Kaiser Aluminum (KALU) 10-K 20 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 16, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	Kaiser Aluminum Corp
Entity Central Index Key	811596
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		17,464,752
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$1.30

Consolidated_Balance_Sheet

Consolidated Balance Sheet (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:
Cash and cash equivalents	$177.70	$169.50
Short-term investments	114	129.5
Receivables:
Trade receivables — net	129.3	119.8
Allowance for Doubtful Accounts Receivable, Current	0.8	0.8
Other	10.9	13.4
Inventories	214.7	214.4
Prepaid expenses and other current assets	178.6	44.2
Total current assets	825.2	690.8
Property, plant and equipment — net	454.9	429.3
Net asset of VEBAs	340.1	406
Deferred tax assets — net (including deferred tax liability relating to the VEBAs of $120.6 at December 31, 2014 and $152.4 at December 31, 2013 - see Note 5)	30.9	69.1
Intangible assets — net	32.1	33.7
Goodwill	37.2	37.2
Other assets	23.3	104.8
Total	1,743.70	1,770.90
Current liabilities:
Accounts payable	81.4	62.9
Accrued salaries, wages and related expenses	39.6	42.7
Other accrued liabilities	132.8	44.8
Current portion of long-term debt	172.5	0
Short-term capital leases	0.1	0.2
Total current liabilities	426.4	150.6
Net liability of VEBA	17.2	0
Deferred tax liabilities	0.9	1.2
Long-term liabilities	58.3	146.4
Long-term debt	225	388.5
Total liabilities	727.8	686.7
Commitments and contingencies — Note 9
Stockholders’ equity:
Preferred stock, 5,000,000 shares authorized at both December 31, 2014 and December 31, 2013; no shares were issued and outstanding at December 31, 2014 and December 31, 2013	0	0
Common stock, par value $0.01, 90,000,000 shares authorized at both December 31, 2014 and December 31, 2013; 21,197,164 shares issued and 17,607,251 shares outstanding at December 31, 2014; 21,103,700 shares issued and 18,147,017 shares outstanding at December 31, 2013	0.2	0.2
Additional paid in capital	1,028.50	1,023.10
Retained earnings	280.4	233.8
Treasury stock, at cost, 3,589,913 shares at December 31, 2014 and 2,956,683 shares at December 31, 2013	-197.1	-152.2
Accumulated other comprehensive loss	-96.1	-20.7
Total stockholders’ equity	1,015.90	1,084.20
Total	$1,743.70	$1,770.90

Consolidated_Balance_Sheet_Par

Consolidated Balance Sheet (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Allowance for Doubtful Accounts Receivable, Current	$0.80	$0.80
Deferred Tax Liabilities, Other	$120.60	$152.40
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share	$0.01	$0.01
Common Stock, Shares Authorized	90,000,000	90,000,000
Common Stock, Shares, Issued	21,197,164	21,103,700
Common Stock, Shares, Outstanding	17,607,251	18,147,017
Treasury Stock, Shares	3,589,913	2,956,683

Statements_of_Consolidated_Inc

Statements of Consolidated Income (USD $)	3 Months Ended								12 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Income Statement [Abstract]
Net sales	$338	$338.90	$344.10	$335.10	$311.30	$319.90	$328.90	$337.40	$1,356.10	$1,297.50		$1,360.10
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	278.7	280.4	275.5	282.9	254.3	259.5	261.5	263.6	1,117.50	1,038.90		1,116.20
Unrealized losses (gains) on derivative instruments	10.4	3.6	-1.6	-2	-4.1	-1.5	4.2	0.7	10.4	-0.7		-15.2
Depreciation and amortization									31.1	28.1		26.5
Selling, administrative, research and development and general									81.4	80.4		74.1
Defined benefit plan, net periodic benefit cost - VEBAs									-23.7	-22.5		-11.9
Total selling, administrative, research and development and general									57.7	57.9		62.2
Other operating charges, net									1.5	0		4.5
Total costs and expenses									1,218.20	1,124.20		1,194.20
Operating income	26.8	32.6	46.4	32.1	41.6	41.6	40.1	50	137.9	173.3		165.9
Other (expense) income:
Interest expense									-37.5	-35.7		-29.1
Other income, net (see Note 15)									6.7	5.6		2.8
Income before income taxes									107.1	143.2		139.6
Income tax provision									-35.3	-38.4		-53.8
Net income	$15.60	$15.90	$24.50	$15.80	$27.30	$25.40	$18.60	$33.50	$71.80	$104.80		$85.80
Net income per common share:
Basic	$0.88	$0.90	$1.38	$0.88	$1.48	$1.37	$0.99	$1.75	$4.02	$5.56		$4.49
Net income per share	$0.85	$0.85	$1.33	$0.85	$1.44	$1.34	$0.98	$1.73	$3.86	$5.44	[1]	$4.45	[1]
Weighted-average number of common shares outstanding (in thousands):
Basic									17,818	18,827	[2]	19,115	[2]
Diluted									18,593	19,246	[1]	19,278	[1]
[1]	The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.
[2]	The basic weighted-average number of common shares outstanding during the period excludes non-vested common shares, restricted stock units and performance shares.

Statements_of_Consolidated_Com

Statements of Consolidated Comprehensive Income (Loss) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$15.60	$15.90	$24.50	$15.80	$27.30	$25.40	$18.60	$33.50	$71.80		$104.80		$85.80
Defined benefit pension plan and VEBAs:
Total actuarial (loss) gain and prior service costs									-39		87	[1]
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments and Tax									129.5		-2.2	[1]	-87.8
Reclassification adjustments:
Amortization of net actuarial (gain) loss									-1.8	[2]	1.5	[1],[2]	3.1	[2]
Amortization of prior service cost									10.6	[2]	4.2	[1],[2]	4.2	[2]
Other comprehensive (loss) income relating to defined benefit pension plan and VEBAs									-120.7		7.9	[1]	95.1
Available for sale securities:
Unrealized (loss) gain on available for sale securities									-0.2		1	[1]	0.6
Reclassification adjustments:
Reclassification of unrealized loss upon sale of available for sale securities									-0.1		-1	[1],[3]	0
Other comprehensive (loss) income relating to available for sale securities									-0.3		0	[1]	0.6
Foreign currency translation adjustment									0.4		0.2	[1]	-0.2
Other comprehensive (loss) income, before tax									-120.6		8.1	[1]	95.5
Income tax benefit (expense) related to items of other comprehensive income (loss)									45.2	[4]	-2.8	[4]	-36.5	[4]
Other comprehensive (loss) income, net of tax									-75.4		5.3		59
Comprehensive (loss) income									($3.60)		$110.10		$144.80
[1]	The presentation of other comprehensive income 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. The 2013 balances were adjusted to reflect this reclassification. The impacts to the prospective amortization of Prior service cost and Accumulated net actuarial (losses) gains were not material.
[2]	Amounts reclassified out of Accumulated other comprehensive income relating to VEBA adjustments were included as a component of Net periodic pension benefit income relating to VEBAs.
[3]	Amounts reclassified out of Accumulated other comprehensive income relating to sales of available for sale securities were included as a component of Other income (expense), net. The Company uses the specific identification method to determine the amount reclassified out of Accumulated other comprehensive income.
[4]	Income tax amounts reclassified out of Accumulated other comprehensive income relating to VEBA adjustments and sales of available for sale securities were included as a component of Income tax provision.

Statement_of_Consolidated_Stoc

Statement of Consolidated Stockholders' Equity (USD $)		Total	Common Stock	Additional Paid in Capital	Retained Earnings	Common Stock Owned by Union VEBA	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
In Millions, except Share data, unless otherwise specified
Beginning balance at Dec. 31, 2011		$872.80	$0.20	$998.40	$84.40	($52.90)	($72.30)	($85)
Beginning balance, shares at Dec. 31, 2011			19,253,185
Stockholders' Equity [Roll Forward]
Net income		85.8			85.8
Other comprehensive income, net of tax		59						59
Release of restriction on Union VEBA shares, net of tax of $19.6, $25.0, and $41.3 for 2010, 2011, and 2012, respectively)		67.3		14.4		52.9
Issuance of non-vested shares to employees			92,949
Issuance of common shares to directors, shares			3,930
Issuance of common shares to non-employee directors		0.2		0.2
Issuance of common shares to employees upon vesting of restricted stock units and performance shares			11,327
Cancellation of employee non-vested shares			-2,355
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares, shares			-45,801
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares		-2.2		-2.2
Repurchase of common stock, shares		0
Shares returned from distribution of third party trust, value		0
Cash dividends on common stock ($0.96, $1.00 and $1.20 per share for 2011, 2012 and 2013, respectively)		-19.6			-19.6
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest		1.3		1.3
Amortization of unearned equity compensation		5.6		5.6
Dividends on unvested equity awards that were canceled		0.6			0.6
Ending balance at Dec. 31, 2012		1,070.80	0.2	1,017.70	151.2	0	-72.3	-26
Ending balance, shares at Dec. 31, 2012			19,313,235
Stockholders' Equity [Roll Forward]
Net income		104.8			104.8
Other comprehensive income, net of tax		5.3						5.3
Issuance of non-vested shares to employees			76,336
Issuance of common shares to directors, shares			2,916
Issuance of common shares to non-employee directors		0.2		0.2
Issuance of common shares to employees upon vesting of restricted stock units and performance shares			36,503
Cancellation of employee non-vested shares			-820
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares, shares			-40,075
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares		-2.5		-2.5
Repurchase of common stock, shares		-1,232,077	-1,232,077
Repurchase of common stock		-79.3					-79.3
Shares returned from distribution of bankruptcy trust, shares		-9,001
Dividends received from distribution of bankruptcy trust		0.6
Shares returned from distribution of third party trust, value	[1]	-0.6
Cash dividends on common stock ($0.96, $1.00 and $1.20 per share for 2011, 2012 and 2013, respectively)		-23			-23
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest		1.1		1.1
Amortization of unearned equity compensation		6.6		6.6
Dividends on unvested equity awards that were canceled		0.2			0.2
Ending balance at Dec. 31, 2013		1,084.20	0.2	1,023.10	233.8	0	-152.2	-20.7
Ending balance, shares at Dec. 31, 2013		18,147,017	18,147,017
Stockholders' Equity [Roll Forward]
Net income		71.8
Other comprehensive income, net of tax		-75.4						-75.4
Issuance of non-vested shares to employees			119,799
Issuance of common shares to directors, shares			2,969
Issuance of common shares to non-employee directors		0.2		0.2
Issuance of common shares to employees upon vesting of restricted stock units and performance shares			44,895
Cancellation of employee non-vested shares			-40,503
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares, shares			-33,696
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares		-2.4		-2.4
Repurchase of common stock, shares		-633,230	-633,230
Repurchase of common stock		-44.9					-44.9
Shares returned from distribution of third party trust, value		0
Cash dividends on common stock ($0.96, $1.00 and $1.20 per share for 2011, 2012 and 2013, respectively)		-25.4			-25.4
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest		0.8		0.8
Amortization of unearned equity compensation		6.8		6.8
Dividends on unvested equity awards that were canceled		0.2			0.2
Ending balance at Dec. 31, 2014		$1,015.90	$0.20	$1,028.50	$280.40	$0	($197.10)	($96.10)
Ending balance, shares at Dec. 31, 2014		17,607,251	17,607,251
[1]	See Note 12 for discussion of the distribution.

Statement_of_Consolidated_Stoc1

Statement of Consolidated Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Common Stock, Dividends, Per Share, Declared	$1.40	$1.20	$1
Tax effect on common stock sold by Union VEBA or on which restriction was lifted	$0	$0	$41.30

Statement_of_Consolidated_Cash

Statement of Consolidated Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Cash flows from operating activities:
Net income	$71.80		$104.80		$85.80
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property, plant and equipment	29.5		26.4		24.7
Amortization of definite-lived intangible assets	1.6		1.7		1.8
Amortization of debt discount and debt issuance costs	11.8		11		9.8
Deferred income taxes	34.3		55.4		52
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	-0.8		-1.1		-1.3
Non-cash equity compensation	7		6.8		5.8
Non-cash unrealized losses (gains) on derivative instruments	6.8		-3.9		-16
Amortization of option premiums (received) paid, net	0		-0.1		0.3
Non-cash impairment charges	1.5		0		4.4
Losses (gains) on disposition of property, plant and equipment	0.2		0.1		-0.1
Losses (gains) on disposition of available for sale securities	0.1		-0.4		0
Non-cash defined benefit net periodic benefit income	-23.5		-22		-11.5
Other non-cash changes in assets and liabilities	0.6		-9.3		1.2
Changes in operating assets and liabilities:
Trade and other receivables	-7		-3.3		-27.1
Inventories	-0.3		-28.4		19.7
Prepaid expenses and other current assets1	-0.6	[1]	1.1	[1]	1.4	[1]
Accounts payable	20.3		-1.6		-1.3
Accrued liabilities1	-6	[1]	1.8	[1]	10.4	[1]
Other Postretirement Benefits Payments	-16		-20		0
Payable to affiliate	0		-7.9		-6.5
Long-term assets and liabilities, net1	-7.2	[1]	0.6	[1]	-1.1	[1]
Net cash provided by operating activities	124.1		111.7		152.4
Cash flows from investing activities:
Capital expenditures	-59.4		-70.4		-44.1
Purchase of available for sale securities	-93.5		-227.8		-85
Proceeds from disposition of available for sale securities	108.2		183.1		0
Proceeds from disposal of property, plant and equipment	0		0		0.3
Change in restricted cash	0		1.7		6.9
Net cash used in investing activities	-44.7		-113.4		-121.9
Cash flows from financing activities:
Proceeds from issuance of Senior Notes	0	[2]	0	[2]	225	[2]
Payment of capital lease liability	-0.1	[2]	-0.1	[2]	-0.1	[2]
Repayment of promissory notes	0	[2]	0	[2]	-4.7	[2]
Cash paid for financing costs	0	[2]	0	[2]	-6.6	[2]
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	0.8	[2]	1.1	[2]	1.3	[2]
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares	-2.4	[2]	-2.5	[2]	-2.2	[2]
Repurchase of common stock	-44.1	[2]	-78.3	[2]	0	[2]
Cash dividend paid to stockholders	-25.4	[2]	-23	[2]	-19.6	[2]
Cash dividend returned to the Company	0	[2]	0.6	[2]	0	[2]
Net cash (used in) provided by financing activities	-71.2	[2]	-102.2	[2]	193.1	[2]
Net increase (decrease) in cash and cash equivalents during the period	8.2		-103.9		223.6
Cash and cash equivalents at beginning of period	169.5		273.4		49.8
Cash and cash equivalents at end of period	$177.70		$169.50		$273.40
[1]	Excludes the reclassification of derivatives relating to the Company's cash convertible senior notes from long-term to current as the amounts have no impact on cash flow - see Note 3 and Note 11.
[2]	See Note 14 for the supplemental disclosure on non-cash transactions.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	Organization and Nature of Operations. Kaiser Aluminum Corporation (together with its subsidiaries, unless the context otherwise requires, the “Company”) specializes in the production of semi-fabricated specialty aluminum products, such as aluminum sheet and plate and extruded and drawn products, primarily used in aerospace/high strength, automotive, general engineering and other industrial end market applications. The Company has one operating segment, Fabricated Products. See Note 13 for additional information regarding the Company's reportable segment and business unit.
	Principles of Consolidation and Basis of Presentation. The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries and are prepared in accordance with United States generally accepted accounting principles (“GAAP”) and the rules and regulations of the Securities and Exchange Commission (the “SEC”). Intercompany balances and transactions are eliminated.
	Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in accordance with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities known to exist as of the date the financial statements are published and the reported amounts of revenues and expenses during the reporting period. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of the Company’s consolidated financial statements; accordingly, it is possible that the actual results could differ from these estimates and assumptions, which could have a material effect on the reported amounts of the Company’s consolidated financial position and results of operations.
	Recognition of Sales. Sales are generally recognized on a gross basis when all of the following criteria are met: (i) persuasive evidence of an arrangement exists; (ii) title, ownership and risk of loss has passed to the customer; (iii) the price to the customer is fixed or determinable; and (iv) collection of the resulting receivable is reasonably assured. A provision for estimated sales returns from and allowances to, customers is made in the same period as the related revenues are recognized, based on historical experience or the specific identification of an event necessitating a reserve.
	From time to time, in the ordinary course of business, the Company may enter into agreements with customers in which the Company, in return for a fee, agrees to reserve certain amounts of its existing production capacity for the customer, defer an existing customer purchase commitment into future periods and reserve certain amounts of its expected production capacity in those periods for the customer, or cancel or reduce existing commitments under existing contracts. These agreements may have terms or impact periods exceeding one year.
	Certain of the capacity reservation and commitment deferral agreements provide for periodic, such as quarterly or annual, billing for the duration of the contract. For capacity reservation agreements, the Company recognizes revenue ratably over the period of the capacity reservation. Accordingly, the Company may recognize revenue prior to billing reservation fees. Unbilled receivables are included within Trade receivables on the Company's Consolidated Balance Sheets (see Note 2). For commitment deferral agreements, the Company recognizes revenue upon the earlier occurrence of the related sale of product or the end of the commitment period. In connection with other agreements, the Company may collect funds from customers in advance of the periods for which (i) the production capacity is reserved; (ii) commitments are deferred; (iii) commitments are reduced; or (iv) performance is completed, in which event the recognition of revenue is deferred until the fee is earned. Any unearned fees are included within Other accrued liabilities or Long-term liabilities, as appropriate, on the Company's Consolidated Balance Sheets (see Note 2).
	Stock-Based Compensation. Stock-based compensation in the form of service-based awards is provided to executive officers, certain employees and non-employee directors and is accounted for at fair value. The Company measures the cost of services received in exchange for an award of equity instruments based on the grant-date fair value of the award and the number of awards expected to ultimately vest. The grant-date fair value is determined based on the stock price on the date of grant, adjusted for expected dividends to be paid during the vesting period.
	The Company also grants performance-based awards to executive officers and other key employees. Performance awards granted prior to 2014 are subject to performance conditions pertaining to specified financial metrics and are valued based on the stock price at the date of grant, adjusted for expected dividends to be paid during the vesting period. Performance awards granted in 2014 are subject to performance conditions pertaining to total shareholder return and are valued on the date of grant using a Monte Carlo valuation model. The key assumptions in applying this model are an expected volatility and a risk free interest rate. For more information on the Company's stock-based compensation, see Note 8.
	The cost of service-based awards, including time-vested restricted stock and performance shares is recognized as an expense over the requisite service period of the award on a straight-line basis. For performance shares, the related expense is updated quarterly by adjusting the estimated number of shares expected to vest based on the most probable outcome of the performance condition (see Note 8).
	Shipping and Handling Costs. Shipping and handling costs are recorded as a component of Cost of products sold, excluding depreciation, amortization and other items.
	Advertising Costs. Advertising costs, which are included in Selling, administrative, research and development and general, are expensed as incurred. Advertising costs for 2014, 2013 and 2012 were $0.6, $1.3 and $0.4, respectively.
	Research and Development Costs. Research and development costs, which are included in Selling, research and development and general, are expensed as incurred. Research and development costs for 2014, 2013 and 2012 were $8.9, $7.8 and $6.4, respectively.
	Major Maintenance Activities. All major maintenance costs are accounted for using the direct expensing method.
	Cash and Cash Equivalents. The Company considers only those short-term, highly liquid investments with original maturities of 90 days or less when purchased to be cash equivalents. The Company’s cash equivalents consist primarily of funds in commercial paper, savings accounts, demand notes, money market funds and other highly liquid investments, which are classified within Level 1 of the fair value hierarchy with the exception of commercial paper, which is classified within Level 2 of the fair value hierarchy.
	Restricted Cash. The Company is required to keep certain amounts on deposit relating to workers’ compensation and other agreements. The Company accounts for such deposits as restricted cash (see Note 2).
	Trade Receivables and Allowance for Doubtful Accounts. Trade receivables primarily consist of amounts billed to customers for products sold. Accounts receivable are generally due within 30 to 60 days. For the majority of its receivables, the Company establishes an allowance for doubtful accounts based upon collection experience and other factors. On certain other receivables where the Company is aware of a specific customer’s inability or reluctance to pay, an allowance for doubtful accounts is established against amounts due, to reduce the net receivable balance to the amount the Company reasonably expects to collect. However, if circumstances change, the Company’s estimate of the recoverability of accounts receivable could be different. Circumstances that could affect the Company’s estimates include, but are not limited to, customer credit issues and general economic conditions. Accounts are written off once deemed to be uncollectible. Any subsequent cash collections relating to accounts that have been previously written off are typically recorded as a reduction to total bad debt expense in the period of payment.
	Inventories. Inventories are stated at the lower of cost or market value. Finished products, work-in-process and raw material inventories are stated on the last-in, first-out (“LIFO”) basis. The excesses of current cost over the stated LIFO value of inventory at December 31, 2014 and December 31, 2013 were $37.6 and $0.4, respectively. Other inventories, principally operating supplies and repair and maintenance parts, are stated at average cost. Inventory costs consist of material, labor and manufacturing overhead, including depreciation. Abnormal costs, such as idle facility expenses, freight, handling costs and spoilage, are accounted for as current period charges. All of the Company's inventories at December 31, 2014 and December 31, 2013 were included in the Fabricated Products segment (see Note 2 for the components of inventories).
	Property, Plant and Equipment - Net. Property, plant and equipment is recorded at cost (see Note 2). Construction in progress is included within Property, plant and equipment - net on the Consolidated Balance Sheets. Interest related to the construction of qualifying assets is capitalized as part of the construction costs. The aggregate amount of interest capitalized is limited to the interest expense incurred in the period. The amount of interest expense capitalized as construction in progress was $2.5, $3.4 and $1.7 during 2014, 2013 and 2012, respectively.
	Depreciation is computed using the straight-line method at rates based on the estimated useful lives of the various classes of assets. Capital lease assets and leasehold improvements are depreciated on a straight-line basis over the shorter of the estimated useful lives of the assets or the lease term. The principal estimated useful lives are as follows:
		Range (in years)
	Land improvements	3	-	25
	Buildings and leasehold improvements	15	-	45
	Machinery and equipment	1	-	24
	Capital lease assets	3	-	5
	Depreciation expense is not included in Cost of products sold, excluding depreciation and amortization and other items, but is included in Depreciation and amortization on the Statements of Consolidated Income. For 2014, 2013 and 2012, the Company recorded depreciation expense of $29.0, $25.8 and $24.2, respectively, relating to the Company's operating facilities in its Fabricated Products segment. An immaterial amount of depreciation expense was also recorded within All Other for all periods presented herein.
	Property, plant and equipment are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset or group of assets may not be recoverable. The Company regularly assesses whether events and circumstances with the potential to trigger impairment have occurred and relies on a number of factors, including operating results, business plans, economic projections and anticipated future cash flow, to make such assessments. The Company uses an estimate of the future undiscounted cash flows of the related asset or asset group over the estimated remaining life of such asset(s) in measuring whether the asset(s) are recoverable. Measurement of the amount of impairment, if any, is based on the difference between the carrying value of the asset(s) and the estimated fair value of such asset(s). Fair value is determined through a series of standard valuation techniques.
	During 2014 and 2012, the Company determined not to deploy some of its property, plant and equipment held for future development and recorded impairment charges of $1.5 and $4.4, respectively, to reflect the scrap value of such assets. There were no impairment charges in 2013. Asset impairment charges are included in Other operating charges, net in the Statements of Consolidated Income and are included in the Fabricated Products segment.
	Available for Sale Securities. The Company accounts for investments in certain marketable debt securities as available for sale securities. Such securities are recorded at fair value (see “Fair Values of Financial Assets and Liabilities - Available for Sale Securities” in Note 11), with net unrealized gains and losses, net of income taxes, reflected in accumulated other comprehensive income (loss) as a component of Stockholders' equity. Realized gains and losses from the sale of marketable debt securities, if any, are determined on a specific identification basis. Debt investment securities with an original maturity of 90 days or less are classified as Cash and cash equivalents (see Note 2). Debt investment securities with an original maturity of greater than 90 days are presented as Short-term investments on the Consolidated Balance Sheets. In addition to debt investment securities, the Company also holds assets in various investment funds managed by a third-party trust in connection with the Company's deferred compensation program (see Note 6).
	Deferred Financing Costs. Costs incurred in connection with debt financing are deferred and amortized over the estimated term of the related borrowing. Such amortization is included in Interest expense and may be capitalized as part of construction in progress (see Note 2 and Note 3).
	Goodwill and Intangible Assets. Goodwill is tested for impairment during the fourth quarter on an annual basis, as well as on an interim basis, as warranted, at the time of relevant events and changes in circumstances. Intangible assets with definite lives are initially recognized at fair value and subsequently amortized over the estimated useful lives to reflect the pattern in which the economic benefits of the intangible assets are consumed. In the event the pattern cannot be reliably determined, the Company uses a straight-line amortization method. Whenever events or changes in circumstances indicate that the carrying amount of the intangible assets may not be recoverable, the intangible assets are reviewed for impairment. A significant amount of synergies resulting from the acquisition of the Company's Florence, Alabama facility was realized by its Newark, Ohio and Jackson, Tennessee manufacturing facilities, which, when combined with the Florence, Alabama facility, are managed into a coordinated manner and comprise the Company's hard alloy rod, bar and wire value chain. Management determined that the hard alloy rod, bar and wire value chain should be considered one reporting unit for the purpose of performing the Company's goodwill impairment test related to the Florence, Alabama facility acquisition. The Company concluded there was no impairment of the carrying value of goodwill at December 31, 2014 or December 31, 2013 (Note 4).
	Conditional Asset Retirement Obligations (“CAROs”). The Company has CAROs at several of its Fabricated Products facilities. The vast majority of such CAROs consist primarily of incremental costs that would be associated with the removal and disposal of asbestos (all of which is believed to be fully contained and encapsulated within walls, floors, roofs, ceilings or piping) at certain of the Company’s older facilities if such facilities were to undergo major renovation or be demolished. The Company estimates incremental costs for special handling, removal and disposal costs of materials that may or will give rise to CAROs and then discounts the expected costs back to the current year using a credit-adjusted, risk-free rate. When it is unclear when or if CAROs will be triggered, the Company uses probability weighting for possible timing scenarios to determine the probability-weighted liability amounts that should be recognized in the Company’s consolidated financial statements (see Note 11).
	Self Insurance of Employee Health and Workers' Compensation Liabilities. The Company is primarily self-insured for group health insurance and workers' compensation benefits provided to employees. Self insurance liabilities are estimated for incurred-but-not-paid claims based on judgment, using the Company's historical claims data and information and analysis provided by actuarial and claims advisors, the Company's insurance carriers and other professionals. The Company's undiscounted workers' compensation liabilities were estimated at $25.9 and $29.1 at December 31, 2014 and December 31, 2013, respectively. However, the Company accounts for its workers' compensation accrued liability on a discounted basis, using a discount rate of 1.75% at both December 31, 2014 and December 31, 2013. The accrued liabilities for health insurance and workers' compensation is included in Other accrued liabilities or Long-term liabilities, as appropriate (see Note 2).
	Environmental Contingencies. With respect to environmental loss contingencies, the Company records a loss contingency whenever a contingency is probable and reasonably estimable (see Note 9). Accruals for estimated losses from environmental remediation obligations are generally recognized no later than the completion of the remedial feasibility study. Such accruals are adjusted as information develops or circumstances change. Costs of future expenditures for environmental remediation obligations are not discounted to their present value. Accruals for expected environmental costs are included in Other accrued liabilities or Long-term liabilities, as appropriate (see Note 2). Environmental expense relating to continuing operations is included in Cost of products sold, excluding depreciation and amortization and other items in the Statements of Consolidated Income. Environmental expense relating to non-operating locations is included in Selling, administrative, research and development and general in the Statements of Consolidated Income.
	Derivative Financial Instruments. Hedging transactions using derivative financial instruments are primarily designed to mitigate the Company's exposure to changes in prices for certain products sold and consumed by the Company and, to a lesser extent, to mitigate the Company's exposure to changes in foreign currency exchange rates. From time to time, the Company also enters into hedging arrangements in connection with financing transactions to mitigate financial risks.
	The Company does not utilize derivative financial instruments for trading or other speculative purposes. The Company's derivative activities are initiated within guidelines established by management and approved by the Company's Board of Directors. Hedging transactions are executed centrally on behalf of all of the Company's operations to minimize transaction costs, monitor consolidated net exposures and allow for increased responsiveness to changes in market factors.
	The Company recognizes all derivative instruments as assets or liabilities in its Consolidated Balance Sheets and measures these instruments at fair value by “marking-to-market” all of its hedging positions at each period's end (see Note 11). Because the Company does not meet the documentation requirements for hedge (deferral) accounting, unrealized and realized gains and losses associated with hedges of operational risks are reflected as a reduction or increase, respectively, in Cost of products sold - Unrealized losses (gains) on derivative instruments and unrealized and realized gains and losses relating to hedges of financing transactions are reflected as a component of Other income (expense) (see Note 15). See Note 10 for additional information about realized and unrealized gains and losses relating to the Company's derivative financial instruments.
	Fair Value Measurements. The Company applies the provisions of Accounting Standards Codification (“ASC”) Topic 820, Fair Value Measurements and Disclosures, in measuring the fair value of its derivative contracts and plan assets invested by certain of the Company’s employee benefit plans (see Note 11).
	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy consists of three broad levels and are described below:
	•	Level 1 — Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.
	•	Level 2 — Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly, including: quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active; inputs other than quoted prices that are observable for the asset or liability (e.g., interest rates); and inputs that are derived principally from or corroborated by observable market data by correlation or other means.
	•	Level 3 — Inputs that are both significant to the fair value measurement and unobservable.
	Income Taxes. Deferred income taxes reflect the future tax effect of temporary differences between the carrying amount of assets and liabilities for financial and income tax reporting and are measured by applying statutory tax rates in effect for the year during which the differences are expected to reverse. In accordance with ASC Topic 740, Income Taxes, the Company uses a “more likely than not” threshold for recognition of tax attributes that are subject to uncertainties and measures any reserves in respect of such expected benefits based on their probability. Deferred tax assets are reduced by a valuation allowance to the extent it is more likely than not that the deferred tax assets will not be realized (see Note 5).
	Net Income per Share. Basic net income per share is computed by dividing distributed and undistributed net income allocable to common shares by the weighted-average number of common shares outstanding during the applicable period. The basic weighted-average number of common shares outstanding during the period excludes unvested share-based payment awards. Diluted net income per share was calculated under the treasury stock method for 2014, 2013 and 2012, which in all years was more dilutive than the two-class method (see Note 12).
	Concentration of Credit Risk. Financial arrangements which potentially subject the Company to concentrations of credit risk consist of metal, natural gas, electricity and foreign currency derivative contracts, certain cash-settled call options that the Company purchased in March 2010 (the “Option Assets”) (see Note 3) and arrangements related to the Company's cash equivalents and short-term investments. If the market value of the Company's net commodity and currency derivative positions with certain counterparties exceeds the applicable threshold, if any, the counterparty is required to post margin by transferring cash collateral in excess of the threshold to the Company. Conversely, if the market value of these net derivative positions falls below a specified threshold, the Company is required to post margin by transferring cash collateral below the threshold to certain counterparties. At both December 31, 2014 and December 31, 2013, the Company had no margin deposits with or from its counterparties.
	The Company is exposed to credit loss in the event of nonperformance by counterparties on derivative contracts used in hedging activities as well as failure of counterparties to return cash collateral previously transferred to the counterparties. The counterparties to the Company's derivative contracts are major financial institutions and the Company does not expect nonperformance by any of its counterparties.
	The Company places its cash in commercial paper, savings accounts, demand notes and money market funds. Such money market funds are with high credit quality financial institutions which invest primarily in commercial paper and time deposits of prime quality, short-term repurchase agreements and U.S. government agency notes.
	For information about concentration risks concerning customers and suppliers, see Note 13.
	Concentration of Labor Subject to Collective Bargaining Agreements. At December 31, 2014, approximately 63% of the Company's employees were covered by collective bargaining agreements and the Company had collective bargaining agreements with expiration dates in 2015 covering approximately 47% of its employees. In January 2015, collective bargaining agreements covering approximately 36% of the Company's employees were extended through September 30, 2020 (see Note 19).
	Leases. For leases that contain predetermined fixed escalations of the minimum rent, the Company recognizes the related rent expense on a straight-line basis from the date it takes possession of the property to the end of the initial lease term. The Company records any difference between the straight-line rent amounts and the amount payable under the lease as part of deferred rent in Other accrued liabilities or Long-term liabilities, as appropriate. Deferred rent for all periods presented was not material.
	Foreign Currency. Certain of the Company’s foreign subsidiaries use the local currency as its functional currency; its assets and liabilities are translated at exchange rates in effect at the balance sheet date; and its statement of operations is translated at weighted-average monthly rates of exchange prevailing during the year. Resulting translation adjustments are recorded directly to a separate component of stockholders’ equity in accordance with ASC Topic 830, Foreign Currency Matters. At both December 31, 2014 and December 31, 2013, the amount of translation adjustment relating to foreign subsidiaries using local currency as their functional currency was immaterial. Where the U.S. dollar is the functional currency of a foreign facility or subsidiary, re-measurement adjustments are recorded in Other income (expense).
	New Accounting Pronouncements. Accounting Standards Update ("ASU") No. 2013-11, Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists. (“ASU 2013-11”), was issued in July 2013. ASU 2013-11 requires an entity to present in the financial statements an unrecognized tax benefit, or a portion of an unrecognized tax benefit, as a reduction to a deferred tax asset resulting from a net operating loss carryforward, a similar tax loss, or a tax credit carryforward. However, when the above situation is not available at the reporting date or the tax law of the applicable jurisdiction does not require the entity to use the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be combined with deferred tax assets. The Company’s adoption of ASU 2013-11 in the first quarter of 2014 did not have a material impact on its consolidated financial statements.
	ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”), was issued in May 2014. ASU 2014-09 requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve this core principle, the guidance provides that an entity should apply the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. The Company expects to adopt ASU 2014-09 for the fiscal year ending December 31, 2017 and the Company will continue to assess the impact on its consolidated financial statements.
	ASU No. 2014-12, Compensation - Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period - Consensus of the FASB Emerging Issues Task Force (“ASU 2014-12”), was issued in June 2014. ASU 2014-12 requires an entity to treat a performance target that affects vesting and that could be achieved after the requisite service period as a performance condition. The performance target should not be reflected in estimating the grant-date fair value of the award. Additionally, compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered; if the performance target becomes probable of being achieved before the end of the requisite service period, then the remaining unrecognized compensation cost should be recognized prospectively over the remaining requisite service period. Finally, the total amount of compensation cost recognized during and after the requisite service period should reflect the number of awards that are expected to vest and should be adjusted to reflect those awards that ultimately vest. The Company expects to adopt ASU 2014-12 for the fiscal year ending December 31, 2015 and does not expect the adoption to have a material impact on its consolidated financial statements.

Supplemental_Balance_Sheet_Inf

Supplemental Balance Sheet Information	12 Months Ended
	Dec. 31, 2014
Supplemental Balance Sheet Information [Abstract]
Supplemental Balance Sheet Information	Supplemental Balance Sheet Information
		December 31, 2014			December 31, 2013
	Cash and Cash Equivalents
	Cash and money market funds	$	29.5		$	57.7
	Commercial paper	148.2			111.8
	Total	$	177.7		$	169.5
	Trade Receivables - Net
	Billed trade receivables	$	128.7		$	120.2
	Unbilled trade receivables — Note 1	1.4			0.4
	Trade receivables, gross	130.1			120.6
	Allowance for doubtful receivables	(0.8		)	(0.8		)
	Trade receivables - net	$	129.3		$	119.8
	Inventories
	Finished products	$	73.6		$	72.5
	Work-in-process	66.7			75.9
	Raw materials	54.2			47.2
	Operating supplies and repair and maintenance parts	20.2			18.8
	Total	$	214.7		$	214.4
		December 31, 2014			December 31, 2013
	Prepaid Expenses and Other Current Assets
	Current derivative assets — Notes 10 and 11	$	85.7		$	2
	Current deferred tax assets	86.4			36.7
	Short-term restricted cash	0.3			0.3
	Other	6.2			5.2
	Total	$	178.6		$	44.2
	Property, Plant and Equipment - Net
	Land and improvements	$	22.9		$	22.6
	Buildings and leasehold improvements	63.8			53
	Machinery and equipment	509.8			425.6
	Construction in progress	25.2			66
	Property, plant and equipment - gross	621.7			567.2
	Accumulated depreciation	(166.8		)	(137.9		)
	Property, plant and equipment - net	$	454.9		$	429.3
	Other Assets
	Derivative assets — Notes 10 and 11	$	—		$	79.8
	Restricted cash	10			9.3
	Deferred financing costs	5.9			8.9
	Deferred compensation plan assets	7.3			6.5
	Other	0.1			0.3
	Total	$	23.3		$	104.8
	Other Accrued Liabilities
	Current derivative liabilities — Notes 10 and 11	$	94.9		$	1.8
	Uncleared cash disbursements	9.1			9.6
	Accrued income taxes and taxes payable	5.2			4.3
	Accrued annual VEBA contribution	13.7			16
	Short-term environmental accrual — Note 9	2.3			2.8
	Accrued interest	3.7			3.7
	Short-term deferred revenue — Note 1	0.2			—
	Other	3.7			6.6
	Total	$	132.8		$	44.8
		December 31, 2014			December 31, 2013
	Long-Term Liabilities
	Derivative liabilities — Notes 10 and 11	$	1.9		$	84.3
	Income tax liabilities	2.4			5
	Workers’ compensation accruals	21.5			23.3
	Long-term environmental accrual — Note 9	17			20
	Long-term asset retirement obligations	4.4			4
	Long-term deferred revenue - Note 1	0.5			—
	Deferred compensation liability	7.2			7
	Long-term capital leases	0.1			0.1
	Other long-term liabilities	3.3			2.7
	Total	$	58.3		$	146.4
	Long-Term Debt — Note 3
	Senior notes	$	225		$	225
Cash convertible senior notes	—			163.5
Total	$	225		$	388.5

LongTerm_Debt_and_Credit_Facil

Long-Term Debt and Credit Facility	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Long-Term Debt and Credit Facility	Debt and Credit Facility
	Senior Notes
	In May 2012, the Company issued $225.0 principal amount of 8.250% unsecured senior notes due June 1, 2020 (“Senior Notes”) at 100% of the principal amount. Interest expense, including amortization of deferred financing costs, relating to the Senior Notes was $19.4 for both 2014 and 2013 and $11.8 for 2012. A portion of the interest relating to the Senior Notes was capitalized as Construction in progress. The effective interest rate of the Senior Notes is approximately 8.6% per annum, taking into account the amortization of deferred financing costs.
	The Senior Notes are unsecured obligations and are guaranteed by existing and future direct and indirect subsidiaries of the Company that are borrowers or guarantors under the Company's revolving credit facility. See Note 17 for condensed Guarantor and Non-Guarantor financial information.
	The indenture governing the Senior Notes places limitations on the ability of the Company and certain of its subsidiaries to, among other things, incur liens, consolidate, merge or sell all or substantially all of the Company's and certain of its subsidiaries' assets, incur or guarantee additional indebtedness, enter into transactions with affiliates and to make "restricted payments" (which are defined in the indenture to include certain loans, investments, dividend payments, share repurchases and prepayments, redemptions or repurchases of certain indebtedness). Certain types and amounts of restricted payments are allowed by various provisions of the indenture. After March 31, 2015, the indenture provisions permit the Company to make restricted payments in any amount if, after giving effect to such restricted payment, its "consolidated total indebtedness" as a ratio of "EBITDA" (each term as defined in the indenture) is less than 2.00:1.00.
	The Senior Notes are redeemable at the option of the Company in whole or part at any time on or after June 1, 2016 at an initial redemption price of 104.125% of the principal amount plus any accrued and unpaid interest, declining to a redemption price of 100% of the principal amount, plus any accrued and unpaid interest, on or after June 1, 2018. At any time prior to June 1, 2015, the Company may redeem up to 35% of the original principal amount of the Senior Notes with the proceeds of certain equity offerings at a redemption price of 108.250% of the principal amount, plus any accrued and unpaid interest. At any time prior to June 1, 2016, the Company may also redeem some or all of the Senior Notes at a redemption price equal to 100% of the principal amount, together with any accrued and unpaid interest, plus a “make-whole premium.”
	Holders of the Senior Notes have the right to require the Company to repurchase the Senior Notes at a price equal to 101% of the principal amount plus any accrued and unpaid interest following a change of control. A change of control includes (i) certain ownership changes; (ii) certain recapitalizations, mergers and dispositions; (iii) certain changes in the composition of the Board of Directors of the Company; and (iv) shareholders' approval of any plan or proposal for the liquidation or dissolution of the Company. The Company may also be required to offer to repurchase the Senior Notes at 100% of the principal amount, plus any accrued and unpaid interest, with the proceeds of certain asset sales.
	See “Fair Values of Financial Assets and Liabilities - All Other Financial Assets and Liabilities” in Note 11 for information relating to the estimated fair value of the Senior Notes.
	Cash Convertible Senior Notes
	Convertible Notes. In March 2010, the Company issued $175.0 principal amount of 4.5% unsecured Cash Convertible Senior Notes due April 1, 2015 ("Convertible Notes"). The Convertible Notes are not convertible into the Company's common stock or any other securities, but instead will be settled in cash. The Company accounts for the cash conversion feature of the Convertible Notes as a separate derivative instrument (“Bifurcated Conversion Feature”) with the fair value on the issuance date equaling the original issuance discount for purposes of accounting for the debt component of the Convertible Notes. The effective interest rate for the term of the Convertible Notes is approximately 11%, taking into account the amortization of the original issuance discount and deferred financing costs.
	The following tables provide additional information regarding the Convertible Notes:
		December 31,			December 31,
		2014			2013
	Principal amount	$	175		$	175
	Less: unamortized issuance discount	(2.5		)	(11.5		)
	Carrying amount, net of discount	$	172.5		$	163.5
		Year Ended December 31,
		2014			2013			2012
	Contractual coupon interest	$	7.9		$	7.9		$	7.9
	Amortization of discount	9.1			8.2			7.3
	Amortization of deferred financing costs	1.1			1.2			1.2
	Total interest expense1	$	18.1		$	17.3		$	16.4
	_______________
	1	A portion of the interest relating to the Convertible Notes was capitalized as Construction in progress.
	The Convertible Notes’ conversion rate is subject to adjustment based on the occurrence of certain events, including, but not limited to, the payment of quarterly cash dividends on the Company's common stock in excess of $0.24 per share. As of December 31, 2014, the conversion rate was 20.9186 shares per $1,000 principal amount of the Convertible Notes and the equivalent conversion price was approximately $47.80 per share, reflecting cumulative adjustments for quarterly dividends paid in excess of $0.24 per share.
	For holders who convert their Convertible Notes during the first quarter of 2015, the final settlement period began on January 15, 2015 and will continue for 50 consecutive trading days, ending on March 27, 2015. The Convertible Notes are convertible at any time prior to 5:00pm New York City time on March 30, 2015. An immaterial amount of Convertible Notes was converted during 2014 pursuant to a provision that permitted early conversion.
	Convertible Note Hedge Transactions. In March 2010, the Company purchased Option Assets that have an exercise price equal to the conversion price of the Convertible Notes, an expiration date that is the same as the maturity date or the earlier conversion date of the Convertible Notes and a final settlement period that is the same as for the Convertible Notes. When exercised, the aggregate amount of cash the Company will receive from the counterparties for the Option Assets will cover the aggregate amount of cash that the Company will be required to pay to the holders of the converted Convertible Notes, less the principal amount thereof and interest payable thereon. Contemporaneous with the purchase of the Option Assets, the Company also sold net-share-settled warrants (“Warrants”) that will settle over a 120-day settlement period beginning on July 1, 2015 relating to approximately 3.7 million shares of the Company’s common stock. The Option Assets and the Warrants have anti-dilution provisions similar to the Convertible Notes. At December 31, 2014, the exercise prices were $47.80 per share and $60.70 per share for the Option Assets and the Warrants, respectively, reflecting cumulative adjustments for quarterly dividends paid in excess of $0.24 per share.
	See “Fair Values of Financial Assets and Liabilities - All Other Financial Assets and Liabilities” in Note 11 for information relating to the estimated fair value of the Bifurcated Conversion Feature and the Option Assets.
	Revolving Credit Facility
	The Company’s credit agreement with JPMorgan Chase Bank, N.A., as administrative agent and the other financial institutions party thereto (“Revolving Credit Facility”) provides the Company with a $300.0 funding commitment through September 30, 2016. The Revolving Credit Facility is secured by a first priority lien on substantially all of the accounts receivable, inventory and certain other related assets and proceeds of the Company and certain of its domestic operating subsidiaries as well as certain machinery and equipment. Under the Revolving Credit Facility, the Company is able to borrow from time to time an aggregate commitment amount equal to the lesser of $300.0 and a borrowing base comprised of (i) 85% of eligible accounts receivable; (ii) the lesser of (a) 65% of eligible inventory and (b) 85% of the net orderly liquidation value of eligible inventory as determined in the most recent inventory appraisal ordered by the administrative agent; and (iii) 85% of certain eligible machinery and equipment, reduced by certain reserves, all as specified in the Revolving Credit Facility. Up to a maximum of $60.0 of availability under the Revolving Credit Facility may be utilized for letters of credit.
	Borrowings under the Revolving Credit Facility bear interest at a rate equal to either a base prime rate or LIBOR, at the Company's option, plus, in each case, a specified variable percentage determined by reference to the then-remaining borrowing availability under the Revolving Credit Facility. The Revolving Credit Facility may, subject to certain conditions and the agreement of lenders thereunder, be increased up to $350.0.
	The Company had $276.7 of borrowing availability under the Revolving Credit Facility at December 31, 2014, based on the borrowing base determination then in effect. At December 31, 2014, there were no borrowings under the Revolving Credit Facility and $7.6 was being used to support outstanding letters of credit, leaving $269.1 of net borrowing availability. The interest rate applicable to any overnight borrowings under the Revolving Credit Facility would have been 4.0% at December 31, 2014.
	Amounts owed under the Revolving Credit Facility may be accelerated upon the occurrence of various events of default including, without limitation, the failure to make principal or interest payments when due and breaches of covenants, representations and warranties set forth therein. The Revolving Credit Facility places limitations on the ability of the Company and certain of its subsidiaries to, among other things, grant liens, engage in mergers, sell assets, incur debt, make investments, undertake transactions with affiliates, prepay certain debt, pay dividends and repurchase shares. The Company is allowed to prepay debt, pay dividends and repurchase shares in any amount if, after giving effect to such payment, $52.5 or more would be available for the Company to borrow under the Revolving Credit Facility. In addition, the Company is required to maintain a fixed charge coverage ratio on a consolidated basis at or above 1.1:1.0 if borrowing availability under the Revolving Credit Facility is less than $30.0.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets
	The Company’s accounting policy is to perform an annual goodwill impairment test during the fourth quarter of each year or whenever events or changes in circumstances indicate that goodwill or the carrying value of intangible assets may not be recoverable. As of December 31, 2014, the Company performed a quantitative impairment test and determined that no impairment of its goodwill and intangible assets was required.
	Goodwill. The Company had goodwill of $37.2 at both December 31, 2014 and December 31, 2013. Such goodwill is related to the Company's acquisitions of the Chandler, Arizona (Extrusion) facility and the Florence, Alabama facility and is included in the Fabricated Products segment.
	Intangible Assets. In 2014 and 2013, the Company's identifiable intangible assets were related to customer relationships. The original cost of these customer relationships was $38.5 million and accumulated amortization and net book value were $6.4 million and $32.1 million, respectively, at December 31, 2014, and $4.8 million and $33.7 million, respectively, at December 31, 2013.
	Amortization expense relating to definite-lived intangible assets is recorded in the Fabricated Products segment. Such expense was $1.6, $1.7 and $1.8 for 2014, 2013 and 2012, respectively. The expected amortization of intangible assets for each of the next five calendar years is $1.6 and $24.1 for years thereafter.

Income_Tax_Matters

Income Tax Matters	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Matters	Income Tax Matters
	Tax Provision. Income before income taxes by geographic area was as follows:
		Year Ended December 31,
		2014				2013				2012
	Domestic	$	102.1			$	138.9			$	134.5
	Foreign	5				4.3				5.1
	Income before income taxes	$	107.1			$	143.2			$	139.6
	Income taxes are classified as either domestic or foreign, based on whether payment is made or due to the United States or a foreign country. Certain income classified as foreign is also subject to domestic income taxes.
	The provision for income taxes consisted of:
		Federal				Foreign				State				Total
	2014
	Current	$	(1.0	)		$	1			$	(0.6	)		$	(0.6	)
	Deferred	6.4				0.3				5.1				11.8
	Expense applied to decrease Additional paid in capital/ Other comprehensive income	(41.6		)		(0.5		)		(4.4		)		(46.5		)
	Total (expense) benefit	$	(36.2	)		$	0.8			$	0.1			$	(35.3	)
	2013
	Current	$	1.1			$	16.2			$	(0.2	)		$	17.1
	Deferred	(49.7		)		(0.5		)		(6.7		)		(56.9		)
	Benefit (expense) applied to increase (decrease) Additional paid in capital/Other comprehensive income	1.3				(0.1		)		0.2				1.4
	Total (expense) benefit	$	(47.3	)		$	15.6			$	(6.7	)		$	(38.4	)
	2012
	Current	$	—			$	(2.3	)		$	0.2			$	(2.1	)
	Deferred	(113.0		)		(0.2		)		(15.3		)		(128.5		)
	Benefit applied to increase Additional paid in capital/ Other comprehensive income	67.4				0.2				9.2				76.8
	Total expense	$	(45.6	)		$	(2.3	)		$	(5.9	)		$	(53.8	)
	A reconciliation between the provision for income taxes and the amount computed by applying the federal statutory income tax rate to income before income taxes is as follows:
		Year Ended December 31,
		2014				2013				2012
	Amount of federal income tax provision based on the statutory rate	$	(37.5	)		$	(50.1	)		$	(48.9	)
	Decrease in federal valuation allowances	—				0.1				0.1
	Non-deductible compensation expense	(0.1		)		(0.3		)		(0.4		)
	Non-deductible expense	(0.3		)		(0.9		)		(0.3		)
	State income taxes, net of federal benefit 1	—				(4.4		)		(3.8		)
	Foreign income tax (expense) benefit	0.3				—				(0.5		)
	Expiration of statute of limitations	2.3				4.6				—
	Settlement with taxing authorities	—				4.4				—
	Advance pricing agreement	—				2.9				—
	Competent Authority settlement	—				5.3				—
	Income tax provision	$	(35.3	)		$	(38.4	)		$	(53.8	)
	___________________________
	1	State income taxes were $2.3 in 2014, but were offset by a $1.6 decrease due to lower tax rates in various states and a $0.7 decrease in the valuation allowance relating to certain state net operating losses. State income taxes of $4.4 in 2013 included a $1.2 increase in the valuation allowance relating to certain unused state net operating losses expected to expire.
	The table above reflects a full statutory U.S. tax provision despite the fact that the Company is only paying U.S. federal alternative minimum tax (“AMT”) and some state income taxes. See “Tax Attributes” below.
	Deferred Income Taxes. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and amounts used for income tax purposes. The components of the Company’s net deferred income tax assets were as follows:
		Year Ended December 31,
		2014				2013
	Deferred income tax assets:
	Loss and credit carryforwards	$	275.4			$	321.8
	VEBAs (see Note 6)	5.1				6.1
	Other assets	35				34.4
	Inventories and other	21.5				2.5
	Valuation allowances	(19.2		)		(19.9		)
	Total deferred income tax assets	317.8				344.9
	Deferred income tax liabilities:
	Property, plant and equipment	(74.1		)		(73.0		)
	VEBAs (see Note 6)	(120.6		)		(152.4		)
	Inventories	(6.7		)		(14.9		)
	Total deferred income tax liabilities	(201.4		)		(240.3		)
	Net deferred income tax assets 1	$	116.4			$	104.6
	__________________________
	1	Of the total net deferred income tax assets of $116.4, $86.4 was included in Prepaid expenses and other current assets, $30.9 was presented as Deferred tax assets, net and $0.9 was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2014. Of the total net deferred income tax assets of $104.6, $36.7 was included in Prepaid expenses and other current assets and $69.1 was presented as Deferred tax assets, net and $1.2 was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2013.
	Tax Attributes. At December 31, 2014, the Company had $606.1 of net operating loss (“NOL”) carryforwards available to reduce future cash payments for income taxes in the United States. Of the $606.1 of NOL carryforwards at December 31, 2014, $1.7 represents excess tax benefits related to the vesting of employee restricted stock, which will result in an increase in equity if and when such excess tax benefits are ultimately realized. The NOL carryforwards expire periodically through 2030. The Company also had $30.1 of AMT credit carryforwards with an indefinite life, available to offset regular federal income tax requirements.
	To preserve the NOL carryforwards available to the Company, the Company’s certificate of incorporation includes certain restrictions on the transfer of the Company’s common stock through July 2016.
	In assessing the realizability of deferred tax assets, management considers whether it is “more likely than not” that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers taxable income in carryback years, the scheduled reversal of deferred tax liabilities, tax planning strategies and projected future taxable income in making this assessment. Due to uncertainties surrounding the realization of some of the Company’s deferred tax assets, primarily including state NOL carryforwards sustained during the prior years and expiring tax benefits, the Company has a valuation allowance against its deferred tax assets. When recognized, the tax benefits relating to any reversal of this valuation allowance will be recorded as a reduction of income tax expense. The increase (decrease) in the valuation allowance was $(0.7), $1.2 and $(0.1) in 2014, 2013 and 2012, respectively.
	The decrease in the valuation allowance for 2014 was primarily due to the projected utilization of state NOL carryforwards. The increase in the valuation allowance in 2013 was primarily due to unutilized state NOL carryforwards that were expected to expire. The decrease in the valuation allowance for 2012 was primarily due to the projected utilization of state NOL carryforwards.
Other. The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction and various states and foreign jurisdictions. In 2013, the Company and the Canada Revenue Agency settled audits of the Company's Canadian tax returns for fiscal years 1998 through 2004 resulting in a cash tax benefit to the Company of $7.9, of which, $6.1 was received in 2013 and the remaining $1.8 was received in 2014. In addition, in 2013, the Company signed an advance pricing agreement with the Canada Revenue Agency, which resulted in an additional cash tax benefit of $2.6, which is expected to be refunded within the next 12 months.
The Company’s tax returns for certain past years are still subject to examination by taxing authorities and the use of NOL carryforwards in future periods could trigger a review of attributes and other tax matters in years that are not otherwise subject to examination.
The Company has gross unrecognized benefits relating to uncertain tax positions. A reconciliation of changes in the gross unrecognized tax benefits is as follows:
		Year Ended December 31,
		2014				2013				2012
Gross unrecognized tax benefits at beginning of period		$	3.8			$	15.7			$	13.7
Gross increases for tax positions of prior years		—				—				1.3
Gross decreases for tax positions of prior years		—				(7.6		)		(0.1		)
Gross increases for tax positions of current years		—				—				0.4
Gross decrease for tax positions relating to lapse of a statute of limitation		(1.4		)		(3.3		)		—
Foreign currency translation		(0.2		)		(1.0		)		0.4
Gross unrecognized tax benefits at end of period		$	2.2			$	3.8			$	15.7
If and when the $2.2 and $3.8 of gross unrecognized tax benefits at December 31, 2014 and December 31, 2013, respectively, are recognized, $1.1 and $2.7 will be reflected in the Company's income tax provision and thus affect the effective tax rate in future periods. For the year ended December 31, 2012, if and when the gross unrecognized tax benefits are ultimately recognized, they will be reflected in the Company’s income tax provision and affect the effective tax rate in future periods.
The change during 2014 was due to the expiration of statutes and foreign currency fluctuations. The change during 2013 was primarily due to the expiration of statutes, settlements with taxing authorities, foreign currency fluctuations and change in tax positions. The change during 2012 was primarily due to foreign currency fluctuations and change in tax positions.
In addition, the Company recognizes interest and penalties related to unrecognized tax benefits in the income tax provision. The Company had $1.4 and $2.3 accrued for interest and penalties at December 31, 2014 and December 31, 2013, respectively. Of these amounts, none were recorded as current liabilities and included in Other accrued liabilities on the Consolidated Balance Sheets at December 31, 2014 and December 31, 2013. The Company recognized a (decrease) increase in interest and penalty of $(0.9), $(5.2) and $0.9 in its tax provision in 2014, 2013 and 2012, respectively.
In connection with the gross unrecognized tax benefits (including interest and penalties) denominated in foreign currency, the Company incurred a foreign currency translation adjustment. During 2014, 2013 and 2012, the foreign currency impact on such liabilities resulted in $0.3, $0.7 and $(0.5) currency translation adjustments, respectively, which increased (decreased)Other comprehensive income (loss).
The Company does not expect its gross unrecognized tax benefits to significantly change within the next 12 months.

Employee_Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Employee Benefits	Employee Benefits
	Employee Plans. Employee benefit plans include:
	•	A defined contribution 401(k) savings plan for hourly bargaining unit employees at seven of the Company’s production facilities based on the specific collective bargaining agreement at each facility. For active bargaining unit employees at three of these production facilities, the Company is required to make fixed rate contributions. For active bargaining unit employees at one of these production facilities, the Company is required to match certain employee contributions. For active bargaining unit employees at two of these production facilities, the Company is required to make both fixed rate contributions and concurrent matches. For active bargaining unit employees at the one remaining production facility, the Company is not required to make any contributions. Fixed rate contributions either (i) range from (in whole dollars) $800 to $2,400 per employee per year, depending on the employee’s age, or (ii) vary between 2% to 10% of the employees’ compensation depending on their age and years of service for employees hired prior to January 1, 2004 or is a fixed 2% annual contribution for employees hired on or after January 1, 2004. The Company currently estimates that contributions to such plans will range from $1.0 to $3.0 per year.
	•	A defined contribution 401(k) savings plan for salaried and certain hourly employees providing for a concurrent match of up to 4% of certain contributions made by employees plus an annual contribution of between 2% and 10% of their compensation depending on their age and years of service to employees hired prior to January 1, 2004. All new hires on or after January 1, 2004 receive a fixed 2% contribution annually. The Company currently estimates that contributions to such plan will range from $5.0 to $7.0 per year.
	•	A defined benefit plan for salaried employees at the Company’s London, Ontario facility, with annual contributions based on each salaried employee’s age and years of service. At December 31, 2014, approximately 66% of the plan assets were invested in equity securities and 31% of plan assets were invested in fixed income securities. The remaining plan assets were invested in short-term securities. The Company’s investment committee reviews and evaluates the investment portfolio. The asset mix target allocation on the long-term investments is approximately 66% in equity securities, 30% in fixed income securities and the remaining assets in short-term securities. See Note 11 for additional information regarding the fair values of the Canadian pension plan assets.
	•	A non-qualified, unfunded, unsecured plan of deferred compensation for key employees who would otherwise suffer a loss of benefits under the Company’s defined contribution plan as a result of the limitations imposed by the Internal Revenue Code of 1986 (the “Code”). Despite the plan being an unfunded plan, the Company makes an annual contribution to a rabbi trust to fulfill future funding obligations, as contemplated by the terms of the plan. The assets in the trust are at all times subject to the claims of the Company’s general creditors and no participant has a claim to any assets of the trust. Plan participants are eligible to receive distributions from the trust subject to vesting and other eligibility requirements. Assets in the rabbi trust relating to the deferred compensation plan are accounted for as available for sale securities and are included as Other assets on the Consolidated Balance Sheets (see Note 2). Liabilities relating to the deferred compensation plan are included on the Consolidated Balance Sheets as Long-term liabilities (see Note 2).
	•	An employment agreement with the Company’s chief executive officer extending through December 31, 2016. The Company also provides certain members of senior management, including each of the Company’s named executive officers, with benefits related to terminations of employment in specified circumstances, including in connection with a change in control, by the Company without cause and by the executive officer with good reason.
	VEBA Postretirement Medical Obligations. Certain eligible retirees receive certain healthcare related benefits through participation in a voluntary employees' beneficiary association ("VEBA") that provides benefits for eligible retirees represented by certain unions and their surviving spouse and eligible dependents (the "Union VEBA") or a VEBA that provides benefits for certain other retirees and their spouse and eligible dependents (the "Salaried VEBA" and, together with the Union VEBA, the "VEBAs"). The Union VEBA covers certain qualifying bargaining unit retirees and future retirees. The Salaried VEBA covers certain retirees who retired prior to the 2004 termination of the prior plan and employees who were hired prior to February 2002 and subsequently retired or will retire with the requisite age and service. The Union VEBA is managed by four trustees, two of which are appointed by the Company and two of which are appointed by the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union, AFL-CIO, CLC ("USW"). Its assets are managed by an independent fiduciary. The Salaried VEBA is managed by trustees who are independent of the Company.
	The Company’s primary financial obligation to the VEBAs is to make an annual variable cash contribution. The formula determining the annual variable contribution amount is 10% of the first $20.0 of annual cash flow (as defined; in general terms, the principal elements of cash flow are earnings before interest expense, provision for income taxes and depreciation and amortization less cash payments for, among other things, interest, income taxes and capital expenditures), plus 20% of annual cash flow (as defined) in excess of $20.0. Such payments may not exceed $20.0 annually and payments are allocated between the Union VEBA and the Salaried VEBA at 85.5% and 14.5%, respectively. The variable cash contribution obligation to the Union VEBA extends through September 2017, while the obligation to the Salaried VEBA has no express termination date.
	Amounts owed by the Company to the VEBAs are recorded in the Company's Consolidated Balance Sheets under Other accrued liabilities, with a corresponding increase in Net assets of VEBAs. Such amounts are determined and paid on an annual basis. As of December 31, 2014, the Company determined that the variable contribution for 2014 was $13.7 (comprised of $11.7 to the Union VEBA and $2.0 to the Salaried VEBA). These amounts will be paid during the first quarter of 2015. The variable contribution relating to 2013 in the amount of $16.0 was paid in 2014.
	The Company has no claim to the plan assets of the VEBAs nor any obligation to fund their liabilities. The VEBA plan designs and benefits paid by the VEBAs are at the sole discretion of the respective VEBA trustees and are outside the Company's control. Nevertheless, the Company accounts for the VEBAs as defined benefit postretirement plans with the current VEBA assets and future variable contributions from the Company and earnings thereon, operating as a cap on the benefits to be paid. Accordingly, the Company accounts for net periodic postretirement benefit costs (income) in accordance with ASC Topic 715, Compensation — Retirement Benefits, and records any difference between the assets of each VEBA and its accumulated postretirement benefit obligation in the Company’s consolidated financial statements. Information necessary for the valuation of the net funded status of the plans must be obtained from the VEBAs on an annual basis.
	Under this accounting treatment, the funding status of each of the VEBAs could result in a liability or asset position on the Company's Consolidated Balance Sheets. Such liability or asset has no impact on the Company's cash flow or liquidity. Only the Company's obligation to make an annual variable cash contribution can have a material impact to the Company's cash flow or liquidity.
	Key Assumptions. The following data presents the key assumptions used and the amounts reflected in the Company’s financial statements with respect to the Company’s Canadian pension plan and the VEBAs. The Company uses a December 31 measurement date for all of the plans.
	Assumptions used to determine benefit obligations as of the periods presented were as follows:
			Canadian Pension Benefits						VEBA Benefits
			December 31, 2014			December 31, 2013			December 31, 2014						December 31, 2013
									Union			Salaried			Union			Salaried
									VEBA			VEBA			VEBA			VEBA
	Discount rate		4	%		4.9	%		3.8	%		3.6	%		4.7	%		4.2	%
	Rate of compensation increase		3	%		3	%		—			—			—			—
	Initial medical trend rate 1		—			—			7	%		—			7.5	%		—
	Ultimate medical trend rate 1		—			—			5	%		—			5	%		—
	_____________________
	1	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.
	Key assumptions made in computing the net asset/obligation of each VEBA and in total include:
	With respect to VEBA assets:
	•	Based on the information received from the VEBAs, at December 31, 2014 and December 31, 2013 both the Salaried VEBA and Union VEBA assets were invested in various managed proprietary funds. VEBA plan assets are managed by various investment advisors selected by the VEBA trustees and are not under the control of the Company.
	•	The Company's variable payment, if any, is treated as a funding/contribution policy and not counted as a VEBA asset at December 31 for actuarial purposes.
	With respect to VEBA obligations:
	•	The accumulated postretirement benefit obligation (“APBO”) for each VEBA was computed based on the level of benefits being provided by it at December 31, 2014 and December 31, 2013.
	•	Since the Salaried VEBA was paying a fixed annual amount to its constituents at both December 31, 2014 and December 31, 2013, no future cost trend rate increase has been assumed in computing the APBO for the Salaried VEBA.
	Assumptions used to determine net periodic benefit cost (income) for the years ended December 31 were:
			Canadian Pension Benefits									VEBA Benefits
			2014			2013			2012			2014						2013						2012
												Union			Salaried			Union			Salaried			Union		Salaried
												VEBA			VEBA			VEBA			VEBA			VEBA		VEBA
	Discount rate		4.9	%		4.4	%		5.6	%		4.7	%		4.2	%		4	%		3.4	%		4.2	%	3.75	%
	Expected long-term return on plan assets 1		4.75	%		4.5	%		4.6	%		6.75	%		7.75	%		6.25	%		7.25	%		7.25	%	7.25	%
	Rate of compensation increase		3	%		3	%		3	%		—			—			—			—			—		—
	Initial medical trend rate2		—			—			—			7.5	%		—			8	%		—			8.5	%	—
	Ultimate medical trend rate2		—			—			—			5	%		—			5	%		—			5	%	—
	_____________________
	1	The expected long-term rate of return assumption is based on the targeted investment portfolios provided to the Company by the VEBAs’ trustees.
	2	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.
	Benefit Obligations and Funded Status — The following table presents the benefit obligations and funded status of the Company’s Canadian pension and the VEBAs as of December 31, 2014 and December 31, 2013 and the corresponding amounts that are included in the Company’s Consolidated Balance Sheets:
			Canadian Pension Benefits								VEBA Benefits
			2014				2013				2014				2013				2013
															(as reclassified)6				(as reported)
	Change in benefit obligation:
	Obligation at beginning of year		$	6.6			$	7			$	374.7			$	384.1			$	384.1
	Foreign currency translation adjustment		(0.5		)		(0.5		)		—				—				—
	Service cost		0.2				0.3				2.2				2.5				2.5
	Interest cost		0.3				0.3				16.7				14.6				14.6
	Prior service cost1		—				—				90.4				84.6				—
	Actuarial loss (gain)2		0.7				(0.2		)		10.2				(91.9		)		(7.3		)
	Plan participant contributions		—				—				—				—				—
	Benefits paid by Company		(0.3		)		(0.3		)		—				—				—
	Benefits paid by VEBAs		—				—				(24.7		)		(21.5		)		(21.5		)
	Reimbursement from retiree drug subsidy3		—				—				1.4				2.3				2.3
	Obligation at end of year		7				6.6				470.9				374.7				374.7
	Change in plan assets:
	Fair market value of plan assets at beginning of year		6.2				5.7				780.7				744.7				744.7
	Foreign currency translation adjustment		(0.5		)		(0.4		)		—				—				—
	Actual return on assets		0.6				0.7				22.7				39.2				39.2
Plan participant contributions		—				—				—				—				—
Sale of Company's common stock by Union VEBA		—				—				—				—				—
Employer/Company contributions5		0.3				0.5				13.7				16				16
Benefits paid by Company		(0.3		)		(0.3		)		—				—				—
Benefits paid by VEBAs		—				—				(24.7		)		(21.5		)		(21.5		)
Reimbursement from retiree drug subsidy3		—				—				1.4				2.3				2.3
Fair market value of plan assets at end of year		6.3				6.2				793.8				780.7				780.7
Net funded status4		$	(0.7	)		$	(0.4	)		$	322.9			$	406			$	406
_____________________________
1	The prior service cost relating to the VEBAs in 2014 was primarily comprised of (i) a loss of $60.5 due to an increase in the healthcare premium reimbursement benefit in the Union VEBA; (ii) a loss of $15.9 resulting from the addition of a new death benefit starting in 2015 for plan participants in the Union VEBA; and (iii) a loss of $14.0 due to an increase in the annual healthcare reimbursement benefit starting in 2015 for plan participants in the Salaried VEBA.
The prior service cost relating to the VEBAs in 2013 was primarily comprised of a loss of $63.8 due to the addition of a new healthcare premium reimbursement benefit starting in 2014 in the Union VEBA and a loss of $20.8 resulting from an increase in the existing benefits reimbursement rates starting in 2014 for plan participants in both VEBAs.
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	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.
5	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.
6	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.
The following table presents the net assets of each VEBA as of the periods presented (such information is also included in the tables required under GAAP above which roll forward the assets and obligations):
		December 31, 2014												December 31, 2013
		Union VEBA				Salaried VEBA				Total				Union VEBA				Salaried VEBA				Total
Accumulated plan benefit obligation		$	(391.5	)		$	(79.4	)		$	(470.9	)		$	(312.7	)		$	(62.0	)		$	(374.7	)
Plan assets		731.6				62.2				793.8				717.5				63.2				780.7
Net funded status		$	340.1			$	(17.2	)		$	322.9			$	404.8			$	1.2			$	406
The accumulated benefit obligation for the Canadian defined benefit pension plan was $6.2 and $5.8 at December 31, 2014 and December 31, 2013, respectively. The Company expects to contribute $0.3 to the Canadian pension plan in 2015.
As of December 31, 2014, the net benefits expected to be paid in each of the next five fiscal years and in aggregate for the five fiscal years thereafter are as follows:
	Benefit Payments Due by Period
	2015				2016				2017				2018				2019				2020-2023
Canadian pension plan benefit payments	$	0.3			$	0.3			$	0.3			$	0.3			$	0.3			$	1.6
VEBA benefit payments1	30.3				30.1				29.9				29.5				29.2				137.9
Total net benefits	$	30.6			$	30.4			$	30.2			$	29.8			$	29.5			$	139.5
__________________________________
1	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.
The amount of loss which is recognized in the Consolidated Balance Sheets (in Accumulated other comprehensive income (loss)) associated with the Company’s Canadian defined benefit pension plan and the VEBAs (before tax) that have not yet been reflected in net periodic benefit cost (income) were as follows for the years ended December 31:
		Canadian Pension Benefits								VEBA Benefits
		2014				2013				2014				2013				2013
														(as reclassified)				(as reported)
Accumulated net actuarial (losses) gains		$	(1.9	)		$	(1.8	)		$	43.6			$	84.3			$	(0.5	)
Transition assets		0.2				0.2				—				—				—
Prior service cost		—				—				(197.4		)		(117.5		)		(32.7		)
Loss recognized in Accumulated other comprehensive income (loss)		$	(1.7	)		$	(1.6	)		$	(153.8	)		$	(33.2	)		$	(33.2	)
The amounts in Accumulated other comprehensive income (loss) that have not yet been recognized as components of net periodic pension benefit income (costs) at December 31, 2014 that are expected to be recognized in 2015 are $0.1 for the Canadian pension plan relating to prior service cost and $18.3 for the VEBAs. Of the $18.3 relating to the VEBAs, $17.3 is related to amortization of prior service cost and $1.0 is related to amortization of net actuarial gain (loss). See the Statement of Comprehensive Income (Loss) for reclassification adjustments of other comprehensive income that were recognized as components of net periodic benefit costs (income) for 2014, 2013 and 2012.
Fair Value of Plan Assets. See Note 11 for the fair values of the assets of the Canadian pension plan and the VEBAs.
Components of Net Periodic Benefit Cost (Income) — The Company’s results of operations included the following impacts associated with the Canadian defined benefit plan and the VEBAs: (a) charges for service rendered by employees; (b) a charge for accretion of interest; (c) a benefit for the return on plan assets; and (d) amortization of net gains or losses on assets, prior service costs associated with plan amendments and actuarial differences. The following table presents the components of net periodic benefit cost (income) for the years ended December 31:
		Canadian Pension Benefits												VEBA Benefits
		2014				2013				2012				2014				2013				2012
Service cost		$	0.2			$	0.3			$	0.2			$	2.2			$	2.5			$	3.4
Interest cost		0.3				0.3				0.3				16.7				14.6				17.9
Expected return on plan assets		(0.3		)		(0.3		)		(0.2		)		(51.4		)		(45.1		)		(40.4		)
Amortization of prior service cost1		—				—				—				10.6				4.2				4.2
Amortization of net actuarial loss (gain)		0.1				0.2				0.1				(1.8		)		1.3				3
Net periodic benefit cost (income)		$	0.3			$	0.5			$	0.4			$	(23.7	)		$	(22.5	)		$	(11.9	)
__________________________
1	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.
The following tables present the total (income) charges related to all benefit plans for the periods presented:
		Year Ended December 31,
		2014				2013				2012
Included within Fabricated Products:
Canadian pension plan		$	0.3			$	0.5			$	0.4
Deferred compensation plan		0.2				0.3				0.2
Defined contribution plans		7.3				7.2				6.8
Total Fabricated Products1		$	7.8			$	8			$	7.4
Included within All Other:
VEBAs2		$	(23.7	)		$	(22.5	)		$	(11.9	)
Deferred compensation plan		0.7				0.9				0.8
Defined contribution plans		0.8				0.7				0.7
Total All Other		$	(22.2	)		$	(20.9	)		$	(10.4	)
Total		$	(14.4	)		$	(12.9	)		$	(3.0	)
___________________________
1	Substantially all of the Fabricated Products segment’s employee benefits related charges are in Cost of products sold, excluding depreciation and amortization and other items with the remaining balance in Selling, administrative, research and development and general.
2	Included within the Statements of Consolidated Income as Net periodic pension benefit income relating to VEBAs.

Multiemployer_Pension_Plans

Multiemployer Pension Plans	12 Months Ended
	Dec. 31, 2014
Multiemployer Plans [Abstract]
Multiemployer Pension Plans Disclosure	Multiemployer Pension Plans
	Overview. The Company contributes to multiemployer defined benefit pension plans under the terms of collective-bargaining agreements that cover its union-represented employees at certain facilities. At December 31, 2014, approximately 55% of the Company's total employees were union-represented employees at facilities participating in these multiemployer pension plans. The Company currently estimates that contributions will range from $3.0 to $5.0 per year through 2015.
	The risks of participating in these multiemployer plans are different from single-employer plans in the following aspects:
	•	Assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers.
	•	If a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers.
	•	If the Company chooses to stop participating in some of its multiemployer plans, the Company may be required to pay those plans an amount based on the underfunded status of the plan, referred to as a withdrawal liability.
	The Company's participation in multiemployer pension plans for the year ended December 31, 2014 is outlined in the table below:
	Pension Fund		Employer Identification Number	Pension Protection Act Zone Status1		FIP/RP Status Pending/Implemented in 20142	Contributions of the Company						Surcharge Imposed in 2014	Expiration Date of Collective-Bargaining Agreement
							2014		2013		2012
				2014	2013
	Steelworkers Pension Trust (USW)3		236648508	Green	Green	No	$	3.1	$	2.9	$	3	No	Sep-15	-	Nov-17
	Other Funds4						0.9		0.9		0.9
							$	4	$	3.8	$	3.9
	________________
	1	The most recent Pension Protection Act zone status available in 2014 and 2013 for the Steelworkers Pension Trust is for the plan's year-end at December 31, 2013 and December 31, 2012, respectively. The zone status is based on information that the Company received from the plan and is certified by the plan's actuary. Among other factors, plans in the green zone are at least 80 percent funded.
	2	The “FIP/RP Status Pending/Implemented” column indicates if a Financial Improvement Plan (FIP) or a Rehabilitation Plan (RP) is either pending or has been implemented for the plan under the Pension Protection Act.
	3	The Company is party to three USW collective-bargaining agreements that require contributions to the Steelworkers Pension Trust. As of December 31, 2014, USW collective bargaining agreements covering employees at the Newark, Ohio ("Newark") and Spokane, Washington ("Trentwood") facilities covers 86% of the Company's USW-represented employees and expires in September 2015. In January 2015, the Company and the USW entered into a new five-year labor agreement relating to these facilities, effective October 1, 2015 through September 30, 2020. The Company's monthly contributions per hour worked by each bargaining unit employee at the Newark and Trentwood facilities are (in whole dollars) $1.25 and will increase to (in whole dollars) $1.50 in July 2015 and $1.75 in 2019. The union contracts covering employees at the Richmond (Bellwood), Virginia facility and Florence, Alabama facility cover 9% and 5% of the Company's USW-represented employees, respectively, and expire in November 2017 and March 2017, respectively.
	4	Other Funds consists of plans that are not individually significant.
	The Company was not listed in any of the plans' Forms 5500 or the Canada-Wide Industrial Pension Plan financial statements as providing more than 5% of the total contributions for any of the plan years disclosed. At December 31, 2014, Forms 5500 were not available for the plan years ending in 2014. Further, there were no significant changes to the number of employees covered by the Company's multiemployer plans that would affect the period-to-period comparability of the contributions for the years presented.

Employee_Incentive_Plans

Employee Incentive Plans	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Incentive Plans	Employee Incentive Plans
	Short-Term Incentive Plans ("STI Plans")
	The Company has annual short-term incentive compensation plans for senior management and certain other employees payable at the Company’s election in cash, shares of common stock, or a combination of cash and shares of common stock. Amounts earned under the 2012 and 2013 STI Plans were based primarily on the economic value added ("EVA") of the Company’s Fabricated Products business, adjusted for certain safety and individual performance factors. EVA, as defined by the Company's 2012 and 2013 STI Plans, is the excess of the Company’s adjusted pre-tax operating income for a particular year over a pre-determined percentage of the adjusted net assets of the immediately preceding year, measured over a one-year period. Amounts, if any, that will be earned under the 2014 STI plan are based on the Company’s adjusted earnings before interest, taxes, depreciation and amortization ("Adjusted EBITDA"), modified for certain safety, quality, delivery, cost and individual performance factors. The Adjusted EBITDA targets under the 2014 STI plan were determined based on the EVA of the Company’s Fabricated Products business. Most of the Company’s production facilities have similar programs for both hourly and salaried employees.
	Total costs relating to STI Plans were recorded as follows for each period presented:
			Year Ended December 31,
			2014				2013				2012
	Cost of products sold, excluding depreciation and amortization and other items		$	4.7			$	4.6			$	4.3
	Selling, administrative, research and development and general		8				11.1				10.1
	Total costs recorded in connection with STI Plans		$	12.7			$	15.7			$	14.4
	The following table presents the allocation of the charges detailed above, by segment:
			Year Ended December 31,
			2014				2013				2012
	Fabricated Products		$	9.6			$	11.2			$	9.9
	All Other		3.1				4.5				4.5
	Total costs recorded in connection with STI Plans		$	12.7			$	15.7			$	14.4
	Long-Term Incentive Programs ("LTI Programs")
	General. Officers and other key employees of the Company or one or more of its subsidiaries, as well as non-employee directors of the Company, are eligible to participate in the Kaiser Aluminum Corporation Amended and Restated 2006 Equity and Performance Incentive Plan (as amended, "Equity Incentive Plan"). The Equity Incentive Plan permits the granting of awards in the form of options to purchase common shares, stock appreciation rights, shares of non-vested and vested stock, restricted stock units, performance shares, performance units and other awards. The Equity Incentive Plan will expire on July 6, 2016 and no grants will be made thereunder after that date. The Company's Board of Directors may, in its discretion, terminate the Equity Incentive Plan at any time. The termination of the Equity Incentive Plan will not affect the rights of participants or their successors under any awards outstanding and not exercised in full on the date of termination and all grants made on or prior to the date of termination will remain in effect thereafter subject to the terms of the applicable grant agreement and the Equity Incentive Plan. Subject to certain adjustments that may be required from time to time to prevent dilution or enlargement of the rights of participants under the Equity Incentive Plan, a total of 2,722,222 common shares have been authorized for issuance under the Equity Incentive Plan. At December 31, 2014, 776,549 common shares were available for additional awards under the Equity Incentive Plan.
	Non-vested Common Shares and Restricted Stock Units. The Company grants non-vested common shares to its non-employee directors, executive officers and other key employees. The Company also grants restricted stock units to certain employees. The restricted stock units have rights similar to the rights of non-vested common shares and each restricted stock unit that becomes vested entitles the recipient to receive one common share. For both non-vested common shares and restricted stock units, the service period is generally one year for non-employee directors and three years for executive officers and other key employees.
	In addition to non-vested common shares and restricted stock units, the Company also grants performance shares to executive officers and other key employees. Each performance share that becomes vested entitles the recipient to receive one common share. Performance shares granted prior to 2014 ("EVA-Based Performance Shares") are subject to performance conditions pertaining to the Company’s EVA performance, measured over specified three-year performance periods. The number of EVA-Based Performance Shares that will ultimately vest and result in the issuance of common shares ranges between 0% to 200% of the target number of underlying common shares (constituting approximately one-half of the maximum payout) and depends on the average annual EVA achieved for the specified three-year performance period. Performance shares granted in 2014 ("TSR-Based Performance Shares") are subject to performance conditions pertaining to the Company’s total shareholder return ("TSR") over a three-year performance period compared to the TSR of a specified group of peer companies. The number of TSR-Based Performance Shares that will ultimately vest under the 2014-2016 LTI Program and result in the issuance of common shares ranges between 0% to 200% of the target number of underlying common shares (constituting approximately one-half of the maximum payout) and depends on the percentile ranking of the Company’s TSR compared to the group of peer companies. During 2014, a portion of the EVA-Based Performance Shares granted under the 2011-2013 LTI Program vested (see "Summary of Activity" below). The vesting of performance shares resulting in the issuance and delivery of common shares, if any, under the 2012-2014, 2013-2015 and 2014-2016 LTI Programs will occur in 2015, 2016 and 2017, respectively.
	Non-Cash Compensation Expense. Compensation expense relating to all awards under the Equity Incentive Plan is included in Selling, administrative, research and development and general. Non-cash compensation expense by type of award under LTI Programs were as follows for each period presented:
		Year Ended December 31,
		2014				2013				2012
	Non-vested common shares and restricted stock units	$	3.9			$	4.3			$	3.8
	EVA-Based Performance Shares	1				2.3				1.8
	TSR-Based Performance Shares	1.9				—				—
	Total non-cash compensation expense	$	6.8			$	6.6			$	5.6
	The following table presents the allocation of the charges detailed above, by segment:
		Year Ended December 31,
		2014				2013				2012
	Fabricated Products	$	3.2			$	2.2			$	1.7
	All Other	3.6				4.4				3.9
	Total non-cash compensation expense	$	6.8			$	6.6			$	5.6
	Recognized tax benefits relating to non-cash compensation expense were $2.5, $2.4 and $2.1 for 2014, 2013 and 2012, respectively.
	Unrecognized Gross Compensation Cost Data. The following table presents unrecognized gross compensation cost data by type of award:
		31-Dec-14
		Unrecognized gross compensation costs				Expected period (in years) over which the remaining gross compensation costs will be recognized
	Non-vested common shares and restricted stock units	$	5.6			2.2
	EVA-Based Performance Shares	$	1.6			1
	TSR-Based Performance Shares	$	4.4			2.1
	Summary of Activity. A summary of the activity with respect to non-vested common shares, restricted stock units, EVA-Based Performance Shares and TSR-Based Performance Shares for the year ended December 31, 2014 is as follows:
		Non-Vested							Restricted					EVA-Based Performance				TSR-Based Performance
		Common Shares							Stock Units					Shares				Shares
		Shares			Weighted-Average				Units			Weighted-Average		Shares		Weighted-Average		Shares		Weighted-Average
					Grant-Date Fair							Grant-Date Fair				Grant-Date Fair				Grant-Date Fair
					Value per Share							Value per Unit				Value per Share				Value per Share
	Outstanding at December 31, 2013	143,967			$	51.09			5,472			$	51.03	562,554		$	49.26	—		$	—
	Granted 1	119,799			66.42				2,235			67.42		—		—		160,868		83.18
	Vested	(64,493	)		52.2				(2,350	)		46.83		(42,545	)	47.21		—		—
	Forfeited 1	(40,503	)		60.21				—			—		(28,613	)	51.44		(10,645	)	83.18
	Canceled 2	—			$	—			—			$	—	(137,820	)	46.65		—		—
	Outstanding at December 31, 2014	158,770			$	59.88			5,357			$	59.71	353,576		$	50.35	150,223		$	83.18
	_____________________
	1	For EVA-Based Performance Shares and TSR-Based Performance Shares, the number of shares granted and forfeited are presented at their maximum payout.
	2	For EVA-Based Performance Shares and TSR-Based Performance Shares, canceled represents the number of shares that did not vest due to EVA or TSR performance results falling below those required for maximum payout.
	The total grant-date fair value for shares granted was $14.8 during both 2014 and 2013 and $13.9 in 2012. The total grant-date fair value for shares that vested during 2014, 2013 and 2012 was $5.5, $5.1 and $3.5, respectively.
	Stock Options. The Company has fully-vested stock options granted in 2007. There were 16,645 and 20,791 fully-vested options outstanding as of December 31, 2014 and December 31, 2013, respectively, in each case exercisable to purchase common shares at $80.01 per share and having a remaining contractual life of 2.25 and 3.25 years, respectively. The average fair value of the options granted was $39.90. During 2014, no options were granted, exercised or forfeited and 4,146 options expired.
	Vested Stock. From time to time, the Company issues common shares to non-employee directors electing to receive common shares in lieu of all or a portion of their annual retainer fees. The fair value of these common shares is based on the fair value of the shares at the date of issuance and is immediately recognized in earnings as a period expense. During each of the periods ending December 31, 2014, 2013 and 2012, the Company recorded $0.2 relating to common shares granted to non-employee directors in lieu of all or a portion of their annual retainer fees.
	Under the Equity Incentive Plan, participants may elect to have the Company withhold common shares to satisfy minimum statutory tax withholding obligations arising in connection with the exercise of stock options and vesting of non-vested shares, restricted stock units and performance shares. Any such shares withheld are canceled by the Company on the applicable vesting dates or earlier dates when service requirements are satisfied, which correspond to the times at which income to the employee is recognized. When the Company withholds these common shares, the Company is required to remit to the appropriate taxing authorities the fair value of the shares withheld as of the vesting date. During 2014, 2013 and 2012, 33,696, 40,075 and 45,801 commons shares, respectively, were withheld and canceled for this purpose. The withholding of common shares by us could be deemed a purchase of the common shares.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Commitments. The Company has a variety of financial commitments, including purchase agreements, forward foreign exchange and forward sales contracts, indebtedness (and related Option Assets and Warrants) and letters of credit (see Note 3 and Note 10).
	Rental expenses were $7.4, $7.5 and $10.0 for 2014, 2013 and 2012, respectively. There are renewal options in various operating leases subject to certain terms and conditions. Minimum rental commitments under operating leases at December 31, 2014 were as follows:
		Year Ended December 31,
		2015			2016			2017			2018		2019		2020 and Thereafter
	Minimum rental commitments	$	4.7		$	3.9		$	3.2		$	2.8	$	2.7	$	27.6
	The Company's purchase obligations at December 31, 2014 consisted of (i) various contracts with suppliers of aluminum that require the Company to purchase minimum quantities of aluminum in 2015 at a price to be determined at the time of purchase based primarily on the underlying metal price at that time and (ii) energy contracts requiring the Company to purchase minimum quantities of electricity in future years at a fixed price. Amounts to be purchased in 2015 under the variable priced metal contracts totaled $283.7 and are included in the table below based on minimum quantities at the metal price as of December 31, 2014. The Company believes the minimum quantities are lower than its current requirements for aluminum. Actual quantities and actual metal prices at the time of purchase could be different. All remaining amounts in the table below relate to the fixed price electricity contracts discussed above. The total amounts due under purchase obligations as of December 31, 2014 were as follows:
		Year Ended December 31,
		2015			2016			2017			2018		2019		2020 and Thereafter
	Purchase obligations	$	294.6		$	8.9		$	2.9		$	1	$	0.5	$	1.4
	Environmental Contingencies. The Company is subject to a number of environmental laws and regulations, to potential fines or penalties assessed for alleged breaches of such laws and regulations and to potential claims based upon such laws and regulations.
	The Company has established procedures for regularly evaluating environmental loss contingencies. The Company’s environmental accruals represent the Company’s undiscounted estimate of costs reasonably expected to be incurred based on presently enacted laws and regulations, existing requirements, currently available facts, existing technology and the Company’s assessment of the likely remediation actions to be taken.
	The following table presents the changes in such accruals, which are primarily included in Long-term liabilities:
		Year Ended December 31,
		2014			2013			2012
	Beginning balance	$	22.8		$	21.7		$	22
	Additional accruals	0.8			4.5			1.2
	Less expenditures	(4.3		)	(3.4		)	(1.5		)
	Ending balance	$	19.3		$	22.8		$	21.7
	In 2012, the Company submitted a final feasibility study to the Washington State Department of Ecology (“Washington State Ecology”) that included recommendations for remediation alternatives primarily to address the historical use of oils containing polychlorinated biphenyls, ("PCBs") at the Trentwood facility. The Company also signed an amended work order in 2012 with Washington State Ecology allowing certain remediation activities to begin the initiation of a treatability study in regards to proposed PCB remediation methods. The Company began implementation of certain approved sections of the work plan in 2013 and continues to work with Washington State Ecology in developing the implementation work plans, which are subject to Washington State Ecology approval.
	During 2013, at the request of the Ohio Environmental Protection Agency ("OEPA"), the Company initiated an investigational study of the Newark facility related to historical on-site waste disposal. As this work continues and progresses to a risk assessment and feasibility study, the Company will establish and update estimates for probable and estimable remediations, if any. The actual and final cost for remediation will not be fully determinable until a final feasibility study is submitted and accepted by the OEPA and work plans are prepared, which is expected to occur in the next 18 to 24 months.
	At December 31, 2014, the Company’s environmental accrual of $19.3 represented the Company’s estimate of the incremental remediation cost based on (i) proposed alternatives in the final feasibility study related to the Trentwood facility; (ii) currently available facts with respect to the Newark, Ohio facility; and (iii) facts related to certain other locations owned or formally owned by the Company. In accordance with approved and proposed remediation action plans, the Company expects that the implementation and ongoing monitoring could occur over a period of 30 or more years.
	As additional facts are developed, feasibility studies are completed, draft remediation plans are modified, necessary regulatory approvals for the implementation of remediation are obtained, alternative technologies are developed and/or other factors change, there may be revisions to management’s estimates and actual costs may exceed the current environmental accruals. The Company believes at this time that it is reasonably possible that undiscounted costs associated with these environmental matters may exceed current accruals by amounts that could be, in the aggregate, up to an estimated $25.1 over the remediation period. It is reasonably possible that the Company’s recorded estimate may change in the next 12 months.
	Other Contingencies. The Company is party to various lawsuits, claims, investigations and administrative proceedings that arise in connection with past and current operations. The Company evaluates such matters on a case-by-case basis and its policy is to vigorously contest any such claims it believes are without merit. The Company accrues for a legal liability when it is both probable that a liability has been incurred and the amount of the loss is reasonably estimable. Quarterly, in addition to when changes in facts and circumstances require it, the Company reviews and adjusts these accruals to reflect the impacts of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular case. While uncertainties are inherent in the final outcome of such matters and it is presently impossible to determine the actual cost that may ultimately be incurred, management believes that it has sufficiently reserved for such matters and that the ultimate resolution of pending matters will not have a material impact on the Company’s consolidated financial position, operating results, or liquidity.

Derivative_Financial_Instrumen

Derivative Financial Instruments and Related Hedging Programs	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments and Related Hedging Programs	Derivative Financial Instruments and Related Hedging Programs
	Overview. In conducting its business, the Company enters into derivative transactions, including forward contracts and options, to limit its economic (i.e. cash) exposure resulting from (i) metal price risk related to its sale of fabricated aluminum products and the purchase of metal used as raw material for its fabrication operations; (ii) energy price risk relating to fluctuating prices of natural gas and electricity used in its production processes; and (iii) foreign currency requirements with respect to its foreign subsidiaries and cash commitments for equipment purchases denominated in foreign currency. Additionally, in connection with the issuance of the Convertible Notes, the Company purchased Option Assets relating to the Company’s common stock to limit its exposure to the cash conversion feature of the Convertible Notes (see Note 3).
	The Company’s derivative activities are overseen by a hedging committee ("Hedging Committee"), which is composed of the Company's chief executive officer, chief financial officer, chief accounting officer, vice president of metal risk and other officers and employees selected by the chief executive officer. The Hedging Committee meets regularly to review derivative positions and strategy and reports to the Company’s Board of Directors on the scope of its activities.
	Hedges of Operational Risks. The Company’s pricing of fabricated aluminum products is generally intended to lock in a conversion margin (representing the value added from the fabrication process(es)) and to pass through metal price fluctuations to its customers. In certain instances the Company enters into firm-price arrangements with its customers for stipulated volumes to be delivered in the future. Additionally, for some of its higher value added products sold on a spot basis, the pass through of metal price movements can sometimes lag by as much as several months, with a favorable impact to the Company when metal prices decline and an adverse impact to the Company when metal prices increases. Because the Company generally purchases primary and secondary aluminum on a floating price basis, the volume that it has committed to sell to its customers under a firm-price arrangement and the lag in passing through metal price movements to customers on some of its higher value added products sold on a spot basis create metal price risk for the Company. The Company uses third-party hedging instruments to limit exposure to metal price risk related to firm-price customer sales contracts and the metal pass through lag on some of its products. See Note 11 for additional information regarding the Company’s material derivative positions relating to hedges of operational risk and their respective fair values.
	A majority of the Company's derivative contracts relating to hedges of operational risks contain liquidity based thresholds that could require the Company to provide additional collateral in the event the Company's liquidity were to fall below specified levels. To minimize the exposure to additional collateral requirements related to its liability hedge positions, the Company allocates hedging transactions among its counterparties, uses options as part of its hedging activities, or both. The aggregate fair value of the Company's derivative instruments that were in a net liability position at December 31, 2014 was $11.4.
	The Company regularly reviews the creditworthiness of its derivative counterparties and does not expect to incur significant loss from the failure of any counterparties to perform under any agreements.
	Hedges Relating to the Convertible Notes. As described in Note 3, the Company issued $175.0 principal amount of Convertible Notes due on April 1, 2015, which can only be settled in cash. The conversion feature of the Convertible Notes was required to be bifurcated from the Convertible Notes and treated as a separate derivative instrument. In order to offset the cash flow risk associated with the Bifurcated Conversion Feature, the Company purchased Option Assets, which are accounted for as derivative instruments. The Company expects that the cash received from the settlement of the Option Assets will equal and offset the cash that it will be required to pay to the holders of any converted Convertible Notes in excess of the principal amount thereof and interest payable thereon. See Note 11 for additional information regarding the fair values of the Bifurcated Conversion Feature and the Option Assets.
	Realized and Unrealized Gains and Losses. Realized and unrealized (losses) gains associated with all derivative contracts consisted of the following for each period presented:
			Year Ended December 31,
			2014				2013				2012
	Realized gains (losses):
	Aluminum		$	6.9			$	(5.5	)		$	(9.0	)
	Natural Gas		1				(1.8		)		(6.7		)
	Electricity		(0.1		)		0.8				(3.4		)
	Total realized gains (losses):		$	7.8			$	(6.5	)		$	(19.1	)
	Unrealized (losses) gains:
	Hedges of operational risk:
	Aluminum		$	(2.6	)		$	(3.1	)		$	10.1
	Natural Gas		(6.0		)		2.6				4.3
	Electricity		(1.8		)		1.1				0.8
	Foreign Currency		—				0.1				—
	Total hedges of operational risk		(10.4		)		0.7				15.2
	Option Assets relating to the Convertible Notes		5.2				24.2				9
	Bifurcated Conversion Feature of the Convertible Notes		(1.6		)		(21.0		)		(8.2		)
	Total unrealized (losses) gains		$	(6.8	)		$	3.9			$	16
	The following table summarizes the Company's material derivative positions at December 31, 2014:
	Aluminum		Maturity Period		Notional Amount of Contracts (mmlbs)
			(month/year)
	Fixed price purchase contracts		1/15 through 1/16		67.3
	Midwest premium swap contracts1		1/15 through 12/15		67.1
	Natural Gas2		Maturity Period		Notional Amount of Contracts (mmbtu)
			(month/year)
	Fixed price purchase contracts		1/15 through 12/17		6,720,000
	Electricity3		Maturity Period		Notional Amount of Contracts (Mwh)
			(month/year)
	Fixed price purchase contracts		1/15 through 12/15		175,200
	Hedges Relating to the Convertible Notes		Contract Period		Notional Amount of Contracts (Common Shares)
			(month/year)
	Bifurcated Conversion Feature4		3/10 through 4/15		3,660,738
	Option Assets4		3/10 through 4/15		3,660,738
	_________________________
	1	Regional premiums represent the premium over the London Metal Exchange price for primary aluminum which is incurred on the Company's purchases of primary aluminum.
	2	As of December 31, 2014, the Company had Henry Hub NYMEX-based hedge positions in place to cover exposure to fluctuations in prices for approximately 81%, 73% and 12% of the expected natural gas purchases for 2015, 2016 and 2017, respectively.
	3	As of December 31, 2014, the Company had Mid-C International Commodity Exchange-based hedge positions in place to cover exposure to fluctuations in prices for approximately 44% of the expected electricity purchases for 2015.
	4	The Bifurcated Conversion Feature represents the cash conversion feature of the Convertible Notes. The Option Assets expire on the maturity or earlier conversion of the Convertible Notes and have an exercise price equal to the conversion price of the Convertible Notes, subject to anti-dilution adjustments substantially similar to the anti-dilution adjustments for the Convertible Notes. Although the fair value of the Option Assets is derived from a notional number of shares of the Company's common stock, the Option Assets may only be settled in cash.
	The Company enters into derivative contracts with counterparties, some of which are subject to enforceable master netting arrangements and some of which are not. The Company reflects the fair value of its derivative contracts on a gross basis on the Consolidated Balance Sheets (see Note 2).
	The following tables present offsetting information regarding the Company's derivatives by type of counterparty as of December 31, 2014:
	Derivative Assets and Collateral Held by Counterparty
														Gross Amounts Not Offset in the Consolidated Balance Sheets
		Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets				Financial Instruments			Cash Collateral Received		Net Amount
	Counterparty (with netting agreements)	$	0.9			$	—			$	0.9			$	0.8		$	—	$	0.1
	Counterparty (without netting agreements)1	84.8				—				84.8				—			—		84.8
	Total	$	85.7			$	—			$	85.7			$	0.8		$	—	$	84.9
	Derivative Liabilities and Collateral Held by Counterparty
														Gross Amounts Not Offset in the Consolidated Balance Sheets
		Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets				Financial Instruments			Cash Collateral Pledged		Net Amount
	Counterparty (with netting agreements)	$	(8.0	)		$	—			$	(8.0	)		$	(0.8	)	$	—	$	(7.2	)
	Counterparty (without netting agreements)1	(85.0		)		—				(85.0		)		—			—		(85.0		)
	Counterparty (with partial netting agreements)	(3.8		)		—				(3.8		)		—			—		(3.8		)
	Total	$	(96.8	)		$	—			$	(96.8	)		$	(0.8	)	$	—	$	(96.0	)
	_________________
	1	Such amounts include the fair value of the Bifurcated Conversion Feature and Option Assets at December 31, 2014 (see Note 11).
	The following tables present offsetting information regarding the Company’s derivatives by type of counterparty as of December 31, 2013:
	Derivative Assets and Collateral Held by Counterparty
													Gross Amounts Not Offset in the Consolidated Balance Sheets
	Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets				Financial Instruments			Cash Collateral Received		Net Amount
Counterparty (with netting agreements)	$	1			$	—			$	1			$	0.8		$	—	$	0.2
Counterparty (without netting agreements)1	80.4				—				80.4				—			—		80.4
Counterparty (with partial netting agreements)	0.4				—				0.4				0.4			—		—
Total	$	81.8			$	—			$	81.8			$	1.2		$	—	$	80.6
Derivative Liabilities and Collateral Held by Counterparty
													Gross Amounts Not Offset in the Consolidated Balance Sheets
	Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets				Financial Instruments			Cash Collateral Pledged		Net Amount
Counterparty (with netting agreements)	$	(1.6	)		$	—			$	(1.6	)		$	(0.8	)	$	—	$	(0.8	)
Counterparty (without netting agreements)1	(83.2		)		—				(83.2		)		—			—		(83.2		)
Counterparty (with partial netting agreements)	(1.3		)		—				(1.3		)		(0.4		)	—		(0.9		)
Total	$	(86.1	)		$	—			$	(86.1	)		$	(1.2	)	$	—	$	(84.9	)
_________________
1	Such amounts include the fair value of the Bifurcated Conversion Feature and Option Assets at December 31, 2013 (see Note 11).

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurements
	Overview
	The Company applies the fair value hierarchy established by GAAP for the recognition and measurement of assets and liabilities. An asset or liability's fair value classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible and considers counterparty risk in its assessment of fair value.
	The fair values of financial assets and liabilities are evaluated and measured on a recurring basis. As part of that evaluation process, the Company reviews the underlying inputs that are significant to the fair value measurement of financial instruments to determine if a transfer among hierarchy levels is appropriate. The Company historically has not had significant transfers into or out of each hierarchy level.
	Financial assets and liabilities that the Company measures at fair value as required by GAAP include: (i) its derivative instruments; (ii) the plan assets of the VEBAs and the Company's Canadian defined benefit pension plan measured annually at December 31; and (iii) available for sale securities, consisting of debt investment securities and investments related to the Company's deferred compensation plan (see Note 6). The Company records certain other financial assets and liabilities at carrying value (see the tables below for the fair value disclosure of those assets and liabilities).
	The majority of the Company's non-financial assets and liabilities, which include goodwill, intangible assets, inventories and property, plant and equipment, are not required to be measured at fair value on a recurring basis. However, if certain triggering events occur (or at least annually for goodwill), an evaluation of a non-financial asset or liability is required, potentially resulting in an adjustment to the carrying amount of such asset or liability.
	Fair Values of Financial Assets and Liabilities
	Derivative Assets and Liabilities. The Company's derivative contracts are valued at fair value using significant observable and unobservable inputs.
	Commodity, Energy and Foreign Currency Derivatives - The fair values of a majority of these derivative contracts are based
	upon trades in liquid markets. Valuation model inputs can generally be verified and valuation techniques do not involve
	significant judgment. The fair values of such financial instruments are generally classified within Level 2 of the fair value hierarchy. The Company, however, has some derivative contracts that do not have observable market quotes. For these financial instruments, management uses significant unobservable inputs (e.g., information concerning regional premiums for swaps). Where appropriate, valuations are adjusted for various factors, such as bid/offer spreads. The fair value of these financial instruments is classified as Level 3 in the fair value hierarchy.
	Bifurcated Conversion Feature and Option Assets - The fair value of the Bifurcated Conversion Feature is measured as the difference in the estimated fair value of the Convertible Notes and the estimated fair value of the Convertible Notes without the cash conversion feature. The Convertible Notes are valued based on the trading price of the Convertible Notes each period end (see “All Other Financial Assets and Liabilities” below). The fair value of the Convertible Notes without the cash conversion feature is the present value of the series of the remaining fixed income cash flows under the Convertible Notes, with a maturity of April 1, 2015. The Bifurcated Conversion Feature and the Option Assets were designed to offset each other upon their maturity. Due to the short duration before maturity, management concluded that the fair value of the Option Assets should equal the fair value of the Bifurcated Conversion Feature as of December 31, 2014.
	As of December 31, 2014, the Bifurcated Conversion Feature and Option Assets were recorded as current liabilities and assets, respectively, and were included in the Consolidated Balance Sheet as a portion of Other accrued liabilities and Prepaid expenses and other current assets, respectively.
	The aggregate fair value of the Company's derivatives, recorded on the Consolidated Balance Sheets at December 31, 2014 and December 31, 2013, was a net liability of $11.1 and $4.3, respectively. The increase in the net liability position during 2014 was primarily due to changes in the underlying commodity and energy prices, as well as settlement of asset positions during such period. Changes in the fair value of the Company's derivative contracts relating to operational hedging activities are reflected in Operating income (see Note 10).
	VEBA and Canadian Pension Plan Assets. The VEBA assets are managed by various investment advisors selected by the trustees of each of the VEBAs. The VEBA assets are outside of the Company's control and the Company does not have insight into the investment strategies. The fair value of the plan assets of the VEBA assets is based on information made available to the Company by the VEBA administrators.
	The assets of the Company's Canadian pension plan are managed by advisors selected by the Company, with the investment portfolio subject to periodic review and evaluation by the Company's investment committee. The investment of assets in the Canadian pension plan is based upon the objective of maintaining a diversified portfolio of investments in order to minimize concentration of credit and market risks (such as interest rate, currency, equity price and liquidity risks). The degree of risk and risk tolerance take into account the obligation structure of the plan, the anticipated demand for funds and the maturity profiles required from the investment portfolio in light of these demands.
	The fair value of the plan assets of the VEBAs and the Company's Canadian pension plan is measured annually on December 31 and is reflected in the Company's Consolidated Balance Sheets at fair value. In determining the fair value of the plan assets at each annual period end, the Company utilizes primarily the results of valuations supplied by the investment advisors responsible for managing the assets of each plan, which the Company independently reviews for reasonableness. With respect to the VEBAs, the investment advisors providing the valuations are engaged by the VEBA trustees.
	Certain assets are valued based upon unadjusted quoted market prices in active markets that are accessible at the measurement date for identical, unrestricted assets (e.g., liquid securities listed on an exchange). Such assets are classified within Level 1 of the fair value hierarchy.
	Valuation of other invested assets is based on significant observable inputs (e.g., net asset values of registered investment companies not listed on an exchange, valuations derived from actual market transactions, broker-dealer supplied valuations, or correlations between a given U.S. market and a non-U.S. security). Valuation model inputs can generally be verified and valuation techniques do not involve significant judgment. The fair values of such financial instruments are classified within Level 2 of the fair value hierarchy.
	Available for Sale Securities. The Company holds debt investment securities. The fair value of the debt investment securities, which consist of commercial paper and corporate bonds, is determined based on valuation models that use observable market data. At December 31, 2014, the remaining maturity period with respect to short-term investments ranged from nine days to approximately 15 months. In addition to debt investment securities, the Company also holds assets in various investment funds at certain registered investment companies in connection with its deferred compensation program (see Note 1 and Note 6). Such assets are accounted for as available for sale securities and are measured and recorded at fair value based on the net asset value of the investment funds on a recurring basis. The fair value input of the available for sale securities is considered either a Level 1 or Level 2 input depending on whether the debt security or investment fund is traded on a public exchange. The amortized cost for available for sale securities approximates their fair value.
	All Other Financial Assets and Liabilities. The Company believes that the fair value of its cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate their respective carrying values due to their short maturities and nominal credit risk.
	The fair value of the Convertible Notes and Senior Notes is based on their trading prices and is considered a Level 1 input in the fair value hierarchy (see Note 3 for the carrying values of the Convertible Notes and the Senior Notes).
	The following table presents the Company's financial instruments, classified under the appropriate level of the fair value hierarchy, as of the period presented:
		31-Dec-14
		Level 1			Level 2				Level 3				Total
	FINANCIAL ASSETS:
	Derivative Instruments
	Aluminum -
	Midwest premium swap contracts	—			—				1				1
	Hedges Relating to the Convertible Notes - Option Assets	—			84.7				—				84.7
	VEBAs and Canadian Pension Plan
	Fixed income investment funds in registered investment companies1	54			340.3				—				394.3
	Mortgage-backed securities	—			30.1				—				30.1
	Corporate debt securities2	—			75.4				—				75.4
	Equity investment funds in registered investment companies3	—			191.3				—				191.3
	United States Treasuries	—			39.5				—				39.5
	Municipal debt securities	—			1.8				—				1.8
	Cash and money market investments4	19.3			—				—				19.3
	Asset-backed securities	—			8.1				—				8.1
	Diversified investment funds in registered investment companies5	20.4			6.2				—				26.6
	All Other Financial Assets
	Cash and cash equivalents6	29.5			148.2				—				177.7
	Short-term investments	—			114				—				114
	Deferred compensation plan assets	—			7.3				—				7.3
	Total assets	$	123.2		$	1,046.90			$	1			$	1,171.10
	FINANCIAL LIABILITIES:
	Derivative Instruments
	Aluminum - Fixed price purchase contracts	$	—		$	(4.2	)		$	—			$	(4.2	)
	Natural Gas - Fixed price purchase contracts	—			(6.2		)		—				(6.2		)
	Electricity - Fixed price purchase contracts	—			(1.7		)		—				(1.7		)
	Hedges Relating to the Convertible Notes - Bifurcated Conversion Feature	—			(84.7		)		—				(84.7		)
	All Other Financial Liabilities
	Senior Notes	(244.5		)	—				—				(244.5		)
	Convertible Notes, including Bifurcated Conversion Feature	(263.3		)	—				—				(263.3		)
	Total liabilities	$	(507.8	)	$	(96.8	)		$	—			$	(604.6	)
	The following table presents the Company's financial instruments, classified under the appropriate level of the fair value hierarchy, as of the period presented:
		31-Dec-13
		Level 1			Level 2				Level 3				Total
	FINANCIAL ASSETS:
	Derivative Instruments
	Aluminum -
	Fixed price purchase contracts	$	—		$	0.1			$	—			$	0.1
	Midwest premium swap contracts	—			—				1.1				1.1
	Natural Gas - Fixed price purchase contracts	—			0.5				—				0.5
Electricity - Fixed price purchase contracts	—			0.5				—				0.5
Foreign Currency - Euro	—			0.1				—				0.1
Hedges Relating to the Convertible Notes - Option Assets	—			79.5				—				79.5
VEBAs and Canadian Pension Plan
Fixed income investment funds in registered investment companies1	57			318				—				375
Mortgage-backed securities	—			25.9				—				25.9
Corporate debt securities2	—			78.2				—				78.2
Equity investment funds in registered investment companies3	—			175.3				—				175.3
United States Treasuries	—			43.3				—				43.3
Municipal debt securities	—			1.6				—				1.6
Cash and money market investments4	36.8			—				—				36.8
Asset-backed securities	—			8.5				—				8.5
Diversified investment funds in registered investment companies5	20.1			6.2				—				26.3
All Other Financial Assets
Cash and cash equivalents6	57.7			111.8				—				169.5
Short-term investments	—			129.5				—				129.5
Deferred compensation plan assets	—			6.5				—				6.5
Total assets	$	171.6		$	985.5			$	1.1			$	1,158.20
FINANCIAL LIABILITIES:
Derivative Instruments
Aluminum - Fixed price purchase contracts	$	—		$	(1.8	)		$	—			$	(1.8	)
Natural Gas - Fixed price purchase contracts	—			(0.8		)		—				(0.8		)
Electricity - Fixed price purchase contracts	—			(0.4		)		—				(0.4		)
Hedges Relating to the Convertible Notes - Bifurcated Conversion Feature	—			(83.1		)		—				(83.1		)
All Other Financial Liabilities
Senior Notes	(255.4		)	—				—				(255.4		)
Convertible Notes, including Bifurcated Conversion Feature	(260.0		)	—				—				(260.0		)
Total liabilities	$	(515.4	)	$	(86.1	)		$	—			$	(601.5	)
_________________________
1.	This category represents investments in various fixed income funds with multiple registered investment companies. Such funds invest in diversified portfolios, including (i) marketable fixed income securities such as (a) U.S. Treasury and other government and agency securities, (b) municipal bonds, (c) mortgage-backed securities, (d) asset-backed securities, (e) corporate bonds, notes and debentures in various sectors, (f) preferred and common stock, (g) investments in affiliated and other investment companies, (h) short-term investments and other net assets and (i) repurchase agreements and reverse repurchase agreements; (ii) other commingled investments; (iii) investment grade debt; (iv) fixed income instruments which may be represented by options, future contracts or swap agreements; and (v) cash and cash equivalents. The fair value of assets in this category is estimated using the net asset value per share of the investments.
2.	This category represents investments in fixed income corporate securities in various sectors. Investments in the industrial, financial and utilities sectors in 2014 represented approximately 51%, 37% and 12% of the total portfolio in this category, respectively. Investments in the industrial, financial and utilities sectors in 2013 represented approximately 56%, 35% and 9% of the total portfolio in this category, respectively. The fair value of assets in this category is estimated using the net asset value per share of the investments.
3.	This category represents investments in equity funds that invest in portfolios comprised of (i) equity and equity-related securities of U.S. and non-U.S. issuers across all market capitalization; (ii) common stock in investment trust funds; and (iii) other short-term investments. The fair value of assets in this category is determined by using quoted prices in active markets for investments considered Level 1 inputs and estimated using the net asset value per share of the investments for investments considered Level 2 inputs.
4.	This category represents cash and investments in various money market funds.
5.	The plan assets are invested in investment funds that hold a diversified portfolio of (i) U.S and international debt and equity securities; (ii) fixed income securities such as corporate bonds and government bonds; (iii) mortgage-related securities; and (iv) cash and cash equivalents. The fair value of assets in this category is estimated using the net asset value per share of the investments.
6.	See Note 2 for components of cash and cash equivalents.
Financial instruments classified as Level 3 in the fair value hierarchy represent Midwest premium swap contracts for which at least one significant unobservable input in the valuation model is a management estimate. This is necessary due to the lack of an exchange traded product with observable market pricing data. Fair value was determined using a forward curve based on the average pricing quotes from the Company's trading counterparties and applying a discount factor based on the risk free interest rate.
The following table presents quantitative information for Level 3 Midwest premium derivative contracts:
		Fair Value at December 31, 2014		Valuation technique		Unobservable input		Range ($ in unit price)
Assets:
Midwest premium contracts		1		Discounted fair value		Pricing forward curve		$0.236 per metric ton in Jan 2015 to $0.205 per metric ton in Dec 2016
The following table presents a reconciliation of activity for the Level 3 Midwest premium derivative contracts on a net basis:
	Year Ended December 31,
	2014			2013
Fair value measurement at beginning of period	$	1.1		$	0.4
Total realized/unrealized gains included in:
Cost of goods sold, excluding depreciation and amortization and other items and Unrealized (gains) losses on derivative instruments	4.4			(0.1		)
Transactions involving Level 3 derivative contracts:
Purchases	2.8			1
Sales	—			—
Issuances	—			—
Settlements	(7.3		)	(0.2		)
Transactions involving Level 3 derivatives - net	(4.5		)	0.8
Transfers in and (or) out of Level 3 valuation hierarchy	—			—
Fair value measurement at end of period	$	1		$	1.1
Total gains included in Unrealized (gains) losses on derivative instruments, attributable to the change in unrealized gains/losses relating to derivative contracts held at December 31:	$	1		$	1.1
Fair Values of Non-Financial Assets and Liabilities
CAROs. The inputs in estimating the fair value of CAROs include: (i) the timing of when any such CARO cash flows may be incurred; (ii) incremental costs associated with special handling or treatment of CARO materials; and (iii) the credit-adjusted risk-free rate applicable at the time additional CARO cash flows are estimated; all of which are considered Level 3 inputs as they involve significant judgment of the Company.
During 2014, the Company re-assessed and revised its estimates relating to the timing and future costs of various asbestos removal projects at one facility. The following table summarizes the activity relating to the Company's CARO liabilities:
		Year Ended December 31,
		2014			2013				2012
Beginning balance		$	4.4		$	4.1			$	4
Liabilities settled during the period		—			(0.2		)		(0.5		)
Accretion expense		0.4			0.4				0.3
Adjustment to accretion expense due to revisions to estimated cash flow and timing of expenditure1		—			0.1				0.3
Ending balance		$	4.8		$	4.4			$	4.1
__________________________________________
1	The adjustments in 2013 did not have a material impact on the basic and diluted net income per share for 2013. The adjustment in 2012 decreased both basic and diluted net income per share for 2012 by approximately $0.02 per share.
The estimated fair value of CARO liabilities at December 31, 2014 and December 31, 2013 were both based upon the application of a weighted-average credit-adjusted risk-free rate of 8.6%. CAROs are included in Other accrued liabilities or Long-term liabilities, as appropriate (see Note 2).
During 2014, the Company performed a review of its property, plant and equipment held for future development that it determined not to deploy for future use, resulting in impairment charges to reflect the scrap value of such assets (see Note 1). With the exception of the impairment of these assets, the Company concluded that none of its non-financial assets, including goodwill and intangible assets and liabilities subject to fair value assessments on a non-recurring basis required a material adjustment to the carrying amount of such assets and liabilities at December 31, 2014 and December 31, 2013.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share	Net Income Per Share
	Basic and diluted net income per share for 2014, 2013 and 2012 were calculated as follows:
			Year Ended December 31,
			2014		2013		2012
	Numerator:
	Net income		$	71.8	$	104.8	$	85.8
	Denominator - Weighted-average common shares outstanding (in thousands):
	Basic1		17,818		18,827		19,115
	Add: dilutive effect of non-vested common shares, restricted stock units and performance shares		179		178		163
	Add: dilutive effect of warrants		596		241		—
	Diluted2		18,593		19,246		19,278
	Net income per common share, Basic:		$	4.02	$	5.56	$	4.49
	Net income per common share, Diluted:		$	3.86	$	5.44	$	4.45
	_____________
	1	The basic weighted-average number of common shares outstanding during the period excludes non-vested common shares, restricted stock units and performance shares.
	2	The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.
	There were 16,645 and 20,791 fully-vested options outstanding as of December 31, 2014 and December 31, 2013, respectively, in each case exercisable to purchase common shares at $80.01 per share. The number of potentially dilutive stock options were excluded from the computation of diluted net income per share as their effect would have been anti-dilutive for each of the periods presented.
	Warrants relating to approximately 3.7 million and 3.6 million common shares were outstanding at December 31, 2014 (at an average exercise price of approximately $60.70 per share) and December 31, 2013 (at an average exercise price of approximately $61.08 per share), respectively.
	During 2014, 2013 and 2012, the Company paid a total of approximately $25.4 ($1.40 per common share), $23.0 ($1.20 per common share) and $19.6 ($1.00 per common share), respectively, in cash dividends to stockholders, including the holders of restricted stock and dividend equivalents to the holders of certain restricted stock units and to the holders of performance shares granted prior to 2014 with respect to the target number of underlying common shares (constituting approximately one-half of the maximum payout). Additionally, during the third quarter of 2013, $0.6 of cash dividends paid in respect of common shares of the Company held in trust by a third-party, as well as 9,001 such common shares were returned to the Company. The fair market value of the shares was included in Other income, net (see Note 15).
	From time to time, the Company repurchases shares pursuant to a stock repurchase program authorized by the Company’s Board of Directors. Repurchase transactions will occur at such times and prices as management deems appropriate and will be funded with the Company’s excess liquidity after giving consideration to internal and external growth opportunities and future cash flows. Repurchases may be in open-market transactions or in privately negotiated transactions and the program may be modified or terminated by the Company’s Board of Directors at any time.
	In 2014 and 2013, the Company repurchased 633,230 and 1,232,077 shares of common stock at a weighted-average price of $70.87 and $64.35 per share, respectively, pursuant to the stock repurchase program. The total cost of $44.9 and $79.3 was recorded as Treasury stock as of December 31, 2014 and December 31, 2013, respectively. The Company purchased no shares under this program during 2012. At December 31, 2014 and December 31, 2013, $72.8 and $117.6, respectively, were available to repurchase the Company’s common shares pursuant to the stock repurchase program.

Segment_and_Geographical_Area_

Segment and Geographical Area Information	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Segment and Geographical Area Information	Segment and Geographical Area Information
	The Company's primary line of business is the production of semi-fabricated specialty aluminum products, such as aluminum sheet and plate and extruded and drawn products, primarily used in aerospace/high strength, automotive, general engineering and other industrial end market applications. The Company operates 11 focused production facilities in the United States and one in Canada. Consistent with the manner in which the Company's chief operating decision maker reviews and evaluates the Company's business, the Fabricated Products business is treated as a single operating segment.
	In addition to the Fabricated Products segment, the Company has a business unit, All Other, which provides general and administrative support for the Company's operations. For purposes of segment reporting under GAAP, the Company treats the Fabricated Products segment as a reportable segment. All Other is not considered a reportable segment.
	The accounting policies of the Fabricated Products segment are the same as those described in Note 1. Segment results are evaluated internally by management before any allocation of corporate overhead and without any charge for income taxes, interest expense, or other net operating charges.
	The following tables provide financial information by reporting segment and business unit for each period or as of each period end, as applicable:
		Year Ended December 31,
		2014				2013				2012
	Net sales:
	Fabricated Products	$	1,356.10			$	1,297.50			$	1,360.10
	Segment operating income (loss):
	Fabricated Products 1,2	$	151.4			$	188.6			$	190.8
	All Other3	(13.5		)		(15.3		)		(24.9		)
	Total operating income	$	137.9			$	173.3			$	165.9
	Interest expense	(37.5		)		(35.7		)		(29.1		)
	Other income, net	6.7				5.6				2.8
	Income before income taxes	$	107.1			$	143.2			$	139.6
	Depreciation and amortization:
	Fabricated Products	$	30.6			$	27.6			$	26
	All Other	0.5				0.5				0.5
	Total depreciation and amortization	$	31.1			$	28.1			$	26.5
	Capital expenditures:
	Fabricated Products	$	58.5			$	69.8			$	43.8
	All Other	0.9				0.6				0.3
	Total capital expenditures	$	59.4			$	70.4			$	44.1
				31-Dec-14				31-Dec-13
	Assets:
	Fabricated Products			$	878.9			$	852.5
	All Other4			864.8				918.4
	Total assets			$	1,743.70			$	1,770.90
	__________________
	1	Operating results in the Fabricated Products segment for 2014, 2013 and 2012 included $1.2, $4.0 and $1.1, respectively, of environmental expense. Fabricated Products segment operating results for 2014 and 2012 included $1.5 and $4.4 of asset impairment charge relating to certain property, plant and equipment.
	2	Fabricated Products segment results for 2014, 2013 and 2012 include non-cash mark-to-market (losses) gains on primary aluminum, natural gas, electricity and foreign currency hedging activities totaling $(10.4), $0.7 and $15.2, respectively. For further discussion regarding mark-to-market matters, see Note 10.
	3	Operating results of All Other include VEBA net periodic pension benefit income of $23.7, $22.5 and $11.9 for 2014, 2013 and 2012, respectively.
	4	Assets in All Other represent primarily all of the Company’s cash and cash equivalents, short-term investments, financial derivative assets, net assets of VEBAs and net deferred income tax assets.
	Net sales by product categories based on end market applications for the Fabricated Products segment were as follows:
		Year Ended December 31,
		2014				2013				2012
	Net sales:
	Aero/HS products	$	686.3			$	677			$	695.1
	Automotive Extrusions	173.5				129.5				125.5
	GE products	419.5				411				441.4
	Other products	76.8				80				98.1
	Total net sales	$	1,356.10			$	1,297.50			$	1,360.10
	Geographic information for net sales based on country of origin, income taxes paid and long-lived assets were as follows:
		Year Ended December 31,
		2014				2013				2012
	Net sales to unaffiliated customers:
	Fabricated Products —
	United States	$	1,254.00			$	1,204.70			$	1,256.50
	Canada	102.1				92.8				103.6
	Total net sales	$	1,356.10			$	1,297.50			$	1,360.10
	Income taxes paid:
	Fabricated Products —
	United States	$	2.1			$	1.2			$	0.5
	Canada	1.4				0.9				1.3
	Total income taxes paid	$	3.5			$	2.1			$	1.8
				Year Ended December 31,
				2014				2013
	Long-lived assets:1
	Fabricated Products —
	United States			$	432.6			$	409.5
	Canada			17.4				15.3
	Total Fabricated Products long-lived assets			450				424.8
	All Other —
United States			4.9				4.5
Total All Other long-lived assets			4.9				4.5
Total long-lived assets			$	454.9			$	429.3
__________________
1    Long-lived assets represent Property, plant and equipment, net.
The aggregate foreign currency transaction gains (losses) included in determining net income were immaterial for 2014, 2013 and 2012.
The Company depends on a core group of significant customers and suppliers of primary aluminum. The loss of the Company’s largest customers or suppliers would have a material adverse effect on the Company taken as a whole. However, in the Company’s opinion, the relationships between the Company and its customers and suppliers are good and the risk of loss of its largest customers or suppliers is remote.
For the years ended December 31, 2014, December 31, 2013 and December 31, 2012 one individual customer represented 22%, 23% and 22%, respectively, of Fabricated Products Net sales. For the years ended December 31, 2014 and December 31, 2013, a second individual customer represented 10% and 12%, respectively, of Fabricated Products Net sales.
At December 31, 2014, two individual customers accounted for 10% and 12% of the trade receivables balance and two individual customers accounted 12% and 14% of the trade receivables balance at December 31, 2013.
Information for export sales and primary aluminum supply from the Company's major suppliers were as follows:
	Year Ended December 31,
	2014			2013			2012
Percentage of Net sales:
Export sales	19	%		17	%		18	%
Percentage of Total Annual Primary Aluminum Supply (lbs):
Supply from the Company's top five major suppliers	71	%		86	%		78	%
Supply from the Company's largest supplier	30	%		25	%		29	%
Supply from the Company's second and third largest suppliers	25	%		35	%		31	%

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2014
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information
		Year Ended December 31,
		2014		2013		2012
	Interest paid	$	25.6	$	28.1	$	19.4
	Income taxes paid	$	3.5	$	2.1	$	1.8
	Non-cash investing and financing activities:
	Stock repurchases not yet settled (accrued in accounts payable)	$	0.8	$	1	$	—
	Unpaid purchases of property and equipment	$	1.8	$	4.4	$	3.4
	Purchases of property and equipment through capital leasing arrangements	$	—	$	0.2	$	0.1

Other_Income_Net

Other Income, Net	12 Months Ended
	Dec. 31, 2014
Other Income and Expenses [Abstract]
Other Income, Net	Other Income, Net
	Other income, net consisted of the following for each period presented:
		Year Ended December 31,
		2014		2013		2012
	Interest income	$	1	$	0.4	$	0.4
	Unrealized gains on financial derivatives1	3.6		3.2		0.8
	Realized gains on investments	1		1.4		0.5
	Distribution from third-party trust2	—		0.6		—
	Insurance settlement	—		—		0.4
	All other, net	1.1		—		0.7
	Other income, net	$	6.7	$	5.6	$	2.8
	____________
	1	See “Derivative Financial Instruments” in Note 1 for a discussion of accounting policy for such instruments.
	2	See Note 12 for discussion of the distribution.

Other_Comprehensive_Loss_Incom

Other Comprehensive (Loss) Income	12 Months Ended
	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Other Comprehensive (Loss) Income	Other Comprehensive (Loss) Income
	The following table presents the tax effect allocated to each component of other comprehensive (loss) income for each period presented:
		Before-Tax			Before-Tax			Income Tax
		Amount			Amount			(Expense)			Net-of-Tax
		(as reported)			(as reclassified)4			Benefit3			Amount
	2014
	Defined benefit pension plan and VEBAs:
	Net actuarial loss arising during the period	$	(39.0	)				$	14.5		$	(24.5	)
	Prior service cost arising during the period	(90.5		)				33.8			(56.7		)
	Total actuarial (loss) gain and prior service costs	(129.5		)				48.3			(81.2		)
	Reclassification adjustments:
	Amortization of net actuarial (gain)1	(1.8		)				0.7			(1.1		)
	Amortization of prior service cost1	10.6						(3.9		)	6.7
	Other comprehensive income relating to defined benefit pension plan and VEBAs	(120.7		)				45.1			(75.6		)
	Available for sale securities:
	Unrealized loss on available for sale securities	(0.2		)				0.1			(0.1		)
	Reclassification adjustments:
	Reclassification of unrealized loss upon sale of available for sale securities2	(0.1		)				—			(0.1		)
	Other comprehensive loss relating to available for sale securities	(0.3		)				0.1			(0.2		)
	Foreign currency translation adjustment	0.4						—			0.4
	Other comprehensive loss	$	(120.6	)				$	45.2		$	(75.4	)
	2013
	Defined benefit pension plan and VEBAs:
	Net actuarial gain arising during the period	$	2.2		$	87		$	(32.5	)	$	54.5
	Prior service cost arising during the period	—			(84.8		)	31.8			(53.0		)
	Total actuarial gain (loss) and prior service costs	2.2			2.2			(0.7		)	1.5
	Reclassification adjustments:
	Amortization of net actuarial loss1	1.5			1.5			(0.5		)	1
	Amortization of prior service cost1	4.2			4.2			(1.6		)	2.6
	Other comprehensive income relating to defined benefit pension plan and VEBAs	7.9			7.9			(2.8		)	5.1
	Available for sale securities:
	Unrealized gain on available for sale securities	1			1			(0.3		)	0.7
	Reclassification adjustments:
	Reclassification of unrealized gain upon sale of available for sale securities2	(1.0		)	(1.0		)	0.3			(0.7		)
	Other comprehensive income relating to available for sale securities	—			—			—			—
	Foreign currency translation adjustment	0.2			0.2			—			0.2
	Other comprehensive income	$	8.1		$	8.1		$	(2.8	)	$	5.3
		Before-Tax			Before-Tax			Income Tax
		Amount			Amount			(Expense)			Net-of-Tax
		(as reported)			(as reclassified)4			Benefit3			Amount
	2012
	Defined benefit pension plan and VEBAs:
	Net actuarial gain arising during the period	$	87.8					$	(33.5	)	$	54.3
	Reclassification adjustments:
	Amortization of net actuarial loss1	3.1						(1.1		)	2
	Amortization of prior service cost1	4.2						(1.7		)	2.5
	Other comprehensive income relating to defined benefit pension plan and VEBAs	95.1						(36.3		)	58.8
	Available for sale securities:
	Unrealized gain on available for sale securities	0.6						(0.2		)	0.4
	Foreign currency translation adjustment	(0.2		)				—			(0.2		)
	Other comprehensive income	$	95.5					$	(36.5	)	$	59
	____________
	1	Amounts reclassified out of Accumulated other comprehensive income relating to VEBA adjustments were included as a component of Net periodic pension benefit income relating to VEBAs.
	2	Amounts reclassified out of Accumulated other comprehensive income relating to sales of available for sale securities were included as a component of Other income (expense), net. The Company uses the specific identification method to determine the amount reclassified out of Accumulated other comprehensive income.
	3	Income tax amounts reclassified out of Accumulated other comprehensive income relating to VEBA adjustments and sales of available for sale securities were included as a component of Income tax provision.
	4	The presentation of other comprehensive income 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. The 2013 balances were adjusted to reflect this reclassification. The impacts to the prospective amortization of Prior service cost and Accumulated net actuarial (losses) gains were not material.

Guarantor_and_NonGuarantor_Fin

Guarantor and Non-Guarantor Financial Statements (Notes)	12 Months Ended
	Dec. 31, 2014
Guarantor and Non-Guarantor Financial Statement [Abstract]
Guarantor and Non-Guarantor Financial Statements	Condensed Guarantor and Non-Guarantor Financial Information
	The Company issued $225.0 aggregate principal amount of its Senior Notes pursuant to an indenture dated May 23, 2012 (“Indenture”), among Kaiser Aluminum Corporation ("Parent"), the subsidiary guarantors party thereto (“Guarantor Subsidiaries”) and Wells Fargo Bank, National Association, as trustee (“Trustee”). The Guarantor Subsidiaries currently include Kaiser Aluminum Investments Company, Kaiser Aluminum Fabricated Products, LLC, Kaiser Aluminum Mill Products, Inc., Kaiser Aluminum Washington, LLC and Kaiser Aluminum Alexco, LLC, all of which are 100% owned by the Parent. The guarantees are full and unconditional and joint and several but have customary releases in the following situations: (i) the sale of the Guarantor Subsidiary or all of its assets; (ii) the declaration of a Guarantor Subsidiary as an unrestricted subsidiary under the Indenture; (iii) the termination or release of the Guarantor Subsidiary’s guarantee of certain other indebtedness; or (iv) the exercise of legal defeasance or covenant defeasance by the Company or the discharge of the Company’s obligations under the Indenture.
	The following condensed consolidating financial information as of December 31, 2014 and December 31, 2013, and for the years ended December 31, 2014, December 31, 2013 and December 31, 2012 present (i) the financial position, results of operation and cash flows for each of (a) Parent, (b) the Guarantor Subsidiaries on a combined basis and (c) the Non-Guarantor Subsidiaries (as defined below) on a combined basis; (ii) the adjustments necessary to eliminate investments in subsidiaries and intercompany balances and transactions among Parent, the Guarantor Subsidiaries and the Non-Guarantor Subsidiaries; and (iii) the resulting totals, reflecting information for the Company on a consolidated basis, as reported. In the following tables, "Non- Guarantor Subsidiaries" refers to Kaiser Aluminum Canada Limited, Trochus Insurance Company, DCO Management, LLC, Kaiser Aluminum France, S.A.S. and Kaiser Aluminum Beijing Trading Company; and "Consolidating Adjustments" represent the adjustments necessary to eliminate the investments in the Company's subsidiaries and other intercompany sales and cost of sales transactions. The condensed consolidating financial information should be read in conjunction with the consolidated financial statements herein.
	CONDENSED CONSOLIDATING BALANCE SHEET
	December 31, 2014
		Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	ASSETS
	Current assets:
	Cash and cash equivalents	$	—		$	175.3		$	2.4		$	—		$	177.7
	Short-term investments	—			114			—			—			114
	Receivables:
	Trade receivables — net	—			126.1			3.2			—			129.3
	Intercompany receivables	204.2			4			0.9			(209.1		)	—
	Other	—			5.6			5.3			—			10.9
	Inventories	—			208			7.6			(0.9		)	214.7
	Prepaid expenses and other current assets	85.1			93.1			0.4			—			178.6
	Total current assets	289.3			726.1			19.8			(210.0		)	825.2
	Investments in and advances to subsidiaries	1,209.20			32.5			—			(1,241.7		)	—
	Property, plant and equipment — net	—			437.4			17.5			—			454.9
	Long-term intercompany receivables	—			—			15.9			(15.9		)	—
	Net assets of VEBAs	—			340.1			—			—			340.1
	Deferred tax assets — net	—			23.8			—			7.1			30.9
	Intangible assets — net	—			32.1			—			—			32.1
	Goodwill	—			37.2			—			—			37.2
	Other assets	4.4			18.8			0.1			—			23.3
	Total	$	1,502.90		$	1,648.00		$	53.3		$	(1,460.5	)	$	1,743.70
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Current liabilities:
	Accounts payable	$	1.3		$	73.8		$	6.3		$	—		$	81.4
	Intercompany payable	—			221.3			3.3			(224.6		)	—
	Accrued salaries, wages and related expenses	—			36.5			3.1			—			39.6
	Other accrued liabilities	88.2			43.8			0.8			—			132.8
	Current portion of long-term debt	172.5			—			—			—			172.5
	Short-term capital lease	—			0.1			—			—			0.1
	Total current liabilities	262			375.5			13.5			(224.6		)	426.4
	Net liability in respect of VEBA	—			17.2			—			—			17.2
	Deferred tax liabilities	—			—			0.9			—			0.9
	Long-term intercompany payable	—			15.9			—			(15.9		)	—
	Long-term liabilities	—			50.3			8			—			58.3
	Long-term debt	225			—			—			—			225
	Total liabilities	487			458.9			22.4			(240.5		)	727.8
	Total stockholders’ equity	1,015.90			1,189.10			30.9			(1,220.0		)	1,015.90
	Total	$	1,502.90		$	1,648.00		$	53.3		$	(1,460.5	)	$	1,743.70
	CONDENSED CONSOLIDATING BALANCE SHEET
	December 31, 2013
		Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	ASSETS
	Current assets:
	Cash and cash equivalents	$	5		$	157.7		$	6.8		$	—		$	169.5
	Short-term investments	—			129.5			—			—			129.5
	Receivables:
	Trade receivables — net	—			117.7			2.1			—			119.8
	Intercompany receivables	—			0.1			0.2			(0.3		)	—
	Other	—			5.3			8.1			—			13.4
	Inventories	—			208.6			6.4			(0.6		)	214.4
	Prepaid expenses and other current assets	0.1			43.7			0.4			—			44.2
	Total current assets	5.1			662.6			24			(0.9		)	690.8
	Investments in and advances to subsidiaries	1,437.90			26.5			—			(1,464.4		)	—
	Property, plant and equipment — net	—			414			15.3			—			429.3
	Long-term intercompany receivables	31.3			1.6			9.5			(42.4		)	—
	Net assets of VEBAs	—			406			—			—			406
	Deferred tax assets — net	—			60.2			—			8.9			69.1
	Intangible assets — net	—			33.7			—			—			33.7
	Goodwill	—			37.2			—			—			37.2
Other assets	86.2			18.5			0.1			—			104.8
Total	$	1,560.50		$	1,660.30		$	48.9		$	(1,498.8	)	$	1,770.90
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities:
Accounts payable	$	1.1		$	56.3		$	5.5		$	—		$	62.9
Intercompany payable	—			13.9			0.1			(14.0		)	—
Accrued salaries, wages and related expenses	—			39.3			3.4			—			42.7
Other accrued liabilities	3.5			39.9			1.4			—			44.8
Short-term capital lease	—			0.2			—			—			0.2
Total current liabilities	4.6			149.6			10.4			(14.0		)	150.6
Deferred tax liabilities	—			—			1.2			—			1.2
Long-term intercompany payable	—			40.7			1.7			(42.4		)	—
Long-term liabilities	83.2			52			11.2			—			146.4
Long-term debt	388.5			—			—			—			388.5
Total liabilities	476.3			242.3			24.5			(56.4		)	686.7
Total stockholders’ equity	1,084.20			1,418.00			24.4			(1,442.4		)	1,084.20
Total	$	1,560.50		$	1,660.30		$	48.9		$	(1,498.8	)	$	1,770.90
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (LOSS)
Year Ended December 31, 2014
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	1,323.40		$	133.9		$	(101.2	)	$	1,356.10
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			1,098.30			117.8			(98.6		)	1,117.50
Unrealized loss on derivative instruments	—			10.4			—			—			10.4
Depreciation and amortization	—			30			1.1			—			31.1
Selling, administrative, research and development and general:
Selling, administrative, research and development and general	4.1			69.7			9.9			(2.3		)	81.4
Net periodic pension benefit income relating to VEBAs	—			(23.7		)	—			—			(23.7		)
Total selling, administrative, research and development and general	4.1			46			9.9			(2.3		)	57.7
Other operating charges, net	—			1.5			—			—			1.5
Total costs and expenses	4.1			1,186.20			128.8			(100.9		)	1,218.20
Operating (loss) income	(4.1		)	137.2			5.1			(0.3		)	137.9
Other (expense) income:
Interest expense	(37.5		)	(0.6		)	—			0.6			(37.5		)
Other income (expense), net	3.7			3.2			0.4			(0.6		)	6.7
(Loss) income before income taxes	(37.9		)	139.8			5.5			(0.3		)	107.1
Income tax (provision) benefit	—			(50.2		)	0.8			14.1			(35.3		)
Earnings in equity of subsidiaries	109.7			6			—			(115.7		)	—
Net income	$	71.8		$	95.6		$	6.3		$	(101.9	)	$	71.8
Comprehensive (loss) income	$	(3.6	)	$	19.9		$	6.6		$	(26.5	)	$	(3.6	)
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Year Ended December 31, 2013
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	1,275.20		$	118		$	(95.7	)	$	1,297.50
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			1,026.00			105.7			(92.8		)	1,038.90
Unrealized gains on derivative instruments	—			(0.7		)	—			—			(0.7		)
Depreciation and amortization	—			27			1.1			—			28.1
Selling, administrative, research and development and general:
Selling, administrative, research and development and general	3.8			70.1			8.9			(2.4		)	80.4
Net periodic pension benefit income relating to VEBAs	—			(22.5		)	—			—			(22.5		)
Total selling, administrative, research and development and general	3.8			47.6			8.9			(2.4		)	57.9
Total costs and expenses	3.8			1,099.90			115.7			(95.2		)	1,124.20
Operating (loss) income	(3.8		)	175.3			2.3			(0.5		)	173.3
Other (expense) income:
Interest expense	(36.6		)	0.5			—			0.4			(35.7		)
Other income (expense), net	3.9			2			—			(0.3		)	5.6
(Loss) income before income taxes	(36.5		)	177.8			2.3			(0.4		)	143.2
Income tax (provision) benefit	—			(68.1		)	15.7			14			(38.4		)
Earnings in equity of subsidiaries	141.3			17.6			—			(158.9		)	—
Net income	$	104.8		$	127.3		$	18		$	(145.3	)	$	104.8
Comprehensive income	$	110.1		$	131.6		$	19		$	(150.6	)	$	110.1
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Year Ended December 31, 2012
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	1,326.00		$	124		$	(89.9	)	$	1,360.10
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			1,090.00			110.2			(84.0		)	1,116.20
Unrealized loss on derivative instruments	—			(15.2		)	—			—			(15.2		)
Depreciation and amortization	—			25.5			1			—			26.5
Selling, administrative, research and development and general:
Selling, administrative, research and development and general	2			69.6			8.2			(5.7		)	74.1
Net periodic pension benefit income relating to VEBAs	—			(11.9		)	—			—			(11.9		)
Total selling, administrative, research and development and general	2			57.7			8.2			(5.7		)	62.2
Other operating charges, net	—			4.5			—			—			4.5
Total costs and expenses	2			1,162.50			119.4			(89.7		)	1,194.20
Operating (loss) income	(2.0		)	163.5			4.6			(0.2		)	165.9
Other (expense) income:
Interest expense	(28.2		)	(1.0		)	—			0.1			(29.1		)
Other income, net	0.8			1.5			0.6			(0.1		)	2.8
(Loss) income before income taxes	(29.4		)	164			5.2			(0.2		)	139.6
Income tax provision	—			(62.6		)	(2.3		)	11.1			(53.8		)
Earnings in equity of subsidiaries	115.2			2.6			—			(117.8		)	—
Net income	$	85.8		$	104		$	2.9		$	(106.9	)	$	85.8
Comprehensive income	$	144.8		$	164		$	1.9		$	(165.9	)	$	144.8
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Year Ended December 31, 2014
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash provided by operating activities	$	35.6		$	81.8		$	6.7		$	—		$	124.1
Cash flows from investing activities:
Capital expenditures	—			(56.4		)	(3.0		)	—			(59.4		)
Purchase of available for sale securities	—			(93.5		)	—			—			(93.5		)
Proceeds from disposition of available for sale securities	—			108.2			—			—			108.2
Net cash used in investing activities	—			(41.7		)	(3.0		)	—			(44.7		)
Cash flows from financing activities:
Payment of capital lease liability	—			(0.1		)	—			—			(0.1		)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	—			0.8			—			—			0.8
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares	(2.4		)	—			—			—			(2.4		)
Repurchase of common stock	(44.1		)	—			—			—			(44.1		)
Cash dividend paid to stockholders	(25.4		)	—			—			—			(25.4		)
Intercompany loan	31.3			(23.2		)	(8.1		)	—			—
Net cash used in financing activities	(40.6		)	(22.5		)	(8.1		)	—			(71.2		)
Net (decrease) increase in cash and cash equivalents during the period	(5.0		)	17.6			(4.4		)	—			8.2
Cash and cash equivalents at beginning of period	5			157.7			6.8			—			169.5
Cash and cash equivalents at end of period	$	—		$	175.3		$	2.4		$	—		$	177.7
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Year Ended December 31, 2013
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash (used in) provided by operating activities1	$	(29.2	)	$	131.7		$	9.2		$	—		$	111.7
Cash flows from investing activities:
Capital expenditures	—			(66.5		)	(3.9		)	—			(70.4		)
Purchase of available for sale securities	—			(227.8		)	—			—			(227.8		)
Proceeds from disposition of available for sale securities	—			183.1			—			—			183.1
Change in restricted cash	—			0.7			1			—			1.7
Net cash used in investing activities	—			(110.5		)	(2.9		)	—			(113.4		)
Cash flows from financing activities:
Payment of capital lease liability	—			(0.1		)	—			—			(0.1		)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	—			1.1			—			—			1.1
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares	(2.5		)	—			—			—			(2.5		)
Repurchase of common stock	(78.3		)	—			—			—			(78.3		)
Cash dividend paid to stockholders	(23.0		)	—			—			—			(23.0		)
Cash dividend returned to the Company	0.6			—			—			—			0.6
Intercompany loan	132.4			(130.5		)	(1.9		)	—			—
Net cash provided by (used in) financing activities	29.2			(129.5		)	(1.9		)	—			(102.2		)
Net (decrease) increase in cash and cash equivalents during the period	—			(108.3		)	4.4			—			(103.9		)
Cash and cash equivalents at beginning of period	5			266			2.4			—			273.4
Cash and cash equivalents at end of period	$	5		$	157.7		$	6.8		$	—		$	169.5
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Year Ended December 31, 2012
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$	(17.8	)	$	164.3		$	5.9		$	—		$	152.4
Cash flows from investing activities:
Capital expenditures	—			(42.6		)	(1.5		)	—			(44.1		)
Purchase of available for sale securities	—			(85.0		)	—			—			(85.0		)
Proceeds from disposal of property, plant and equipment	—			0.3			—			—			0.3
Change in restricted cash	6.9			0.4			(0.4		)	—			6.9
Net cash provided by (used in) investing activities	6.9			(126.9		)	(1.9		)	—			(121.9		)
Cash flows from financing activities:
Proceeds from issuance of Senior Notes	225			—			—			—			225
Payment of capital lease liability	—			(0.1		)	—			—			(0.1		)
Repayment of promissory notes	—			(4.7		)	—			—			(4.7		)
Cash paid for financing costs	(6.6		)	—			—			—			(6.6		)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	—			1.3			—			—			1.3
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares	(2.2		)	—			—			—			(2.2		)
Cash dividend paid to stockholders	(19.6		)	—			—			—			(19.6		)
Intercompany loan	(185.7		)	189.1			(3.4		)	—			—
Net cash provided by (used in) financing activities	10.9			185.6			(3.4		)	—			193.1
Net increase in cash and cash equivalents during the period	—			223			0.6			—			223.6
Cash and cash equivalents at beginning of period	5			43			1.8			—			49.8
Cash and cash equivalents at end of period	$	5		$	266		$	2.4		$	—		$	273.4

Quarterly_Financial_Data

Quarterly Financial Data	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Data [Abstract]
Quarterly Financial Information	Quarterly Financial Data (Unaudited)
	The following tables present the unaudited financial data for each of the interim periods in 2014 and 2013.
		Quarter			Quarter			Quarter			Quarter
		Ended			Ended			Ended			Ended
		31-Mar			30-Jun			30-Sep			31-Dec
	2014
	Net sales	$	335.1		$	344.1		$	338.9		$	338
	Cost of products sold, excluding depreciation, amortization and other items	282.9			275.5			280.4			278.7
	Unrealized (gains) losses on derivative instruments	(2.0		)	(1.6		)	3.6			10.4
	Gross profit	54.2			70.2			54.9			48.9
	Operating income	32.1			46.4			32.6			26.8
	Net income	$	15.8		$	24.5		$	15.9		$	15.6
	Net income per common share, Basic	$	0.88		$	1.38		$	0.9		$	0.88
	Net income per common share, Diluted	$	0.85		$	1.33		$	0.85		$	0.85
		Quarter			Quarter			Quarter			Quarter
		Ended			Ended			Ended			Ended
		31-Mar			30-Jun			30-Sep			31-Dec
	2013
	Net sales	$	337.4		$	328.9		$	319.9		$	311.3
	Cost of products sold, excluding depreciation, amortization and other items	263.6			261.5			259.5			254.3
	Unrealized losses (gains) on derivative instruments	0.7			4.2			(1.5		)	(4.1		)
	Gross profit	73.1			63.2			61.9			61.1
	Operating income	50			40.1			41.6			41.6
	Net income	$	33.5		$	18.6		$	25.4		$	27.3
	Net income per common share, Basic	$	1.75		$	0.99		$	1.37		$	1.48
	Net income per common share, Diluted	$	1.73		$	0.98		$	1.34		$	1.44

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events
	Dividend Declaration. On January 13, 2015, the Company announced that its Board of Directors declared a quarterly cash dividend of $0.40 per common share, or approximately $7.1 (including dividend equivalents), which was paid on February 13, 2015 to stockholders of record at the close of business on January 23, 2015.
	Anti-dilution Adjustments to Convertible Notes and Convertible Note Hedge Transactions. Following the open of business on January 21, 2015, the ex-dividend date for the Company's February 13, 2015 dividend, (a) the Convertible Notes' conversion rate increased slightly to 20.9664 shares per $1,000 principal amount of the Convertible Notes and the equivalent conversion price decreased slightly to $47.70 per share, (b) the Option Assets' exercise price decreased slightly to $47.70 per share and (c) the Warrants' exercise price decreased slightly to $60.57 per share.
	Ratification of New Five-Year Labor Agreement with the USW. On January 28, 2015, union members at the Company's Newark, Ohio and Trentwood facilities ratified a new five-year labor agreement. The agreement affects approximately 900 union members and is effective on October 1, 2015 and extends through September 30, 2020. The new labor agreement also extends the term of the Director Designation Agreement that allows the USW to nominate candidates to the Company's board of directors through December 31, 2020. In addition, the Company's obligation for annual contribution payments, capped at $17.1 per year, to the Union VEBA will expire in September 2017. The Company is currently assessing the impact the expiration of the Union VEBA funding requirement will have on its consolidated financial statements.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Organization and Nature of Operations	Organization and Nature of Operations. Kaiser Aluminum Corporation (together with its subsidiaries, unless the context otherwise requires, the “Company”) specializes in the production of semi-fabricated specialty aluminum products, such as aluminum sheet and plate and extruded and drawn products, primarily used in aerospace/high strength, automotive, general engineering and other industrial end market applications. The Company has one operating segment, Fabricated Products. See Note 13 for additional information regarding the Company's reportable segment and business unit.
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation. The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries and are prepared in accordance with United States generally accepted accounting principles (“GAAP”) and the rules and regulations of the Securities and Exchange Commission (the “SEC”). Intercompany balances and transactions are eliminated.
Use of Estimates in the Preparation of Financial Statements	Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in accordance with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities known to exist as of the date the financial statements are published and the reported amounts of revenues and expenses during the reporting period. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of the Company’s consolidated financial statements; accordingly, it is possible that the actual results could differ from these estimates and assumptions, which could have a material effect on the reported amounts of the Company’s consolidated financial position and results of operations.
Recognition of Sales	Recognition of Sales. Sales are generally recognized on a gross basis when all of the following criteria are met: (i) persuasive evidence of an arrangement exists; (ii) title, ownership and risk of loss has passed to the customer; (iii) the price to the customer is fixed or determinable; and (iv) collection of the resulting receivable is reasonably assured. A provision for estimated sales returns from and allowances to, customers is made in the same period as the related revenues are recognized, based on historical experience or the specific identification of an event necessitating a reserve.
	From time to time, in the ordinary course of business, the Company may enter into agreements with customers in which the Company, in return for a fee, agrees to reserve certain amounts of its existing production capacity for the customer, defer an existing customer purchase commitment into future periods and reserve certain amounts of its expected production capacity in those periods for the customer, or cancel or reduce existing commitments under existing contracts. These agreements may have terms or impact periods exceeding one year.
	Certain of the capacity reservation and commitment deferral agreements provide for periodic, such as quarterly or annual, billing for the duration of the contract. For capacity reservation agreements, the Company recognizes revenue ratably over the period of the capacity reservation. Accordingly, the Company may recognize revenue prior to billing reservation fees. Unbilled receivables are included within Trade receivables on the Company's Consolidated Balance Sheets (see Note 2). For commitment deferral agreements, the Company recognizes revenue upon the earlier occurrence of the related sale of product or the end of the commitment period. In connection with other agreements, the Company may collect funds from customers in advance of the periods for which (i) the production capacity is reserved; (ii) commitments are deferred; (iii) commitments are reduced; or (iv) performance is completed, in which event the recognition of revenue is deferred until the fee is earned. Any unearned fees are included within Other accrued liabilities or Long-term liabilities, as appropriate, on the Company's Consolidated Balance Sheets (see Note 2).
Stock-Based Compensation	Stock-Based Compensation. Stock-based compensation in the form of service-based awards is provided to executive officers, certain employees and non-employee directors and is accounted for at fair value. The Company measures the cost of services received in exchange for an award of equity instruments based on the grant-date fair value of the award and the number of awards expected to ultimately vest. The grant-date fair value is determined based on the stock price on the date of grant, adjusted for expected dividends to be paid during the vesting period.
	The Company also grants performance-based awards to executive officers and other key employees. Performance awards granted prior to 2014 are subject to performance conditions pertaining to specified financial metrics and are valued based on the stock price at the date of grant, adjusted for expected dividends to be paid during the vesting period. Performance awards granted in 2014 are subject to performance conditions pertaining to total shareholder return and are valued on the date of grant using a Monte Carlo valuation model. The key assumptions in applying this model are an expected volatility and a risk free interest rate. For more information on the Company's stock-based compensation, see Note 8.
	The cost of service-based awards, including time-vested restricted stock and performance shares is recognized as an expense over the requisite service period of the award on a straight-line basis. For performance shares, the related expense is updated quarterly by adjusting the estimated number of shares expected to vest based on the most probable outcome of the performance condition (see Note 8).
Shipping and Handling Costs	Shipping and Handling Costs. Shipping and handling costs are recorded as a component of Cost of products sold, excluding depreciation, amortization and other items.
Advertising Costs	Advertising Costs. Advertising costs, which are included in Selling, administrative, research and development and general, are expensed as incurred. Advertising costs for 2014, 2013 and 2012 were $0.6, $1.3 and $0.4, respectively.
Research and Development Costs	Research and Development Costs. Research and development costs, which are included in Selling, research and development and general, are expensed as incurred. Research and development costs for 2014, 2013 and 2012 were $8.9, $7.8 and $6.4, respectively.
Major Maintenance Activities	Major Maintenance Activities. All major maintenance costs are accounted for using the direct expensing method.
Cash and Cash Equivalents	Cash and Cash Equivalents. The Company considers only those short-term, highly liquid investments with original maturities of 90 days or less when purchased to be cash equivalents. The Company’s cash equivalents consist primarily of funds in commercial paper, savings accounts, demand notes, money market funds and other highly liquid investments, which are classified within Level 1 of the fair value hierarchy with the exception of commercial paper, which is classified within Level 2 of the fair value hierarchy.
Restricted Cash	Restricted Cash. The Company is required to keep certain amounts on deposit relating to workers’ compensation and other agreements. The Company accounts for such deposits as restricted cash (see Note 2).
Trade Receivables and Allowance for Doubtful Accounts	Trade Receivables and Allowance for Doubtful Accounts. Trade receivables primarily consist of amounts billed to customers for products sold. Accounts receivable are generally due within 30 to 60 days. For the majority of its receivables, the Company establishes an allowance for doubtful accounts based upon collection experience and other factors. On certain other receivables where the Company is aware of a specific customer’s inability or reluctance to pay, an allowance for doubtful accounts is established against amounts due, to reduce the net receivable balance to the amount the Company reasonably expects to collect. However, if circumstances change, the Company’s estimate of the recoverability of accounts receivable could be different. Circumstances that could affect the Company’s estimates include, but are not limited to, customer credit issues and general economic conditions. Accounts are written off once deemed to be uncollectible. Any subsequent cash collections relating to accounts that have been previously written off are typically recorded as a reduction to total bad debt expense in the period of payment.
Inventories	Inventories. Inventories are stated at the lower of cost or market value. Finished products, work-in-process and raw material inventories are stated on the last-in, first-out (“LIFO”) basis. The excesses of current cost over the stated LIFO value of inventory at December 31, 2014 and December 31, 2013 were $37.6 and $0.4, respectively. Other inventories, principally operating supplies and repair and maintenance parts, are stated at average cost. Inventory costs consist of material, labor and manufacturing overhead, including depreciation. Abnormal costs, such as idle facility expenses, freight, handling costs and spoilage, are accounted for as current period charges. All of the Company's inventories at December 31, 2014 and December 31, 2013 were included in the Fabricated Products segment (see Note 2 for the components of inventories).
Property, Plant and Equipment - Net	Property, Plant and Equipment - Net. Property, plant and equipment is recorded at cost (see Note 2). Construction in progress is included within Property, plant and equipment - net on the Consolidated Balance Sheets. Interest related to the construction of qualifying assets is capitalized as part of the construction costs. The aggregate amount of interest capitalized is limited to the interest expense incurred in the period. The amount of interest expense capitalized as construction in progress was $2.5, $3.4 and $1.7 during 2014, 2013 and 2012, respectively.
	Depreciation is computed using the straight-line method at rates based on the estimated useful lives of the various classes of assets. Capital lease assets and leasehold improvements are depreciated on a straight-line basis over the shorter of the estimated useful lives of the assets or the lease term. The principal estimated useful lives are as follows:
		Range (in years)
	Land improvements	3	-	25
	Buildings and leasehold improvements	15	-	45
	Machinery and equipment	1	-	24
	Capital lease assets	3	-	5
	Depreciation expense is not included in Cost of products sold, excluding depreciation and amortization and other items, but is included in Depreciation and amortization on the Statements of Consolidated Income. For 2014, 2013 and 2012, the Company recorded depreciation expense of $29.0, $25.8 and $24.2, respectively, relating to the Company's operating facilities in its Fabricated Products segment. An immaterial amount of depreciation expense was also recorded within All Other for all periods presented herein.
	Property, plant and equipment are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset or group of assets may not be recoverable. The Company regularly assesses whether events and circumstances with the potential to trigger impairment have occurred and relies on a number of factors, including operating results, business plans, economic projections and anticipated future cash flow, to make such assessments. The Company uses an estimate of the future undiscounted cash flows of the related asset or asset group over the estimated remaining life of such asset(s) in measuring whether the asset(s) are recoverable. Measurement of the amount of impairment, if any, is based on the difference between the carrying value of the asset(s) and the estimated fair value of such asset(s). Fair value is determined through a series of standard valuation techniques.
	During 2014 and 2012, the Company determined not to deploy some of its property, plant and equipment held for future development and recorded impairment charges of $1.5 and $4.4, respectively, to reflect the scrap value of such assets. There were no impairment charges in 2013. Asset impairment charges are included in Other operating charges, net in the Statements of Consolidated Income and are included in the Fabricated Products segment.
Available for Sale Securities	Available for Sale Securities. The Company accounts for investments in certain marketable debt securities as available for sale securities. Such securities are recorded at fair value (see “Fair Values of Financial Assets and Liabilities - Available for Sale Securities” in Note 11), with net unrealized gains and losses, net of income taxes, reflected in accumulated other comprehensive income (loss) as a component of Stockholders' equity. Realized gains and losses from the sale of marketable debt securities, if any, are determined on a specific identification basis. Debt investment securities with an original maturity of 90 days or less are classified as Cash and cash equivalents (see Note 2). Debt investment securities with an original maturity of greater than 90 days are presented as Short-term investments on the Consolidated Balance Sheets. In addition to debt investment securities, the Company also holds assets in various investment funds managed by a third-party trust in connection with the Company's deferred compensation program (see Note 6).
Deferred Financing Costs	Deferred Financing Costs. Costs incurred in connection with debt financing are deferred and amortized over the estimated term of the related borrowing. Such amortization is included in Interest expense and may be capitalized as part of construction in progress (see Note 2 and Note 3).
Goodwill and Intangible Assets	Goodwill and Intangible Assets. Goodwill is tested for impairment during the fourth quarter on an annual basis, as well as on an interim basis, as warranted, at the time of relevant events and changes in circumstances. Intangible assets with definite lives are initially recognized at fair value and subsequently amortized over the estimated useful lives to reflect the pattern in which the economic benefits of the intangible assets are consumed. In the event the pattern cannot be reliably determined, the Company uses a straight-line amortization method. Whenever events or changes in circumstances indicate that the carrying amount of the intangible assets may not be recoverable, the intangible assets are reviewed for impairment. A significant amount of synergies resulting from the acquisition of the Company's Florence, Alabama facility was realized by its Newark, Ohio and Jackson, Tennessee manufacturing facilities, which, when combined with the Florence, Alabama facility, are managed into a coordinated manner and comprise the Company's hard alloy rod, bar and wire value chain. Management determined that the hard alloy rod, bar and wire value chain should be considered one reporting unit for the purpose of performing the Company's goodwill impairment test related to the Florence, Alabama facility acquisition. The Company concluded there was no impairment of the carrying value of goodwill at December 31, 2014 or December 31, 2013 (Note 4).
Conditional Asset Retirement Obligations ("CAROs")	Conditional Asset Retirement Obligations (“CAROs”). The Company has CAROs at several of its Fabricated Products facilities. The vast majority of such CAROs consist primarily of incremental costs that would be associated with the removal and disposal of asbestos (all of which is believed to be fully contained and encapsulated within walls, floors, roofs, ceilings or piping) at certain of the Company’s older facilities if such facilities were to undergo major renovation or be demolished. The Company estimates incremental costs for special handling, removal and disposal costs of materials that may or will give rise to CAROs and then discounts the expected costs back to the current year using a credit-adjusted, risk-free rate. When it is unclear when or if CAROs will be triggered, the Company uses probability weighting for possible timing scenarios to determine the probability-weighted liability amounts that should be recognized in the Company’s consolidated financial statements (see Note 11).
Self Insurance of Employee Health and Workers' Compensation Liabilities	Self Insurance of Employee Health and Workers' Compensation Liabilities. The Company is primarily self-insured for group health insurance and workers' compensation benefits provided to employees. Self insurance liabilities are estimated for incurred-but-not-paid claims based on judgment, using the Company's historical claims data and information and analysis provided by actuarial and claims advisors, the Company's insurance carriers and other professionals. The Company's undiscounted workers' compensation liabilities were estimated at $25.9 and $29.1 at December 31, 2014 and December 31, 2013, respectively. However, the Company accounts for its workers' compensation accrued liability on a discounted basis, using a discount rate of 1.75% at both December 31, 2014 and December 31, 2013. The accrued liabilities for health insurance and workers' compensation is included in Other accrued liabilities or Long-term liabilities, as appropriate (see Note 2).
Environmental Contingencies	Environmental Contingencies. With respect to environmental loss contingencies, the Company records a loss contingency whenever a contingency is probable and reasonably estimable (see Note 9). Accruals for estimated losses from environmental remediation obligations are generally recognized no later than the completion of the remedial feasibility study. Such accruals are adjusted as information develops or circumstances change. Costs of future expenditures for environmental remediation obligations are not discounted to their present value. Accruals for expected environmental costs are included in Other accrued liabilities or Long-term liabilities, as appropriate (see Note 2). Environmental expense relating to continuing operations is included in Cost of products sold, excluding depreciation and amortization and other items in the Statements of Consolidated Income. Environmental expense relating to non-operating locations is included in Selling, administrative, research and development and general in the Statements of Consolidated Income.
Derivative Financial Instruments	Derivative Financial Instruments. Hedging transactions using derivative financial instruments are primarily designed to mitigate the Company's exposure to changes in prices for certain products sold and consumed by the Company and, to a lesser extent, to mitigate the Company's exposure to changes in foreign currency exchange rates. From time to time, the Company also enters into hedging arrangements in connection with financing transactions to mitigate financial risks.
	The Company does not utilize derivative financial instruments for trading or other speculative purposes. The Company's derivative activities are initiated within guidelines established by management and approved by the Company's Board of Directors. Hedging transactions are executed centrally on behalf of all of the Company's operations to minimize transaction costs, monitor consolidated net exposures and allow for increased responsiveness to changes in market factors.
	The Company recognizes all derivative instruments as assets or liabilities in its Consolidated Balance Sheets and measures these instruments at fair value by “marking-to-market” all of its hedging positions at each period's end (see Note 11). Because the Company does not meet the documentation requirements for hedge (deferral) accounting, unrealized and realized gains and losses associated with hedges of operational risks are reflected as a reduction or increase, respectively, in Cost of products sold - Unrealized losses (gains) on derivative instruments and unrealized and realized gains and losses relating to hedges of financing transactions are reflected as a component of Other income (expense) (see Note 15). See Note 10 for additional information about realized and unrealized gains and losses relating to the Company's derivative financial instruments.
Fair Value Measurement	Fair Value Measurements. The Company applies the provisions of Accounting Standards Codification (“ASC”) Topic 820, Fair Value Measurements and Disclosures, in measuring the fair value of its derivative contracts and plan assets invested by certain of the Company’s employee benefit plans (see Note 11).
	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy consists of three broad levels and are described below:
	•	Level 1 — Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.
	•	Level 2 — Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly, including: quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active; inputs other than quoted prices that are observable for the asset or liability (e.g., interest rates); and inputs that are derived principally from or corroborated by observable market data by correlation or other means.
	•	Level 3 — Inputs that are both significant to the fair value measurement and unobservable.
Income Taxes	Income Taxes. Deferred income taxes reflect the future tax effect of temporary differences between the carrying amount of assets and liabilities for financial and income tax reporting and are measured by applying statutory tax rates in effect for the year during which the differences are expected to reverse. In accordance with ASC Topic 740, Income Taxes, the Company uses a “more likely than not” threshold for recognition of tax attributes that are subject to uncertainties and measures any reserves in respect of such expected benefits based on their probability. Deferred tax assets are reduced by a valuation allowance to the extent it is more likely than not that the deferred tax assets will not be realized (see Note 5).
Earnings per Share	Net Income per Share. Basic net income per share is computed by dividing distributed and undistributed net income allocable to common shares by the weighted-average number of common shares outstanding during the applicable period. The basic weighted-average number of common shares outstanding during the period excludes unvested share-based payment awards. Diluted net income per share was calculated under the treasury stock method for 2014, 2013 and 2012, which in all years was more dilutive than the two-class method (see Note 12).
Concentration of Credit Risk	Concentration of Credit Risk. Financial arrangements which potentially subject the Company to concentrations of credit risk consist of metal, natural gas, electricity and foreign currency derivative contracts, certain cash-settled call options that the Company purchased in March 2010 (the “Option Assets”) (see Note 3) and arrangements related to the Company's cash equivalents and short-term investments. If the market value of the Company's net commodity and currency derivative positions with certain counterparties exceeds the applicable threshold, if any, the counterparty is required to post margin by transferring cash collateral in excess of the threshold to the Company. Conversely, if the market value of these net derivative positions falls below a specified threshold, the Company is required to post margin by transferring cash collateral below the threshold to certain counterparties. At both December 31, 2014 and December 31, 2013, the Company had no margin deposits with or from its counterparties.
	The Company is exposed to credit loss in the event of nonperformance by counterparties on derivative contracts used in hedging activities as well as failure of counterparties to return cash collateral previously transferred to the counterparties. The counterparties to the Company's derivative contracts are major financial institutions and the Company does not expect nonperformance by any of its counterparties.
	The Company places its cash in commercial paper, savings accounts, demand notes and money market funds. Such money market funds are with high credit quality financial institutions which invest primarily in commercial paper and time deposits of prime quality, short-term repurchase agreements and U.S. government agency notes.
	For information about concentration risks concerning customers and suppliers, see Note 13.
Concentration of Labor Subject to Collective Bargaining Agreements [Policy Text Block]	Concentration of Labor Subject to Collective Bargaining Agreements. At December 31, 2014, approximately 63% of the Company's employees were covered by collective bargaining agreements and the Company had collective bargaining agreements with expiration dates in 2015 covering approximately 47% of its employees. In January 2015, collective bargaining agreements covering approximately 36% of the Company's employees were extended through September 30, 2020 (see Note 19).
Leases	Leases. For leases that contain predetermined fixed escalations of the minimum rent, the Company recognizes the related rent expense on a straight-line basis from the date it takes possession of the property to the end of the initial lease term. The Company records any difference between the straight-line rent amounts and the amount payable under the lease as part of deferred rent in Other accrued liabilities or Long-term liabilities, as appropriate. Deferred rent for all periods presented was not material.
Foreign Currency	Foreign Currency. Certain of the Company’s foreign subsidiaries use the local currency as its functional currency; its assets and liabilities are translated at exchange rates in effect at the balance sheet date; and its statement of operations is translated at weighted-average monthly rates of exchange prevailing during the year. Resulting translation adjustments are recorded directly to a separate component of stockholders’ equity in accordance with ASC Topic 830, Foreign Currency Matters. At both December 31, 2014 and December 31, 2013, the amount of translation adjustment relating to foreign subsidiaries using local currency as their functional currency was immaterial. Where the U.S. dollar is the functional currency of a foreign facility or subsidiary, re-measurement adjustments are recorded in Other income (expense).
New Accounting Pronouncements	New Accounting Pronouncements. Accounting Standards Update ("ASU") No. 2013-11, Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists. (“ASU 2013-11”), was issued in July 2013. ASU 2013-11 requires an entity to present in the financial statements an unrecognized tax benefit, or a portion of an unrecognized tax benefit, as a reduction to a deferred tax asset resulting from a net operating loss carryforward, a similar tax loss, or a tax credit carryforward. However, when the above situation is not available at the reporting date or the tax law of the applicable jurisdiction does not require the entity to use the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be combined with deferred tax assets. The Company’s adoption of ASU 2013-11 in the first quarter of 2014 did not have a material impact on its consolidated financial statements.
	ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”), was issued in May 2014. ASU 2014-09 requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve this core principle, the guidance provides that an entity should apply the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. The Company expects to adopt ASU 2014-09 for the fiscal year ending December 31, 2017 and the Company will continue to assess the impact on its consolidated financial statements.
	ASU No. 2014-12, Compensation - Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period - Consensus of the FASB Emerging Issues Task Force (“ASU 2014-12”), was issued in June 2014. ASU 2014-12 requires an entity to treat a performance target that affects vesting and that could be achieved after the requisite service period as a performance condition. The performance target should not be reflected in estimating the grant-date fair value of the award. Additionally, compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered; if the performance target becomes probable of being achieved before the end of the requisite service period, then the remaining unrecognized compensation cost should be recognized prospectively over the remaining requisite service period. Finally, the total amount of compensation cost recognized during and after the requisite service period should reflect the number of awards that are expected to vest and should be adjusted to reflect those awards that ultimately vest. The Company expects to adopt ASU 2014-12 for the fiscal year ending December 31, 2015 and does not expect the adoption to have a material impact on its consolidated financial statements.

Supplemental_Balance_Sheet_Inf1

Supplemental Balance Sheet Information (Tables)	12 Months Ended
	Dec. 31, 2014
Supplemental Balance Sheet Information [Abstract]
Cash and Cash Equivalents
		December 31, 2014			December 31, 2013
	Cash and Cash Equivalents
	Cash and money market funds	$	29.5		$	57.7
	Commercial paper	148.2			111.8
	Total	$	177.7		$	169.5
Trade Receivables
	Trade Receivables - Net
	Billed trade receivables	$	128.7		$	120.2
	Unbilled trade receivables — Note 1	1.4			0.4
	Trade receivables, gross	130.1			120.6
	Allowance for doubtful receivables	(0.8		)	(0.8		)
	Trade receivables - net	$	129.3		$	119.8
Inventories
	Inventories
	Finished products	$	73.6		$	72.5
	Work-in-process	66.7			75.9
	Raw materials	54.2			47.2
	Operating supplies and repair and maintenance parts	20.2			18.8
	Total	$	214.7		$	214.4
Prepaid Expenses and Other Current Assets
		December 31, 2014			December 31, 2013
	Prepaid Expenses and Other Current Assets
	Current derivative assets — Notes 10 and 11	$	85.7		$	2
	Current deferred tax assets	86.4			36.7
	Short-term restricted cash	0.3			0.3
	Other	6.2			5.2
	Total	$	178.6		$	44.2
Property, Plant and Equipment - Net
	Property, Plant and Equipment - Net
	Land and improvements	$	22.9		$	22.6
	Buildings and leasehold improvements	63.8			53
	Machinery and equipment	509.8			425.6
	Construction in progress	25.2			66
	Property, plant and equipment - gross	621.7			567.2
	Accumulated depreciation	(166.8		)	(137.9		)
	Property, plant and equipment - net	$	454.9		$	429.3
Other Assets
	Other Assets
	Derivative assets — Notes 10 and 11	$	—		$	79.8
	Restricted cash	10			9.3
	Deferred financing costs	5.9			8.9
	Deferred compensation plan assets	7.3			6.5
	Other	0.1			0.3
	Total	$	23.3		$	104.8
Other Accrued Liabilities
	Other Accrued Liabilities
	Current derivative liabilities — Notes 10 and 11	$	94.9		$	1.8
	Uncleared cash disbursements	9.1			9.6
	Accrued income taxes and taxes payable	5.2			4.3
	Accrued annual VEBA contribution	13.7			16
	Short-term environmental accrual — Note 9	2.3			2.8
	Accrued interest	3.7			3.7
	Short-term deferred revenue — Note 1	0.2			—
	Other	3.7			6.6
	Total	$	132.8		$	44.8
Long-term Liabilities
		December 31, 2014			December 31, 2013
	Long-Term Liabilities
	Derivative liabilities — Notes 10 and 11	$	1.9		$	84.3
	Income tax liabilities	2.4			5
	Workers’ compensation accruals	21.5			23.3
	Long-term environmental accrual — Note 9	17			20
	Long-term asset retirement obligations	4.4			4
	Long-term deferred revenue - Note 1	0.5			—
	Deferred compensation liability	7.2			7
	Long-term capital leases	0.1			0.1
	Other long-term liabilities	3.3			2.7
	Total	$	58.3		$	146.4
Long-term Debt
	Long-Term Debt — Note 3
	Senior notes	$	225		$	225
	Cash convertible senior notes	—			163.5
	Total	$	225		$	388.5

LongTerm_Debt_and_Credit_Facil1

Long-Term Debt and Credit Facility (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Principal amount, carrying amount, and interest expense of the notes	The following tables provide additional information regarding the Convertible Notes:
		December 31,			December 31,
		2014			2013
	Principal amount	$	175		$	175
	Less: unamortized issuance discount	(2.5		)	(11.5		)
	Carrying amount, net of discount	$	172.5		$	163.5
		Year Ended December 31,
		2014			2013			2012
	Contractual coupon interest	$	7.9		$	7.9		$	7.9
	Amortization of discount	9.1			8.2			7.3
	Amortization of deferred financing costs	1.1			1.2			1.2
	Total interest expense1	$	18.1		$	17.3		$	16.4
	_______________
	1	A portion of the interest relating to the Convertible Notes was capitalized as Construction in progress.

Income_Tax_Matters_Tables

Income Tax Matters (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income before income taxes by geographic area	Tax Provision. Income before income taxes by geographic area was as follows:
		Year Ended December 31,
		2014				2013				2012
	Domestic	$	102.1			$	138.9			$	134.5
	Foreign	5				4.3				5.1
	Income before income taxes	$	107.1			$	143.2			$	139.6
Tax Provision	The provision for income taxes consisted of:
		Federal				Foreign				State				Total
	2014
	Current	$	(1.0	)		$	1			$	(0.6	)		$	(0.6	)
	Deferred	6.4				0.3				5.1				11.8
	Expense applied to decrease Additional paid in capital/ Other comprehensive income	(41.6		)		(0.5		)		(4.4		)		(46.5		)
	Total (expense) benefit	$	(36.2	)		$	0.8			$	0.1			$	(35.3	)
	2013
	Current	$	1.1			$	16.2			$	(0.2	)		$	17.1
	Deferred	(49.7		)		(0.5		)		(6.7		)		(56.9		)
	Benefit (expense) applied to increase (decrease) Additional paid in capital/Other comprehensive income	1.3				(0.1		)		0.2				1.4
	Total (expense) benefit	$	(47.3	)		$	15.6			$	(6.7	)		$	(38.4	)
	2012
	Current	$	—			$	(2.3	)		$	0.2			$	(2.1	)
	Deferred	(113.0		)		(0.2		)		(15.3		)		(128.5		)
	Benefit applied to increase Additional paid in capital/ Other comprehensive income	67.4				0.2				9.2				76.8
	Total expense	$	(45.6	)		$	(2.3	)		$	(5.9	)		$	(53.8	)
Reconciliation of income tax provision based on effective income tax rate and statutory tax rate	A reconciliation between the provision for income taxes and the amount computed by applying the federal statutory income tax rate to income before income taxes is as follows:
		Year Ended December 31,
		2014				2013				2012
	Amount of federal income tax provision based on the statutory rate	$	(37.5	)		$	(50.1	)		$	(48.9	)
	Decrease in federal valuation allowances	—				0.1				0.1
	Non-deductible compensation expense	(0.1		)		(0.3		)		(0.4		)
	Non-deductible expense	(0.3		)		(0.9		)		(0.3		)
	State income taxes, net of federal benefit 1	—				(4.4		)		(3.8		)
	Foreign income tax (expense) benefit	0.3				—				(0.5		)
	Expiration of statute of limitations	2.3				4.6				—
	Settlement with taxing authorities	—				4.4				—
	Advance pricing agreement	—				2.9				—
	Competent Authority settlement	—				5.3				—
	Income tax provision	$	(35.3	)		$	(38.4	)		$	(53.8	)
	___________________________
	1	State income taxes were $2.3 in 2014, but were offset by a $1.6 decrease due to lower tax rates in various states and a $0.7 decrease in the valuation allowance relating to certain state net operating losses. State income taxes of $4.4 in 2013 included a $1.2 increase in the valuation allowance relating to certain unused state net operating losses expected to expire.
Deferred tax assets and liabilities	Deferred Income Taxes. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and amounts used for income tax purposes. The components of the Company’s net deferred income tax assets were as follows:
		Year Ended December 31,
		2014				2013
	Deferred income tax assets:
	Loss and credit carryforwards	$	275.4			$	321.8
	VEBAs (see Note 6)	5.1				6.1
	Other assets	35				34.4
	Inventories and other	21.5				2.5
	Valuation allowances	(19.2		)		(19.9		)
	Total deferred income tax assets	317.8				344.9
	Deferred income tax liabilities:
	Property, plant and equipment	(74.1		)		(73.0		)
	VEBAs (see Note 6)	(120.6		)		(152.4		)
	Inventories	(6.7		)		(14.9		)
	Total deferred income tax liabilities	(201.4		)		(240.3		)
	Net deferred income tax assets 1	$	116.4			$	104.6
	__________________________
	1	Of the total net deferred income tax assets of $116.4, $86.4 was included in Prepaid expenses and other current assets, $30.9 was presented as Deferred tax assets, net and $0.9 was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2014. Of the total net deferred income tax assets of $104.6, $36.7 was included in Prepaid expenses and other current assets and $69.1 was presented as Deferred tax assets, net and $1.2 was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2013.
Reconciliation of changes in the gross unrecognized tax benefits	The Company has gross unrecognized benefits relating to uncertain tax positions. A reconciliation of changes in the gross unrecognized tax benefits is as follows:
			Year Ended December 31,
			2014				2013				2012
	Gross unrecognized tax benefits at beginning of period		$	3.8			$	15.7			$	13.7
	Gross increases for tax positions of prior years		—				—				1.3
	Gross decreases for tax positions of prior years		—				(7.6		)		(0.1		)
	Gross increases for tax positions of current years		—				—				0.4
	Gross decrease for tax positions relating to lapse of a statute of limitation		(1.4		)		(3.3		)		—
	Foreign currency translation		(0.2		)		(1.0		)		0.4
	Gross unrecognized tax benefits at end of period		$	2.2			$	3.8			$	15.7

Employee_Benefits_Tables

Employee Benefits (Tables)	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Schedule of Assumptions Used to Determine Benefit Obligations	Assumptions used to determine benefit obligations as of the periods presented were as follows:
			Canadian Pension Benefits						VEBA Benefits
			December 31, 2014			December 31, 2013			December 31, 2014						December 31, 2013
									Union			Salaried			Union			Salaried
									VEBA			VEBA			VEBA			VEBA
	Discount rate		4	%		4.9	%		3.8	%		3.6	%		4.7	%		4.2	%
	Rate of compensation increase		3	%		3	%		—			—			—			—
	Initial medical trend rate 1		—			—			7	%		—			7.5	%		—
	Ultimate medical trend rate 1		—			—			5	%		—			5	%		—
	_____________________
	1	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.
Schedule of Assumptions Used to Determine Net Periodic Benefit Cost (Income)	Assumptions used to determine net periodic benefit cost (income) for the years ended December 31 were:
			Canadian Pension Benefits									VEBA Benefits
			2014			2013			2012			2014						2013						2012
												Union			Salaried			Union			Salaried			Union		Salaried
												VEBA			VEBA			VEBA			VEBA			VEBA		VEBA
	Discount rate		4.9	%		4.4	%		5.6	%		4.7	%		4.2	%		4	%		3.4	%		4.2	%	3.75	%
	Expected long-term return on plan assets 1		4.75	%		4.5	%		4.6	%		6.75	%		7.75	%		6.25	%		7.25	%		7.25	%	7.25	%
	Rate of compensation increase		3	%		3	%		3	%		—			—			—			—			—		—
	Initial medical trend rate2		—			—			—			7.5	%		—			8	%		—			8.5	%	—
	Ultimate medical trend rate2		—			—			—			5	%		—			5	%		—			5	%	—
	_____________________
	1	The expected long-term rate of return assumption is based on the targeted investment portfolios provided to the Company by the VEBAs’ trustees.
	2	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.
Schedule of Changes in Benefit Obligations	The following table presents the benefit obligations and funded status of the Company’s Canadian pension and the VEBAs as of December 31, 2014 and December 31, 2013 and the corresponding amounts that are included in the Company’s Consolidated Balance Sheets:
			Canadian Pension Benefits								VEBA Benefits
			2014				2013				2014				2013				2013
															(as reclassified)6				(as reported)
	Change in benefit obligation:
	Obligation at beginning of year		$	6.6			$	7			$	374.7			$	384.1			$	384.1
	Foreign currency translation adjustment		(0.5		)		(0.5		)		—				—				—
	Service cost		0.2				0.3				2.2				2.5				2.5
	Interest cost		0.3				0.3				16.7				14.6				14.6
	Prior service cost1		—				—				90.4				84.6				—
	Actuarial loss (gain)2		0.7				(0.2		)		10.2				(91.9		)		(7.3		)
	Plan participant contributions		—				—				—				—				—
	Benefits paid by Company		(0.3		)		(0.3		)		—				—				—
	Benefits paid by VEBAs		—				—				(24.7		)		(21.5		)		(21.5		)
	Reimbursement from retiree drug subsidy3		—				—				1.4				2.3				2.3
	Obligation at end of year		7				6.6				470.9				374.7				374.7
Schedule of Changes in Plan Assets
	Change in plan assets:
	Fair market value of plan assets at beginning of year		6.2				5.7				780.7				744.7				744.7
	Foreign currency translation adjustment		(0.5		)		(0.4		)		—				—				—
	Actual return on assets		0.6				0.7				22.7				39.2				39.2
	Plan participant contributions		—				—				—				—				—
	Sale of Company's common stock by Union VEBA		—				—				—				—				—
	Employer/Company contributions5		0.3				0.5				13.7				16				16
	Benefits paid by Company		(0.3		)		(0.3		)		—				—				—
	Benefits paid by VEBAs		—				—				(24.7		)		(21.5		)		(21.5		)
	Reimbursement from retiree drug subsidy3		—				—				1.4				2.3				2.3
	Fair market value of plan assets at end of year		6.3				6.2				793.8				780.7				780.7
	Net funded status4		$	(0.7	)		$	(0.4	)		$	322.9			$	406			$	406
	_____________________________
	1	The prior service cost relating to the VEBAs in 2014 was primarily comprised of (i) a loss of $60.5 due to an increase in the healthcare premium reimbursement benefit in the Union VEBA; (ii) a loss of $15.9 resulting from the addition of a new death benefit starting in 2015 for plan participants in the Union VEBA; and (iii) a loss of $14.0 due to an increase in the annual healthcare reimbursement benefit starting in 2015 for plan participants in the Salaried VEBA.
	The prior service cost relating to the VEBAs in 2013 was primarily comprised of a loss of $63.8 due to the addition of a new healthcare premium reimbursement benefit starting in 2014 in the Union VEBA and a loss of $20.8 resulting from an increase in the existing benefits reimbursement rates starting in 2014 for plan participants in both VEBAs.
	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	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.
	5	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.
	6	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.
Schedule of Net Funded Status	The following table presents the net assets of each VEBA as of the periods presented (such information is also included in the tables required under GAAP above which roll forward the assets and obligations):
			December 31, 2014												December 31, 2013
			Union VEBA				Salaried VEBA				Total				Union VEBA				Salaried VEBA				Total
	Accumulated plan benefit obligation		$	(391.5	)		$	(79.4	)		$	(470.9	)		$	(312.7	)		$	(62.0	)		$	(374.7	)
	Plan assets		731.6				62.2				793.8				717.5				63.2				780.7
	Net funded status		$	340.1			$	(17.2	)		$	322.9			$	404.8			$	1.2			$	406
Schedule of Expected Benefit Payments	As of December 31, 2014, the net benefits expected to be paid in each of the next five fiscal years and in aggregate for the five fiscal years thereafter are as follows:
		Benefit Payments Due by Period
		2015				2016				2017				2018				2019				2020-2023
	Canadian pension plan benefit payments	$	0.3			$	0.3			$	0.3			$	0.3			$	0.3			$	1.6
	VEBA benefit payments1	30.3				30.1				29.9				29.5				29.2				137.9
	Total net benefits	$	30.6			$	30.4			$	30.2			$	29.8			$	29.5			$	139.5
	__________________________________
	1	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.
Schedule of Net Periodic Benefit Cost Not yet Recognized	The amount of loss which is recognized in the Consolidated Balance Sheets (in Accumulated other comprehensive income (loss)) associated with the Company’s Canadian defined benefit pension plan and the VEBAs (before tax) that have not yet been reflected in net periodic benefit cost (income) were as follows for the years ended December 31:
			Canadian Pension Benefits								VEBA Benefits
			2014				2013				2014				2013				2013
															(as reclassified)				(as reported)
	Accumulated net actuarial (losses) gains		$	(1.9	)		$	(1.8	)		$	43.6			$	84.3			$	(0.5	)
	Transition assets		0.2				0.2				—				—				—
	Prior service cost		—				—				(197.4		)		(117.5		)		(32.7		)
	Loss recognized in Accumulated other comprehensive income (loss)		$	(1.7	)		$	(1.6	)		$	(153.8	)		$	(33.2	)		$	(33.2	)
Schedule of Net Periodic Benefit Costs (Income)	The following table presents the components of net periodic benefit cost (income) for the years ended December 31:
			Canadian Pension Benefits												VEBA Benefits
			2014				2013				2012				2014				2013				2012
	Service cost		$	0.2			$	0.3			$	0.2			$	2.2			$	2.5			$	3.4
	Interest cost		0.3				0.3				0.3				16.7				14.6				17.9
	Expected return on plan assets		(0.3		)		(0.3		)		(0.2		)		(51.4		)		(45.1		)		(40.4		)
	Amortization of prior service cost1		—				—				—				10.6				4.2				4.2
	Amortization of net actuarial loss (gain)		0.1				0.2				0.1				(1.8		)		1.3				3
	Net periodic benefit cost (income)		$	0.3			$	0.5			$	0.4			$	(23.7	)		$	(22.5	)		$	(11.9	)
	__________________________
	1	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.
Schedule of Income (Charges) Related to All Benefit Plans	The following tables present the total (income) charges related to all benefit plans for the periods presented:
			Year Ended December 31,
			2014				2013				2012
	Included within Fabricated Products:
	Canadian pension plan		$	0.3			$	0.5			$	0.4
	Deferred compensation plan		0.2				0.3				0.2
	Defined contribution plans		7.3				7.2				6.8
	Total Fabricated Products1		$	7.8			$	8			$	7.4
	Included within All Other:
	VEBAs2		$	(23.7	)		$	(22.5	)		$	(11.9	)
	Deferred compensation plan		0.7				0.9				0.8
	Defined contribution plans		0.8				0.7				0.7
	Total All Other		$	(22.2	)		$	(20.9	)		$	(10.4	)
	Total		$	(14.4	)		$	(12.9	)		$	(3.0	)
	___________________________
	1	Substantially all of the Fabricated Products segment’s employee benefits related charges are in Cost of products sold, excluding depreciation and amortization and other items with the remaining balance in Selling, administrative, research and development and general.
	2	Included within the Statements of Consolidated Income as Net periodic pension benefit income relating to VEBAs.
Allocation of Income (Charges) Relating to Retirement Plans	The following tables present the total (income) charges related to all benefit plans for the periods presented:
			Year Ended December 31,
			2014				2013				2012
	Included within Fabricated Products:
	Canadian pension plan		$	0.3			$	0.5			$	0.4
	Deferred compensation plan		0.2				0.3				0.2
	Defined contribution plans		7.3				7.2				6.8
	Total Fabricated Products1		$	7.8			$	8			$	7.4
	Included within All Other:
	VEBAs2		$	(23.7	)		$	(22.5	)		$	(11.9	)
	Deferred compensation plan		0.7				0.9				0.8
	Defined contribution plans		0.8				0.7				0.7
	Total All Other		$	(22.2	)		$	(20.9	)		$	(10.4	)
	Total		$	(14.4	)		$	(12.9	)		$	(3.0	)
	___________________________
	1	Substantially all of the Fabricated Products segment’s employee benefits related charges are in Cost of products sold, excluding depreciation and amortization and other items with the remaining balance in Selling, administrative, research and development and general.
	2	Included within the Statements of Consolidated Income as Net periodic pension benefit income relating to VEBAs

Multiemployer_Pension_Plans_Ta

Multiemployer Pension Plans (Tables)	12 Months Ended
	Dec. 31, 2014
Multiemployer Plans [Abstract]
Multiemployer Pension Plan Description and Contributions	The Company's participation in multiemployer pension plans for the year ended December 31, 2014 is outlined in the table below:
	Pension Fund		Employer Identification Number	Pension Protection Act Zone Status1		FIP/RP Status Pending/Implemented in 20142	Contributions of the Company						Surcharge Imposed in 2014	Expiration Date of Collective-Bargaining Agreement
							2014		2013		2012
				2014	2013
	Steelworkers Pension Trust (USW)3		236648508	Green	Green	No	$	3.1	$	2.9	$	3	No	Sep-15	-	Nov-17
	Other Funds4						0.9		0.9		0.9
							$	4	$	3.8	$	3.9
	________________
	1	The most recent Pension Protection Act zone status available in 2014 and 2013 for the Steelworkers Pension Trust is for the plan's year-end at December 31, 2013 and December 31, 2012, respectively. The zone status is based on information that the Company received from the plan and is certified by the plan's actuary. Among other factors, plans in the green zone are at least 80 percent funded.
	2	The “FIP/RP Status Pending/Implemented” column indicates if a Financial Improvement Plan (FIP) or a Rehabilitation Plan (RP) is either pending or has been implemented for the plan under the Pension Protection Act.
	3	The Company is party to three USW collective-bargaining agreements that require contributions to the Steelworkers Pension Trust. As of December 31, 2014, USW collective bargaining agreements covering employees at the Newark, Ohio ("Newark") and Spokane, Washington ("Trentwood") facilities covers 86% of the Company's USW-represented employees and expires in September 2015. In January 2015, the Company and the USW entered into a new five-year labor agreement relating to these facilities, effective October 1, 2015 through September 30, 2020. The Company's monthly contributions per hour worked by each bargaining unit employee at the Newark and Trentwood facilities are (in whole dollars) $1.25 and will increase to (in whole dollars) $1.50 in July 2015 and $1.75 in 2019. The union contracts covering employees at the Richmond (Bellwood), Virginia facility and Florence, Alabama facility cover 9% and 5% of the Company's USW-represented employees, respectively, and expire in November 2017 and March 2017, respectively.
	4	Other Funds consists of plans that are not individually significant.

Employee_Incentive_Plans_Table

Employee Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Compensation expense relating to short term incentive plans	Total costs relating to STI Plans were recorded as follows for each period presented:
			Year Ended December 31,
			2014				2013				2012
	Cost of products sold, excluding depreciation and amortization and other items		$	4.7			$	4.6			$	4.3
	Selling, administrative, research and development and general		8				11.1				10.1
	Total costs recorded in connection with STI Plans		$	12.7			$	15.7			$	14.4
	The following table presents the allocation of the charges detailed above, by segment:
			Year Ended December 31,
			2014				2013				2012
	Fabricated Products		$	9.6			$	11.2			$	9.9
	All Other		3.1				4.5				4.5
	Total costs recorded in connection with STI Plans		$	12.7			$	15.7			$	14.4
Non-cash compensation expense	-cash compensation expense by type of award under LTI Programs were as follows for each period presented:
		Year Ended December 31,
		2014				2013				2012
	Non-vested common shares and restricted stock units	$	3.9			$	4.3			$	3.8
	EVA-Based Performance Shares	1				2.3				1.8
	TSR-Based Performance Shares	1.9				—				—
	Total non-cash compensation expense	$	6.8			$	6.6			$	5.6
	The following table presents the allocation of the charges detailed above, by segment:
		Year Ended December 31,
		2014				2013				2012
	Fabricated Products	$	3.2			$	2.2			$	1.7
	All Other	3.6				4.4				3.9
	Total non-cash compensation expense	$	6.8			$	6.6			$	5.6
Unrecognized gross compensation cost data	Unrecognized Gross Compensation Cost Data. The following table presents unrecognized gross compensation cost data by type of award:
		31-Dec-14
		Unrecognized gross compensation costs				Expected period (in years) over which the remaining gross compensation costs will be recognized
	Non-vested common shares and restricted stock units	$	5.6			2.2
	EVA-Based Performance Shares	$	1.6			1
	TSR-Based Performance Shares	$	4.4			2.1
Summary of activity of non-vested common shares, restricted stock units, and performance shares	A summary of the activity with respect to non-vested common shares, restricted stock units, EVA-Based Performance Shares and TSR-Based Performance Shares for the year ended December 31, 2014 is as follows:
		Non-Vested							Restricted					EVA-Based Performance				TSR-Based Performance
		Common Shares							Stock Units					Shares				Shares
		Shares			Weighted-Average				Units			Weighted-Average		Shares		Weighted-Average		Shares		Weighted-Average
					Grant-Date Fair							Grant-Date Fair				Grant-Date Fair				Grant-Date Fair
					Value per Share							Value per Unit				Value per Share				Value per Share
	Outstanding at December 31, 2013	143,967			$	51.09			5,472			$	51.03	562,554		$	49.26	—		$	—
	Granted 1	119,799			66.42				2,235			67.42		—		—		160,868		83.18
	Vested	(64,493	)		52.2				(2,350	)		46.83		(42,545	)	47.21		—		—
	Forfeited 1	(40,503	)		60.21				—			—		(28,613	)	51.44		(10,645	)	83.18
	Canceled 2	—			$	—			—			$	—	(137,820	)	46.65		—		—
	Outstanding at December 31, 2014	158,770			$	59.88			5,357			$	59.71	353,576		$	50.35	150,223		$	83.18
	_____________________
	1	For EVA-Based Performance Shares and TSR-Based Performance Shares, the number of shares granted and forfeited are presented at their maximum payout.
	2	For EVA-Based Performance Shares and TSR-Based Performance Shares, canceled represents the number of shares that did not vest due to EVA or TSR performance results falling below those required for maximum payout.

Commitments_and_Contingencies_

Commitments and Contingencies Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum rental payments	Minimum rental commitments under operating leases at December 31, 2014 were as follows:
		Year Ended December 31,
		2015			2016			2017			2018		2019		2020 and Thereafter
	Minimum rental commitments	$	4.7		$	3.9		$	3.2		$	2.8	$	2.7	$	27.6
Schedule of future purchase obligations	mounts due under purchase obligations as of December 31, 2014 were as follows:
		Year Ended December 31,
		2015			2016			2017			2018		2019		2020 and Thereafter
	Purchase obligations	$	294.6		$	8.9		$	2.9		$	1	$	0.5	$	1.4
Environmental accrual rollforward	The following table presents the changes in such accruals, which are primarily included in Long-term liabilities:
		Year Ended December 31,
		2014			2013			2012
	Beginning balance	$	22.8		$	21.7		$	22
	Additional accruals	0.8			4.5			1.2
	Less expenditures	(4.3		)	(3.4		)	(1.5		)
	Ending balance	$	19.3		$	22.8		$	21.7

Derivative_Financial_Instrumen1

Derivative Financial Instruments and Related Hedging Programs (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of realized and unrealized gains and losses	Realized and unrealized (losses) gains associated with all derivative contracts consisted of the following for each period presented:
			Year Ended December 31,
			2014				2013				2012
	Realized gains (losses):
	Aluminum		$	6.9			$	(5.5	)		$	(9.0	)
	Natural Gas		1				(1.8		)		(6.7		)
	Electricity		(0.1		)		0.8				(3.4		)
	Total realized gains (losses):		$	7.8			$	(6.5	)		$	(19.1	)
	Unrealized (losses) gains:
	Hedges of operational risk:
	Aluminum		$	(2.6	)		$	(3.1	)		$	10.1
	Natural Gas		(6.0		)		2.6				4.3
	Electricity		(1.8		)		1.1				0.8
	Foreign Currency		—				0.1				—
	Total hedges of operational risk		(10.4		)		0.7				15.2
	Option Assets relating to the Convertible Notes		5.2				24.2				9
	Bifurcated Conversion Feature of the Convertible Notes		(1.6		)		(21.0		)		(8.2		)
	Total unrealized (losses) gains		$	(6.8	)		$	3.9			$	16
Summary of material derivative positions	The following table summarizes the Company's material derivative positions at December 31, 2014:
	Aluminum		Maturity Period		Notional Amount of Contracts (mmlbs)
			(month/year)
	Fixed price purchase contracts		1/15 through 1/16		67.3
	Midwest premium swap contracts1		1/15 through 12/15		67.1
	Natural Gas2		Maturity Period		Notional Amount of Contracts (mmbtu)
			(month/year)
	Fixed price purchase contracts		1/15 through 12/17		6,720,000
	Electricity3		Maturity Period		Notional Amount of Contracts (Mwh)
			(month/year)
	Fixed price purchase contracts		1/15 through 12/15		175,200
	Hedges Relating to the Convertible Notes		Contract Period		Notional Amount of Contracts (Common Shares)
			(month/year)
	Bifurcated Conversion Feature4		3/10 through 4/15		3,660,738
	Option Assets4		3/10 through 4/15		3,660,738
	_________________________
	1	Regional premiums represent the premium over the London Metal Exchange price for primary aluminum which is incurred on the Company's purchases of primary aluminum.
	2	As of December 31, 2014, the Company had Henry Hub NYMEX-based hedge positions in place to cover exposure to fluctuations in prices for approximately 81%, 73% and 12% of the expected natural gas purchases for 2015, 2016 and 2017, respectively.
	3	As of December 31, 2014, the Company had Mid-C International Commodity Exchange-based hedge positions in place to cover exposure to fluctuations in prices for approximately 44% of the expected electricity purchases for 2015.
	4	The Bifurcated Conversion Feature represents the cash conversion feature of the Convertible Notes. The Option Assets expire on the maturity or earlier conversion of the Convertible Notes and have an exercise price equal to the conversion price of the Convertible Notes, subject to anti-dilution adjustments substantially similar to the anti-dilution adjustments for the Convertible Notes. Although the fair value of the Option Assets is derived from a notional number of shares of the Company's common stock, the Option Assets may only be settled in cash.
Schedule of Offsetting Derivative Instruments by Counterparty [Table Text Block]	The Company enters into derivative contracts with counterparties, some of which are subject to enforceable master netting arrangements and some of which are not. The Company reflects the fair value of its derivative contracts on a gross basis on the Consolidated Balance Sheets (see Note 2).
	The following tables present offsetting information regarding the Company's derivatives by type of counterparty as of December 31, 2014:
	Derivative Assets and Collateral Held by Counterparty
														Gross Amounts Not Offset in the Consolidated Balance Sheets
		Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets				Financial Instruments			Cash Collateral Received		Net Amount
	Counterparty (with netting agreements)	$	0.9			$	—			$	0.9			$	0.8		$	—	$	0.1
	Counterparty (without netting agreements)1	84.8				—				84.8				—			—		84.8
	Total	$	85.7			$	—			$	85.7			$	0.8		$	—	$	84.9
	Derivative Liabilities and Collateral Held by Counterparty
														Gross Amounts Not Offset in the Consolidated Balance Sheets
		Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets				Financial Instruments			Cash Collateral Pledged		Net Amount
	Counterparty (with netting agreements)	$	(8.0	)		$	—			$	(8.0	)		$	(0.8	)	$	—	$	(7.2	)
	Counterparty (without netting agreements)1	(85.0		)		—				(85.0		)		—			—		(85.0		)
	Counterparty (with partial netting agreements)	(3.8		)		—				(3.8		)		—			—		(3.8		)
	Total	$	(96.8	)		$	—			$	(96.8	)		$	(0.8	)	$	—	$	(96.0	)
	_________________
	1	Such amounts include the fair value of the Bifurcated Conversion Feature and Option Assets at December 31, 2014 (see Note 11).
	The following tables present offsetting information regarding the Company’s derivatives by type of counterparty as of December 31, 2013:
	Derivative Assets and Collateral Held by Counterparty
														Gross Amounts Not Offset in the Consolidated Balance Sheets
		Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets				Financial Instruments			Cash Collateral Received		Net Amount
	Counterparty (with netting agreements)	$	1			$	—			$	1			$	0.8		$	—	$	0.2
	Counterparty (without netting agreements)1	80.4				—				80.4				—			—		80.4
	Counterparty (with partial netting agreements)	0.4				—				0.4				0.4			—		—
	Total	$	81.8			$	—			$	81.8			$	1.2		$	—	$	80.6
	Derivative Liabilities and Collateral Held by Counterparty
														Gross Amounts Not Offset in the Consolidated Balance Sheets
		Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets				Financial Instruments			Cash Collateral Pledged		Net Amount
	Counterparty (with netting agreements)	$	(1.6	)		$	—			$	(1.6	)		$	(0.8	)	$	—	$	(0.8	)
	Counterparty (without netting agreements)1	(83.2		)		—				(83.2		)		—			—		(83.2		)
	Counterparty (with partial netting agreements)	(1.3		)		—				(1.3		)		(0.4		)	—		(0.9		)
	Total	$	(86.1	)		$	—			$	(86.1	)		$	(1.2	)	$	—	$	(84.9	)
	_________________
	1	Such amounts include the fair value of the Bifurcated Conversion Feature and Option Assets at December 31, 2013 (see Note 11).

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Summary of assets and liabilities measured and recognized at fair value on a recurring basis	The following table presents the Company's financial instruments, classified under the appropriate level of the fair value hierarchy, as of the period presented:
		31-Dec-14
		Level 1			Level 2				Level 3				Total
	FINANCIAL ASSETS:
	Derivative Instruments
	Aluminum -
	Midwest premium swap contracts	—			—				1				1
	Hedges Relating to the Convertible Notes - Option Assets	—			84.7				—				84.7
	VEBAs and Canadian Pension Plan
	Fixed income investment funds in registered investment companies1	54			340.3				—				394.3
	Mortgage-backed securities	—			30.1				—				30.1
	Corporate debt securities2	—			75.4				—				75.4
	Equity investment funds in registered investment companies3	—			191.3				—				191.3
	United States Treasuries	—			39.5				—				39.5
	Municipal debt securities	—			1.8				—				1.8
	Cash and money market investments4	19.3			—				—				19.3
	Asset-backed securities	—			8.1				—				8.1
	Diversified investment funds in registered investment companies5	20.4			6.2				—				26.6
	All Other Financial Assets
	Cash and cash equivalents6	29.5			148.2				—				177.7
	Short-term investments	—			114				—				114
	Deferred compensation plan assets	—			7.3				—				7.3
	Total assets	$	123.2		$	1,046.90			$	1			$	1,171.10
	FINANCIAL LIABILITIES:
	Derivative Instruments
	Aluminum - Fixed price purchase contracts	$	—		$	(4.2	)		$	—			$	(4.2	)
	Natural Gas - Fixed price purchase contracts	—			(6.2		)		—				(6.2		)
	Electricity - Fixed price purchase contracts	—			(1.7		)		—				(1.7		)
	Hedges Relating to the Convertible Notes - Bifurcated Conversion Feature	—			(84.7		)		—				(84.7		)
	All Other Financial Liabilities
	Senior Notes	(244.5		)	—				—				(244.5		)
	Convertible Notes, including Bifurcated Conversion Feature	(263.3		)	—				—				(263.3		)
	Total liabilities	$	(507.8	)	$	(96.8	)		$	—			$	(604.6	)
	The following table presents the Company's financial instruments, classified under the appropriate level of the fair value hierarchy, as of the period presented:
		31-Dec-13
		Level 1			Level 2				Level 3				Total
	FINANCIAL ASSETS:
	Derivative Instruments
	Aluminum -
	Fixed price purchase contracts	$	—		$	0.1			$	—			$	0.1
	Midwest premium swap contracts	—			—				1.1				1.1
	Natural Gas - Fixed price purchase contracts	—			0.5				—				0.5
	Electricity - Fixed price purchase contracts	—			0.5				—				0.5
	Foreign Currency - Euro	—			0.1				—				0.1
	Hedges Relating to the Convertible Notes - Option Assets	—			79.5				—				79.5
	VEBAs and Canadian Pension Plan
	Fixed income investment funds in registered investment companies1	57			318				—				375
	Mortgage-backed securities	—			25.9				—				25.9
	Corporate debt securities2	—			78.2				—				78.2
	Equity investment funds in registered investment companies3	—			175.3				—				175.3
	United States Treasuries	—			43.3				—				43.3
	Municipal debt securities	—			1.6				—				1.6
	Cash and money market investments4	36.8			—				—				36.8
	Asset-backed securities	—			8.5				—				8.5
	Diversified investment funds in registered investment companies5	20.1			6.2				—				26.3
	All Other Financial Assets
	Cash and cash equivalents6	57.7			111.8				—				169.5
	Short-term investments	—			129.5				—				129.5
	Deferred compensation plan assets	—			6.5				—				6.5
	Total assets	$	171.6		$	985.5			$	1.1			$	1,158.20
	FINANCIAL LIABILITIES:
	Derivative Instruments
	Aluminum - Fixed price purchase contracts	$	—		$	(1.8	)		$	—			$	(1.8	)
	Natural Gas - Fixed price purchase contracts	—			(0.8		)		—				(0.8		)
Electricity - Fixed price purchase contracts	—			(0.4		)		—				(0.4		)
Hedges Relating to the Convertible Notes - Bifurcated Conversion Feature	—			(83.1		)		—				(83.1		)
All Other Financial Liabilities
Senior Notes	(255.4		)	—				—				(255.4		)
Convertible Notes, including Bifurcated Conversion Feature	(260.0		)	—				—				(260.0		)
Total liabilities	$	(515.4	)	$	(86.1	)		$	—			$	(601.5	)
_________________________
1.	This category represents investments in various fixed income funds with multiple registered investment companies. Such funds invest in diversified portfolios, including (i) marketable fixed income securities such as (a) U.S. Treasury and other government and agency securities, (b) municipal bonds, (c) mortgage-backed securities, (d) asset-backed securities, (e) corporate bonds, notes and debentures in various sectors, (f) preferred and common stock, (g) investments in affiliated and other investment companies, (h) short-term investments and other net assets and (i) repurchase agreements and reverse repurchase agreements; (ii) other commingled investments; (iii) investment grade debt; (iv) fixed income instruments which may be represented by options, future contracts or swap agreements; and (v) cash and cash equivalents. The fair value of assets in this category is estimated using the net asset value per share of the investments.
2.	This category represents investments in fixed income corporate securities in various sectors. Investments in the industrial, financial and utilities sectors in 2014 represented approximately 51%, 37% and 12% of the total portfolio in this category, respectively. Investments in the industrial, financial and utilities sectors in 2013 represented approximately 56%, 35% and 9% of the total portfolio in this category, respectively. The fair value of assets in this category is estimated using the net asset value per share of the investments.
3.	This category represents investments in equity funds that invest in portfolios comprised of (i) equity and equity-related securities of U.S. and non-U.S. issuers across all market capitalization; (ii) common stock in investment trust funds; and (iii) other short-term investments. The fair value of assets in this category is determined by using quoted prices in active markets for investments considered Level 1 inputs and estimated using the net asset value per share of the investments for investments considered Level 2 inputs.
4.	This category represents cash and investments in various money market funds.
5.	The plan assets are invested in investment funds that hold a diversified portfolio of (i) U.S and international debt and equity securities; (ii) fixed income securities such as corporate bonds and government bonds; (iii) mortgage-related securities; and (iv) cash and cash equivalents. The fair value of assets in this category is estimated using the net asset value per share of the investments.
6.	See Note 2 for components of cash and cash equivalents.
Schedule of quantitative information for Level 3 Midwest premiums derivative contracts	The following table presents quantitative information for Level 3 Midwest premium derivative contracts:
			Fair Value at December 31, 2014		Valuation technique		Unobservable input		Range ($ in unit price)
	Assets:
	Midwest premium contracts		1		Discounted fair value		Pricing forward curve		$0.236 per metric ton in Jan 2015 to $0.205 per metric ton in Dec 2016
Reconciliation of activity for financial instruments classified as Level 3	The following table presents a reconciliation of activity for the Level 3 Midwest premium derivative contracts on a net basis:
		Year Ended December 31,
		2014			2013
	Fair value measurement at beginning of period	$	1.1		$	0.4
	Total realized/unrealized gains included in:
	Cost of goods sold, excluding depreciation and amortization and other items and Unrealized (gains) losses on derivative instruments	4.4			(0.1		)
	Transactions involving Level 3 derivative contracts:
	Purchases	2.8			1
	Sales	—			—
	Issuances	—			—
	Settlements	(7.3		)	(0.2		)
	Transactions involving Level 3 derivatives - net	(4.5		)	0.8
	Transfers in and (or) out of Level 3 valuation hierarchy	—			—
	Fair value measurement at end of period	$	1		$	1.1
	Total gains included in Unrealized (gains) losses on derivative instruments, attributable to the change in unrealized gains/losses relating to derivative contracts held at December 31:	$	1		$	1.1
Summary of activities relating to the Company's CARO liabilities	The following table summarizes the activity relating to the Company's CARO liabilities:
			Year Ended December 31,
			2014			2013				2012
	Beginning balance		$	4.4		$	4.1			$	4
	Liabilities settled during the period		—			(0.2		)		(0.5		)
	Accretion expense		0.4			0.4				0.3
	Adjustment to accretion expense due to revisions to estimated cash flow and timing of expenditure1		—			0.1				0.3
	Ending balance		$	4.8		$	4.4			$	4.1
	__________________________________________
	1	The adjustments in 2013 did not have a material impact on the basic and diluted net income per share for 2013. The adjustment in 2012 decreased both basic and diluted net income per share for 2012 by approximately $0.02 per share.

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Calculation of basic and diluted earnings per share	Basic and diluted net income per share for 2014, 2013 and 2012 were calculated as follows:
			Year Ended December 31,
			2014		2013		2012
	Numerator:
	Net income		$	71.8	$	104.8	$	85.8
	Denominator - Weighted-average common shares outstanding (in thousands):
	Basic1		17,818		18,827		19,115
	Add: dilutive effect of non-vested common shares, restricted stock units and performance shares		179		178		163
	Add: dilutive effect of warrants		596		241		—
	Diluted2		18,593		19,246		19,278
	Net income per common share, Basic:		$	4.02	$	5.56	$	4.49
	Net income per common share, Diluted:		$	3.86	$	5.44	$	4.45
	_____________
	1	The basic weighted-average number of common shares outstanding during the period excludes non-vested common shares, restricted stock units and performance shares.
	2	The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.

Segment_and_Geographical_Area_1

Segment and Geographical Area Information (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Summary of financial information by operating segment	The following tables provide financial information by reporting segment and business unit for each period or as of each period end, as applicable:
		Year Ended December 31,
		2014				2013				2012
	Net sales:
	Fabricated Products	$	1,356.10			$	1,297.50			$	1,360.10
	Segment operating income (loss):
	Fabricated Products 1,2	$	151.4			$	188.6			$	190.8
	All Other3	(13.5		)		(15.3		)		(24.9		)
	Total operating income	$	137.9			$	173.3			$	165.9
	Interest expense	(37.5		)		(35.7		)		(29.1		)
	Other income, net	6.7				5.6				2.8
	Income before income taxes	$	107.1			$	143.2			$	139.6
	Depreciation and amortization:
	Fabricated Products	$	30.6			$	27.6			$	26
	All Other	0.5				0.5				0.5
	Total depreciation and amortization	$	31.1			$	28.1			$	26.5
	Capital expenditures:
	Fabricated Products	$	58.5			$	69.8			$	43.8
	All Other	0.9				0.6				0.3
	Total capital expenditures	$	59.4			$	70.4			$	44.1
				31-Dec-14				31-Dec-13
	Assets:
	Fabricated Products			$	878.9			$	852.5
	All Other4			864.8				918.4
	Total assets			$	1,743.70			$	1,770.90
	__________________
	1	Operating results in the Fabricated Products segment for 2014, 2013 and 2012 included $1.2, $4.0 and $1.1, respectively, of environmental expense. Fabricated Products segment operating results for 2014 and 2012 included $1.5 and $4.4 of asset impairment charge relating to certain property, plant and equipment.
	2	Fabricated Products segment results for 2014, 2013 and 2012 include non-cash mark-to-market (losses) gains on primary aluminum, natural gas, electricity and foreign currency hedging activities totaling $(10.4), $0.7 and $15.2, respectively. For further discussion regarding mark-to-market matters, see Note 10.
	3	Operating results of All Other include VEBA net periodic pension benefit income of $23.7, $22.5 and $11.9 for 2014, 2013 and 2012, respectively.
	4	Assets in All Other represent primarily all of the Company’s cash and cash equivalents, short-term investments, financial derivative assets, net assets of VEBAs and net deferred income tax assets.
Schedule of net sales by end market segment applications	Net sales by product categories based on end market applications for the Fabricated Products segment were as follows:
		Year Ended December 31,
		2014				2013				2012
	Net sales:
	Aero/HS products	$	686.3			$	677			$	695.1
	Automotive Extrusions	173.5				129.5				125.5
	GE products	419.5				411				441.4
	Other products	76.8				80				98.1
	Total net sales	$	1,356.10			$	1,297.50			$	1,360.10
Schedule of net sales, income taxes paid, and long-lived assets, by geographical area	Geographic information for net sales based on country of origin, income taxes paid and long-lived assets were as follows:
		Year Ended December 31,
		2014				2013				2012
	Net sales to unaffiliated customers:
	Fabricated Products —
	United States	$	1,254.00			$	1,204.70			$	1,256.50
	Canada	102.1				92.8				103.6
	Total net sales	$	1,356.10			$	1,297.50			$	1,360.10
	Income taxes paid:
	Fabricated Products —
	United States	$	2.1			$	1.2			$	0.5
	Canada	1.4				0.9				1.3
	Total income taxes paid	$	3.5			$	2.1			$	1.8
				Year Ended December 31,
				2014				2013
	Long-lived assets:1
	Fabricated Products —
	United States			$	432.6			$	409.5
	Canada			17.4				15.3
	Total Fabricated Products long-lived assets			450				424.8
	All Other —
	United States			4.9				4.5
	Total All Other long-lived assets			4.9				4.5
	Total long-lived assets			$	454.9			$	429.3
	__________________
	1    Long-lived assets represent Property, plant and equipment, net.
Schedules of Concentration of Risk, by Risk Factor [Table Text Block]	Information for export sales and primary aluminum supply from the Company's major suppliers were as follows:
		Year Ended December 31,
		2014			2013			2012
	Percentage of Net sales:
	Export sales	19	%		17	%		18	%
	Percentage of Total Annual Primary Aluminum Supply (lbs):
	Supply from the Company's top five major suppliers	71	%		86	%		78	%
	Supply from the Company's largest supplier	30	%		25	%		29	%
	Supply from the Company's second and third largest suppliers	25	%		35	%		31	%

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2014
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information
		Year Ended December 31,
		2014		2013		2012
	Interest paid	$	25.6	$	28.1	$	19.4
	Income taxes paid	$	3.5	$	2.1	$	1.8
	Non-cash investing and financing activities:
	Stock repurchases not yet settled (accrued in accounts payable)	$	0.8	$	1	$	—
	Unpaid purchases of property and equipment	$	1.8	$	4.4	$	3.4
	Purchases of property and equipment through capital leasing arrangements	$	—	$	0.2	$	0.1

Other_Income_Net_Tables

Other Income, Net (Tables)	12 Months Ended
	Dec. 31, 2014
Other Income and Expenses [Abstract]
Other Income (Expense), Net	Other income, net consisted of the following for each period presented:
		Year Ended December 31,
		2014		2013		2012
	Interest income	$	1	$	0.4	$	0.4
	Unrealized gains on financial derivatives1	3.6		3.2		0.8
	Realized gains on investments	1		1.4		0.5
	Distribution from third-party trust2	—		0.6		—
	Insurance settlement	—		—		0.4
	All other, net	1.1		—		0.7
	Other income, net	$	6.7	$	5.6	$	2.8
	____________
	1	See “Derivative Financial Instruments” in Note 1 for a discussion of accounting policy for such instruments.
	2	See Note 12 for discussion of the distribution.

Other_Comprehensive_Loss_Incom1

Other Comprehensive (Loss) Income (Tables)	12 Months Ended
	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Schedule of Other Comprehensive (Loss) Income	The following table presents the tax effect allocated to each component of other comprehensive (loss) income for each period presented:
		Before-Tax			Before-Tax			Income Tax
		Amount			Amount			(Expense)			Net-of-Tax
		(as reported)			(as reclassified)4			Benefit3			Amount
	2014
	Defined benefit pension plan and VEBAs:
	Net actuarial loss arising during the period	$	(39.0	)				$	14.5		$	(24.5	)
	Prior service cost arising during the period	(90.5		)				33.8			(56.7		)
	Total actuarial (loss) gain and prior service costs	(129.5		)				48.3			(81.2		)
	Reclassification adjustments:
	Amortization of net actuarial (gain)1	(1.8		)				0.7			(1.1		)
	Amortization of prior service cost1	10.6						(3.9		)	6.7
	Other comprehensive income relating to defined benefit pension plan and VEBAs	(120.7		)				45.1			(75.6		)
	Available for sale securities:
	Unrealized loss on available for sale securities	(0.2		)				0.1			(0.1		)
	Reclassification adjustments:
	Reclassification of unrealized loss upon sale of available for sale securities2	(0.1		)				—			(0.1		)
	Other comprehensive loss relating to available for sale securities	(0.3		)				0.1			(0.2		)
	Foreign currency translation adjustment	0.4						—			0.4
	Other comprehensive loss	$	(120.6	)				$	45.2		$	(75.4	)
	2013
	Defined benefit pension plan and VEBAs:
	Net actuarial gain arising during the period	$	2.2		$	87		$	(32.5	)	$	54.5
	Prior service cost arising during the period	—			(84.8		)	31.8			(53.0		)
	Total actuarial gain (loss) and prior service costs	2.2			2.2			(0.7		)	1.5
	Reclassification adjustments:
	Amortization of net actuarial loss1	1.5			1.5			(0.5		)	1
	Amortization of prior service cost1	4.2			4.2			(1.6		)	2.6
	Other comprehensive income relating to defined benefit pension plan and VEBAs	7.9			7.9			(2.8		)	5.1
	Available for sale securities:
	Unrealized gain on available for sale securities	1			1			(0.3		)	0.7
	Reclassification adjustments:
	Reclassification of unrealized gain upon sale of available for sale securities2	(1.0		)	(1.0		)	0.3			(0.7		)
	Other comprehensive income relating to available for sale securities	—			—			—			—
	Foreign currency translation adjustment	0.2			0.2			—			0.2
	Other comprehensive income	$	8.1		$	8.1		$	(2.8	)	$	5.3
		Before-Tax			Before-Tax			Income Tax
		Amount			Amount			(Expense)			Net-of-Tax
		(as reported)			(as reclassified)4			Benefit3			Amount
	2012
	Defined benefit pension plan and VEBAs:
	Net actuarial gain arising during the period	$	87.8					$	(33.5	)	$	54.3
	Reclassification adjustments:
	Amortization of net actuarial loss1	3.1						(1.1		)	2
	Amortization of prior service cost1	4.2						(1.7		)	2.5
	Other comprehensive income relating to defined benefit pension plan and VEBAs	95.1						(36.3		)	58.8
	Available for sale securities:
	Unrealized gain on available for sale securities	0.6						(0.2		)	0.4
	Foreign currency translation adjustment	(0.2		)				—			(0.2		)
	Other comprehensive income	$	95.5					$	(36.5	)	$	59
	____________
	1	Amounts reclassified out of Accumulated other comprehensive income relating to VEBA adjustments were included as a component of Net periodic pension benefit income relating to VEBAs.
	2	Amounts reclassified out of Accumulated other comprehensive income relating to sales of available for sale securities were included as a component of Other income (expense), net. The Company uses the specific identification method to determine the amount reclassified out of Accumulated other comprehensive income.
	3	Income tax amounts reclassified out of Accumulated other comprehensive income relating to VEBA adjustments and sales of available for sale securities were included as a component of Income tax provision.
	4	The presentation of other comprehensive income 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. The 2013 balances were adjusted to reflect this reclassification. The impacts to the prospective amortization of Prior service cost and Accumulated net actuarial (losses) gains were not material.

Guarantor_and_NonGuarantor_Fin1

Guarantor and Non-Guarantor Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2014
Guarantor and Non-Guarantor Financial Statement [Abstract]
Schedule of Condensed Financial Statements	CONDENSED CONSOLIDATING BALANCE SHEET
	December 31, 2014
		Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	ASSETS
	Current assets:
	Cash and cash equivalents	$	—		$	175.3		$	2.4		$	—		$	177.7
	Short-term investments	—			114			—			—			114
	Receivables:
	Trade receivables — net	—			126.1			3.2			—			129.3
	Intercompany receivables	204.2			4			0.9			(209.1		)	—
	Other	—			5.6			5.3			—			10.9
	Inventories	—			208			7.6			(0.9		)	214.7
	Prepaid expenses and other current assets	85.1			93.1			0.4			—			178.6
	Total current assets	289.3			726.1			19.8			(210.0		)	825.2
	Investments in and advances to subsidiaries	1,209.20			32.5			—			(1,241.7		)	—
	Property, plant and equipment — net	—			437.4			17.5			—			454.9
	Long-term intercompany receivables	—			—			15.9			(15.9		)	—
	Net assets of VEBAs	—			340.1			—			—			340.1
	Deferred tax assets — net	—			23.8			—			7.1			30.9
	Intangible assets — net	—			32.1			—			—			32.1
	Goodwill	—			37.2			—			—			37.2
	Other assets	4.4			18.8			0.1			—			23.3
	Total	$	1,502.90		$	1,648.00		$	53.3		$	(1,460.5	)	$	1,743.70
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Current liabilities:
	Accounts payable	$	1.3		$	73.8		$	6.3		$	—		$	81.4
	Intercompany payable	—			221.3			3.3			(224.6		)	—
	Accrued salaries, wages and related expenses	—			36.5			3.1			—			39.6
	Other accrued liabilities	88.2			43.8			0.8			—			132.8
	Current portion of long-term debt	172.5			—			—			—			172.5
	Short-term capital lease	—			0.1			—			—			0.1
	Total current liabilities	262			375.5			13.5			(224.6		)	426.4
	Net liability in respect of VEBA	—			17.2			—			—			17.2
	Deferred tax liabilities	—			—			0.9			—			0.9
	Long-term intercompany payable	—			15.9			—			(15.9		)	—
	Long-term liabilities	—			50.3			8			—			58.3
	Long-term debt	225			—			—			—			225
	Total liabilities	487			458.9			22.4			(240.5		)	727.8
	Total stockholders’ equity	1,015.90			1,189.10			30.9			(1,220.0		)	1,015.90
	Total	$	1,502.90		$	1,648.00		$	53.3		$	(1,460.5	)	$	1,743.70
	CONDENSED CONSOLIDATING BALANCE SHEET
	December 31, 2013
		Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	ASSETS
	Current assets:
	Cash and cash equivalents	$	5		$	157.7		$	6.8		$	—		$	169.5
	Short-term investments	—			129.5			—			—			129.5
	Receivables:
	Trade receivables — net	—			117.7			2.1			—			119.8
	Intercompany receivables	—			0.1			0.2			(0.3		)	—
	Other	—			5.3			8.1			—			13.4
	Inventories	—			208.6			6.4			(0.6		)	214.4
	Prepaid expenses and other current assets	0.1			43.7			0.4			—			44.2
	Total current assets	5.1			662.6			24			(0.9		)	690.8
	Investments in and advances to subsidiaries	1,437.90			26.5			—			(1,464.4		)	—
	Property, plant and equipment — net	—			414			15.3			—			429.3
	Long-term intercompany receivables	31.3			1.6			9.5			(42.4		)	—
	Net assets of VEBAs	—			406			—			—			406
	Deferred tax assets — net	—			60.2			—			8.9			69.1
	Intangible assets — net	—			33.7			—			—			33.7
	Goodwill	—			37.2			—			—			37.2
	Other assets	86.2			18.5			0.1			—			104.8
	Total	$	1,560.50		$	1,660.30		$	48.9		$	(1,498.8	)	$	1,770.90
	LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities:
Accounts payable	$	1.1		$	56.3		$	5.5		$	—		$	62.9
Intercompany payable	—			13.9			0.1			(14.0		)	—
Accrued salaries, wages and related expenses	—			39.3			3.4			—			42.7
Other accrued liabilities	3.5			39.9			1.4			—			44.8
Short-term capital lease	—			0.2			—			—			0.2
Total current liabilities	4.6			149.6			10.4			(14.0		)	150.6
Deferred tax liabilities	—			—			1.2			—			1.2
Long-term intercompany payable	—			40.7			1.7			(42.4		)	—
Long-term liabilities	83.2			52			11.2			—			146.4
Long-term debt	388.5			—			—			—			388.5
Total liabilities	476.3			242.3			24.5			(56.4		)	686.7
Total stockholders’ equity	1,084.20			1,418.00			24.4			(1,442.4		)	1,084.20
Total	$	1,560.50		$	1,660.30		$	48.9		$	(1,498.8	)	$	1,770.90
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (LOSS)
Year Ended December 31, 2014
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	1,323.40		$	133.9		$	(101.2	)	$	1,356.10
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			1,098.30			117.8			(98.6		)	1,117.50
Unrealized loss on derivative instruments	—			10.4			—			—			10.4
Depreciation and amortization	—			30			1.1			—			31.1
Selling, administrative, research and development and general:
Selling, administrative, research and development and general	4.1			69.7			9.9			(2.3		)	81.4
Net periodic pension benefit income relating to VEBAs	—			(23.7		)	—			—			(23.7		)
Total selling, administrative, research and development and general	4.1			46			9.9			(2.3		)	57.7
Other operating charges, net	—			1.5			—			—			1.5
Total costs and expenses	4.1			1,186.20			128.8			(100.9		)	1,218.20
Operating (loss) income	(4.1		)	137.2			5.1			(0.3		)	137.9
Other (expense) income:
Interest expense	(37.5		)	(0.6		)	—			0.6			(37.5		)
Other income (expense), net	3.7			3.2			0.4			(0.6		)	6.7
(Loss) income before income taxes	(37.9		)	139.8			5.5			(0.3		)	107.1
Income tax (provision) benefit	—			(50.2		)	0.8			14.1			(35.3		)
Earnings in equity of subsidiaries	109.7			6			—			(115.7		)	—
Net income	$	71.8		$	95.6		$	6.3		$	(101.9	)	$	71.8
Comprehensive (loss) income	$	(3.6	)	$	19.9		$	6.6		$	(26.5	)	$	(3.6	)
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Year Ended December 31, 2013
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	1,275.20		$	118		$	(95.7	)	$	1,297.50
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			1,026.00			105.7			(92.8		)	1,038.90
Unrealized gains on derivative instruments	—			(0.7		)	—			—			(0.7		)
Depreciation and amortization	—			27			1.1			—			28.1
Selling, administrative, research and development and general:
Selling, administrative, research and development and general	3.8			70.1			8.9			(2.4		)	80.4
Net periodic pension benefit income relating to VEBAs	—			(22.5		)	—			—			(22.5		)
Total selling, administrative, research and development and general	3.8			47.6			8.9			(2.4		)	57.9
Total costs and expenses	3.8			1,099.90			115.7			(95.2		)	1,124.20
Operating (loss) income	(3.8		)	175.3			2.3			(0.5		)	173.3
Other (expense) income:
Interest expense	(36.6		)	0.5			—			0.4			(35.7		)
Other income (expense), net	3.9			2			—			(0.3		)	5.6
(Loss) income before income taxes	(36.5		)	177.8			2.3			(0.4		)	143.2
Income tax (provision) benefit	—			(68.1		)	15.7			14			(38.4		)
Earnings in equity of subsidiaries	141.3			17.6			—			(158.9		)	—
Net income	$	104.8		$	127.3		$	18		$	(145.3	)	$	104.8
Comprehensive income	$	110.1		$	131.6		$	19		$	(150.6	)	$	110.1
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Year Ended December 31, 2012
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	1,326.00		$	124		$	(89.9	)	$	1,360.10
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			1,090.00			110.2			(84.0		)	1,116.20
Unrealized loss on derivative instruments	—			(15.2		)	—			—			(15.2		)
Depreciation and amortization	—			25.5			1			—			26.5
Selling, administrative, research and development and general:
Selling, administrative, research and development and general	2			69.6			8.2			(5.7		)	74.1
Net periodic pension benefit income relating to VEBAs	—			(11.9		)	—			—			(11.9		)
Total selling, administrative, research and development and general	2			57.7			8.2			(5.7		)	62.2
Other operating charges, net	—			4.5			—			—			4.5
Total costs and expenses	2			1,162.50			119.4			(89.7		)	1,194.20
Operating (loss) income	(2.0		)	163.5			4.6			(0.2		)	165.9
Other (expense) income:
Interest expense	(28.2		)	(1.0		)	—			0.1			(29.1		)
Other income, net	0.8			1.5			0.6			(0.1		)	2.8
(Loss) income before income taxes	(29.4		)	164			5.2			(0.2		)	139.6
Income tax provision	—			(62.6		)	(2.3		)	11.1			(53.8		)
Earnings in equity of subsidiaries	115.2			2.6			—			(117.8		)	—
Net income	$	85.8		$	104		$	2.9		$	(106.9	)	$	85.8
Comprehensive income	$	144.8		$	164		$	1.9		$	(165.9	)	$	144.8
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Year Ended December 31, 2014
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash provided by operating activities	$	35.6		$	81.8		$	6.7		$	—		$	124.1
Cash flows from investing activities:
Capital expenditures	—			(56.4		)	(3.0		)	—			(59.4		)
Purchase of available for sale securities	—			(93.5		)	—			—			(93.5		)
Proceeds from disposition of available for sale securities	—			108.2			—			—			108.2
Net cash used in investing activities	—			(41.7		)	(3.0		)	—			(44.7		)
Cash flows from financing activities:
Payment of capital lease liability	—			(0.1		)	—			—			(0.1		)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	—			0.8			—			—			0.8
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares	(2.4		)	—			—			—			(2.4		)
Repurchase of common stock	(44.1		)	—			—			—			(44.1		)
Cash dividend paid to stockholders	(25.4		)	—			—			—			(25.4		)
Intercompany loan	31.3			(23.2		)	(8.1		)	—			—
Net cash used in financing activities	(40.6		)	(22.5		)	(8.1		)	—			(71.2		)
Net (decrease) increase in cash and cash equivalents during the period	(5.0		)	17.6			(4.4		)	—			8.2
Cash and cash equivalents at beginning of period	5			157.7			6.8			—			169.5
Cash and cash equivalents at end of period	$	—		$	175.3		$	2.4		$	—		$	177.7
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Year Ended December 31, 2013
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash (used in) provided by operating activities1	$	(29.2	)	$	131.7		$	9.2		$	—		$	111.7
Cash flows from investing activities:
Capital expenditures	—			(66.5		)	(3.9		)	—			(70.4		)
Purchase of available for sale securities	—			(227.8		)	—			—			(227.8		)
Proceeds from disposition of available for sale securities	—			183.1			—			—			183.1
Change in restricted cash	—			0.7			1			—			1.7
Net cash used in investing activities	—			(110.5		)	(2.9		)	—			(113.4		)
Cash flows from financing activities:
Payment of capital lease liability	—			(0.1		)	—			—			(0.1		)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	—			1.1			—			—			1.1
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares	(2.5		)	—			—			—			(2.5		)
Repurchase of common stock	(78.3		)	—			—			—			(78.3		)
Cash dividend paid to stockholders	(23.0		)	—			—			—			(23.0		)
Cash dividend returned to the Company	0.6			—			—			—			0.6
Intercompany loan	132.4			(130.5		)	(1.9		)	—			—
Net cash provided by (used in) financing activities	29.2			(129.5		)	(1.9		)	—			(102.2		)
Net (decrease) increase in cash and cash equivalents during the period	—			(108.3		)	4.4			—			(103.9		)
Cash and cash equivalents at beginning of period	5			266			2.4			—			273.4
Cash and cash equivalents at end of period	$	5		$	157.7		$	6.8		$	—		$	169.5
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Year Ended December 31, 2012
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$	(17.8	)	$	164.3		$	5.9		$	—		$	152.4
Cash flows from investing activities:
Capital expenditures	—			(42.6		)	(1.5		)	—			(44.1		)
Purchase of available for sale securities	—			(85.0		)	—			—			(85.0		)
Proceeds from disposal of property, plant and equipment	—			0.3			—			—			0.3
Change in restricted cash	6.9			0.4			(0.4		)	—			6.9
Net cash provided by (used in) investing activities	6.9			(126.9		)	(1.9		)	—			(121.9		)
Cash flows from financing activities:
Proceeds from issuance of Senior Notes	225			—			—			—			225
Payment of capital lease liability	—			(0.1		)	—			—			(0.1		)
Repayment of promissory notes	—			(4.7		)	—			—			(4.7		)
Cash paid for financing costs	(6.6		)	—			—			—			(6.6		)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	—			1.3			—			—			1.3
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares	(2.2		)	—			—			—			(2.2		)
Cash dividend paid to stockholders	(19.6		)	—			—			—			(19.6		)
Intercompany loan	(185.7		)	189.1			(3.4		)	—			—
Net cash provided by (used in) financing activities	10.9			185.6			(3.4		)	—			193.1
Net increase in cash and cash equivalents during the period	—			223			0.6			—			223.6
Cash and cash equivalents at beginning of period	5			43			1.8			—			49.8
Cash and cash equivalents at end of period	$	5		$	266		$	2.4		$	—		$	273.4

Quarterly_Financial_Data_Quart

Quarterly Financial Data Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Data [Abstract]
Schedule of Quarterly Financial Information	The following tables present the unaudited financial data for each of the interim periods in 2014 and 2013.
		Quarter			Quarter			Quarter			Quarter
		Ended			Ended			Ended			Ended
		31-Mar			30-Jun			30-Sep			31-Dec
	2014
	Net sales	$	335.1		$	344.1		$	338.9		$	338
	Cost of products sold, excluding depreciation, amortization and other items	282.9			275.5			280.4			278.7
	Unrealized (gains) losses on derivative instruments	(2.0		)	(1.6		)	3.6			10.4
	Gross profit	54.2			70.2			54.9			48.9
	Operating income	32.1			46.4			32.6			26.8
	Net income	$	15.8		$	24.5		$	15.9		$	15.6
	Net income per common share, Basic	$	0.88		$	1.38		$	0.9		$	0.88
	Net income per common share, Diluted	$	0.85		$	1.33		$	0.85		$	0.85
		Quarter			Quarter			Quarter			Quarter
		Ended			Ended			Ended			Ended
		31-Mar			30-Jun			30-Sep			31-Dec
	2013
	Net sales	$	337.4		$	328.9		$	319.9		$	311.3
	Cost of products sold, excluding depreciation, amortization and other items	263.6			261.5			259.5			254.3
	Unrealized losses (gains) on derivative instruments	0.7			4.2			(1.5		)	(4.1		)
	Gross profit	73.1			63.2			61.9			61.1
	Operating income	50			40.1			41.6			41.6
	Net income	$	33.5		$	18.6		$	25.4		$	27.3
	Net income per common share, Basic	$	1.75		$	0.99		$	1.37		$	1.48
	Net income per common share, Diluted	$	1.73		$	0.98		$	1.34		$	1.44

Summary_of_Significant_Account2

Summary of Significant Accounting Policies, Textuals (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting policies additional disclosures
Advertising costs	$0.60	$1.30	$0.40
Research and development costs	8.9	7.8	6.4
Excess of current cost over the stated LIFO value of inventory	37.6	0.4
Impairment of the carrying value of goodwill	0	0
Discount rate used in estimating liabilities for worker compensation claims	1.75%	1.75%
Undiscounted workers' compensation liabilities	25.9	29.1
Margin deposits with counterparties	0	0
Margin deposits from counterparties	$0	$0
Percentage of Employees Covered by Collective Bargaining Agreements	63.00%
Percentage of Employees Covered by Collective Bargaining Agreements Expiring Within One Year	47.00%
Percentage of Employees Covered by Collective Bargaining Agreements Extended Beyond One Year	36.00%
Minimum
Accounting policies additional disclosures
Period over which accounts receivable is due, days	30 days
Number of days in maturity for debt investment securities to be classified as short-term investments	90 days
Maximum
Accounting policies additional disclosures
Number of days to maturity for debt investment securities to be classified as cash and cash equivalents	90 days
Period over which accounts receivable is due, days	60 days

Summary_of_Significant_Account3

Summary of Significant Accounting Policies, Textuals, Property, Plant and Equipment (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment
Interest expense capitalized as construction in progress	$2.50	$3.40	$1.70
Depreciation expense	29.5	26.4	24.7
Asset impairment charge	1.5	0	4.4
Fabricated Products
Property, Plant and Equipment
Depreciation expense	29	25.8	24.2
Asset impairment charge	1.5		4.4
Fabricated Products | Idled equipment
Property, Plant and Equipment
Asset impairment charge		$0
Minimum | Land improvements
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	3 years
Minimum | Buildings and leasehold improvements
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	15 years
Minimum | Machinery and equipment
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	1 year
Minimum | Capital lease assets
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	3 years
Maximum | Land improvements
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	25 years
Maximum | Buildings and leasehold improvements
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	45 years
Maximum | Machinery and equipment
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	24 years
Maximum | Capital lease assets
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	5 years

Supplemental_Balance_Sheet_Inf2

Supplemental Balance Sheet Information (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
In Millions, unless otherwise specified
Cash and Cash Equivalents
Total	$177.70	$169.50	$273.40	$49.80	$49.80
Trade Receivables - Net
Billed trade receivables	128.7	120.2
Unbilled trade receivables — Note 1	1.4	0.4
Trade receivables, gross	130.1	120.6
Allowance for doubtful receivables	-0.8	-0.8
Trade receivables - net	129.3	119.8
Inventories
Finished products	73.6	72.5
Work-in-process	66.7	75.9
Raw materials	54.2	47.2
Operating supplies and repair and maintenance parts	20.2	18.8
Total	214.7	214.4
Prepaid Expenses and Other Current Assets
Current derivative assets — Notes 10 and 11	85.7	2
Current deferred tax assets	86.4	36.7
Short-term restricted cash	0.3	0.3
Other	6.2	5.2
Total	178.6	44.2
Property, Plant and Equipment - Net
Land and improvements	22.9	22.6
Buildings and leasehold improvements	63.8	53
Machinery and equipment	509.8	425.6
Construction in progress	25.2	66
Property, plant and equipment - gross	621.7	567.2
Accumulated depreciation	-166.8	-137.9
Property, plant and equipment - net	454.9	429.3
Other Assets
Derivative assets — Notes 10 and 11	0	79.8
Restricted cash	10	9.3
Deferred financing costs	5.9	8.9
Deferred compensation plan assets	7.3	6.5
Other	0.1	0.3
Total	23.3	104.8
Other Accrued Liabilities
Current derivative liabilities — Notes 10 and 11	94.9	1.8
Uncleared cash disbursements	9.1	9.6
Accrued income taxes and taxes payable	5.2	4.3
Accrued annual VEBA contribution	13.7	16
Short-term environmental accrual — Note 9	2.3	2.8
Accrued interest	3.7	3.7
Short-term deferred revenue — Note 1	0.2	0
Other	3.7	6.6
Total	132.8	44.8
Long-Term Liabilities
Derivative liabilities — Notes 10 and 11	1.9	84.3
Income tax liabilities	2.4	5
Workers’ compensation accruals	21.5	23.3
Long-term environmental accrual — Note 9	17	20
Long-term asset retirement obligations	4.4	4
Long-term deferred revenue - Note 1	0.5	0
Deferred compensation liability	7.2	7
Long-term capital leases	0.1	0.1
Other long-term liabilities	3.3	2.7
Total	58.3	146.4
Long-Term Debt — Note 3
Senior notes	225	225
Cash convertible senior notes	0	163.5
Total	225	388.5
Fair Value, Measurements, Recurring [Member]
Other Assets
Deferred compensation plan assets	7.3	6.5
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Cash and Cash Equivalents
Cash and money market funds	29.5	57.7
Other Assets
Deferred compensation plan assets	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Cash and Cash Equivalents
Commercial paper	148.2	111.8
Other Assets
Deferred compensation plan assets	$7.30	$6.50

LongTerm_Debt_and_Credit_Facil2

Long-Term Debt and Credit Facility, Textuals (Details) (USD $)	12 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 29, 2010	Mar. 30, 2010	23-May-12
Debt Instruments
Principal amount of notes	$225,000,000	$225,000,000
Effective interest rate	8.60%
Consolidated Total Indebtedness to EBITDA Ratio	2.00:1.00
Conversion price of note	$47.80
Payment of quarterly cash dividends	$1.40	$1.20	$1
Line of Credit Facility [Abstract]
Maximum borrowing capacity	300,000,000
Percentage of eligible accounts receivable for borrowing base	85.00%
Percentage of eligible inventory for borrowing base	65.00%
Percentage of net orderly liquidation value of eligible inventory	85.00%
Percent of eligible machinery and equipment for borrowing base	85.00%
Available borrowing capacity	276,700,000
Remaining available borrowing capacity	269,100,000
Interest on line of credit	4.00%
Minimum Amount of Available Borrowing to Maintain	52,500,000
Fixed Charge Coverage Ratio	1.1:1.0
Convertible Notes
Debt Instruments
Principal amount of notes				175,000,000
Interest rate				4.50%
Effective interest rate	11.00%
Conversion rate of common stock shares per $1,000 of principal amount	20.9186
Principal amount in conversion feature	1,000
Call Options
Debt Instruments
Exercise price of call options	$47.80
Warrant Transactions
Debt Instruments
Common stock sold related to option counterparties net share-settled warrants	3.7	3.6			3.7
Exercise price per share of Warrants	$60.70	$61.08
Senior Notes
Debt Instruments
Principal amount of notes						225,000,000
Interest rate						8.25%
Debt issuance, percentage of principal amount						100.00%
Interest expense	19,400,000	19,400,000	11,800,000
Line of Credit
Line of Credit Facility [Abstract]
Outstanding line of credit	0
Letter of Credit
Line of Credit Facility [Abstract]
Maximum borrowing capacity	60,000,000
Outstanding line of credit	-7,600,000
Maximum Credit Line Extension [Domain]
Line of Credit Facility [Abstract]
Maximum borrowing capacity	350,000,000
Minimum
Debt Instruments
Payment of quarterly cash dividends	$0.24
Line of Credit Facility [Abstract]
Available borrowing capacity	$30,000,000
On or after June 1, 2016 | Senior Notes
Debt Instruments
Redemption price percentage of principal amount	104.13%
On or after June 1, 2018 | Senior Notes
Debt Instruments
Redemption price percentage of principal amount	100.00%
Prior to June 1, 2015 | Senior Notes
Debt Instruments
Redemption price percentage of principal amount	108.25%
Percentage of original principal amount that may be redeemed	35.00%
On or after June 1, 2015 but prior to June 1, 2016 | Senior Notes
Debt Instruments
Redemption price percentage of principal amount	100.00%
Change in control | Senior Notes
Debt Instruments
Redemption price percentage of principal amount	101.00%

LongTerm_Debt_and_Credit_Facil3

Long-Term Debt and Credit Facility, Carrying Amount Table (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Principal amount, carrying amount and interest expense of notes
Principal amount	$225		$225
Carrying amount, net of discount	0		163.5
Convertible Notes
Principal amount, carrying amount and interest expense of notes
Principal amount	175		175
Less: unamortized issuance discount	-2.5		-11.5
Carrying amount, net of discount	172.5		163.5
Contractual coupon interest	7.9		7.9		7.9
Amortization of discount	9.1		8.2		7.3
Amortization of deferred financing costs	1.1		1.2		1.2
Total interest expense	$18.10	[1]	$17.30	[1]	$16.40	[1]
[1]	A portion of the interest relating to the Convertible Notes was capitalized as Construction in progress.

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets, Goodwill (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Goodwill
Goodwill and intangible asset impairment	$0
Goodwill	37.2	37.2
Fabricated Products
Goodwill
Goodwill	$37.20

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets, Identifiable Intangible Table (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Identifiable intangible assets
Net book value	$32.10	$33.70
Customer relationships
Identifiable intangible assets
Original cost	38.5	38.5
Accumulated amortization	-6.4	-4.8
Net book value	$32.10	$33.70

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets, Intangible Assets (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense related to definite-lived intangible assets	$1.60	$1.70	$1.80
Expected amortization of intangible assets for the next five years
Expected amortization of intangible assets for the next year	1.6
2016	1.6
2017	1.6
2018	1.6
2019	1.6
Expected amortization of intangible assets, year six and thereafter	$24.10

Income_Tax_Matters_Income_Befo

Income Tax Matters, Income Before Income Taxes and Tax Provision Table (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income before income taxes by geographic area
Domestic	$102.10	$138.90	$134.50
Foreign	5	4.3	5.1
Income before income taxes	107.1	143.2	139.6
Federal income tax (expense) benefit
Current federal tax (expense) benefit	-1	1.1	0
Deferred federal income tax (expense) benefit	6.4	-49.7	-113
Federal benefit (expense) applied to increase (decrease) Additional capital/Other comprehensive income	-41.6	1.3	67.4
Federal income tax (expense) benefit	-36.2	-47.3	-45.6
Foreign income tax (expense) benefit
Current foreign tax (expense) benefit	1	16.2	-2.3
Deferred foreign income tax (expense) benefit	0.3	-0.5	-0.2
Foreign benefit (expense) applied to increase (decrease) Additional capital/Other comprehensive income	-0.5	-0.1	0.2
Foreign income tax (expense) benefit	0.8	15.6	-2.3
State income tax (expense) benefit
Current state tax (expense) benefit	-0.6	-0.2	0.2
Deferred state income tax (expense) benefit	5.1	-6.7	-15.3
State benefit (expense) applied to increase (decrease) additional capital/Other comprehensive income	-4.4	0.2	9.2
State income tax (expense) benefit	0.1	-6.7	-5.9
Total income tax (expense) benefit
Current income tax (expense) benefit	-0.6	17.1	-2.1
Deferred income tax (expense) benefit	11.8	-56.9	-128.5
Benefit (expense) applied to increase (decrease) Additional capital/Other comprehensive income	-46.5	1.4	76.8
Income tax provision	($35.30)	($38.40)	($53.80)

Income_Tax_Matters_Effective_T

Income Tax Matters, Effective Tax Rate Reconciliation (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Reconciliation between income tax provision and statutory income tax provision:
Amount of federal income tax provision based on the statutory rate	($37.50)		($50.10)		($48.90)
Decrease in federal valuation allowances	0		0.1		0.1
Non-deductible compensation expense	-0.1		-0.3		-0.4
Non-deductible expense	-0.3		-0.9		-0.3
State income taxes, net of federal benefit	0	[1]	-4.4	[1]	-3.8	[1]
Decrease in state tax rates	1.6
Foreign income tax (expense) benefit	0.3		0		-0.5
Expiration of statute of limitations	2.3		4.6		0
Settlement with taxing authorities	0		4.4		0
Advance pricing agreement	0		2.9		0
Competent Authority settlement	0		5.3		0
Income tax provision	-35.3		-38.4		-53.8
Valuation Allowance
Current State and Local Tax Expense (Benefit)	2.3	[1]
Deferred Tax Assets, Net of Valuation Allowance, Current	86.4		36.7
Increase (Decrease) in valuation allowance	0.7		-1.2		0.1
Unused state net operating losses
Valuation Allowance
Increase (Decrease) in valuation allowance			($1.20)
[1]	State income taxes were $2.3 in 2014, but were offset by a $1.6 decrease due to lower tax rates in various states and a $0.7 decrease in the valuation allowance relating to certain state net operating losses. State income taxes of $4.4 in 2013 included a $1.2 increase in the valuation allowance relating to certain unused state net operating losses expected to expire.

Income_Tax_Matters_Components_

Income Tax Matters, Components of Deferred Tax Assets and Liabilities (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Deferred income tax assets:
Loss and credit carryforwards	$275.40		$321.80
VEBAs (see Note 6)	5.1		6.1
Other assets	35		34.4
Inventories and other	21.5		2.5
Valuation allowances	-19.2		-19.9
Total deferred income tax assets	317.8		344.9
Deferred income tax liabilities:
Property, plant and equipment	-74.1		-73
VEBAs (see Note 6)	-120.6		-152.4
Inventories	-6.7		-14.9
Total deferred income tax liabilities	-201.4		-240.3
Net deferred income tax assets	116.4	[1]	104.6	[1]
Net deferred income tax assets, current			36.7
Net deferred income tax assets, long term	30.9		69.1
Deferred tax liability, long term	($0.90)		($1.20)
[1]	Of the total net deferred income tax assets of $116.4, $86.4 was included in Prepaid expenses and other current assets, $30.9 was presented as Deferred tax assets, net and $0.9 was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2014. Of the total net deferred income tax assets of $104.6, $36.7 was included in Prepaid expenses and other current assets and $69.1 was presented as Deferred tax assets, net and $1.2 was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2013.

Income_Tax_Matters_NOL_Details

Income Tax Matters, NOL (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$606.10
NOL carryforwards related to the excess tax benefits from vesting of employee restricted stock	1.7
AMT credit carryforwards	30.1
Increase (Decrease) in valuation allowance	($0.70)	$1.20	($0.10)

Income_Tax_Matters_Tax_Uncerta

Income Tax Matters, Tax Uncertainties (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Other, settlements from tax audit
Cash tax benefit from settlement of tax audit	$7.90
Cash received from settlement of tax audit	1.8	6.1
Cash tax benefit from advance pricing agreement	0	2.9		0
Reconciliation of changes in the gross unrecognized tax benefits:
Gross unrecognized tax benefits at beginning of period	3.8	15.7		13.7
Gross increases for tax positions of prior years	0	0		1.3
Gross decreases for tax positions of prior years	0	-7.6		-0.1
Gross increases for tax positions of current years	0	0		0.4
Gross decrease for tax positions relating to lapse of a statute of limitation	-1.4	-3.3		0
Foreign currency translation	-0.2	-1		0.4
Gross unrecognized tax benefits at end of period	2.2	3.8		15.7
Unrecognized tax benefits that would impact effective tax rate if recognized	1.1	2.7
Unrecognized tax benefits, income tax penalties and interest accrued:
Accrued interest and penalties on unrecognized tax benefits	1.4	2.3
Accrued interest and penalties on unrecognized tax benefits, current	0
(Decrease) increase in interest and penalty	-0.9	-5.2		0.9
Foreign currency impact on gross unrecognized tax benefit (including interest and penalties) which increased (decreased) Other comprehensive income (loss)	0.4	0.2	[1]	-0.2
FIN 48
Unrecognized tax benefits, income tax penalties and interest accrued:
Foreign currency impact on gross unrecognized tax benefit (including interest and penalties) which increased (decreased) Other comprehensive income (loss)	0.3	0.7		-0.5
Canada Revenue Agency
Other, settlements from tax audit
Cash tax benefit from advance pricing agreement		$2.60
[1]	The presentation of other comprehensive income 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. The 2013 balances were adjusted to reflect this reclassification. The impacts to the prospective amortization of Prior service cost and Accumulated net actuarial (losses) gains were not material.

Employee_Benefits_Defined_Cont

Employee Benefits, Defined Contribution Plans (Details) (Defined Contribution Plan, USD $)	12 Months Ended
	Dec. 31, 2014
	productionfacilities
Hourly bargaining unit employees
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Number of production facilities	7
Hourly bargaining unit employees | Fixed rate contributions
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Number of production facilities	3
Hourly bargaining unit employees | Concurrent match
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Number of production facilities	1
Hourly bargaining unit employees | Fixed rate and concurrent match
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Number of production facilities	2
Hourly bargaining unit employees | No contributions required
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Number of production facilities	1
Salaried and certain hourly employee | Concurrent match
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan employer concurrent match percentage	4.00%
Hired on or after January 1, 2004 | Hourly bargaining unit employees | Fixed rate contributions
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan annual employer contribution percentage	2.00%
Hired on or after January 1, 2004 | Salaried and certain hourly employee | Fixed rate contributions
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan annual employer contribution percentage	2.00%
Minimum | Hourly bargaining unit employees
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Estimated annual contribution to pension and other postretirement benefit plans	1,000,000
Minimum | Hourly bargaining unit employees | Fixed rate contributions
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan annual employer contribution	800
Minimum | Salaried and certain hourly employee
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Estimated annual contribution to pension and other postretirement benefit plans	5,000,000
Minimum | Hired prior to January 1, 2004 | Hourly bargaining unit employees | Fixed rate contributions
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan annual employer contribution percentage	2.00%
Minimum | Hired prior to January 1, 2004 | Salaried and certain hourly employee | Fixed rate contributions
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan annual employer contribution percentage	2.00%
Maximum | Hourly bargaining unit employees
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Estimated annual contribution to pension and other postretirement benefit plans	3,000,000
Maximum | Hourly bargaining unit employees | Fixed rate contributions
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan annual employer contribution	2,400
Maximum | Salaried and certain hourly employee
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Estimated annual contribution to pension and other postretirement benefit plans	7,000,000
Maximum | Hired prior to January 1, 2004 | Hourly bargaining unit employees | Fixed rate contributions
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan annual employer contribution percentage	10.00%
Maximum | Hired prior to January 1, 2004 | Salaried and certain hourly employee | Fixed rate contributions
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan annual employer contribution percentage	10.00%

Employee_Benefits_Defined_Bene

Employee Benefits, Defined Benefit Plans (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Postretirement Medical Obligations
Accrued annual VEBA contribution	$13.70		$16
Benefit Obligations and Funded Status Additional Disclosure
Net asset In respect of VEBAs	340.1		406
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		-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
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		6.6		7
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		-6.6		-7
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
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	[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	[1],[5]
Benefit Obligations and Funded Status Additional Disclosure
Actuarial gain due to a decrease in discount rate	-45		-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	[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
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
VEBAs | Maximum
Postretirement Medical Obligations
Variable cash contribution obligation to VEBAs	20
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		2.5
Effect of one-percentage-point decrease on service and interest cost components	2		1.5		2
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		54.9
Actuarial gain due to higher than expected mortality rate			-8
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
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
Obligation at end of year	79.4		62
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
Net Funded Status
Accumulated plan benefit obligation	-79.4		-62
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
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	[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	[1],[5]
Net Funded Status
Accumulated plan benefit obligation			-374.7	[1]
Plan assets			780.7	[1]
Net funded status			406	[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.

Employee_Benefits_Net_Periodic

Employee Benefits, Net Periodic Benefit Costs and Charges Relating To Other Benefit Plans(Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Net Periodic Benefit Costs and Charges Relating to Other Benefit Plans
Non-cash net periodic benefit income	($23.50)		($22)		($11.50)
Total	-14.4		-12.9		-3
Fabricated Products
Net Periodic Benefit Costs and Charges Relating to Other Benefit Plans
Deferred compensation plan	0.2		0.3		0.2
Defined contribution plans	7.3		7.2		6.8
Total	7.8	[1]	8	[1]	7.4	[1]
All Other
Net Periodic Benefit Costs and Charges Relating to Other Benefit Plans
Deferred compensation plan	0.7		0.9		0.8
Defined contribution plans	0.8		0.7		0.7
Total	-22.2		-20.9		-10.4
Canadian pension plan | Fabricated Products
Net Periodic Benefit Costs and Charges Relating to Other Benefit Plans
Non-cash net periodic benefit income	0.3		0.5		0.4
VEBAs | All Other
Net Periodic Benefit Costs and Charges Relating to Other Benefit Plans
Non-cash net periodic benefit income	($23.70)	[2]	($22.50)	[2]	($11.90)	[2]
[1]	Substantially all of the Fabricated Products segment’s employee benefits related charges are in Cost of products sold, excluding depreciation and amortization and other items with the remaining balance in Selling, administrative, research and development and general.
[2]	Included within the Statements of Consolidated Income as Net periodic pension benefit income relating to VEBAs.

Multiemployer_Pension_Plans_De

Multiemployer Pension Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Multiemployer Pension Plan Disclosure
Percentage of employees participating in multiemployer pension plans to total employees	55.00%
Contributions of the Company	$4,000,000		$3,800,000		$3,900,000
Company's contributions to the multiemployer plans is less than			5.00%
USW Plan
Multiemployer Pension Plan Disclosure
Employer Identification Number	236648508
Pension Protection Act Zone Status			Green	[1]	Green	[1]
FIP/RP Status Pending/Implemented in 2013	No	[2]
Contributions of the Company	3,100,000	[3]	2,900,000	[3]	3,000,000	[3]
Surcharge Imposed in 2014	No
Expiration Date of Collective-Bargaining Agreement, First	30-Sep-15
Expiration Date of Collective-Bargaining Agreement, Last	30-Nov-17
Number of collective-bargaining agreements	3
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities
Multiemployer Pension Plan Disclosure
Percentage of employees covered by bargaining agreement	86.00%
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities | Starting July 2010 Until July 2015
Multiemployer Pension Plan Disclosure
Monthly contributions per hour worked by each bargaining unit employee	1.25
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities | Starting July 2015
Multiemployer Pension Plan Disclosure
Monthly contributions per hour worked by each bargaining unit employee	1.5
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities | Ending in July Two Thousand Nineteen [Member] [Domain]
Multiemployer Pension Plan Disclosure
Monthly contributions per hour worked by each bargaining unit employee	1.75
USW Plan | Richmond (Bellwood), Virginia Facility
Multiemployer Pension Plan Disclosure
Percentage of employees covered by bargaining agreement	9.00%
USW Plan | Florence, Alabama Facility
Multiemployer Pension Plan Disclosure
Percentage of employees covered by bargaining agreement	5.00%
Other Funds
Multiemployer Pension Plan Disclosure
Contributions of the Company	900,000	[4]	900,000	[4]	900,000	[4]
Multiemployer Pension Plans | Minimum
Multiemployer Pension Plan Disclosure
Estimated annual contribution to pension and other postretirement benefit plans	3,000,000
Multiemployer Pension Plans | Maximum
Multiemployer Pension Plan Disclosure
Estimated annual contribution to pension and other postretirement benefit plans	$5,000,000
[1]	The most recent Pension Protection Act zone status available in 2014 and 2013 for the Steelworkers Pension Trust is for the plan's year-end at December 31, 2013 and December 31, 2012, respectively. The zone status is based on information that the Company received from the plan and is certified by the plan's actuary. Among other factors, plans in the green zone are at least 80 percent funded.
[2]	The “FIP/RP Status Pending/Implemented” column indicates if a Financial Improvement Plan (FIP) or a Rehabilitation Plan (RP) is either pending or has been implemented for the plan under the Pension Protection Act.
[3]	The Company is party to three USW collective-bargaining agreements that require contributions to the Steelworkers Pension Trust. As of December 31, 2014, USW collective bargaining agreements covering employees at the Newark, Ohio ("Newark") and Spokane, Washington ("Trentwood") facilities covers 86% of the Company's USW-represented employees and expires in September 2015. In January 2015, the Company and the USW entered into a new five-year labor agreement relating to these facilities, effective October 1, 2015 through September 30, 2020. The Company's monthly contributions per hour worked by each bargaining unit employee at the Newark and Trentwood facilities are (in whole dollars) $1.25 and will increase to (in whole dollars) $1.50 in July 2015 and $1.75 in 2019. The union contracts covering employees at the Richmond (Bellwood), Virginia facility and Florence, Alabama facility cover 9% and 5% of the Company's USW-represented employees, respectively, and expire in November 2017 and March 2017, respectively.
[4]	Other Funds consists of plans that are not individually significant.

Employee_Incentive_Plans_Short

Employee Incentive Plans, Short Term Incentive Plans (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
EVA measurement period	1 year
Compensation charges associated with STI Plans
Costs recorded in connection with STI plans	$12.70	$15.70	$14.40
Fabricated Products
Compensation charges associated with STI Plans
Costs recorded in connection with STI plans	9.6	11.2	9.9
All Other
Compensation charges associated with STI Plans
Costs recorded in connection with STI plans	3.1	4.5	4.5
Cost of products sold, excluding depreciation and amortization and other items
Compensation charges associated with STI Plans
Costs recorded in connection with STI plans	4.7	4.6	4.3
Selling, administrative, research and development and general
Compensation charges associated with STI Plans
Costs recorded in connection with STI plans	$8	$11.10	$10.10

Employee_Incentive_Plans_Long_

Employee Incentive Plans, Long term Incentive Plans (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award
Number of common shares authorized for issuance under Equity Incentive Plan	2,722,222
Number of common shares available for additional awards under Equity Incentive Plan	776,549
Non-employee directors time to vest in long-term incentive plan	1 year
Time for executives and other employees to vest in long-term incentive plan	3 years
Non-cash compensation expense	$6.80		$6.60	$5.60
Recognized tax benefit relating to non-cash compensation expense	2.5		2.4	2.1
Summary of Activity
Total grant-date fair value for shares granted	14.8		14.8	13.9
Total grant-date fair value for shares that vested	5.5		5.1	3.5
Stock Options
Fully-vested options outstanding	16,645		20,791
Exercise price of options to purchase common stock	$80.01		$80.01
Remaining contractual life of options outstanding	2 years 3 months		3 years 3 months
Grant date fair value of options outstanding	$39.90
Stock options granted	0		0
Stock options forfeited	4,146		0
Stock options expired			0
Stock options exercised	0		0
Vested Stock
Common shares granted to non-employee directors	0.2		0.2	0.2
Common shares withheld and canceled	33,696		40,075	45,801
Fabricated Products
Share-based Compensation Arrangement by Share-based Payment Award
Non-cash compensation expense	3.2		2.2	1.7
All Other
Share-based Compensation Arrangement by Share-based Payment Award
Non-cash compensation expense	3.6		4.4	3.9
Non-vested common shares
Summary of Activity
Outstanding Beginning Balance, Shares/Units	143,967
Outstanding Beginning Balance, Weighted-Average Grant-Date Fair Value per Share	$51.09
Granted, shares/units	119,799	[1]
Granted, Weighted-Average Grant-Date Fair Value per Share	$66.42	[1]
Vested, shares/units	-64,493
Vested, Weighted-Average Grant-Date Fair Value per Share	$52.20
Forfeited, shares/units	-40,503	[1]
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$60.21	[1]
Outstanding Ending Balance, Shares/Units	158,770
Outstanding Ending Balance, Weighted-Average Grant-Date Fair Value per Share	$59.88
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award
Number of common share received by the employee on vesting of restricted stock unit	1
Summary of Activity
Outstanding Beginning Balance, Shares/Units	5,472
Outstanding Beginning Balance, Weighted-Average Grant-Date Fair Value per Share	$51.03
Granted, shares/units	2,235	[1]
Granted, Weighted-Average Grant-Date Fair Value per Share	$67.42	[1]
Vested, shares/units	-2,350
Vested, Weighted-Average Grant-Date Fair Value per Share	$46.83
Forfeited, shares/units	0	[1]
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$0	[1]
Outstanding Ending Balance, Shares/Units	5,357
Outstanding Ending Balance, Weighted-Average Grant-Date Fair Value per Share	$59.71
Service-based non-vested common shares and restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award
Non-cash compensation expense	3.9		4.3	3.8
Unrecognized gross compensation costs	5.6
Expected period (in years) over which the remaining gross compensation costs will be recognized	2 years 2 months 28 days
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award
Non-cash compensation expense	1		2.3	1.8
Unrecognized gross compensation costs	1.6
Expected period (in years) over which the remaining gross compensation costs will be recognized	1 year 0 months 1 day
Summary of Activity
Outstanding Beginning Balance, Shares/Units	562,554
Outstanding Beginning Balance, Weighted-Average Grant-Date Fair Value per Share	$49.26
Granted, shares/units	0	[1]
Granted, Weighted-Average Grant-Date Fair Value per Share	$0	[1]
Vested, shares/units	-42,545
Vested, Weighted-Average Grant-Date Fair Value per Share	$47.21
Forfeited, shares/units	-28,613	[1]
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$51.44	[1]
Canceled, shares/units	-137,820	[2]
Canceled, Weighted-Average Grant-Date Fair Value per Share	$46.65	[2]
Outstanding Ending Balance, Shares/Units	353,576		562,554
Outstanding Ending Balance, Weighted-Average Grant-Date Fair Value per Share	$50.35		$49.26
Market-based shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Non-cash compensation expense	1.9		0	0
Unrecognized gross compensation costs	$4.40
Expected period (in years) over which the remaining gross compensation costs will be recognized	2 years 1 month 14 days
Summary of Activity
Outstanding Beginning Balance, Shares/Units	0
Outstanding Beginning Balance, Weighted-Average Grant-Date Fair Value per Share	$0
Granted, shares/units	160,868	[1]
Granted, Weighted-Average Grant-Date Fair Value per Share	$83.18	[1]
Vested, shares/units	0
Vested, Weighted-Average Grant-Date Fair Value per Share	$0
Forfeited, shares/units	-10,645	[1]
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$83.18	[1]
Outstanding Ending Balance, Shares/Units	150,223		0
Outstanding Ending Balance, Weighted-Average Grant-Date Fair Value per Share	$83.18		$0
Minimum | Performance shares
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	0.00%
Minimum | Market-based shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	0.00%
Maximum | Performance shares
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	200.00%
Maximum | Market-based shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	200.00%
[1]	For EVA-Based Performance Shares and TSR-Based Performance Shares, the number of shares granted and forfeited are presented at their maximum payout.
[2]	For EVA-Based Performance Shares and TSR-Based Performance Shares, canceled represents the number of shares that did not vest due to EVA or TSR performance results falling below those required for maximum payout.

Commitments_and_Contingencies_1

Commitments and Contingencies, Commitments (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Minimum rental commitments
Rental expense	$7.40	$7.50	$10
Minimum rental commitments, 2015	4.7
Minimum rental commitments, 2016	3.9
Minimum rental commitments, 2017	3.2
Minimum rental commitments, 2018	2.8
Minimum rental commitments, 2019	2.7
Minimum rental commitments, 2020 and thereafter	27.6
Purchase obligations
2015 Metal Purchase Commitments	283.7
Purchase Obligation, 2015	294.6
Purchase Obligation, 2016	8.9
Purchase Obligation, 2017	2.9
Purchase Obligation, 2018	1
Purchase Obligation, 2019	0.5
Purchase Obligation, 2020 and thereafter	$1.40

Commitments_and_Contingencies_2

Commitments and Contingencies, Environmental Contingencies (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accrual for Environmental Loss Contingencies, Gross, Fiscal Year Maturity
Environmental accrual	$19.30	$22.80	$21.70
Expected period related to remediation expenditures for environmental contingencies	30 years
Estimated environmental contingency loss exposure in excess of current accrual	25.1
Time period within which Company's recorded estimate of its obligation may change	12 months
Accrual for Environmental Loss Contingencies
Beginning balance	22.8	21.7	22
Additional accruals	0.8	4.5	1.2
Less expenditures	-4.3	-3.4	-1.5
Ending balance	$19.30	$22.80	$21.70
Minimum
Accrual for Environmental Loss Contingencies, Gross, Fiscal Year Maturity
Period for feasibility study completion	18 months
Maximum
Accrual for Environmental Loss Contingencies, Gross, Fiscal Year Maturity
Period for feasibility study completion	24 months

Derivative_Financial_Instrumen2

Derivative Financial Instruments and Related Hedging Programs, Hedging Discussion (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Mar. 29, 2010
In Millions, unless otherwise specified
Derivative Financial Instruments and Related Hedging Programs (Textuals) [Abstract]
Aggregate fair value of derivative instruments in a net liability position	($11.40)
Principal amount of notes	225	225
Convertible Notes
Derivative Financial Instruments and Related Hedging Programs (Textuals) [Abstract]
Principal amount of notes			$175

Derivative_Financial_Instrumen3

Derivative Financial Instruments and Related Hedging Programs, Realized and Unrealized Gains and Losses Table (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary Of Realized And Unrealized Gains Losses
Unrealized gains (losses)	($6.80)	$3.90	$16
Not Designated as Hedging Instrument
Summary Of Realized And Unrealized Gains Losses
Realized (losses) gains	7.8	-6.5	-19.1
Unrealized gains (losses)	-6.8	3.9	16
Not Designated as Hedging Instrument | Aluminum
Summary Of Realized And Unrealized Gains Losses
Realized (losses) gains	6.9	-5.5	-9
Unrealized gains (losses)	-2.6	-3.1	10.1
Not Designated as Hedging Instrument | Natural Gas
Summary Of Realized And Unrealized Gains Losses
Realized (losses) gains	1	-1.8	-6.7
Unrealized gains (losses)	-6	2.6	4.3
Not Designated as Hedging Instrument | Electricity
Summary Of Realized And Unrealized Gains Losses
Realized (losses) gains	-0.1	0.8	-3.4
Unrealized gains (losses)	-1.8	1.1	0.8
Not Designated as Hedging Instrument | Foreign Currency
Summary Of Realized And Unrealized Gains Losses
Unrealized gains (losses)	0	0.1	0
Not Designated as Hedging Instrument | Operational Risk Hedges [Member]
Summary Of Realized And Unrealized Gains Losses
Unrealized gains (losses)	-10.4	0.7	15.2
Not Designated as Hedging Instrument | Option Assets relating to the Convertible Notes | Hedges Relating to the Convertible Notes
Summary Of Realized And Unrealized Gains Losses
Unrealized gains (losses)	5.2	24.2	9
Not Designated as Hedging Instrument | Bifurcated Conversion Feature of the Convertible Notes | Hedges Relating to the Convertible Notes
Summary Of Realized And Unrealized Gains Losses
Unrealized gains (losses)	($1.60)	($21)	($8.20)

Derivative_Financial_Instrumen4

Derivative Financial Instruments and Related Hedging Programs, Notional Quantity Table (Details)	Dec. 31, 2014
2014
Summary of material derivative positions
Percentage of natural gas purchases for which the Company's exposure to fluctuations in gas prices have been reduced	81.00%
Percentage of Electricity Purchases For Which Company Exposure To Fluctuations In Electricity Prices Have Been Reduced	44.00%
2015
Summary of material derivative positions
Percentage of natural gas purchases for which the Company's exposure to fluctuations in gas prices have been reduced	73.00%
2016
Summary of material derivative positions
Percentage of natural gas purchases for which the Company's exposure to fluctuations in gas prices have been reduced	12.00%
Not Designated as Hedging Instrument | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature
Summary of material derivative positions
Notional Amount of Contracts	3,660,738	[1]
Not Designated as Hedging Instrument | Hedges Relating to the Convertible Notes | Call Options
Summary of material derivative positions
Notional Amount of Contracts	3,660,738	[2]
Purchase | Not Designated as Hedging Instrument | Aluminum | Fixed priced contracts
Summary of material derivative positions
Notional Amount of Contracts	67.3
Purchase | Not Designated as Hedging Instrument | Aluminum | Midwest premium swap contracts
Summary of material derivative positions
Notional Amount of Contracts	67.1	[3]
Purchase | Not Designated as Hedging Instrument | Natural Gas | Fixed priced contracts
Summary of material derivative positions
Notional Amount of Contracts	6,720,000	[4]
Purchase | Not Designated as Hedging Instrument | Electricity | Fixed priced contracts
Summary of material derivative positions
Notional Amount of Contracts	175,200	[5]
[1]	Such amounts include the fair value of the Bifurcated Conversion Feature and Option Assets at December 31, 2013 (see Note 11).
[2]	Such amounts include the fair value of the Bifurcated Conversion Feature and Option Assets at December 31, 2014 (see Note 11).
[3]	Regional premiums represent the premium over the London Metal Exchange price for primary aluminum which is incurred on the Company's purchases of primary aluminum.
[4]	As of December 31, 2014, the Company had Henry Hub NYMEX-based hedge positions in place to cover exposure to fluctuations in prices for approximately 81%, 73% and 12% of the expected natural gas purchases for 2015, 2016 and 2017, respectively.
[5]	As of December 31, 2014, the Company had Mid-C International Commodity Exchange-based hedge positions in place to cover exposure to fluctuations in prices for approximately 44% of the expected electricity purchases for 2015

Derivative_Financial_Instrumen5

Derivative Financial Instruments and Related Hedging Programs, Offsetting of Derivative Instruments by Counterparty (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Assets	$85.70		$81.80
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	85.7		81.8
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0.8		1.2
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	0		0
Net Amount	84.9		80.6
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Liabilities	-96.8		-86.1
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	-96.8		-86.1
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	-0.8		-1.2
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Net Amount	-96		-84.9
Counterparty (with Netting Agreements)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Assets	0.9		1
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	0.9		1
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0.8		0.8
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	0		0
Net Amount	0.1		0.2
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Liabilities	-8		-1.6
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	-8		-1.6
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	-0.8		-0.8
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Net Amount	-7.2		-0.8
Counterparty (without Netting Agreements)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Assets	84.8	[1]	80.4	[1]
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	84.8	[1]	80.4	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0		0
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	0		0
Net Amount	84.8	[2]	80.4	[1]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Liabilities	-85	[1]	-83.2	[1]
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	-85	[1]	-83.2	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0		0
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Net Amount	-85	[2]	-83.2	[1]
Counterparty (with partial Netting Agreements)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Assets			0.4
Gross Amounts Offset in the Consolidated Balance Sheets			0
Net Amounts of Assets Presented in the Consolidated Balance Sheets			0.4
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments			0.4
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received			0
Net Amount			0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Liabilities	-3.8		-1.3
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	-3.8		-1.3
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0		-0.4
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Net Amount	($3.80)		($0.90)
[1]	Such amounts include the fair value of the Bifurcated Conversion Feature and Option Assets at December 31, 2013 (see Note 11).
[2]	Such amounts include the fair value of the Bifurcated Conversion Feature and Option Assets at December 31, 2014 (see Note 11).

Fair_Value_Measurements_Fair_V

Fair Value Measurements, Fair Value Hierarchy Table (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Financial Assets:
Derivative Asset	$85.70		$81.80
Deferred compensation plan assets	7.3		6.5
Investment Percentage in Industrial Sector	51.00%		56.00%
Investment Percentage in Financial Sector	37.00%		35.00%
Investment Percentage in Utilities Sector	12.00%		9.00%
Financial Liabilities:
Derivative Liabilities	-96.8		-86.1
Fair Value, Measurements, Recurring [Member]
Financial Assets:
Cash and cash equivalents	177.7	[1]	169.5	[1]
Deferred compensation plan assets	7.3		6.5
Total Assets	1,171.10		1,158.20
Financial Liabilities:
Convertible Notes, including Bifurcated Conversion Feature	-263.3		-260
Total Liabilities	-604.6		-601.5
Fair Value, Measurements, Recurring [Member] | VEBAs and Canadian Pension Plan | Fixed income investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	394.3	[2]	375	[2]
Fair Value, Measurements, Recurring [Member] | VEBAs and Canadian Pension Plan | Mortgage backed securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	30.1		25.9
Fair Value, Measurements, Recurring [Member] | VEBAs and Canadian Pension Plan | Corporate debt securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	75.4	[3]	78.2	[3]
Fair Value, Measurements, Recurring [Member] | VEBAs and Canadian Pension Plan | Equity investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	191.3	[4]	175.3	[4]
Fair Value, Measurements, Recurring [Member] | VEBAs and Canadian Pension Plan | United States Treasuries
Financial Assets:
VEBAs and Canadian Pension Plan Assets	39.5		43.3
Fair Value, Measurements, Recurring [Member] | VEBAs and Canadian Pension Plan | Municipal debt securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	1.8		1.6
Fair Value, Measurements, Recurring [Member] | VEBAs and Canadian Pension Plan | Cash and money market investments
Financial Assets:
VEBAs and Canadian Pension Plan Assets	19.3	[5]	36.8	[5]
Fair Value, Measurements, Recurring [Member] | VEBAs and Canadian Pension Plan | Asset backed securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	8.1		8.5
Fair Value, Measurements, Recurring [Member] | VEBAs and Canadian Pension Plan | Diversified investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	26.6	[6]	26.3	[6]
Fair Value, Measurements, Recurring [Member] | Senior Notes
Financial Liabilities:
Senior Notes	-244.5		-255.4
Fair Value, Measurements, Recurring [Member] | Debt Securities
Financial Assets:
Short-term investments	114		129.5
Fair Value, Measurements, Recurring [Member] | Aluminum | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0.1
Financial Liabilities:
Derivative Liabilities	-4.2		-1.8
Fair Value, Measurements, Recurring [Member] | Aluminum | Midwest premium swap contracts
Financial Assets:
Derivative Asset	1		1.1
Fair Value, Measurements, Recurring [Member] | Natural Gas | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0.5
Financial Liabilities:
Derivative Liabilities	-6.2		-0.8
Fair Value, Measurements, Recurring [Member] | Electricity | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0.5
Financial Liabilities:
Derivative Liabilities	-1.7		-0.4
Fair Value, Measurements, Recurring [Member] | Foreign Currency | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0.1
Fair Value, Measurements, Recurring [Member] | Hedges Relating to the Convertible Notes | Call Options
Financial Assets:
Derivative Asset	84.7		79.5
Fair Value, Measurements, Recurring [Member] | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature
Financial Liabilities:
Derivative Liabilities	-84.7		-83.1
Fair Value, Measurements, Recurring [Member] | Level 1
Financial Assets:
Cash and cash equivalents	29.5		57.7	[1]
Deferred compensation plan assets	0		0
Total Assets	123.2		171.6
Financial Liabilities:
Convertible Notes, including Bifurcated Conversion Feature	-263.3		-260
Total Liabilities	-507.8		-515.4
Fair Value, Measurements, Recurring [Member] | Level 1 | VEBAs and Canadian Pension Plan | Fixed income investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	54	[2]	57	[2]
Fair Value, Measurements, Recurring [Member] | Level 1 | VEBAs and Canadian Pension Plan | Mortgage backed securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | VEBAs and Canadian Pension Plan | Corporate debt securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | VEBAs and Canadian Pension Plan | Equity investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0	[4]
Fair Value, Measurements, Recurring [Member] | Level 1 | VEBAs and Canadian Pension Plan | United States Treasuries
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | VEBAs and Canadian Pension Plan | Municipal debt securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | VEBAs and Canadian Pension Plan | Cash and money market investments
Financial Assets:
VEBAs and Canadian Pension Plan Assets	19.3	[5]	36.8	[5]
Fair Value, Measurements, Recurring [Member] | Level 1 | VEBAs and Canadian Pension Plan | Asset backed securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | VEBAs and Canadian Pension Plan | Diversified investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	20.4	[6]	20.1	[6]
Fair Value, Measurements, Recurring [Member] | Level 1 | Senior Notes
Financial Liabilities:
Senior Notes	-244.5		-255.4
Fair Value, Measurements, Recurring [Member] | Level 1 | Debt Securities
Financial Assets:
Short-term investments	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | Aluminum | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0
Financial Liabilities:
Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | Aluminum | Midwest premium swap contracts
Financial Assets:
Derivative Asset	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | Natural Gas | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0
Financial Liabilities:
Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | Electricity | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0
Financial Liabilities:
Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | Foreign Currency | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0
Fair Value, Measurements, Recurring [Member] | Level 1 | Hedges Relating to the Convertible Notes | Call Options
Financial Assets:
Derivative Asset	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature
Financial Liabilities:
Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 2
Financial Assets:
Cash and cash equivalents	148.2		111.8	[1]
Short-term investments	114
Deferred compensation plan assets	7.3		6.5
Total Assets	1,046.90		985.5
Financial Liabilities:
Convertible Notes, including Bifurcated Conversion Feature	0		0
Total Liabilities	-96.8		-86.1
Fair Value, Measurements, Recurring [Member] | Level 2 | VEBAs and Canadian Pension Plan | Fixed income investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	340.3	[2]	318	[2]
Fair Value, Measurements, Recurring [Member] | Level 2 | VEBAs and Canadian Pension Plan | Mortgage backed securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	30.1		25.9
Fair Value, Measurements, Recurring [Member] | Level 2 | VEBAs and Canadian Pension Plan | Corporate debt securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	75.4	[3]	78.2	[3]
Fair Value, Measurements, Recurring [Member] | Level 2 | VEBAs and Canadian Pension Plan | Equity investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	191.3	[4]	175.3	[4]
Fair Value, Measurements, Recurring [Member] | Level 2 | VEBAs and Canadian Pension Plan | United States Treasuries
Financial Assets:
VEBAs and Canadian Pension Plan Assets	39.5		43.3
Fair Value, Measurements, Recurring [Member] | Level 2 | VEBAs and Canadian Pension Plan | Municipal debt securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	1.8		1.6
Fair Value, Measurements, Recurring [Member] | Level 2 | VEBAs and Canadian Pension Plan | Cash and money market investments
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 | VEBAs and Canadian Pension Plan | Asset backed securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	8.1		8.5
Fair Value, Measurements, Recurring [Member] | Level 2 | VEBAs and Canadian Pension Plan | Diversified investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	6.2	[6]	6.2	[6]
Fair Value, Measurements, Recurring [Member] | Level 2 | Senior Notes
Financial Liabilities:
Senior Notes	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 | Debt Securities
Financial Assets:
Short-term investments			129.5
Fair Value, Measurements, Recurring [Member] | Level 2 | Aluminum | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0.1
Financial Liabilities:
Derivative Liabilities	-4.2		-1.8
Fair Value, Measurements, Recurring [Member] | Level 2 | Aluminum | Midwest premium swap contracts
Financial Assets:
Derivative Asset	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 | Natural Gas | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0.5
Financial Liabilities:
Derivative Liabilities	-6.2		-0.8
Fair Value, Measurements, Recurring [Member] | Level 2 | Electricity | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0.5
Financial Liabilities:
Derivative Liabilities	-1.7		-0.4
Fair Value, Measurements, Recurring [Member] | Level 2 | Foreign Currency | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0.1
Fair Value, Measurements, Recurring [Member] | Level 2 | Hedges Relating to the Convertible Notes | Call Options
Financial Assets:
Derivative Asset	84.7		79.5
Fair Value, Measurements, Recurring [Member] | Level 2 | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature
Financial Liabilities:
Derivative Liabilities	-84.7		-83.1
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Cash and cash equivalents	0		0
Deferred compensation plan assets	0		0
Total Assets	1		1.1
Financial Liabilities:
Convertible Notes, including Bifurcated Conversion Feature	0		0
Total Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | VEBAs and Canadian Pension Plan | Fixed income investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | VEBAs and Canadian Pension Plan | Mortgage backed securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | VEBAs and Canadian Pension Plan | Corporate debt securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | VEBAs and Canadian Pension Plan | Equity investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | VEBAs and Canadian Pension Plan | United States Treasuries
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | VEBAs and Canadian Pension Plan | Municipal debt securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | VEBAs and Canadian Pension Plan | Cash and money market investments
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | VEBAs and Canadian Pension Plan | Asset backed securities
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | VEBAs and Canadian Pension Plan | Diversified investment funds in registered investment companies
Financial Assets:
VEBAs and Canadian Pension Plan Assets	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Senior Notes
Financial Liabilities:
Senior Notes	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities
Financial Assets:
Short-term investments	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Aluminum | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0
Financial Liabilities:
Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Aluminum | Midwest premium swap contracts
Financial Assets:
Derivative Asset			1.1
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Natural Gas | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0
Financial Liabilities:
Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Electricity | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0
Financial Liabilities:
Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign Currency | Fixed priced contracts | Purchase
Financial Assets:
Derivative Asset			0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Hedges Relating to the Convertible Notes | Call Options
Financial Assets:
Derivative Asset	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature
Financial Liabilities:
Derivative Liabilities	0		0
Income Approach Valuation Technique | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Aluminum | Midwest premium swap contracts
Financial Assets:
Derivative Asset	$1
[1]	See Note 2 for components of cash and cash equivalents.
[2]	This category represents investments in various fixed income funds with multiple registered investment companies. Such funds invest in diversified portfolios, including (i) marketable fixed income securities such as (a) U.S. Treasury and other government and agency securities, (b) municipal bonds, (c) mortgage-backed securities, (d) asset-backed securities, (e) corporate bonds, notes and debentures in various sectors, (f) preferred and common stock, (g) investments in affiliated and other investment companies, (h) short-term investments and other net assets and (i) repurchase agreements and reverse repurchase agreements; (ii) other commingled investments; (iii) investment grade debt; (iv) fixed income instruments which may be represented by options, future contracts or swap agreements; and (v) cash and cash equivalents. The fair value of assets in this category is estimated using the net asset value per share of the investments.
[3]	This category represents investments in fixed income corporate securities in various sectors. Investments in the industrial, financial and utilities sectors in 2014 represented approximately 51%, 37% and 12% of the total portfolio in this category, respectively. Investments in the industrial, financial and utilities sectors in 2013 represented approximately 56%, 35% and 9% of the total portfolio in this category, respectively. The fair value of assets in this category is estimated using the net asset value per share of the investments.
[4]	This category represents investments in equity funds that invest in portfolios comprised of (i) equity and equity-related securities of U.S. and non-U.S. issuers across all market capitalization; (ii) common stock in investment trust funds; and (iii) other short-term investments. The fair value of assets in this category is determined by using quoted prices in active markets for investments considered Level 1 inputs and estimated using the net asset value per share of the investments for investments considered Level 2 inputs.
[5]	This category represents cash and investments in various money market funds.
[6]	The plan assets are invested in investment funds that hold a diversified portfolio of (i) U.S and international debt and equity securities; (ii) fixed income securities such as corporate bonds and government bonds; (iii) mortgage-related securities; and (iv) cash and cash equivalents. The fair value of assets in this category is estimated using the net asset value per share of the investments.

Fair_Value_Measurements_Level_

Fair Value Measurements, Level 3 Fair Value Input Reconciliation Table (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of activity for financial instruments classified as Level 3:
Fair value measurement at beginning of period	$1	$1.10	$0.40
Total realized/unrealized gains included in:
Cost of goods sold, excluding depreciation and amortization and other items and Unrealized (gains) losses on derivative instruments	-4.4	0.1
Transactions involving Level 3 derivative contracts:
Purchases	2.8	1
Sales	0	0
Issuances	0	0
Settlements	-7.3	-0.2
Transactions involving Level 3 derivatives - net	-4.5	0.8
Transfers in and (or) out of Level 3 valuation hierarchy	0	0
Fair value measurement at end of period	1	1.1	0.4
Total gains included in Unrealized (gains) losses on derivative instruments, attributable to the change in unrealized gains/losses relating to derivative contracts held at December 31:	-1	-1.1
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Commercial paper	$148.20	$111.80

Fair_Value_Measurements_Fair_V1

Fair Value Measurements, Fair Value of Non financial Assets and Liabilities (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Asset Retirement Obligation, Roll Forward
Beginning balance	$4,400,000		$4,100,000		$4,000,000
Liabilities settled during the period	0		-200,000		-500,000
Accretion expense	400,000		400,000		300,000
Adjustment to accretion expense due to revisions to estimated cash flow and timing of expenditure	0	[1]	100,000	[1]	300,000
Ending balance	4,800,000		4,400,000		4,100,000
(Decrease)/increase in basic earnings per share resulting from adjustment					$0.02
(Decrease)/increase in diluted earnings per share resulting from adjustment			$0.02
Weighted-average credit-adjusted risk-free rate	8.60%
Midwest Premium Swap Contracts Beginning Curve Value	0.236
Midwest Premium Swap Contracts Ending Curve Value	$0.21
[1]	The adjustments in 2013 did not have a material impact on the basic and diluted net income per share for 2013. The adjustment in 2012 decreased both basic and diluted net income per share for 2012 by approximately $0.02 per share.

Fair_Value_Measurements_Fair_V2

Fair Value Measurements Fair Value - Schedule of Quantitative Information for Level 3 Derivative Contracts (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative Asset	$85.70	$81.80
Fair Value, Measurements, Recurring [Member] | Midwest premium swap contracts | Aluminum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative Asset	1	1.1
Fair Value, Measurements, Recurring [Member] | Midwest premium swap contracts | Aluminum | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative Asset		1.1
Fair Value, Measurements, Recurring [Member] | Midwest premium swap contracts | Aluminum | Income Approach Valuation Technique | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative Asset	$1

Fair_Value_Measurements_Fair_V3

Fair Value Measurements Fair Value Measurements, Textual (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Net Asset (Liability)	-11.1	($4.30)
Minimum
Schedule of Available-for-sale Securities [Line Items]
Short Term Investment Maturity Period	9 days
Maximum
Schedule of Available-for-sale Securities [Line Items]
Short Term Investment Maturity Period	15 months

Earnings_Per_Share_Calculation

Earnings Per Share, Calculation of EPS (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Numerator:
Net income	$15.60	$15.90	$24.50	$15.80	$27.30	$25.40	$18.60	$33.50	$71.80	$104.80		$85.80
Denominator - Weighted-average common shares outstanding (in thousands):
Basic									17,818	18,827	[1]	19,115	[1]
Add: dilutive effect of non-vested common shares, restricted stock units and performance shares									179	178		163
Add: dilutive effect of warrants									596	241		0
Diluted									18,593	19,246	[2]	19,278	[2]
Net income per common share:
Basic	$0.88	$0.90	$1.38	$0.88	$1.48	$1.37	$0.99	$1.75	$4.02	$5.56		$4.49
Earnings per common share, Diluted:
Net income per share	$0.85	$0.85	$1.33	$0.85	$1.44	$1.34	$0.98	$1.73	$3.86	$5.44	[2]	$4.45	[2]
[1]	The basic weighted-average number of common shares outstanding during the period excludes non-vested common shares, restricted stock units and performance shares.
[2]	The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.

Earnings_Per_Share_Other_Discl

Earnings Per Share, Other Disclosures (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Mar. 30, 2010
Potential dilutive effect of options and Warrants
Options outstanding to purchase common shares		16,645		20,791
Average exercise price per share		$80.01		$80.01
Potential dilutive effect of shares underlying the options				0		0
Dividends
Payment of cash dividends to stockholders		$25.40	[1]	$23	[1]	$19.60	[1]
Payment of quarterly cash dividends		$1.40		$1.20		$1
Cash dividend returned to the Company	0.6	0	[1]	0.6	[1]	0	[1]
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]
Shares returned from distribution of bankruptcy trust, shares				9,001
Repurchase of common shares pursuant to an authorization from the Board, shares		633,230		1,232,077		0
Weighted-average price of repurchases of common shares		$70.87		$64.35
Repurchase of common shares pursuant to an authorization from the Board, value		44.9		79.3
Common shares available for additional share repurchase		$72.80		$117.60
Warrant Transactions
Potential dilutive effect of options and Warrants
Number of common shares underlying the Warrants outstanding		3,700,000		3,600,000				3,700,000
Average exercise price of common shares underlying warrants		$60.70		$61.08
Common Stock
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]
Shares returned from distribution of bankruptcy trust, shares	9,001
Repurchase of common shares pursuant to an authorization from the Board, shares		633,230		1,232,077
[1]	See Note 14 for the supplemental disclosure on non-cash transactions.

Segment_and_Geographical_Area_2

Segment and Geographical Area Information, Textuals (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information
Environmental expense	$0.80		$4.50		$1.20
Asset impairment charge	1.5		0		4.4
Unrealized gains (losses) on derivatives	-6.8		3.9		16
Non-cash defined benefit net periodic benefit income	-23.5		-22		-11.5
Fabricated Products
Segment Reporting Information
Environmental expense	1.2		4		1.1
Asset impairment charge	1.5				4.4
Unrealized gains (losses) on derivatives	-10.4		0.7		15.2
United States
Segment Reporting Information
Number of production facilities	11
Canada
Segment Reporting Information
Number of production facilities	1
VEBAs | All Other
Segment Reporting Information
Non-cash defined benefit net periodic benefit income	($23.70)	[1]	($22.50)	[1]	($11.90)	[1]
Customer Concentration Risk | Net sales | Largest Customer | Fabricated Products
Segment Reporting Information
Concentration risk, percentage	22.00%		23.00%		22.00%
Customer Concentration Risk | Net sales | Second Largest Customer | Fabricated Products
Segment Reporting Information
Concentration risk, percentage	10.00%		12.00%
Customer Concentration Risk | Trade Receivables | Largest Customer
Segment Reporting Information
Concentration risk, percentage	10.00%		12.00%
Customer Concentration Risk | Trade Receivables | Second Largest Customer
Segment Reporting Information
Concentration risk, percentage	12.00%		14.00%
[1]	Included within the Statements of Consolidated Income as Net periodic pension benefit income relating to VEBAs.

Segment_and_Geographical_Area_3

Segment and Geographical Area Information, Financial Information by Reporting Segment Table (Details) (USD $)	3 Months Ended										12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Net Sales:
Net sales	$338		$338.90	$344.10	$335.10	$311.30		$319.90	$328.90	$337.40	$1,356.10		$1,297.50		$1,360.10
Segment Operating Income (Loss):
Total operating income (loss)	26.8		32.6	46.4	32.1	41.6		41.6	40.1	50	137.9		173.3		165.9
Interest expense											-37.5		-35.7		-29.1
Other income, net											6.7		5.6		2.8
Income before income taxes											107.1		143.2		139.6
Depreciation and Amortization:
Depreciation and amortization											31.1		28.1		26.5
Capital expenditures:
Capital expenditures											59.4		70.4		44.1
Segment assets:
Total	1,743.70					1,770.90					1,743.70		1,770.90
Fabricated Products
Net Sales:
Net sales											1,356.10		1,297.50		1,360.10
Segment Operating Income (Loss):
Total operating income (loss)											151.4	[1],[2]	188.6	[1],[2]	190.8	[1],[2]
Depreciation and Amortization:
Depreciation and amortization											30.6		27.6		26
Capital expenditures:
Capital expenditures											58.5		69.8		43.8
Segment assets:
Total	878.9					852.5					878.9		852.5
All Other
Segment Operating Income (Loss):
Total operating income (loss)											-13.5	[3]	-15.3	[3]	-24.9	[3]
Depreciation and Amortization:
Depreciation and amortization											0.5		0.5		0.5
Capital expenditures:
Capital expenditures											0.9		0.6		0.3
Segment assets:
Total	$864.80	[4]				$918.40	[4]				$864.80	[4]	$918.40	[4]
[1]	Fabricated Products segment results for 2014, 2013 and 2012 include non-cash mark-to-market (losses) gains on primary aluminum, natural gas, electricity and foreign currency hedging activities totaling $(10.4), $0.7 and $15.2, respectively. For further discussion regarding mark-to-market matters, see Note 10.
[2]	Operating results in the Fabricated Products segment for 2014, 2013 and 2012 included $1.2, $4.0 and $1.1, respectively, of environmental expense. Fabricated Products segment operating results for 2014 and 2012 included $1.5 and $4.4 of asset impairment charge relating to certain property, plant and equipment.
[3]	Operating results of All Other include VEBA net periodic pension benefit income of $23.7, $22.5 and $11.9 for 2014, 2013 and 2012, respectively.
[4]	Assets in All Other represent primarily all of the Company’s cash and cash equivalents, short-term investments, financial derivative assets, net assets of VEBAs and net deferred income tax assets.

Segment_and_Geographical_Area_4

Segment and Geographical Area Information, Revenues from External Customers by Products (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue from External Customer
Non-cash impairment charges									$1.50	$0	$4.40
Net sales	338	338.9	344.1	335.1	311.3	319.9	328.9	337.4	1,356.10	1,297.50	1,360.10
Aero/HS products
Revenue from External Customer
Net sales									686.3	677	695.1
Automotive Extrusions
Revenue from External Customer
Net sales									173.5	129.5	125.5
GE products
Revenue from External Customer
Net sales									419.5	411	441.4
Other products
Revenue from External Customer
Net sales									$76.80	$80	$98.10

Segment_and_Geographical_Area_5

Segment and Geographical Area Information Segment and Geographical Area Information, Information by Geographical Area (Details) (USD $)	3 Months Ended										12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Net sales to unaffiliated customers	$338		$338.90	$344.10	$335.10	$311.30		$319.90	$328.90	$337.40	$1,356.10		$1,297.50		$1,360.10
Income taxes paid											3.5		2.1		1.8
Long-lived assets	454.9	[1]				429.3	[1]				454.9	[1]	429.3	[1]
Fabricated Products
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Net sales to unaffiliated customers											1,356.10		1,297.50		1,360.10
Long-lived assets	450	[1]				424.8	[1]				450	[1]	424.8	[1]
Fabricated Products | United States
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Net sales to unaffiliated customers											1,254		1,204.70		1,256.50
Income taxes paid											2.1		1.2		0.5
Long-lived assets	432.6	[1]				409.5	[1]				432.6	[1]	409.5	[1]
Fabricated Products | Canada
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Net sales to unaffiliated customers											102.1		92.8		103.6
Income taxes paid											1.4		0.9		1.3
Long-lived assets	17.4	[1]				15.3	[1]				17.4	[1]	15.3	[1]
All Other
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Long-lived assets	4.9	[1]				4.5	[1]				4.9	[1]	4.5	[1]
All Other | United States
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Long-lived assets	$4.90	[1]				$4.50	[1]				$4.90	[1]	$4.50	[1]
[1]	Long-lived assets represent Property, plant and equipment, net.

Segment_and_Geographical_Area_6

Segment and Geographical Area Information Sales and Supply Information (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Export sales | Net sales
Concentration Risk
Concentration risk, percentage	19.00%	17.00%	18.00%
Supplier concentration risk | Aluminum | Top five major suppliers
Concentration Risk
Concentration risk, percentage	71.00%	86.00%	78.00%
Supplier concentration risk | Aluminum | Largest supplier
Concentration Risk
Concentration risk, percentage	30.00%	25.00%	29.00%
Supplier concentration risk | Aluminum | Second and third largest suppliers
Concentration Risk
Concentration risk, percentage	25.00%	35.00%	31.00%

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental disclosure of cash flow information:
Interest paid	$25.60	$28.10	$19.40
Income taxes paid	3.5	2.1	1.8
Non-cash investing and financing activities:
Stock repurchases not yet settled (accrued in accounts payable)	0.8	1	0
Unpaid purchases of property and equipment	1.8	4.4	3.4
Purchases of property and equipment through capital leasing arrangements	$0	$0.20	$0.10

Other_Income_Net_Details

Other Income, Net (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Other Income and Expenses [Abstract]
Interest income	$1		$0.40		$0.40
Unrealized gains on financial derivatives	3.6	[1]	3.2	[1]	0.8	[1]
Realized gains on investments	1		1.4		0.5
Distribution from third party trust	0		0.6	[2]	0
Insurance settlement	0		0		0.4
All other, net	1.1		0		0.7
Other income, net	$6.70		$5.60		$2.80
[1]	See “Derivative Financial Instruments” in Note 1 for a discussion of accounting policy for such instruments.
[2]	See Note 12 for discussion of the distribution.

Other_Comprehensive_Loss_Incom2

Other Comprehensive (Loss) Income (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Defined benefit pension plan and VEBAs:
Net actuarial (loss) gain arising during the period	($39)		$87	[1]
Prior service cost arising during the period	-90.5		-84.8	[1]
Total actuarial (loss) gain and prior service costs	-129.5		2.2	[1]	87.8
Reclassification adjustments:
Amortization of net actuarial (gain) loss	-1.8	[2]	1.5	[1],[2]	3.1	[2]
Amortization of prior service cost	10.6	[2]	4.2	[1],[2]	4.2	[2]
Other comprehensive (loss) income relating to defined benefit pension plan and VEBAs	-120.7		7.9	[1]	95.1
Available for sale securities:
Unrealized (loss) gain on available for sale securities	-0.2		1	[1]	0.6
Reclassification adjustments:
Reclassification of unrealized (loss) gain upon sale of available for sale securities	-0.1		-1	[1],[3]	0
Other comprehensive (loss) income relating to available for sale securities	-0.3		0	[1]	0.6
Foreign currency translation adjustment	0.4		0.2	[1]	-0.2
Other comprehensive (loss) income, before tax	-120.6		8.1	[1]	95.5
Defined benefit pension plan and VEBAs:
Net actuarial loss (gain) arising during the period	14.5	[4]	-32.5	[4]
Prior service cost arising during the period	33.8	[4]	31.8	[4]
Total actuarial (loss) gain and prior service costs	48.3	[4]	-0.7	[4]	-33.5	[4]
Reclassification adjustments:
Amortization of net actuarial loss (gain)	0.7	[2],[4]	-0.5	[2],[4]	-1.1	[2],[4]
Amortization of prior service cost	-3.9	[2],[4]	-1.6	[2],[4]	-1.7	[2],[4]
Other comprehensive income relating to defined benefit pension plan and VEBAs	45.1	[4]	-2.8	[4]	-36.3	[4]
Available for sale securities:
Unrealized gain (loss) on available for sale securities	0.1	[4]	-0.3	[4]	-0.2	[4]
Reclassification adjustments:
Reclassification of unrealized gain upon sale of available for sale securities	0	[3],[4]	0.3	[3],[4]
Other comprehensive income relating to available for sale securities	0.1	[4]	0	[4]
Foreign currency translation adjustment	0	[4]	0	[4]	0	[4]
Other comprehensive income (loss)	45.2	[4]	-2.8	[4]	-36.5	[4]
Defined benefit pension plan and VEBAs:
Net actuarial (loss) gain arising during the period	-24.5		54.5
Prior service cost arising during the period	-56.7		-53
Total actuarial (loss) gain and prior service costs	-81.2		1.5		54.3
Reclassification adjustments:
Amortization of net actuarial (gain) loss	-1.1	[2]	1	[2]	2	[2]
Amortization of prior service cost	6.7	[2]	2.6	[2]	2.5	[2]
Other comprehensive income relating to defined benefit pension plan and VEBAs	-75.6		5.1		58.8
Available for sale securities:
Unrealized (loss) gain on available for sale securities	-0.1		0.7		0.4
Reclassification adjustments:
Reclassification of unrealized loss upon sale of available for sale securities	-0.1	[3]	-0.7	[3]
Other comprehensive loss relating to available for sale securities	-0.2		0
Foreign currency translation adjustment	0.4		0.2		-0.2
Other comprehensive (loss) income, net of tax	-75.4		5.3		59
As Reported
Defined benefit pension plan and VEBAs:
Net actuarial (loss) gain arising during the period			2.2
Prior service cost arising during the period			0
Total actuarial (loss) gain and prior service costs			2.2
Reclassification adjustments:
Amortization of net actuarial (gain) loss			1.5	[2]
Amortization of prior service cost			4.2	[2]
Other comprehensive (loss) income relating to defined benefit pension plan and VEBAs			7.9
Available for sale securities:
Unrealized (loss) gain on available for sale securities			1
Reclassification adjustments:
Reclassification of unrealized (loss) gain upon sale of available for sale securities			-1	[3]
Other comprehensive (loss) income relating to available for sale securities			0
Foreign currency translation adjustment			0.2
Other comprehensive (loss) income, before tax			$8.10
[1]	The presentation of other comprehensive income 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. The 2013 balances were adjusted to reflect this reclassification. The impacts to the prospective amortization of Prior service cost and Accumulated net actuarial (losses) gains were not material.
[2]	Amounts reclassified out of Accumulated other comprehensive income relating to VEBA adjustments were included as a component of Net periodic pension benefit income relating to VEBAs.
[3]	Amounts reclassified out of Accumulated other comprehensive income relating to sales of available for sale securities were included as a component of Other income (expense), net. The Company uses the specific identification method to determine the amount reclassified out of Accumulated other comprehensive income.
[4]	Income tax amounts reclassified out of Accumulated other comprehensive income relating to VEBA adjustments and sales of available for sale securities were included as a component of Income tax provision.

Guarantor_and_NonGuarantor_Fin2

Guarantor and Non-Guarantor Financial Statements (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010	23-May-12
Current assets:
Cash and cash equivalents	$177.70				$169.50				$177.70		$169.50		$273.40			$49.80
Short-term investments	114				129.5				114		129.5
Receivables:
Trade, less allowance for doubtful receivables	129.3				119.8				129.3		119.8
Intercompany receivables	0				0				0		0
Other	10.9				13.4				10.9		13.4
Inventories	214.7				214.4				214.7		214.4
Prepaid expenses and other current assets	178.6				44.2				178.6		44.2
Total current assets	825.2				690.8				825.2		690.8
Investments in and advances to unconsolidated affiliates	0				0				0		0
Property, plant and equipment — net	454.9				429.3				454.9		429.3
Long-term intercompany receivables	0				0				0		0
Net asset of VEBAs	340.1				406				340.1		406
Deferred tax assets — net	30.9				69.1				30.9		69.1
Intangible assets — net	32.1				33.7				32.1		33.7
Goodwill	37.2				37.2				37.2		37.2
Other assets	23.3				104.8				23.3		104.8
Total	1,743.70				1,770.90				1,743.70		1,770.90
Current liabilities:
Accounts payable	81.4				62.9				81.4		62.9
Intercompany payable	0				0				0		0
Accrued salaries, wages and related expenses	39.6				42.7				39.6		42.7
Other accrued liabilities	132.8				44.8				132.8		44.8
Current portion of long-term debt	172.5				0				172.5		0
Short-term capital leases	0.1				0.2				0.1		0.2
Total current liabilities	426.4				150.6				426.4		150.6
Net liability of VEBA	17.2				0				17.2		0
Deferred tax liabilities	0.9				1.2				0.9		1.2
Long-term intercompany payable	0				0				0		0
Long-term liabilities	58.3				146.4				58.3		146.4
Long-term debt	225				388.5				225		388.5
Total liabilities	727.8				686.7				727.8		686.7
Total stockholders’ equity	1,015.90				1,084.20				1,015.90		1,084.20		1,070.80		872.8
Total	1,743.70				1,770.90				1,743.70		1,770.90
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales	338	338.9	344.1	335.1	311.3	319.9	328.9	337.4	1,356.10		1,297.50		1,360.10
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	278.7	280.4	275.5	282.9	254.3	259.5	261.5	263.6	1,117.50		1,038.90		1,116.20
Unrealized losses (gains) on derivative instruments	10.4	3.6	-1.6	-2	-4.1	-1.5	4.2	0.7	10.4		-0.7		-15.2
Depreciation and amortization									31.1		28.1		26.5
Selling, administrative, research and development and general									81.4		80.4		74.1
Non-cash defined benefit net periodic benefit income									-23.5		-22		-11.5
Defined benefit plan, net periodic benefit cost - VEBAs									-23.7		-22.5		-11.9
Total selling, administrative, research and development and general									57.7		57.9		62.2
Other operating charges, net									1.5		0		4.5
Total costs and expenses									1,218.20		1,124.20		1,194.20
Operating (loss) income	26.8	32.6	46.4	32.1	41.6	41.6	40.1	50	137.9		173.3		165.9
Interest expense									-37.5		-35.7		-29.1
Other (expense) income:
Other income, net									6.7		5.6		2.8
(Loss) income before income taxes									107.1		143.2		139.6
Income tax provision									-35.3		-38.4		-53.8
Earnings in equity of subsidiaries									0		0		0
Net income	15.6	15.9	24.5	15.8	27.3	25.4	18.6	33.5	71.8		104.8		85.8
Comprehensive (loss) income									-3.6		110.1		144.8
Cash flows from operating activities:
Net cash (used in) provided by operating activities									124.1		111.7		152.4
Cash flows from investing activities:
Capital expenditures									-59.4		-70.4		-44.1
Payments to Acquire Available-for-sale Securities									93.5		227.8		85
Proceeds from disposal of property, plant and equipment									0		0		0.3
Proceeds from disposition of available for sale securities									108.2		183.1		0
Change in restricted cash									0		1.7		6.9
Net cash used in investing activities									-44.7		-113.4		-121.9
Cash flows from financing activities:
Proceeds from issuance of Senior Notes									0	[1]	0	[1]	225	[1]
Repayments of capital lease									-0.1	[1]	-0.1	[1]	-0.1	[1]
Repayment of promissory notes									0	[1]	0	[1]	-4.7	[1]
Cash paid for financing costs									0	[1]	0	[1]	-6.6	[1]
Repurchase of common stock									-44.1	[1]	-78.3	[1]	0	[1]
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0.8	[1]	1.1	[1]	1.3	[1]
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									-2.4	[1]	-2.5	[1]	-2.2	[1]
Cash dividend paid to stockholders									-25.4	[1]	-23	[1]	-19.6	[1]
Cash dividend returned to the Company			0.6						0	[1]	0.6	[1]	0	[1]
Intercompany loan									0		0		0
Net cash provided by (used in) financing activities									-71.2	[1]	-102.2	[1]	193.1	[1]
Net increase (decrease) in cash and cash equivalents during the period									8.2		-103.9		223.6
Cash and cash equivalents at beginning of period				169.5				273.4	169.5		273.4		49.8			49.8
Cash and cash equivalents at end of period	177.7				169.5				177.7		169.5		273.4			49.8
Principal amount of notes	225				225				225		225
Ownership interest by parent	100.00%								100.00%
Parent
Current assets:
Cash and cash equivalents	0				5				0		5		5			5
Short-term investments	0				0				0		0
Receivables:
Trade, less allowance for doubtful receivables	0				0				0		0
Intercompany receivables	204.2				0				204.2		0
Other	0				0				0		0
Inventories	0				0				0		0
Prepaid expenses and other current assets	85.1				0.1				85.1		0.1
Total current assets	289.3				5.1				289.3		5.1
Investments in and advances to unconsolidated affiliates	1,209.20				1,437.90				1,209.20		1,437.90
Property, plant and equipment — net	0				0				0		0
Long-term intercompany receivables	0				31.3				0		31.3
Net asset of VEBAs	0				0				0		0
Deferred tax assets — net	0				0				0		0
Intangible assets — net	0				0				0		0
Goodwill	0				0				0		0
Other assets	4.4				86.2				4.4		86.2
Total	1,502.90				1,560.50				1,502.90		1,560.50
Current liabilities:
Accounts payable	1.3				1.1				1.3		1.1
Intercompany payable	0				0				0		0
Accrued salaries, wages and related expenses	0				0				0		0
Other accrued liabilities	88.2				3.5				88.2		3.5
Current portion of long-term debt	172.5								172.5
Short-term capital leases	0				0				0		0
Total current liabilities	262				4.6				262		4.6
Net liability of VEBA	0								0
Deferred tax liabilities	0				0				0		0
Long-term intercompany payable	0				0				0		0
Long-term liabilities	0				83.2				0		83.2
Long-term debt	225				388.5				225		388.5
Total liabilities	487				476.3				487		476.3
Total stockholders’ equity	1,015.90				1,084.20				1,015.90		1,084.20
Total	1,502.90				1,560.50				1,502.90		1,560.50
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales									0		0		0
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items									0		0		0
Unrealized losses (gains) on derivative instruments									0		0		0
Depreciation and amortization									0		0		0
Selling, administrative, research and development and general									4.1		3.8		2
Non-cash defined benefit net periodic benefit income									0		0		0
Total selling, administrative, research and development and general									4.1		3.8		2
Other operating charges, net									0				0
Total costs and expenses									4.1		3.8		2
Operating (loss) income									-4.1		-3.8		-2
Interest expense									-37.5		-36.6		-28.2
Other (expense) income:
Other income, net									3.7		3.9		0.8
(Loss) income before income taxes									-37.9		-36.5		-29.4
Income tax provision									0		0		0
Earnings in equity of subsidiaries									109.7		141.3		115.2
Net income									71.8		104.8		85.8
Comprehensive (loss) income									-3.6		110.1		144.8
Cash flows from operating activities:
Net cash (used in) provided by operating activities									35.6		-29.2		-17.8
Cash flows from investing activities:
Capital expenditures									0		0		0
Payments to Acquire Available-for-sale Securities									0		0		0
Proceeds from disposal of property, plant and equipment													0
Proceeds from disposition of available for sale securities									0		0
Change in restricted cash											0		6.9
Net cash used in investing activities									0		0		6.9
Cash flows from financing activities:
Proceeds from issuance of Senior Notes													225
Repayments of capital lease									0		0		0
Repayment of promissory notes													0
Cash paid for financing costs													-6.6
Repurchase of common stock									-44.1		-78.3
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0		0		0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									-2.4		-2.5		-2.2
Cash dividend paid to stockholders									-25.4		-23		-19.6
Cash dividend returned to the Company											0.6
Intercompany loan									31.3		132.4		-185.7
Net cash provided by (used in) financing activities									-40.6		29.2		10.9
Net increase (decrease) in cash and cash equivalents during the period									-5		0		0
Cash and cash equivalents at beginning of period				5				5	5		5					5
Cash and cash equivalents at end of period	0				5				0		5		5			5
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	175.3				157.7				175.3		157.7		266			43
Short-term investments	114				129.5				114		129.5
Receivables:
Trade, less allowance for doubtful receivables	126.1				117.7				126.1		117.7
Intercompany receivables	4				0.1				4		0.1
Other	5.6				5.3				5.6		5.3
Inventories	208				208.6				208		208.6
Prepaid expenses and other current assets	93.1				43.7				93.1		43.7
Total current assets	726.1				662.6				726.1		662.6
Investments in and advances to unconsolidated affiliates	32.5				26.5				32.5		26.5
Property, plant and equipment — net	437.4				414				437.4		414
Long-term intercompany receivables	0				1.6				0		1.6
Net asset of VEBAs	340.1				406				340.1		406
Deferred tax assets — net	23.8				60.2				23.8		60.2
Intangible assets — net	32.1				33.7				32.1		33.7
Goodwill	37.2				37.2				37.2		37.2
Other assets	18.8				18.5				18.8		18.5
Total	1,648				1,660.30				1,648		1,660.30
Current liabilities:
Accounts payable	73.8				56.3				73.8		56.3
Intercompany payable	221.3				13.9				221.3		13.9
Accrued salaries, wages and related expenses	36.5				39.3				36.5		39.3
Other accrued liabilities	43.8				39.9				43.8		39.9
Current portion of long-term debt	0								0
Short-term capital leases	0.1				0.2				0.1		0.2
Total current liabilities	375.5				149.6				375.5		149.6
Net liability of VEBA	17.2								17.2
Deferred tax liabilities	0				0				0		0
Long-term intercompany payable	15.9				40.7				15.9		40.7
Long-term liabilities	50.3				52				50.3		52
Long-term debt	0				0				0		0
Total liabilities	458.9				242.3				458.9		242.3
Total stockholders’ equity	1,189.10				1,418				1,189.10		1,418
Total	1,648				1,660.30				1,648		1,660.30
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales									1,323.40		1,275.20		1,326
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items									1,098.30		1,026		1,090
Unrealized losses (gains) on derivative instruments									10.4		-0.7		-15.2
Depreciation and amortization									30		27		25.5
Selling, administrative, research and development and general									69.7		70.1		69.6
Non-cash defined benefit net periodic benefit income									-23.7				-11.9
Total selling, administrative, research and development and general									46		47.6		57.7
Other operating charges, net									1.5				4.5
Total costs and expenses									1,186.20		1,099.90		1,162.50
Operating (loss) income									137.2		175.3		163.5
Interest expense									-0.6		0.5		-1
Other (expense) income:
Other income, net									3.2		2		1.5
(Loss) income before income taxes									139.8		177.8		164
Income tax provision									-50.2		-68.1		-62.6
Earnings in equity of subsidiaries									6		17.6		2.6
Net income									95.6		127.3		104
Comprehensive (loss) income									19.9		131.6		164
Cash flows from operating activities:
Net cash (used in) provided by operating activities									81.8		131.7		164.3
Cash flows from investing activities:
Capital expenditures									-56.4		-66.5		-42.6
Payments to Acquire Available-for-sale Securities									93.5		227.8		85
Proceeds from disposal of property, plant and equipment													0.3
Proceeds from disposition of available for sale securities									108.2		183.1
Change in restricted cash											0.7		0.4
Net cash used in investing activities									-41.7		-110.5		-126.9
Cash flows from financing activities:
Proceeds from issuance of Senior Notes													0
Repayments of capital lease									-0.1		-0.1		-0.1
Repayment of promissory notes													-4.7
Cash paid for financing costs													0
Repurchase of common stock									0		0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0.8		1.1		1.3
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									0		0		0
Cash dividend paid to stockholders									0		0		0
Cash dividend returned to the Company											0
Intercompany loan									-23.2		-130.5		189.1
Net cash provided by (used in) financing activities									-22.5		-129.5		185.6
Net increase (decrease) in cash and cash equivalents during the period									17.6		-108.3		223
Cash and cash equivalents at beginning of period				157.7				266	157.7		266					43
Cash and cash equivalents at end of period	175.3				157.7				175.3		157.7		266			43
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	2.4				6.8				2.4		6.8		2.4			1.8
Short-term investments	0				0				0		0
Receivables:
Trade, less allowance for doubtful receivables	3.2				2.1				3.2		2.1
Intercompany receivables	0.9				0.2				0.9		0.2
Other	5.3				8.1				5.3		8.1
Inventories	7.6				6.4				7.6		6.4
Prepaid expenses and other current assets	0.4				0.4				0.4		0.4
Total current assets	19.8				24				19.8		24
Investments in and advances to unconsolidated affiliates	0				0				0		0
Property, plant and equipment — net	17.5				15.3				17.5		15.3
Long-term intercompany receivables	15.9				9.5				15.9		9.5
Net asset of VEBAs	0				0				0		0
Deferred tax assets — net	0				0				0		0
Intangible assets — net	0				0				0		0
Goodwill	0				0				0		0
Other assets	0.1				0.1				0.1		0.1
Total	53.3				48.9				53.3		48.9
Current liabilities:
Accounts payable	6.3				5.5				6.3		5.5
Intercompany payable	3.3				0.1				3.3		0.1
Accrued salaries, wages and related expenses	3.1				3.4				3.1		3.4
Other accrued liabilities	0.8				1.4				0.8		1.4
Current portion of long-term debt	0								0
Short-term capital leases	0				0				0		0
Total current liabilities	13.5				10.4				13.5		10.4
Net liability of VEBA	0								0
Deferred tax liabilities	0.9				1.2				0.9		1.2
Long-term intercompany payable	0				1.7				0		1.7
Long-term liabilities	8				11.2				8		11.2
Long-term debt	0				0				0		0
Total liabilities	22.4				24.5				22.4		24.5
Total stockholders’ equity	30.9				24.4				30.9		24.4
Total	53.3				48.9				53.3		48.9
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales									133.9		118		124
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items									117.8		105.7		110.2
Unrealized losses (gains) on derivative instruments									0		0		0
Depreciation and amortization									1.1		1.1		1
Selling, administrative, research and development and general									9.9		8.9		8.2
Non-cash defined benefit net periodic benefit income									0		0		0
Total selling, administrative, research and development and general									9.9		8.9		8.2
Other operating charges, net									0				0
Total costs and expenses									128.8		115.7		119.4
Operating (loss) income									5.1		2.3		4.6
Interest expense									0		0		0
Other (expense) income:
Other income, net									0.4		0		0.6
(Loss) income before income taxes									5.5		2.3		5.2
Income tax provision									0.8		15.7		-2.3
Earnings in equity of subsidiaries									0		0		0
Net income									6.3		18		2.9
Comprehensive (loss) income									6.6		19		1.9
Cash flows from operating activities:
Net cash (used in) provided by operating activities									6.7		9.2		5.9
Cash flows from investing activities:
Capital expenditures									-3		-3.9		-1.5
Payments to Acquire Available-for-sale Securities									0		0		0
Proceeds from disposal of property, plant and equipment													0
Proceeds from disposition of available for sale securities									0		0
Change in restricted cash											1		-0.4
Net cash used in investing activities									-3		-2.9		-1.9
Cash flows from financing activities:
Proceeds from issuance of Senior Notes													0
Repayments of capital lease									0		0		0
Repayment of promissory notes													0
Cash paid for financing costs													0
Repurchase of common stock									0		0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0		0		0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									0		0		0
Cash dividend paid to stockholders									0		0		0
Cash dividend returned to the Company											0
Intercompany loan									-8.1		-1.9		-3.4
Net cash provided by (used in) financing activities									-8.1		-1.9		-3.4
Net increase (decrease) in cash and cash equivalents during the period									-4.4		4.4		0.6
Cash and cash equivalents at beginning of period				6.8				2.4	6.8		2.4					1.8
Cash and cash equivalents at end of period	2.4				6.8				2.4		6.8		2.4			1.8
Consolidating Adjustments
Current assets:
Cash and cash equivalents	0				0				0		0		0			0
Short-term investments	0				0				0		0
Receivables:
Trade, less allowance for doubtful receivables	0				0				0		0
Intercompany receivables	-209.1				-0.3				-209.1		-0.3
Other	0				0				0		0
Inventories	-0.9				-0.6				-0.9		-0.6
Prepaid expenses and other current assets	0				0				0		0
Total current assets	-210				-0.9				-210		-0.9
Investments in and advances to unconsolidated affiliates	-1,241.70				-1,464.40				-1,241.70		-1,464.40
Property, plant and equipment — net	0				0				0		0
Long-term intercompany receivables	-15.9				-42.4				-15.9		-42.4
Net asset of VEBAs	0				0				0		0
Deferred tax assets — net	7.1				8.9				7.1		8.9
Intangible assets — net	0				0				0		0
Goodwill	0				0				0		0
Other assets	0				0				0		0
Total	-1,460.50				-1,498.80				-1,460.50		-1,498.80
Current liabilities:
Accounts payable	0				0				0		0
Intercompany payable	-224.6				-14				-224.6		-14
Accrued salaries, wages and related expenses	0				0				0		0
Other accrued liabilities	0				0				0		0
Current portion of long-term debt	0								0
Short-term capital leases	0				0				0		0
Total current liabilities	-224.6				-14				-224.6		-14
Net liability of VEBA	0								0
Deferred tax liabilities	0				0				0		0
Long-term intercompany payable	-15.9				-42.4				-15.9		-42.4
Long-term liabilities	0				0				0		0
Long-term debt	0				0				0		0
Total liabilities	-240.5				-56.4				-240.5		-56.4
Total stockholders’ equity	-1,220				-1,442.40				-1,220		-1,442.40
Total	-1,460.50				-1,498.80				-1,460.50		-1,498.80
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales									-101.2		-95.7		-89.9
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items									-98.6		-92.8		-84
Unrealized losses (gains) on derivative instruments									0		0		0
Depreciation and amortization									0		0		0
Selling, administrative, research and development and general									-2.3		-2.4		-5.7
Non-cash defined benefit net periodic benefit income									0		0		0
Total selling, administrative, research and development and general									-2.3		-2.4		-5.7
Other operating charges, net									0				0
Total costs and expenses									-100.9		-95.2		-89.7
Operating (loss) income									-0.3		-0.5		-0.2
Interest expense									0.6		0.4		0.1
Other (expense) income:
Other income, net									-0.6		-0.3		-0.1
(Loss) income before income taxes									-0.3		-0.4		-0.2
Income tax provision									14.1		14		11.1
Earnings in equity of subsidiaries									-115.7		-158.9		-117.8
Net income									-101.9		-145.3		-106.9
Comprehensive (loss) income									-26.5		-150.6		-165.9
Cash flows from operating activities:
Net cash (used in) provided by operating activities									0		0		0
Cash flows from investing activities:
Capital expenditures									0		0		0
Payments to Acquire Available-for-sale Securities									0		0		0
Proceeds from disposal of property, plant and equipment													0
Proceeds from disposition of available for sale securities									0		0
Change in restricted cash											0		0
Net cash used in investing activities									0		0		0
Cash flows from financing activities:
Proceeds from issuance of Senior Notes													0
Repayments of capital lease									0		0		0
Repayment of promissory notes													0
Cash paid for financing costs													0
Repurchase of common stock									0		0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0		0		0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									0		0		0
Cash dividend paid to stockholders									0		0		0
Cash dividend returned to the Company											0
Intercompany loan									0		0		0
Net cash provided by (used in) financing activities									0		0		0
Net increase (decrease) in cash and cash equivalents during the period									0		0		0
Cash and cash equivalents at beginning of period				0				0	0		0					0
Cash and cash equivalents at end of period	0				0				0		0		0			0
Senior Notes
Cash flows from financing activities:
Principal amount of notes																	225
VEBAs [Member]
Cost of products sold:
Non-cash defined benefit net periodic benefit income									($23.70)		($22.50)		($11.90)
[1]	See Note 14 for the supplemental disclosure on non-cash transactions.

Quarterly_Financial_Data_Detai

Quarterly Financial Data (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Quarterly Financial Data [Abstract]
Net sales	$338	$338.90	$344.10	$335.10	$311.30	$319.90	$328.90	$337.40	$1,356.10	$1,297.50		$1,360.10
Cost of products sold, excluding depreciation and amortization and other items	278.7	280.4	275.5	282.9	254.3	259.5	261.5	263.6	1,117.50	1,038.90		1,116.20
Unrealized losses (gains) on derivative instruments	10.4	3.6	-1.6	-2	-4.1	-1.5	4.2	0.7	10.4	-0.7		-15.2
Gross Profit	48.9	54.9	70.2	54.2	61.1	61.9	63.2	73.1
Operating income	26.8	32.6	46.4	32.1	41.6	41.6	40.1	50	137.9	173.3		165.9
Net income	$15.60	$15.90	$24.50	$15.80	$27.30	$25.40	$18.60	$33.50	$71.80	$104.80		$85.80
Net income per common share:
Basic	$0.88	$0.90	$1.38	$0.88	$1.48	$1.37	$0.99	$1.75	$4.02	$5.56		$4.49
Earnings per common share, Diluted:
Net income per share	$0.85	$0.85	$1.33	$0.85	$1.44	$1.34	$0.98	$1.73	$3.86	$5.44	[1]	$4.45	[1]
[1]	The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 13, 2015	Jan. 21, 2015	Jan. 28, 2015
Subsequent Events (Textuals) [Abstract]
Cash dividend declared per common share	$1.40	$1.20	$1
Conversion price of note	$47.80
Subsequent Event
Subsequent Events (Textuals) [Abstract]
Cash dividend declared per common share				$0.40
Dividends				$7,100,000
Conversion price of note					$47.70
Convertible Notes
Subsequent Events (Textuals) [Abstract]
Conversion rate of common stock shares per $1,000 of principal amount	20.9186
Principal amount in conversion feature	1,000
Convertible Notes | Subsequent Event
Subsequent Events (Textuals) [Abstract]
Conversion rate of common stock shares per $1,000 of principal amount					20.9664
Principal amount in conversion feature					1,000
Call Options
Subsequent Events (Textuals) [Abstract]
Exercise price of call options	$47.80
Call Options | Subsequent Event
Subsequent Events (Textuals) [Abstract]
Exercise price of call options					$47.70
Warrants
Subsequent Events (Textuals) [Abstract]
Exercise price per share of Warrants	$60.70	$61.08
Warrants | Subsequent Event
Subsequent Events (Textuals) [Abstract]
Exercise price per share of Warrants					$60.57
Union VEBA | Subsequent Event
Subsequent Events (Textuals) [Abstract]
Maximum Contribution						$17,100,000