variable cash contribution | VEBAs
Postretirement Medical Obligations
Annual VEBA contribution paid	16.0
As Reported | VEBAs
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Amendments			0	[1]
Change in benefit obligation:
Obligation at beginning of year			384.1	[1]
Foreign currency translation adjustment			0	[1]
Service cost			2.5	[1]
Interest cost			14.6	[1]
Actuarial (gain) loss			(7.3)	[1],[2]
Plan participant contributions			0	[1]
Benefits paid by VEBAs			(21.5)	[1]
Reimbursement from Retiree Drug Subsidy			2.3	[1],[3]
Obligation at end of year			374.7	[1]
Change in plan assets:
Fair market value of plan assets at beginning of year			744.7	[1]
Foreign currency translation adjustment			0	[1]
Actual return on assets			39.2	[1]
Plan participant contributions			0	[1]
Employer/Company contributions			16.0	[1],[4]
Benefits paid by VEBAs			(21.5)	[1]
Reimbursement from Retiree Drug Subsidy			2.3	[1],[3]
Fair market value of plan assets at end of year			780.7	[1]
Net funded status			406.0	[1],[5]
Net Funded Status
Accumulated plan benefit obligation			(374.7)	[1]
Plan assets			780.7	[1]
Net funded status			406.0	[1],[5]
Accumulated other comprehensive (loss) income
Accumulated net actuarial (losses) gains			(0.5)
Prior service cost			(32.7)
Loss recognized in Accumulated other comprehensive income (loss)			(33.2)
Components of Net Periodic Benefit Cost (Income)
Service cost			2.5	[1]
Interest cost			14.6	[1]
As Reported | Union VEBA
Change in plan assets:
Sale of Company's common stock by Union VEBA			$ 0	[1]

[1] The presentation of Change in benefit obligation in the table above has been revised from the prior year presentation to reflect separate amounts for actuarial gains and losses and prior service costs related to plan amendments. This information was presented in a footnote to the table in the prior year. The 2013 balances shown above were adjusted to reflect this reclassification. The impacts to the prospective amortization of Prior service cost and Actuarial loss (gain) were not material.

[2] The actuarial gain relating to the VEBAs in 2014 was primarily comprised of (i) a gain of $53.6 due to projected lower benefit utilization; (ii) a gain of $18.0 due to projected lower drug claim cost in the future because of lower than expected drug claim costs in 2014 in the Union VEBA; (iii) a gain of $0.4 due primarily to a reduction in administrative cost in the Union VEBA; partially offset by (iv) a loss of $45.0 due primarily to reductions in the discount rates; and (v) a loss of $37.2 due primarily to updated actuarial mortality rates in both VEBAs.The actuarial gain relating to the VEBAs in 2013 was primarily comprised of (i) a gain of $54.9 due to projected lower drug claim cost in the future because of lower than expected drug claim costs in 2013 in the Union VEBA; (ii) a gain of $30.5 due to a decrease in discount rates used to determine benefit obligations for both VEBAs; (iii) a gain of $8.0 due primarily to a higher than expected mortality rate in the Union VEBA; partially offset by (iv) a loss of $2.7 due primarily to an increase in administrative cost in the Union VEBA.

[3] The Union VEBA is eligible for the retiree drug subsidy of the Medicare Modernization Act that went into effect January 1, 2006. As a result, the Company has measured the Union VEBA’s obligations and costs to take into account this subsidy.

[4] The Company accrued a liability for a variable cash contribution of $13.7 to the VEBAs with respect to calendar year 2014, which will be paid in the first quarter of 2015. The Company accrued a liability for a variable cash contribution of $16.0 to the VEBAs with respect to calendar year 2013, which was paid in the first quarter of 2014.

[5] Prepaid benefits of $322.9 at December 31, 2014 was comprised of $340.1 presented as Net asset of VEBAs on the Consolidated Balance Sheet related to the Union VEBA, offset by $17.2 presented as Net liability in respect of VEBA related to the Salaried VEBA. Prepaid benefits of $406.0 relating to both VEBAs at December 31, 2013 were presented as Net asset of VEBAs on the Consolidated Balance Sheet.

[6] Such amounts were obtained from the VEBAs. The Company's only financial obligations to the VEBAs are to pay the variable contributions, which may not exceed $20.0 annually, and certain administrative fees.

[7] The Company amortizes prior service cost on a straight-line basis over the average remaining years of service to full eligibility for benefits of the active plan participants.

[8] The medical trend rate assumptions used for the Union VEBA were provided by the Union VEBA and certain industry data were provided by the Company's actuaries. The trend rate is assumed to decline to 5% by 2019 at each of December 31, 2014 and December 31, 2013. A one-percentage-point increase in the assumed medical trend rates would increase the accumulated postretirement benefit obligation of the Union VEBA by $37.7 and $27.8 at December 31, 2014 and December 31, 2013, respectively. A one-percentage-point decrease in the assumed medical trend rates would decrease the accumulated postretirement benefit obligation of the Union VEBA by $29.9 and $22.7 at December 31, 2014 and December 31, 2013, respectively.

[9] The medical trend rate assumptions used for the Union VEBA, which is currently paying certain prescription drug benefits, were provided by the Union VEBA and certain industry data were provided by the Company's actuaries. The trend rate is assumed to decline to 5% by 2019 for each of 2014, 2013 and 2012. A one-percentage-point increase in the assumed medical trend rates would increase the aggregate of the service and interest cost components of net periodic benefit costs by $2.6, $2.0 and $2.5 for 2014, 2013 and 2012, respectively. A one-percentage-point decrease in the assumed medical trend rates would decrease the aggregate of the service and interest cost components of net periodic benefit costs by $2.0, $1.5 and $2.0 for 2014, 2013 and 2012, respectively.

[10] The expected long-term rate of return assumption is based on the targeted investment portfolios provided to the Company by the VEBAs’ trustees.