Kaiser Aluminum (KALU) 10-Q 25 Apr 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 17, 2014
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'Kaiser Aluminum Corp	'
Entity Central Index Key	'0000811596	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	18,030,319

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$185.60	$169.50
Short-term investments	104.5	129.5
Receivables:	'	'
Trade, less allowance for doubtful receivables of $0.8 at March 31, 2014 and December 31, 2013	123.5	119.8
Other	11.7	13.4
Inventories	203.1	214.4
Prepaid expenses and other current assets	48.6	44.2
Total current assets	677	690.8
Property, plant, and equipment – net	436.7	429.3
Net asset of VEBAs	414.1	406
Deferred tax assets – net (including deferred tax liability relating to the VEBAs of $155.4 at March 31, 2014 and $152.4 at December 31, 2013)	59.2	69.1
Intangible assets – net	33.3	33.7
Goodwill	37.2	37.2
Other assets	108.5	104.8
Total	1,766	1,770.90
Current liabilities:	'	'
Accounts payable	72.3	62.9
Accrued salaries, wages, and related expenses	33.2	42.7
Other accrued liabilities	37.1	44.8
Short-term capital lease	0.2	0.2
Total current liabilities	142.8	150.6
Deferred tax liability	1.2	1.2
Long-term liabilities	149	146.4
Long-term debt	390.7	388.5
Total liabilities	683.7	686.7
Commitments and contingencies – Note 7	'	'
Stockholders’ equity:	'	'
Preferred stock, 5,000,000 shares authorized at both March 31, 2014 and December 31, 2013; no shares were issued and outstanding at March 31, 2014 and December 31, 2013	0	0
Common stock, par value $0.01, 90,000,000 shares authorized at both March 31, 2014 and at December 31, 2013; 21,171,683 shares issued and 18,030,600 shares outstanding at March 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	1,023.60	1,023.10
Retained earnings	243.2	233.8
Treasury stock, at cost, 3,141,083 shares at March 31, 2014 and 2,956,683 shares at December 31, 2013, respectively	-164.9	-152.2
Accumulated other comprehensive loss	-19.8	-20.7
Total stockholders’ equity	1,082.30	1,084.20
Total	$1,766	$1,770.90

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Receivables:	'	'
Allowance for doubtful receivables	$0.80	$0.80
Deferred tax liabilities relating to the VEBAs	$155.40	$152.40
Stockholders' equity:	'	'
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 value	$0.01	$0.01
Common stock, shares authorized	90,000,000	90,000,000
Common Stock, shares issued	21,171,683	21,103,700
Common stock, shares outstanding	18,030,600	18,147,017
Treasury stock, shares	3,141,083	2,956,683

Statements_of_Consolidated_Inc

Statements of Consolidated Income (USD $)	3 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Net sales	$335.10		$337.40
Cost of products sold:	'		'
Cost of products sold, excluding depreciation and amortization and other items	282.9		263.6
Unrealized (gains) losses on derivative instruments	-2		0.7
Depreciation and amortization	7.4		7
Selling, administrative, research and development, and general	20.3		21.7
Net periodic pension benefit income relating to VEBAs (includes accumulated other comprehensive income reclassifications related to VEBA of $2.5 and $1.4 for the quarters ended March 31, 2014 and March 31, 2013, respectively)	-5.6		-5.6
Total selling, administrative, research and development, and general	14.7		16.1
Total costs and expenses	303		287.4
Operating income	32.1		50
Other (expense) income:	'		'
Interest expense	-8.8		-9.3
Other income, net (includes accumulated other comprehensive income reclassifications for realized gains on available for sale securities of $0.1 and $0.4 for the quarters ended March 31, 2014 and March 31, 2013, respectively)	1.9		1
Income before income taxes	25.2		41.7
Income tax provision (includes aggregate income tax expense from reclassification items of $(0.9) and $(0.4) for the quarters ended March 31, 2014 and March 31, 2013, respectively)	-9.4		-8.2
Net income	$15.80		$33.50
Earnings per common share, Basic:	'		'
Net income per share	$0.88		$1.75
Earnings per common share, Diluted:	'		'
Net income per share	$0.85		$1.73
Weighted-average number of common shares outstanding (in thousands):	'		'
Basic	17,921	[1]	19,143	[1]
Diluted	18,514	[2]	19,366	[2]
Add: dilutive effect of non-vested common shares, restricted stock units, performance shares and market-based shares	122		131
[1]	The basic weighted-average number of common shares outstanding during the period excludes non-vested common shares, restricted stock units, performance shares and market-based shares.
[2]	The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.

Statements_of_Consolidated_Inc1

Statements of Consolidated Income (Parentheticals) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Other comprehensive income relating to VEBAs, before tax	$2.50	$1.40
Reclassification of unrealized gain upon sale of available for sale securities	0.1	0.4
Other Comprehensive Income Loss Reclassification Adjustment Tax	($0.90)	($0.40)

Statements_of_Consolidated_Com

Statements of Consolidated Comprehensive Income (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'
Net income	$15.80	$33.50
Reclassification adjustments:	'	'
Amortization of net actuarial (gain) loss	-0.3	0.3
Amortization of prior service cost	2.8	1.1
Other comprehensive income relating to VEBAs	2.5	1.4
Available for sale securities	'	'
Unrealized gain on available for sale securities	0.1	0.3
Reclassification adjustments:	'	'
Reclassification of unrealized gain upon sale of available for sale securities	-0.1	-0.4
Other comprehensive income (loss) relating to available for sale securities	0	-0.1
Foreign currency translation adjustment	0.2	0.4
Other comprehensive income, before tax	2.7	1.7
Income tax expense related to items of other comprehensive income	-1.8	-0.5
Other comprehensive income, net of tax	0.9	1.2
Comprehensive income	$16.70	$34.70

Statement_of_Consolidated_Stoc

Statement of Consolidated Stockholders' Equity (USD $)	Total	Common Stock	Additional Paid in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
In Millions, except Share data, unless otherwise specified
Beginning balance at Dec. 31, 2013	$1,084.20	$0.20	$1,023.10	$233.80	($152.20)	($20.70)
Beginning balance, shares at Dec. 31, 2013	18,147,017	18,147,017	'	'	'	'
Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Net income	15.8	'	'	15.8	'	'
Other comprehensive income, net of tax	0.9	'	'	'	'	0.9
Issuance of non-vested shares to employees, shares	'	55,613	'	'	'	'
Issuance of common shares to employees upon vesting of restricted stock units and performance shares, shares	'	43,562	'	'	'	'
Cancellation of employee non-vested shares	'	-323	'	'	'	'
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares, shares	'	-30,869	'	'	'	'
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	-2.2	'	-2.2	'	'	'
Repurchase of common stock, shares	-184,400	-184,400	'	'	'	'
Repurchase of common stock	-12.7	'	'	'	-12.7	'
Cash dividends on common stock ($0.35 per share)	-6.4	'	'	-6.4	'	'
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	0.7	'	0.7	'	'	'
Amortization of unearned equity compensation	2	'	2	'	'	'
Ending balance at Mar. 31, 2014	$1,082.30	$0.20	$1,023.60	$243.20	($164.90)	($19.80)
Ending balance, shares at Mar. 31, 2014	18,030,600	18,030,600	'	'	'	'

Statements_of_Consolidated_Sto

Statements of Consolidated Stockholders' Equity Unaudited (Parenthetical) (Retained Earnings, USD $)	3 Months Ended
	Mar. 31, 2014
Retained Earnings	'
Cash dividends declared on common stock (per share)	$0.35

Statement_of_Consolidated_Cash

Statement of Consolidated Cash Flows (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:	'	'
Net income	$15.80	$33.50
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation of property, plant and equipment	7	6.6
Amortization of definite-lived intangible assets	0.4	0.4
Amortization of debt discount and debt issuance costs	2.9	2.7
Deferred income taxes	8.7	15.3
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	-0.7	-0.8
Non-cash equity compensation	2	2.6
Non-cash unrealized (gains) losses on derivative positions	-2.9	0.3
Gain on disposition of available for sale securities	0	-0.5
Non-cash net periodic pension benefit income relating to VEBAs	-5.6	-5.6
Other non-cash changes in assets and liabilities	0.1	-2.4
Changes in operating assets and liabilities:	'	'
Trade and other receivables	-2.2	-23.6
Inventories	11.3	-13.3
Prepaid expenses and other current assets	-2.3	-2.3
Accounts payable	10.4	9.9
Accrued liabilities	-1.4	0.5
Annual variable cash contribution to VEBAs	-16	-20
Payable to affiliate	0	4.4
Long-term assets and liabilities, net	-0.4	-1.4
Net cash provided by operating activities	27.1	6.3
Cash flows from investing activities:	'	'
Capital expenditures	-15.4	-9.3
Purchase of available for sale securities	0	-85.6
Proceeds from disposition of available for sale securities	25	85.2
Net cash provided by (used) in investing activities	9.6	-9.7
Cash flows from financing activities:	'	'
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	0.7	0.8
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	-2.2	-2.2
Repurchase of common stock	-12.7	-14.7
Cash dividend paid to stockholders	-6.4	-5.9
Net cash used in financing activities	-20.6	-22
Net increase (decrease) in cash and cash equivalents during the period	16.1	-25.4
Cash and cash equivalents at beginning of period	169.5	273.4
Cash and cash equivalents at end of period	$185.60	$248

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	Summary of Significant Accounting Policies
	This Quarterly Report on Form 10-Q (this "Report") should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
	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, general engineering, automotive, and other industrial end market applications. The Company has one operating segment, Fabricated Products. See Note 11 for additional information regarding the Company’s reportable segment and its other business units.
	Principles of Consolidation and Basis of Presentation. The accompanying unaudited 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”) applicable for interim periods and, therefore, do not include all information and footnotes required by GAAP for complete financial statements. In management’s opinion, all adjustments (which include normal recurring adjustments) considered necessary for a fair presentation have been included. The results of operations for the Company’s interim periods are not necessarily indicative of the results of operations that may be achieved for the entire 2014 fiscal year. The financial information as of December 31, 2013 is derived from the Company’s audited consolidated financial statements and footnotes for the year ended December 31, 2013 included in the Company’s Annual Report on Form 10-K.
	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.
	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. During the quarter ended March 31, 2014, the Company decremented a prior year, higher cost LIFO layer which resulted in a $1.8 charge. The excess of current cost over the stated LIFO value of inventory at March 31, 2014 and December 31, 2013 was $11.1 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 March 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 $1.1 and $0.4 during the quarters ended March 31, 2014 and March 31, 2013, 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. Depreciation expense is not included in Cost of products sold, excluding depreciation and amortization, but is included in Depreciation and amortization on the Statements of Consolidated Income. For the quarters ended March 31, 2014 and March 31, 2013, the Company recorded depreciation expense of $6.8 and $6.5, respectively, relating to the Company’s operating facilities in its Fabricated Products segment. An immaterial amount of depreciation expense was also recorded relating to the Company’s Corporate and Other business unit for all periods presented in this Report.
	New Accounting Pronouncements.
	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. An entity is required to adopt ASU 2013-11 for annual and interim periods beginning after December 15, 2013. The Company’s adoption of ASU 2013-11 in the first quarter of 2014 did not have a material impact on its financial statements.

Supplemental_Balance_Sheet_Inf

Supplemental Balance Sheet Information	3 Months Ended
	Mar. 31, 2014
Supplemental Balance Sheet Information [Abstract]	'
Supplemental Balance Sheet Information	'
	Supplemental Balance Sheet Information
		March 31, 2014			December 31, 2013
	Cash and Cash Equivalents.
	Cash and money market funds	$	68.5		$	57.7
	Commercial paper	117.1			111.8
	Total	$	185.6		$	169.5
	Trade Receivables.
	Billed trade receivables	$	124.1		$	120.2
	Unbilled trade receivables	0.2			0.4
	Trade receivables, gross	124.3			120.6
	Allowance for doubtful receivables	(0.8		)	(0.8		)
	Trade receivables, net	$	123.5		$	119.8
	Inventories.
	Finished products	$	65.9		$	72.5
	Work-in-process	66.9			75.9
	Raw materials	51.5			47.2
	Operating supplies and repair and maintenance parts	18.8			18.8
	Total	$	203.1		$	214.4
	Prepaid Expenses and Other Current Assets.
	Current derivative assets – Notes 8 and 9	$	4.1		$	2
	Current deferred tax assets	36.7			36.7
	Short-term restricted cash	0.3			0.3
	Prepaid taxes	2.8			—
	Prepaid expenses	4.7			5.2
	Total	$	48.6		$	44.2
	Property, Plant and Equipment - Net.
	Land and improvements	$	22.8		$	22.6
	Buildings and leasehold improvements	54.2			53
	Machinery and equipment	455.3			425.6
	Construction in progress	49.3			66
	Property, plant and equipment, gross	581.6			567.2
	Accumulated depreciation	(144.9		)	(137.9		)
	Total	$	436.7		$	429.3
	Other Assets.
	Derivative assets – Notes 8 and 9	$	84.2		$	79.8
	Restricted cash	9.3			9.3
	Deferred financing costs	8.2			8.9
	Deferred compensation plan assets	6.6			6.5
	Other	0.2			0.3
	Total	$	108.5		$	104.8
	Other Accrued Liabilities.
	Current derivative liabilities – Notes 8 and 9	$	2		$	1.8
	Uncleared cash disbursements	10.5			9.6
	Accrued income taxes and taxes payable	7.6			4.3
	Accrued annual VEBA contribution	—			16
	Short-term environmental accrual – Note 7	3.6			2.8
	Accrued interest	10.3			3.7
	Other	3.1			6.6
	Total	$	37.1		$	44.8
	Long-term Liabilities.
	Derivative liabilities – Notes 8 and 9	$	87.7		$	84.3
	Income tax liabilities	4.9			5
	Workers’ compensation accruals	23.4			23.3
	Long-term environmental accrual – Note 7	18.9			20
	Long-term asset retirement obligations	4.1			4
	Deferred compensation liability	7.2			7
	Long-term capital lease	0.1			0.1
	Other long-term liabilities	2.7			2.7
	Total	$	149		$	146.4
	Long-term Debt. — Note 3
	Senior notes	$	225		$	225
	Cash convertible senior notes	165.7			163.5
	Total	$	390.7		$	388.5

LongTerm_Debt_and_Credit_Facil

Long-Term Debt and Credit Facility	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	Long-Term Debt and Credit Facility
	Senior Notes
	In May 2012, the Company issued $225.0 principal amount of 8.25% Senior Notes due June 1, 2020 (the “Senior Notes”) at 100% of the principal amount. Interest expense, including amortization of deferred financing costs, relating to the Senior Notes was $4.8 for both quarters ended March 31, 2014 and March 31, 2013. A portion of the interest relating to the Senior Notes is capitalized as Construction in progress. See Note 3 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report Form 10-K for the year ended December 31, 2013 for additional information regarding the Senior Notes.
	Cash Convertible Senior Notes
	Convertible Notes. In March 2010, the Company issued $175.0 principal amount of 4.50% Cash Convertible Senior Notes due April 1, 2015 (the “Convertible Notes”). The Convertible Notes are unsecured obligations of the Company. 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 (the “Bifurcated Conversion Feature”) with the fair value on the issuance date equaling the original issue discount for purposes of accounting for the debt component of the Convertible Notes. The following tables provide additional information regarding the Convertible Notes:
		March 31, 2014			December 31, 2013
	Principal amount	$	175		$	175
	Less: unamortized issuance discount	(9.3		)	(11.5		)
	Carrying amount, net of discount	$	165.7		$	163.5
		Quarter Ended
		March 31,
		2014			2013
	Contractual coupon interest	$	2		$	2
	Amortization of discount	2.1			1.9
	Amortization of deferred financing costs	0.3			0.3
	Total interest expense1	$	4.4		$	4.2
	____________
	1	A portion of the interest relating to the Convertible Notes is 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 March 31, 2014, the conversion rate was 20.8234 shares per $1,000 principal amount of the Convertible Notes and the equivalent conversion price was approximately $48.02 per share, reflecting cumulative adjustments for quarterly dividends paid in excess of $0.24 per share.
	Holders may convert their Convertible Notes at any time on or after January 1, 2015. Additionally, holders may convert the Convertible Notes before January 1, 2015 in certain limited circumstances determined by (i) the trading price of the Convertible Notes, (ii) the occurrence of specified corporate events, or (iii) the market price of the Company's common stock. Because the Company's closing stock price exceeded 130% of the conversion price for 20 trading days during a period of 30 consecutive trading days ending on March 31, 2014, the last trading date of the first quarter of 2014, holders may convert the Convertible Notes during the second quarter of 2014. The Company believes that the market value of the Convertible Notes will continue to exceed the amount of cash payable upon conversion, making early conversion unlikely. As of March 31, 2014, no Convertible Notes had been converted.
	Convertible Note Hedge Transactions. In March 2010, the Company purchased cash-settled call options (the “Call Options”) that have an exercise price equal to the conversion price of the Convertible Notes and an expiration date that is the same as the maturity or on the earlier conversion date of the Convertible Notes. If the Company exercises the Call Options, the aggregate amount of cash it would receive from the counterparties to the Call Options will cover the aggregate amount of cash that the Company would be required to pay to the holders of the converted Convertible Notes, less the principal amount thereof. Contemporaneous with the purchase of the Call Options, the Company also sold net-share-settled warrants (the “Warrants”) with an exercise date of July 1, 2015 relating to approximately 3.6 million shares of the Company’s common stock. The Call Option and the Warrants have anti-dilution provisions similar to the Convertible Notes. At March 31, 2014, the exercise prices were $48.02 per share and $60.98 per share for the Call Options and the Warrants, respectively, reflecting cumulative adjustments for quarterly dividends paid in excess of $0.24 per share.
	See Note 3 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for additional information regarding the Convertible Notes, the Call Options and the Warrants.
	See “Fair Values of Financial Assets and Liabilities - All Other Financial Assets and Liabilities” in Note 9 for information relating to the estimated fair value of the Senior Notes and Convertible Notes.
	Revolving Credit Facility
	The Company’s credit agreement with JPMorgan Chase Bank, N.A., as administrative agent, and the other financial institutions party thereto (the “Revolving Credit Facility”) provides the Company with a $300.0 funding commitment through September 30, 2016. The Company had $263.4 of borrowing availability under the Revolving Credit Facility at March 31, 2014, based on the borrowing base determination then in effect. At March 31, 2014, there were no borrowings under the Revolving Credit Facility and $7.0 was being used to support outstanding letters of credit, leaving $256.4 of net borrowing availability. The interest rate applicable to any overnight borrowings under the Revolving Credit Facility would have been 4.00% at March 31, 2014.
	See Note 3 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for additional information regarding the Revolving Credit Facility.

Income_Tax_Matters

Income Tax Matters	3 Months Ended
	Mar. 31, 2014
Income Tax Disclosure [Abstract]	'
Income Tax Matters	'
	Income Tax Matters
	The provision for incomes taxes, for each period presented, consisted of the following:
		Quarter Ended
		March 31,
		2014		2013
	Domestic	$	9.1	$	15.4
	Foreign	0.3		(7.2		)
	Total	$	9.4	$	8.2
	The income tax provision for the quarters ended March 31, 2014 and March 31, 2013 was $9.4 and $8.2, reflecting an effective tax rate of 37.4% and 19.7%, respectively.
	The difference between the effective tax rate and projected blended statutory tax rate for the quarter ended March 31, 2013 was the result of a decrease in unrecognized tax benefits, including interest and penalties, of $7.5, resulting in a 17.9% decrease in the effective tax rate. The decrease in unrecognized tax benefits was a result of an audit settlement with the Canada Revenue Agency Competent Authority on February 28, 2013 for the 1998-2004 tax years which resulted in a cash tax benefit to the Company of $7.6, of which $7.2 has been received as of March 31, 2014. In addition, during the third quarter of 2013, the Company signed an advance pricing agreement with Canada Revenue Agency, which resulted in an additional cash tax benefit of $2.8, which is expected to be refunded within the next 12 months.
	The Company’s gross unrecognized benefits relating to uncertain tax positions were $3.7 and $3.8 at March 31, 2014 and December 31, 2013, respectively, of which, $2.6 and $2.7 will go through the Company’s income tax provision and thus impact the effective tax rate at March 31, 2014 and December 31, 2013, respectively, if and when the gross unrecognized tax benefits are recognized.
	The Company expects its gross unrecognized tax benefits to be reduced by $1.5 within the next 12 months.
	See Note 6 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for additional information regarding income taxes.

Employee_Benefits

Employee Benefits	3 Months Ended
	Mar. 31, 2014
Compensation and Retirement Disclosure [Abstract]	'
Employee Benefits	'
	Employee Benefits
	Pension and Similar Benefit Plans. The Company has provided contributions to (i) multi-employer pension plans sponsored by the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union AFL-CIO, CLC (“USW”) and International Association of Machinists and certain other unions at certain of the Company’s production facilities, (ii) defined contribution 401(k) savings plans for hourly bargaining unit employees and salaried and certain hourly non-bargaining unit employees, (iii) a defined benefit plan for salaried employees at the Company’s London, Ontario facility, and (iv) 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. See Note 7 and Note 8 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for additional information with respect to the Company’s benefit plans.
	VEBA Postretirement Medical Obligations. Certain retirees receive medical coverage through participation in a voluntary employees beneficiary association (“VEBA”) for the benefit of certain union retirees, their surviving spouses and eligible dependents (the “Union VEBA”) or a VEBA that provides benefits for certain other eligible retirees, their surviving spouses and eligible dependents (the “Salaried VEBA” and, together with the Union VEBA, the “VEBAs”). The Union VEBA is managed by four trustees, two of which are appointed by the Company and two of which are appointed by the USW. Its assets are managed by an independent fiduciary. The Salaried VEBA is managed by trustees who are independent of the Company.
	The Company has no ownership interest in the assets of the VEBAs nor any obligation to fund their liabilities. The benefits paid by the VEBAs to the plan participants are made at the sole discretion of the respective VEBA trustees and are outside the Company's control. The Company’s only financial obligations to the VEBAs are (i) an annual variable cash contribution (described below) and (ii) reimbursement of annual administrative expenses of the VEBAs up to $0.3 in the aggregate. Nevertheless, the Company accounts for the VEBAs as defined benefit postretirement plans with the maximum benefits payable equal to the total of the current VEBA assets and any future variable contributions from the Company and earnings thereon.
	Under this accounting treatment, the funding status of the VEBAs is reflected as a net asset or liability on the Company's Consolidated Balance Sheets, but such net asset or liability has no impact on the Company's cash flow or liquidity. The only impact that the VEBAs have on the Company’s cash flow or liquidity is with respect to the Company's obligations to make an annual variable cash contribution and to reimburse the VEBAs’ administrative expenses. The amount of annual variable contribution to be made by the Company is determined as follows: 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. Amounts owing by the Company to the VEBAs are recorded on the Company’s Consolidated Balance Sheets at the end of each year, in Other accrued liabilities (until paid in cash), with a corresponding increase in Net assets in respect of VEBA, a decrease in Net liability in respect of VEBA, or a combination thereof. The annual variable contributions with respect to 2013 and 2012 totaled $16.0 and $20.0 at December 31, 2013 and December 31, 2012, respectively, and were paid during the subsequent first quarters.
	Components of Net Periodic Pension Benefit (Income) Cost. The Company’s results of operations included the following impacts associated with the VEBAs and the Canadian defined benefit plan: (i) charges for service rendered by employees; (ii) a charge for accretion of interest; (iii) a benefit for the return on plan assets; and (iv) amortization of net gains or losses on assets, prior service costs associated with plan amendments and actuarial differences. Net periodic pension benefit cost related to the Canadian defined benefit plan was not material for the quarters ended March 31, 2014 and March 31, 2013. The following table presents the components of net periodic pension benefit income for the VEBAs and charges relating to all other employee benefit plans for the quarters ended March 31, 2014 and March 31, 2013:
		Quarter Ended
		March 31,
		2014			2013
	VEBAs:
	Service cost	$	0.6		$	0.6
	Interest cost	4.1			3.6
	Expected return on plan assets	(12.8		)	(11.2		)
	Amortization of prior service cost	2.8			1.1
	Amortization of net actuarial (gain) loss	(0.3		)	0.3
	Total net periodic pension benefit income relating to VEBAs	(5.6		)	(5.6		)
	Deferred compensation plan	0.2			0.4
	Defined contribution plans	4			4
	Multiemployer pension plans	0.9			0.8
	Total	$	(0.5	)	$	(0.4	)
	The following table presents the allocation of the (income) charges detailed above, by reportable segment and business unit(see Note 11):
		Quarter Ended
		March 31,
		2014			2013
	Fabricated Products	$	4.6		$	4.6
	All Other	(5.1		)	(5.0		)
	Total	$	(0.5	)	$	(0.4	)
	For all periods presented, the net periodic pension benefit income relating to the VEBAs are included as Net periodic pension benefit income relating to VEBAs within All Other. Further, 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.
	See Note 7 of Notes to Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for additional information with respect to the VEBAs and key assumptions used with respect to the Company’s pension plans and key assumptions made in computing the net obligation of each VEBA.

Employee_Incentive_Plans

Employee Incentive Plans	3 Months Ended
	Mar. 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 2013 STI plan 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 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 EBIDTA”), adjusted for certain safety, quality, delivery, cost and individual performance factors. The Adjusted EBITDA goals 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:
		Quarter Ended
		March 31,
		2014			2013
	Cost of products sold, excluding depreciation and amortization and other items	$	1.1		$	1.1
	Selling, administrative, research and development, and general	1.3			3
	Total costs recorded in connection with STI Plans	$	2.4		$	4.1
	The following table presents the allocation of the charges detailed above, by reportable segment and business unit:
		Quarter Ended
		March 31,
		2014			2013
	Fabricated Products	$	1.9		$	2.9
	All Other	0.5			1.2
	Total costs recorded in connection with STI Plans	$	2.4		$	4.1
	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 directors of the Company, are eligible to participate in the Kaiser Aluminum Corporation Amended and Restated 2006 Equity and Performance Incentive Plan (as amended, 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 March 31, 2014, 761,462 common shares were available for additional awards under the Equity Incentive Plan.
	Non-vested Common Shares, Restricted Stock Units and Performance Shares. 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 the employee will receive one common share for each restricted stock unit upon the vesting of the restricted stock unit. In addition to non-vested common shares and restricted stock units, the Company also grants performance shares to executive officers and other key employees. Performance shares granted prior to 2014 are subject to performance requirements pertaining to the Company’s EVA as set forth in each year’s LTI Program, measured over a three-year performance period. EVA, as defined in the Company’s LTI Programs, 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. The number of performance shares, if any, that will ultimately vest under the prior year programs and result in the issuance of common shares depends on the average annual EVA achieved for the specified three-year performance period. Performance shares granted in 2014 are subject to market-based requirements 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 performance shares, if any, that will ultimately vest under the 2014-2016 LTI program and result in the issuance of common shares depends on the percentile ranking of the Company’s TSR compared to the group of peer companies.
	During the first quarter of 2014, a portion of the performance shares granted under the 2011-2013 LTI program vested (see “Summary of Activity” below). The vesting of performance shares and resulting issuance and delivery of common shares, if any, under the 2012-2014 and 2013-2015 LTI programs will occur in 2015 and 2016, respectively. The vesting of performance shares and resulting issuance and delivery of common shares, if any, under the 2014-2016 LTI program will occur in 2017. Holders of performance shares do not receive voting rights through the ownership of such shares.
	See Note 9 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for additional information with respect to the Equity Incentive Plan and the detailed vesting requirements for the different types of equity awards described above.
	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. Recorded non-cash compensation expense by type of award under LTI Programs was as follows, for each period presented:
		Quarter Ended
		March 31,
		2014			2013
	Service-based non-vested common shares and restricted stock units	$	1.1		$	1.7
	Performance shares	0.5			0.9
	Market-based shares	0.4			—
	Total non-cash compensation expense	$	2		$	2.6
	The following table presents the allocation of the charges detailed above, by reportable segment and business unit:
		Quarter Ended
		March 31,
		2014			2013
	Fabricated Products	$	1		$	0.6
	All Other	1			2
	Total non-cash compensation expense	$	2		$	2.6
	Unrecognized Gross Compensation Cost Data. The following table presents unrecognized gross compensation cost data as of March 31, 2014:
		Unrecognized gross compensation costs, by award type			Expected period (in years) over which the remaining gross compensation costs will be recognized, by award type
	Service-based non-vested common shares and restricted stock units	$	6.6		2.1
	Performance shares	$	3.7		1.7
	Market-based shares	$	6.3		2.9
	Summary of Activity. A summary of the activity with respect to non-vested common shares, restricted stock units and performance shares (both financial performance-based and market-based) for the quarter ended March 31, 2014 is as follows:
		Non-Vested					Restricted				Performance				Performance Shares (Market-Based)
		Common Shares					Stock Units				Shares (Financial performance-based)
		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	55,613		67.42			2,235		67.42		—		—		160,868	83.18
	Vested	(43,640	)	48.61			(2,350	)	46.83		(41,212	)	46.65		—	—
	Forfeited	(323	)	52.32			—		—		(1,111	)	50.51		—	—
	Canceled	—		—			—		—		(138,051	)	46.65		—	—
	Outstanding at March 31, 2014	155,617		$	57.62		5,357		$	59.71	382,180		$	50.49	160,868	$	83.18
	A summary of select activity with respect to non-vested common shares, restricted stock units and performance shares for the quarter ended March 31, 2013 is as follows:
		Non-Vested					Restricted				Performance
		Common Shares					Stock Units				Shares
		Shares		Weighted-Average			Units		Weighted-Average		Shares		Weighted-Average
				Grant-Date Fair					Grant-Date Fair				Grant-Date Fair
				Value per Share					Value per Unit				Value per Share
	Granted	57,190		$	57.54		2,333		$	57.54	167,312		$	57.54
	Vested	(65,646	)	$	40.29		(2,311	)	$	42.74	(32,312	)	$	34.13
	Stock Options. The Company has fully-vested stock options from a one-time issuance in 2007. As of both March 31, 2014 and December 31, 2013, 20,791 fully-vested options were outstanding, in each case exercisable to purchase common shares at $80.01 per share and having a remaining contractual life of 3.0 and 3.25 years, respectively. The average fair value of the options granted was $39.90. No new options were granted and no existing options were forfeited or exercised during the quarter ended March 31, 2014.
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. Such shares are generally issued during the second quarter of each fiscal year.
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 the quarters ended March 31, 2014 and March 31, 2013, 30,869 and 35,838 common shares, respectively, were withheld and canceled for this purpose.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 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 Call Options and Warrants) and letters of credit (see Note 3 and Note 8).
	Refer to Note 10 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for information relating to minimum rental commitments under operating leases and purchase obligations. There were no material changes to such scheduled rental commitments and purchase obligations as of March 31, 2014.
	Environmental Contingencies. The Company is subject to a number of environmental laws and regulations, to potential fines or penalties assessed for alleged breaches of the environmental 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.
	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 Company’s Spokane (Trentwood), Washington 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 during the third quarter of 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 (the “OEPA”), the Company initiated an investigational study of its Newark, Ohio 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 March 31, 2014, the Company’s environmental accrual of $22.5 represented the Company’s estimate of the incremental remediation cost based on proposed alternatives in the final feasibility study related to the Company’s Spokane (Trentwood), Washington facility and currently available facts with respect to its Newark, Ohio facility and certain other locations owned or formally owned by the Company. Once the proposed remediation actions are approved for these sites, 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 $24.9 over the remediation period. It is reasonably possible that the Company’s recorded estimate may change in the next 12 months. Refer to Note 10 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for information relating to environmental contingencies.
	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 accrued 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	3 Months Ended
	Mar. 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 cash-settled Call Options relating to the Company’s common stock to limit its exposure to the cash conversion feature of the Convertible Notes (see Note 3).
	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 metal price fluctuations to its customers. However, in certain instances the Company enters into firm-price arrangements with its customers for stipulated volumes to be delivered in the future. 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 creates metal price risks for the Company. The Company uses third-party hedging instruments to limit exposure to metal price risks related to firm-price customer sales contracts. See Note 9 for additional information regarding the Company’s material derivative positions relating to hedges of operational risks, and their respective fair values.
	A majority of the Company’s derivative contracts relating to hedges of operational risks contain credit risk-related contingency features that could require the Company to provide additional collateral in the event the Company’s credit rating were to be downgraded. 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 contain credit risk-related contingency features and were in a net liability position at March 31, 2014 and December 31, 2013 were $1.3 and $1.6, respectively.
	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.
	During the quarters ended March 31, 2014 and March 31, 2013, total fabricated products shipments sold under firm-price arrangements were (in millions of pounds) 34.4 and 29.8, respectively. At March 31, 2014, the Company had customer sales contracts for the delivery of fabricated aluminum products pursuant to firm-price arrangements for the remainder of 2014 and 2015, totaling approximately (in millions of pounds) 62.3 and 2.6, respectively.
	Hedges Relating to the Convertible Notes. As described in Note 3, the Company issued Convertible Notes in the aggregate principal amount of $175.0 in March 2010. The conversion feature of the Convertible Notes can only be settled in cash and must be bifurcated from the Convertible Notes and treated as a separate derivative instrument for financial reporting purposes. In order to offset the cash flow risk associated with the Bifurcated Conversion Feature, the Company purchased Call Options, which are accounted for as derivative instruments. The Company expects that the realized gain or loss from the Call Options will substantially offset the realized loss or gain of the Bifurcated Conversion Feature upon maturity of the Convertible Notes. However, because valuation assumptions for the Bifurcated Conversion Feature and the Call Option are not identical, over time the Company expects to record net unrealized gains and losses due to mark-to-market adjustments to the fair values of the two derivatives. See Note 9 for additional information regarding the fair values of the Bifurcated Conversion Feature and the Call Options.
	Realized and Unrealized Gains and Losses. Realized and unrealized gains (losses) associated with all derivative contracts consisted of the following, for each period presented:
		Quarter Ended
		March 31,
		2014				2013
	Realized gains (losses):
	Aluminum	$	0.8			$	—
	Natural Gas	0.7				(0.7		)
	Electricity	0.5				—
	Total realized gains (losses)	$	2			$	(0.7	)
	Unrealized gains (losses):
	Aluminum	$	1.7			$	(4.4	)
	Natural Gas	0.8				2.7
	Electricity	(0.5		)		1.2
	Foreign Currency	—				(0.2		)
	Call Options relating to the Convertible Notes	4.4				6
	Bifurcated Conversion Feature of the Convertible Notes	(3.5		)		(5.6		)
	Total unrealized gains (losses)	$	2.9			$	(0.3	)
	The following table summarizes the Company’s material derivative positions at March 31, 2014:
	Aluminum		Maturity Period (month/year)	Notional Amount of contracts (mmlbs)
	Fixed priced purchase contracts		4/14 through 12/15	54
	Fixed priced sales contracts		6/14 through 11/14	0.4
	Midwest premium swap contracts1		4/14 through 12/15	52.4
	Natural Gas2		Maturity Period (month/year)	Notional Amount of contracts (mmbtu)
	Fixed priced purchase contracts		4/14 through 12/16	6,120,000
	Electricity		Maturity Period (month/year)	Notional Amount of contracts (Mwh)
	Fixed priced purchase contracts		4/14 through 12/15	340,225
	Foreign Currency		Maturity Period (month/year)	Notional Amount of contracts (as shown)
	GBP —
	Fixed priced purchase contracts		4/14 through 5/14	£	44,106
	Hedges Relating to the Convertible Notes		Contract Period (month/year)	Notional Amount of contracts (Common Shares)
	Bifurcated Conversion Feature3		3/10 through 3/15	3,644,095
	Call Options3		3/10 through 3/15	3,644,095
	______________________
	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 March 31, 2014, the Company’s exposure to fluctuations in natural gas prices had been substantially reduced for approximately 89%, 73% and 18% of the expected natural gas purchases for the remainder of 2014, 2015 and 2016, respectively.
	3	The Bifurcated Conversion Feature represents the cash conversion feature of the Convertible Notes. The Call Options 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 Call Options is derived from a notional number of shares of the Company’s common stock, the Call Options 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 March 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)	$	1.4			$	—		$	1.4		$	1.2		$	—	$	0.2
	Counterparty (without Netting Agreements)1	85.7				—			85.7			—			—		85.7
	Counterparty (with partial Netting Agreements)	1.2				—			1.2			0.6			—		0.6
	Total	$	88.3			$	—		$	88.3		$	1.8		$	—	$	86.5
	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)	$	(1.9	)		$	—		$	(1.9	)	$	(1.2	)	$	—	$	(0.7	)
	Counterparty (without Netting Agreements)1	(86.9		)		—			(86.9		)	—			—		(86.9		)
	Counterparty (with partial Netting Agreements)	(0.9		)		—			(0.9		)	(0.6		)	—		(0.3		)
	Total	$	(89.7	)		$	—		$	(89.7	)	$	(1.8	)	$	—	$	(87.9	)
	_________________
	1	Such amounts include the fair value of the Bifurcated Conversion Feature and Call Options at March 31, 2014 (see Note 9).
	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 Call Options at December 31, 2013 (see Note 9).

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 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 measured on a recurring basis. The Company has elected not to carry any financial assets and liabilities at fair value, other than as required by GAAP. Financial assets and liabilities that the Company carries 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 5). 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 carried 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. For the quarters ended March 31, 2014 and March 31, 2013, the Company concluded that none of its non-financial 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.
	Fair Values of Financial Assets and Liabilities
	Fair Values of Derivative Assets and Liabilities. The Company’s derivative contracts are valued at fair value using significant observable and unobservable inputs.
	Commodity, Energy, Electricity and Foreign Currency Hedges - 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 other observable 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 are classified as Level 3 in the fair value hierarchy.
	Bifurcated Conversion Feature and Call Options - 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 mandatory redemption on April 1, 2015.
	The Company determines the fair value of the Call Options using a binomial lattice valuation model. The inputs to the model at March 31, 2014 were as follows:
	The Company’s stock price at March 31, 2014	$	71.42
	Quarterly dividend yield (per share) upon purchase of the Call Option1	$	0.24
	Risk-free interest rate2	0.13		%
	Credit spread (basis points)3	154
	Expected volatility rate4	17		%
	______________________
	1	The quarterly dividend in the first quarter of 2014 was $0.35 per share, but the model assumes a discrete $0.24 per share quarterly dividend as was paid at the inception of the Call Options. Quarterly dividends in excess of $0.24 per share do not affect the Call Options’ value due to anti-dilution adjustments.
	2	The risk-free rate was based on the one-year Constant Maturity Treasury rate on March 31, 2014.
	3	The credit spread is based on the Company’s long-term credit rating of BB- issued by Standard & Poor’s and a senior unsecured credit rating of Ba3 issued by Moody’s.
	4	The volatility rate was based on both observed volatility, which is based on the Company’s historical stock price, and implied volatility from the Company’s traded options. Such volatility was further adjusted to take into consideration market participant risk tolerance.
	The aggregate fair value of our derivatives, recorded on the Consolidated Balance Sheets at March 31, 2014 and December 31, 2013, was a net liability of $1.4 and $4.3, respectively. The decrease in net liability during the quarter ended March 31, 2014 was primarily due to changes in the underlying commodity prices during such quarter as well as an increase in our stock price which contributed to fluctuations in the values of the derivatives related to the Convertible Notes. Changes in the fair value of our derivative contracts relating to operational hedging activities are reflected in operating income. Such changes in the fair value of these contracts resulted in the recognition of a $2.0 unrealized mark-to-market gain during the quarter ended March 31, 2014.
	VEBA and Canadian Pension Plan Assets. The fair value of the plan assets of the VEBAs and the Company’s Canadian pension plan is measured annually on December 31. 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. See Note 12 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for additional information with respect to the fair value of the plan assets of the VEBAs and the Company’s Canadian pension plan.
	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 March 31, 2014, the remaining maturity period with respect to short-term investments ranged from four months to approximately 12 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 5). 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 March 31, 2014:
		Level 1			Level 2			Level 3		Total
	FINANCIAL ASSETS:
	Derivative instruments:
	Aluminum -
	Fixed priced purchase contracts	$	—		$	0.2		$	—	$	0.2
	Fixed priced sales contracts	—			0.1			—		0.1
	Midwest premium swap contracts	—			—			2.6		2.6
	Natural Gas -
	Fixed priced purchase contracts	—			1.1			—		1.1
	Electricity -
	Fixed priced purchase contracts	—			0.4			—		0.4
	Hedges Relating to the Convertible Notes -
	Call Options	—			83.9			—		83.9
	All Other Financial Assets:
	Cash and cash equivalents	68.5			117.1			—		185.6
	Short-term investments	—			104.5			—		104.5
	Deferred compensation plan asset	—			6.6			—		6.6
	Total Assets	$	68.5		$	313.9		$	2.6	$	385
	FINANCIAL LIABILITIES:
	Derivative instruments:
	Aluminum -
	Fixed priced purchase contracts	$	—		$	(1.7	)	$	—	$	(1.7	)
	Natural Gas -
	Fixed priced purchase contracts	—			(0.5		)	—		(0.5		)
	Electricity -
	Fixed priced purchase contracts	—			(0.9		)	—		(0.9		)
	Hedges Relating to the Convertible Notes -
	Bifurcated Conversion Feature	—			(86.6		)	—		(86.6		)
	All Other Financial Liabilities:
	Senior Notes	(255.4		)	—			—		(255.4		)
	Convertible Notes	(266.2		)	—			—		(266.2		)
	Total Liabilities	$	(521.6	)	$	(89.7	)	$	—	$	(611.3	)
	The following table presents the Company’s financial instruments, classified under the appropriate level of the fair value hierarchy, as of December 31, 2013:
		Level 1			Level 2			Level 3		Total
	FINANCIAL ASSETS:
	Derivative instruments:
	Aluminum -
Fixed priced purchase contracts	$	—		$	0.1		$	—	$	0.1
Midwest premium swap contracts	—			—			1.1		1.1
Natural Gas -
Fixed priced purchase contracts	—			0.5			—		0.5
Electricity -
Fixed priced purchase contracts	—			0.5			—		0.5
Foreign Currency -
Euro	—			0.1			—		0.1
Hedges Relating to the Convertible Notes -
Call Options	—			79.5			—		79.5
All Other Financial Assets:
Cash and cash equivalents	57.7			111.8			—		169.5
Short-term investments	—			129.5			—		129.5
Deferred compensation plan asset	—			6.5			—		6.5
Total Assets	$	57.7		$	328.5		$	1.1	$	387.3
FINANCIAL LIABILITIES:
Derivative instruments:
Aluminum -
Fixed priced purchase contracts	$	—		$	(1.8	)	$	—	$	(1.8	)
Natural Gas -
Fixed priced purchase contracts	—			(0.8		)	—		(0.8		)
Electricity -
Fixed priced 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	(260.0		)	—			—		(260.0		)
Total Liabilities	$	(515.4	)	$	(86.1	)	$	—	$	(601.5	)
Financial instruments classified as Level 3 in the fair value hierarchy represent derivative contracts in which management has used at least one significant unobservable input in the valuation model. The following table presents a reconciliation of activity for the Midwest premium derivative contracts on a net basis:
	Level 3
Balance at December 31, 2013	$	1.1
Total realized/unrealized gains included in:
Cost of goods sold excluding depreciation and amortization and other items and Unrealized losses (gains) on derivative instruments	1.8
Transactions involving Level 3 derivative contracts:
Purchases	0.4
Sales	—
Issuances	—
Settlements	(0.7		)
Transactions involving Level 3 derivatives — net	(0.3		)
Transfers in and (or) out of Level 3 valuation hierarchy	—
Balance at March 31, 2014	$	2.6
Total gains included in Unrealized losses (gains) on derivative instruments, attributable to the change in unrealized gains/losses relating to derivative contracts held at March 31, 2014:	$	2.1
Fair Values of Non-financial Assets and Liabilities
See Note 12 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 for additional information on the fair value of the Company’s non-financial assets and liabilities.

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	Earnings Per Share
	Basic and diluted earnings per share were calculated as follows, for each period presented:
		Quarter Ended
		March 31,
		2014		2013
	Numerator:
	Net income	$	15.8	$	33.5
	Denominator — Weighted-average common shares outstanding (in thousands):
	Basic1	17,921		19,143
	Add: dilutive effect of non-vested common shares, restricted stock units, performance shares and market-based shares	122		131
	Add: dilutive effect of warrants	471		92
	Diluted2	18,514		19,366
	Earnings per common share, Basic:
	Net income per share	$	0.88	$	1.75
	Earnings per common share, Diluted:
	Net income per share	$	0.85	$	1.73
	______________________
	1	The basic weighted-average number of common shares outstanding during the period excludes non-vested common shares, restricted stock units, performance shares and market-based shares.
	2	The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.
	Options to purchase 20,791 common shares at an average exercise price of $80.01 per share were outstanding at both March 31, 2014 and December 31, 2013. The potential dilutive effect of options outstanding was zero for both quarters ended March 31, 2014 and March 31, 2013.
	Warrants relating to approximately 3.6 million common shares were outstanding at both March 31, 2014 (at which date the average exercise price was approximately $60.98 per share) and March 31, 2013 (at which date the average exercise price was approximately $61.25 per share).
	During the quarters ended March 31, 2014 and March 31, 2013, the Company paid approximately $6.4 ($0.35 per common share) and $5.9 ($0.30 per common share), respectively, in cash dividends to stockholders, including the holders of non-vested common shares, and dividend equivalents to the holders of certain restricted stock units and to the holders of performance shares with respect to approximately one-half of the performance shares.
	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.
	During the quarters ended March 31, 2014 and March 31, 2013, the Company repurchased 184,400 shares of common stock (at a weighted-average price of $69.07 per share) and 259,596 shares of common stock (at a weighted-average price of $62.62 per share), respectively, pursuant to the stock repurchase program. The total cost of $12.7 and $16.2 was recorded as Treasury Stock at March 31, 2014 and March 31, 2013, respectively. At March 31, 2014 and December 31, 2013, $104.9 and $117.6, respectively, were available to repurchase the Company’s common shares pursuant to the stock repurchase program.

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Segment and Geographical Area Information	'
	Segment 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, general engineering, automotive, 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 called 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 operating charges, net.
	The following tables provide financial information by reporting segment for each period or as of each period-end, as applicable. For periods or period-ends prior to March 31, 2014, All Other also included activity relating to Anglesey Aluminum Limited (“Anglesey”). The Company sold its non-controlling interest in Anglesey during the quarter ended December 31, 2013.
		Quarter Ended
		March 31,
		2014			2013
	Net sales:
	Fabricated Products	$	335.1		$	337.4
	Segment operating income (loss):
	Fabricated Products 1,2	$	35.4		$	55.2
	All Other3	(3.3		)	(5.2		)
	Total operating income	$	32.1		$	50
	Interest expense	(8.8		)	(9.3		)
	Other income, net	1.9			1
	Income before income taxes	$	25.2		$	41.7
	Depreciation and amortization:
	Fabricated Products	$	7.2		$	6.9
	All Other	0.2			0.1
	Total depreciation and amortization	$	7.4		$	7
	Capital expenditures:
	Fabricated Products	$	15.3		$	8.9
	All Other	0.1			0.4
	Total capital expenditures	$	15.4		$	9.3
	Income taxes paid:
	Fabricated Products —
	United States	$	0.1		$	0.4
	Canada	0.6			0.3
	Total income taxes paid	$	0.7		$	0.7
	______________________
	1.	Operating results in the Fabricated Products segment for the quarter ended March 31, 2014 included a charge of $1.8 as a result of decrementing a prior year, higher cost LIFO layer.
	2.	Fabricated Products segment results include non-cash mark-to-market gains (losses) on primary aluminum, natural gas, electricity and foreign currency hedging activities totaling $2.0 and $(0.7) for the quarters ended March 31, 2014 and March 31, 2013, respectively. For further discussion regarding mark-to-market matters, see Note 8.
	3.	Operating results in All Other include VEBA net periodic pension benefit income of $5.6 for both quarters ended March 31, 2014 and March 31, 2013, respectively.
		March 31, 2014			December 31, 2013
	Assets:
	Fabricated Products	$	853.7		$	852.5
	All Other1	912.3			918.4
	Total assets	$	1,766.00		$	1,770.90
	_____________________
	1.	Assets in All Other represent primarily all of the Company’s cash and cash equivalents, short-term investments, financial derivative assets, net assets of VEBA(s) (see Note 5) and net deferred income tax assets.
	Net sales by product categories, which are based on end market applications, for the Fabricated Products segment are as follows:
		Quarter Ended
		March 31,
		2014			2013
	Net sales:
	Aero/HS products	$	163.6		$	179.6
	GE products	112.2			105.8
	Automotive Extrusions	40.8			30.8
	Other products	18.5			21.2
	Total net sales	$	335.1		$	337.4

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	3 Months Ended
	Mar. 31, 2014
Supplemental Cash Flow Elements [Abstract]	'
Supplemental Cash Flow Information	'
	Supplemental Cash Flow Information
		Quarter Ended
		March 31,
		2014		2013
	Supplemental disclosure of cash flow information:
	Interest paid	$	0.4	$	0.4
	Income taxes paid	$	0.7	$	0.7
	Supplemental disclosure of non-cash transactions:
	Stock repurchases not yet settled (accrued in accounts payable)	$	—	$	1.5
	Non-cash capital expenditures	$	3.4	$	2.7
	Capital leases acquired	$	—	$	0.1

Other_Income_Expense_Net

Other Income (Expense), Net	3 Months Ended
	Mar. 31, 2014
Other Income and Expenses [Abstract]	'
Other Income (Expense), Net	'
	Other Income (Expense), Net
	Other income (expense), net consisted of the following, for each period presented:
		Quarter Ended
		March 31,
		2014		2013
	Interest income	$	0.3	$	0.1
	Unrealized gains on financial derivatives1	0.9		0.4
	Realized gains on investments	0.2		0.5
	All other, net	0.5		—
	Other non-operating income, net	$	1.9	$	1
	______________________
	1	See “Hedges Relating to the Convertible Notes” in Note 8 for discussion of such instruments.

Other_Comprehensive_Income

Other Comprehensive Income	3 Months Ended
	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]	'
Other Comprehensive Income Disclosure	'
	Other Comprehensive Income
	The following table presents the tax effect allocated to each component of Other comprehensive income for each period presented:
		Before-Tax			Income Tax			Net-of-Tax
		Amount			(Expense) Benefit3			Amount
	Quarter Ended March 31, 2014
	VEBAs:
	Reclassification adjustments
	Amortization of net actuarial gain1	$	(0.3	)	$	0.1		$	(0.2	)
	Amortization of prior service cost1	2.8			(1.0		)	1.8
	Other comprehensive income relating to VEBAs	2.5			(0.9		)	1.6
	Available for sale securities
	Unrealized gains on available for sale securities	0.1			—			0.1
	Reclassification adjustments
	Reclassification of unrealized gain upon sale of available for sale securities2	(0.1		)	—			(0.1		)
	Other comprehensive income relating to available for sale securities	—			—			—
	Foreign currency translation adjustment	0.2			—			0.2
	Cumulative tax rate adjustment	—			(0.9		)	(0.9		)
	Other comprehensive income	$	2.7		$	(1.8	)	$	0.9
	Quarter Ended March 31, 2013
	VEBAs:
	Reclassification adjustments
	Amortization of net actuarial loss1	$	0.3		$	(0.1	)	$	0.2
	Amortization of prior service cost1	1.1			(0.4		)	0.7
	Other comprehensive income relating to VEBAs	1.4			(0.5		)	0.9
	Available for sale securities
	Unrealized gains on available for sale securities	0.3			(0.1		)	0.2
	Reclassification Adjustments
	Reclassification of unrealized gain upon sale of available for sale securities2	(0.4		)	0.1			(0.3		)
	Other comprehensive loss relating to available for sale securities	(0.1		)	—			(0.1		)
	Foreign currency translation adjustment	0.4			—			0.4
	Other comprehensive income	$	1.7		$	(0.5	)	$	1.2
	________________
	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 (expense) income, 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.

Guarantor_and_NonGuarantor_Fin

Guarantor and Non-Guarantor Financial Statements (Notes)	3 Months Ended
	Mar. 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(the “Indenture”), among Kaiser Aluminum Corporation (the “Parent”), the subsidiary guarantors party thereto (the “Guarantor Subsidiaries”) and Wells Fargo Bank, National Association, as trustee (the “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 the following customary releases upon: 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 is; or iv) the exercise of legal defeasance or covenant defeasance by the Company or the discharge of the Company’s obligations under the Indenture.
	Pursuant to the requirements of Section 210.3-10(f) of Regulation S-X, the following condensed consolidating financial information as of March 31, 2014 and December 31, 2013, and for the quarters ended March 31, 2014 and March 31, 2013 present (i) the financial position, results of operation and cash flows for each of (a) the 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 the 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
	Quarter Ended March 31, 2014
		Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	ASSETS
	Current assets:
	Cash and cash equivalents	$	5		$	174.3		$	6.3		$	—		$	185.6
	Short-term investments	—			104.5			—			—			104.5
	Receivables:
	Trade, less allowance for doubtful receivables	—			119.5			4			—			123.5
	Intercompany receivables	32.2			25.4			0.7			(58.3		)	—
	Other	—			5.9			5.8			—			11.7
	Inventories	—			198			5.8			(0.7		)	203.1
	Prepaid expenses and other current assets	0.1			48			0.5			—			48.6
	Total current assets	37.3			675.6			23.1			(59.0		)	677
	Investments in and advances to subsidiaries	1,466.50			26.9			—			(1,493.4		)	—
	Property, plant, and equipment — net	—			421.6			15.1			—			436.7
	Long-term intercompany receivables	—			1.1			10.6			(11.7		)	—
	Net asset of VEBAs	—			414.1			—			—			414.1
	Deferred tax assets — net	—			50.2			—			9			59.2
	Intangible assets — net	—			33.3			—			—			33.3
	Goodwill	—			37.2			—			—			37.2
	Other assets	90.1			18.3			0.1			—			108.5
	Total	$	1,593.90		$	1,678.30		$	48.9		$	(1,555.1	)	$	1,766.00
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Current liabilities:
	Accounts payable	$	0.4		$	66.6		$	5.3		$	—		$	72.3
	Intercompany payable	22.8			36.9			1.9			(61.6		)	—
	Accrued salaries, wages, and related expenses	—			29.9			3.3			—			33.2
	Other accrued liabilities	10.1			25.8			1.2			—			37.1
	Short-term capital lease	—			0.2			—			—			0.2
	Total current liabilities	33.3			159.4			11.7			(61.6		)	142.8
	Deferred tax liability	—			—			1.2			—			1.2
	Long-term intercompany payable	1			10.7			—			(11.7		)	—
	Long-term liabilities	86.6			51.3			11.1			—			149
	Long-term debt	390.7			—			—			—			390.7
	Total liabilities	511.6			221.4			24			(73.3		)	683.7
	Total stockholders’ equity	1,082.30			1,456.90			24.9			(1,481.8		)	1,082.30
	Total	$	1,593.90		$	1,678.30		$	48.9		$	(1,555.1	)	$	1,766.00
	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, less allowance for doubtful receivables	—			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 asset 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 liability	—			—			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 COMPREHESIVE INCOME
Quarter Ended March 31, 2014
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	327.1		$	33.1		$	(25.1	)	$	335.1
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			278.9			28.4			(24.4		)	282.9
Unrealized gains on derivative instruments	—			(2.0		)	—			—			(2.0		)
Depreciation and amortization	—			7.1			0.3			—			7.4
Selling, administrative, research and development, and general:
Selling, administrative, research and development, and general	1			16.6			3.3			(0.6		)	20.3
Net periodic pension benefit income relating to VEBAs	—			(5.6		)	—			—			(5.6		)
Total selling, administrative, research and development, and general	1			11			3.3			(0.6		)	14.7
Total costs and expenses	1			295			32			(25.0		)	303
Operating (loss) income	(1.0		)	32.1			1.1			(0.1		)	32.1
Other (expense) income:
Interest (expense) income	(9.3		)	0.4			—			0.1			(8.8		)
Other income, net	1			1.2			(0.2		)	(0.1		)	1.9
(Loss) income before income taxes	(9.3		)	33.7			0.9			(0.1		)	25.2
Income tax provision	—			(12.6		)	(0.3		)	3.5			(9.4		)
Earnings in equity of subsidiaries	25.1			0.4			—			(25.5		)	—
Net income	$	15.8		$	21.5		$	0.6		$	(22.1	)	$	15.8
Comprehensive income	$	16.7		$	22.2		$	0.8		$	(23.0	)	$	16.7
CONDENSED CONSOLIDATING STATEMENT OF COMPREHESIVE INCOME
Quarter Ended March 31, 2013
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	331.8		$	30.4		$	(24.8	)	$	337.4
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			259.7			27			(23.1		)	263.6
Unrealized losses on derivative instruments	—			0.7			—			—			0.7
Depreciation and amortization	—			6.7			0.3			—			7
Selling, administrative, research and development, and general
Selling, administrative, research and development and general	0.4			20.4			2.4			(1.5		)	21.7
Net periodic pension benefit income relating to VEBAs	—			(5.6		)	—			—			(5.6		)
Total selling, administrative, research and development, and general	0.4			14.8			2.4			(1.5		)	16.1
Total costs and expenses	0.4			281.9			29.7			(24.6		)	287.4
Operating (loss) income	(0.4		)	49.9			0.7			(0.2		)	50
Other (expense) income:
Interest expense	(9.1		)	(0.3		)	—			0.1			(9.3		)
Other income, net	0.4			0.6			0.1			(0.1		)	1
(Loss) income before income taxes	(9.1		)	50.2			0.8			(0.2		)	41.7
Income tax (provision) benefit	—			(19.0		)	7.2			3.6			(8.2		)
Earnings in equity of subsidiaries	42.6			7.8			—			(50.4		)	—
Net income	$	33.5		$	39		$	8		$	(47.0	)	$	33.5
Comprehensive income	$	34.7		$	39.8		$	8.4		$	(48.2	)	$	34.7
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Quarter Ended March 31, 2014
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$	(11.0	)	$	35.8		$	2.3		$	—		$	27.1
Cash flows from investing activities:
Capital expenditures	—			(15.4		)	—			—			(15.4		)
Proceeds from disposition of available for sale securities	—			25			—			—			25
Net cash provided by investing activities	—			9.6			—			—			9.6
Cash flows from financing activities:
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	—			0.7			—			—			0.7
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	(2.2		)	—			—			—			(2.2		)
Cash dividend paid to stockholders	(6.4		)	—			—			—			(6.4		)
Repurchase of common stock	(12.7		)	—			—			—			(12.7		)
Intercompany loan	32.3			(29.5		)	(2.8		)	—			—
Net cash provided by (used in) financing activities	11			(28.8		)	(2.8		)	—			(20.6		)
Net increase (decrease) in cash and cash equivalents during the period	—			16.6			(0.5		)	—			16.1
Cash and cash equivalents at beginning of period	5			157.7			6.8			—			169.5
Cash and cash equivalents at end of period	$	5		$	174.3		$	6.3		$	—		$	185.6
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Quarter Ended March 31, 2013
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$	(0.5	)	$	5.4		$	1.4		$	—		$	6.3
Cash flows from investing activities:
Capital expenditures	—			(9.0		)	(0.3		)	—			(9.3		)
Purchase of available for sale securities	—			(85.6		)	—			—			(85.6		)
Proceeds from disposition of available for sale securities	—			85.2			—			—			85.2
Net cash used in investing activities	—			(9.4		)	(0.3		)	—			(9.7		)
Cash flows from financing activities:
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	(2.2		)	—			—			—			(2.2		)
Cash dividend paid to stockholders	(5.9		)	—			—			—			(5.9		)
Repurchase of common stock	(14.7		)	—			—			—			(14.7		)
Intercompany loan	23.3			(21.2		)	(2.1		)	—			—
Net cash provided by (used in) financing activities	0.5			(20.4		)	(2.1		)	—			(22.0		)
Net decrease in cash and cash equivalents during the period	—			(24.4		)	(1.0		)	—			(25.4		)
Cash and cash equivalents at beginning of period	5			266			2.4			—			273.4
Cash and cash equivalents at end of period	$	5		$	241.6		$	1.4		$	—		$	248

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Events
	Dividend Declaration. On April 15, 2014, the Company announced that its Board of Directors declared a cash dividend of $0.35 per common share or approximately $6.4 (including dividend equivalents), which will be paid on or about May 15, 2014 to stockholders of record at the close of business on April 25, 2014.
	Anti-dilution Adjustments to Convertible Notes and Convertible Note Hedge Transactions. Based on the Company’s closing stock price for its common stock on the ex-dividend date for the quarterly dividend declared in April 2014, (a) the Convertible Notes’ conversion rate will be 20.8549 shares per $1,000 principal amount of the Convertible Notes and the equivalent conversion price will be $47.95 per share, (b) the Call Options’ exercise price will be approximately $47.95 per share, and (c) the Warrants’ exercise price will each be $60.89 per share.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 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, general engineering, automotive, and other industrial end market applications. The Company has one operating segment, Fabricated Products. See Note 11 for additional information regarding the Company’s reportable segment and its other business units.
Principles of Consolidation and Basis of Presentation	'
	Principles of Consolidation and Basis of Presentation. The accompanying unaudited 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”) applicable for interim periods and, therefore, do not include all information and footnotes required by GAAP for complete financial statements. In management’s opinion, all adjustments (which include normal recurring adjustments) considered necessary for a fair presentation have been included. The results of operations for the Company’s interim periods are not necessarily indicative of the results of operations that may be achieved for the entire 2014 fiscal year. The financial information as of December 31, 2013 is derived from the Company’s audited consolidated financial statements and footnotes for the year ended December 31, 2013 included in the Company’s Annual Report on Form 10-K.
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.
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. During the quarter ended March 31, 2014, the Company decremented a prior year, higher cost LIFO layer which resulted in a $1.8 charge. The excess of current cost over the stated LIFO value of inventory at March 31, 2014 and December 31, 2013 was $11.1 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 March 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 $1.1 and $0.4 during the quarters ended March 31, 2014 and March 31, 2013, 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. Depreciation expense is not included in Cost of products sold, excluding depreciation and amortization, but is included in Depreciation and amortization on the Statements of Consolidated Income. For the quarters ended March 31, 2014 and March 31, 2013, the Company recorded depreciation expense of $6.8 and $6.5, respectively, relating to the Company’s operating facilities in its Fabricated Products segment. An immaterial amount of depreciation expense was also recorded relating to the Company’s Corporate and Other business unit for all periods presented in this Report.
New Accounting Pronouncements	'
	New Accounting Pronouncements.
	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. An entity is required to adopt ASU 2013-11 for annual and interim periods beginning after December 15, 2013. The Company’s adoption of ASU 2013-11 in the first quarter of 2014 did not have a material impact on its financial statements.

Supplemental_Balance_Sheet_Inf1

Supplemental Balance Sheet Information (Tables)	3 Months Ended
	Mar. 31, 2014
Supplemental Balance Sheet Information [Abstract]	'
Cash and Cash Equivalents	'
		March 31, 2014			December 31, 2013
	Cash and Cash Equivalents.
	Cash and money market funds	$	68.5		$	57.7
	Commercial paper	117.1			111.8
	Total	$	185.6		$	169.5
Trade Receivables	'
	Trade Receivables.
	Billed trade receivables	$	124.1		$	120.2
	Unbilled trade receivables	0.2			0.4
	Trade receivables, gross	124.3			120.6
	Allowance for doubtful receivables	(0.8		)	(0.8		)
	Trade receivables, net	$	123.5		$	119.8
Inventories	'
	Inventories.
	Finished products	$	65.9		$	72.5
	Work-in-process	66.9			75.9
	Raw materials	51.5			47.2
	Operating supplies and repair and maintenance parts	18.8			18.8
	Total	$	203.1		$	214.4
Prepaid Expenses and Other Current Assets	'
	Prepaid Expenses and Other Current Assets.
	Current derivative assets – Notes 8 and 9	$	4.1		$	2
	Current deferred tax assets	36.7			36.7
	Short-term restricted cash	0.3			0.3
	Prepaid taxes	2.8			—
	Prepaid expenses	4.7			5.2
	Total	$	48.6		$	44.2
Property, Plant and Equipment - Net	'
	Property, Plant and Equipment - Net.
	Land and improvements	$	22.8		$	22.6
	Buildings and leasehold improvements	54.2			53
	Machinery and equipment	455.3			425.6
	Construction in progress	49.3			66
	Property, plant and equipment, gross	581.6			567.2
	Accumulated depreciation	(144.9		)	(137.9		)
	Total	$	436.7		$	429.3
Other Assets	'
	Other Assets.
	Derivative assets – Notes 8 and 9	$	84.2		$	79.8
	Restricted cash	9.3			9.3
	Deferred financing costs	8.2			8.9
	Deferred compensation plan assets	6.6			6.5
	Other	0.2			0.3
	Total	$	108.5		$	104.8
Other Accrued Liabilities	'
	Other Accrued Liabilities.
	Current derivative liabilities – Notes 8 and 9	$	2		$	1.8
	Uncleared cash disbursements	10.5			9.6
	Accrued income taxes and taxes payable	7.6			4.3
	Accrued annual VEBA contribution	—			16
	Short-term environmental accrual – Note 7	3.6			2.8
	Accrued interest	10.3			3.7
	Other	3.1			6.6
	Total	$	37.1		$	44.8
Long-term Liabilities	'
	Long-term Liabilities.
	Derivative liabilities – Notes 8 and 9	$	87.7		$	84.3
	Income tax liabilities	4.9			5
	Workers’ compensation accruals	23.4			23.3
	Long-term environmental accrual – Note 7	18.9			20
	Long-term asset retirement obligations	4.1			4
	Deferred compensation liability	7.2			7
	Long-term capital lease	0.1			0.1
	Other long-term liabilities	2.7			2.7
	Total	$	149		$	146.4
Long-term Debt	'
	Long-term Debt. — Note 3
	Senior notes	$	225		$	225
	Cash convertible senior notes	165.7			163.5
	Total	$	390.7		$	388.5

LongTerm_Debt_and_Credit_Facil1

Long-Term Debt and Credit Facility (Tables)	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Principal amount, carrying amount, and interest expense of the notes	'							[1]
	The following tables provide additional information regarding the Convertible Notes:
		March 31, 2014			December 31, 2013
	Principal amount	$	175		$	175
	Less: unamortized issuance discount	(9.3		)	(11.5		)
	Carrying amount, net of discount	$	165.7		$	163.5
		Quarter Ended
		March 31,
		2014			2013
	Contractual coupon interest	$	2		$	2
	Amortization of discount	2.1			1.9
	Amortization of deferred financing costs	0.3			0.3
	Total interest expense1	$	4.4		$	4.2
	____________
	1	A portion of the interest relating to the Convertible Notes is capitalized as Construction in progress.
[1]	A portion of the interest relating to the Convertible Notes is capitalized as Construction in progress.

Income_Tax_Matters_Tables

Income Tax Matters (Tables)	3 Months Ended
	Mar. 31, 2014
Income Tax Disclosure [Abstract]	'
Tax Provision	'
	The provision for incomes taxes, for each period presented, consisted of the following:
		Quarter Ended
		March 31,
		2014		2013
	Domestic	$	9.1	$	15.4
	Foreign	0.3		(7.2		)
	Total	$	9.4	$	8.2

Employee_Benefits_Tables

Employee Benefits (Tables)	3 Months Ended
	Mar. 31, 2014
Compensation and Retirement Disclosure [Abstract]	'
Schedule of (Income) Charges Related to Benefit Plans	'
	The following table presents the components of net periodic pension benefit income for the VEBAs and charges relating to all other employee benefit plans for the quarters ended March 31, 2014 and March 31, 2013:
		Quarter Ended
		March 31,
		2014			2013
	VEBAs:
	Service cost	$	0.6		$	0.6
	Interest cost	4.1			3.6
	Expected return on plan assets	(12.8		)	(11.2		)
	Amortization of prior service cost	2.8			1.1
	Amortization of net actuarial (gain) loss	(0.3		)	0.3
	Total net periodic pension benefit income relating to VEBAs	(5.6		)	(5.6		)
	Deferred compensation plan	0.2			0.4
	Defined contribution plans	4			4
	Multiemployer pension plans	0.9			0.8
	Total	$	(0.5	)	$	(0.4	)
Allocation of (Income) Charges Relating to Benefit Plans by Segment	'
	The following table presents the allocation of the (income) charges detailed above, by reportable segment and business unit(see Note 11):
		Quarter Ended
		March 31,
		2014			2013
	Fabricated Products	$	4.6		$	4.6
	All Other	(5.1		)	(5.0		)
	Total	$	(0.5	)	$	(0.4	)

Employee_Incentive_Plans_Table

Employee Incentive Plans (Tables)	3 Months Ended
	Mar. 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:
		Quarter Ended
		March 31,
		2014			2013
	Cost of products sold, excluding depreciation and amortization and other items	$	1.1		$	1.1
	Selling, administrative, research and development, and general	1.3			3
	Total costs recorded in connection with STI Plans	$	2.4		$	4.1
	The following table presents the allocation of the charges detailed above, by reportable segment and business unit:
		Quarter Ended
		March 31,
		2014			2013
	Fabricated Products	$	1.9		$	2.9
	All Other	0.5			1.2
	Total costs recorded in connection with STI Plans	$	2.4		$	4.1
Non-cash compensation expense	'
	Recorded non-cash compensation expense by type of award under LTI Programs was as follows, for each period presented:
		Quarter Ended
		March 31,
		2014			2013
	Service-based non-vested common shares and restricted stock units	$	1.1		$	1.7
	Performance shares	0.5			0.9
	Market-based shares	0.4			—
	Total non-cash compensation expense	$	2		$	2.6
	The following table presents the allocation of the charges detailed above, by reportable segment and business unit:
		Quarter Ended
		March 31,
		2014			2013
	Fabricated Products	$	1		$	0.6
	All Other	1			2
	Total non-cash compensation expense	$	2		$	2.6
Unrecognized gross compensation cost data	'
	The following table presents unrecognized gross compensation cost data as of March 31, 2014:
		Unrecognized gross compensation costs, by award type			Expected period (in years) over which the remaining gross compensation costs will be recognized, by award type
	Service-based non-vested common shares and restricted stock units	$	6.6		2.1
	Performance shares	$	3.7		1.7
	Market-based shares	$	6.3		2.9
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 and performance shares (both financial performance-based and market-based) for the quarter ended March 31, 2014 is as follows:
		Non-Vested					Restricted				Performance				Performance Shares (Market-Based)
		Common Shares					Stock Units				Shares (Financial performance-based)
		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	55,613		67.42			2,235		67.42		—		—		160,868	83.18
	Vested	(43,640	)	48.61			(2,350	)	46.83		(41,212	)	46.65		—	—
	Forfeited	(323	)	52.32			—		—		(1,111	)	50.51		—	—
	Canceled	—		—			—		—		(138,051	)	46.65		—	—
	Outstanding at March 31, 2014	155,617		$	57.62		5,357		$	59.71	382,180		$	50.49	160,868	$	83.18
	A summary of select activity with respect to non-vested common shares, restricted stock units and performance shares for the quarter ended March 31, 2013 is as follows:
		Non-Vested					Restricted				Performance
		Common Shares					Stock Units				Shares
		Shares		Weighted-Average			Units		Weighted-Average		Shares		Weighted-Average
				Grant-Date Fair					Grant-Date Fair				Grant-Date Fair
				Value per Share					Value per Unit				Value per Share
	Granted	57,190		$	57.54		2,333		$	57.54	167,312		$	57.54
	Vested	(65,646	)	$	40.29		(2,311	)	$	42.74	(32,312	)	$	34.13

Derivative_Financial_Instrumen1

Derivative Financial Instruments and Related Hedging Programs (Tables)	3 Months Ended
	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Summary of realized and unrealized gains and losses	'
	Realized and unrealized gains (losses) associated with all derivative contracts consisted of the following, for each period presented:
		Quarter Ended
		March 31,
		2014				2013
	Realized gains (losses):
	Aluminum	$	0.8			$	—
	Natural Gas	0.7				(0.7		)
	Electricity	0.5				—
	Total realized gains (losses)	$	2			$	(0.7	)
	Unrealized gains (losses):
	Aluminum	$	1.7			$	(4.4	)
	Natural Gas	0.8				2.7
	Electricity	(0.5		)		1.2
	Foreign Currency	—				(0.2		)
	Call Options relating to the Convertible Notes	4.4				6
	Bifurcated Conversion Feature of the Convertible Notes	(3.5		)		(5.6		)
	Total unrealized gains (losses)	$	2.9			$	(0.3	)
Summary of material derivative positions	'
	The following table summarizes the Company’s material derivative positions at March 31, 2014:
	Aluminum		Maturity Period (month/year)	Notional Amount of contracts (mmlbs)
	Fixed priced purchase contracts		4/14 through 12/15	54
	Fixed priced sales contracts		6/14 through 11/14	0.4
	Midwest premium swap contracts1		4/14 through 12/15	52.4
	Natural Gas2		Maturity Period (month/year)	Notional Amount of contracts (mmbtu)
	Fixed priced purchase contracts		4/14 through 12/16	6,120,000
	Electricity		Maturity Period (month/year)	Notional Amount of contracts (Mwh)
	Fixed priced purchase contracts		4/14 through 12/15	340,225
	Foreign Currency		Maturity Period (month/year)	Notional Amount of contracts (as shown)
	GBP —
	Fixed priced purchase contracts		4/14 through 5/14	£	44,106
	Hedges Relating to the Convertible Notes		Contract Period (month/year)	Notional Amount of contracts (Common Shares)
	Bifurcated Conversion Feature3		3/10 through 3/15	3,644,095
	Call Options3		3/10 through 3/15	3,644,095
	______________________
	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 March 31, 2014, the Company’s exposure to fluctuations in natural gas prices had been substantially reduced for approximately 89%, 73% and 18% of the expected natural gas purchases for the remainder of 2014, 2015 and 2016, respectively.
	3	The Bifurcated Conversion Feature represents the cash conversion feature of the Convertible Notes. The Call Options 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 Call Options is derived from a notional number of shares of the Company’s common stock, the Call Options may only be settled in cash.
Summary of offsetting derivative instruments by counterparty	'
	The following tables present offsetting information regarding the Company’s derivatives by type of counterparty as of March 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)	$	1.4			$	—		$	1.4		$	1.2		$	—	$	0.2
	Counterparty (without Netting Agreements)1	85.7				—			85.7			—			—		85.7
	Counterparty (with partial Netting Agreements)	1.2				—			1.2			0.6			—		0.6
	Total	$	88.3			$	—		$	88.3		$	1.8		$	—	$	86.5
	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)	$	(1.9	)		$	—		$	(1.9	)	$	(1.2	)	$	—	$	(0.7	)
	Counterparty (without Netting Agreements)1	(86.9		)		—			(86.9		)	—			—		(86.9		)
	Counterparty (with partial Netting Agreements)	(0.9		)		—			(0.9		)	(0.6		)	—		(0.3		)
	Total	$	(89.7	)		$	—		$	(89.7	)	$	(1.8	)	$	—	$	(87.9	)
	_________________
	1	Such amounts include the fair value of the Bifurcated Conversion Feature and Call Options at March 31, 2014 (see Note 9).
	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 Call Options at December 31, 2013 (see Note 9).

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Assumptions used in determining fair value of the Call Option	'
	The Company determines the fair value of the Call Options using a binomial lattice valuation model. The inputs to the model at March 31, 2014 were as follows:
	The Company’s stock price at March 31, 2014	$	71.42
	Quarterly dividend yield (per share) upon purchase of the Call Option1	$	0.24
	Risk-free interest rate2	0.13		%
	Credit spread (basis points)3	154
	Expected volatility rate4	17		%
	______________________
	1	The quarterly dividend in the first quarter of 2014 was $0.35 per share, but the model assumes a discrete $0.24 per share quarterly dividend as was paid at the inception of the Call Options. Quarterly dividends in excess of $0.24 per share do not affect the Call Options’ value due to anti-dilution adjustments.
	2	The risk-free rate was based on the one-year Constant Maturity Treasury rate on March 31, 2014.
	3	The credit spread is based on the Company’s long-term credit rating of BB- issued by Standard & Poor’s and a senior unsecured credit rating of Ba3 issued by Moody’s.
	4	The volatility rate was based on both observed volatility, which is based on the Company’s historical stock price, and implied volatility from the Company’s traded options. Such volatility was further adjusted to take into consideration market participant risk tolerance.
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 March 31, 2014:
		Level 1			Level 2			Level 3		Total
	FINANCIAL ASSETS:
	Derivative instruments:
	Aluminum -
	Fixed priced purchase contracts	$	—		$	0.2		$	—	$	0.2
	Fixed priced sales contracts	—			0.1			—		0.1
	Midwest premium swap contracts	—			—			2.6		2.6
	Natural Gas -
	Fixed priced purchase contracts	—			1.1			—		1.1
	Electricity -
	Fixed priced purchase contracts	—			0.4			—		0.4
	Hedges Relating to the Convertible Notes -
	Call Options	—			83.9			—		83.9
	All Other Financial Assets:
	Cash and cash equivalents	68.5			117.1			—		185.6
	Short-term investments	—			104.5			—		104.5
	Deferred compensation plan asset	—			6.6			—		6.6
	Total Assets	$	68.5		$	313.9		$	2.6	$	385
	FINANCIAL LIABILITIES:
	Derivative instruments:
	Aluminum -
	Fixed priced purchase contracts	$	—		$	(1.7	)	$	—	$	(1.7	)
	Natural Gas -
	Fixed priced purchase contracts	—			(0.5		)	—		(0.5		)
	Electricity -
	Fixed priced purchase contracts	—			(0.9		)	—		(0.9		)
	Hedges Relating to the Convertible Notes -
	Bifurcated Conversion Feature	—			(86.6		)	—		(86.6		)
	All Other Financial Liabilities:
	Senior Notes	(255.4		)	—			—		(255.4		)
	Convertible Notes	(266.2		)	—			—		(266.2		)
	Total Liabilities	$	(521.6	)	$	(89.7	)	$	—	$	(611.3	)
	The following table presents the Company’s financial instruments, classified under the appropriate level of the fair value hierarchy, as of December 31, 2013:
		Level 1			Level 2			Level 3		Total
	FINANCIAL ASSETS:
	Derivative instruments:
	Aluminum -
	Fixed priced purchase contracts	$	—		$	0.1		$	—	$	0.1
	Midwest premium swap contracts	—			—			1.1		1.1
	Natural Gas -
	Fixed priced purchase contracts	—			0.5			—		0.5
	Electricity -
	Fixed priced purchase contracts	—			0.5			—		0.5
	Foreign Currency -
	Euro	—			0.1			—		0.1
	Hedges Relating to the Convertible Notes -
	Call Options	—			79.5			—		79.5
	All Other Financial Assets:
	Cash and cash equivalents	57.7			111.8			—		169.5
	Short-term investments	—			129.5			—		129.5
	Deferred compensation plan asset	—			6.5			—		6.5
	Total Assets	$	57.7		$	328.5		$	1.1	$	387.3
	FINANCIAL LIABILITIES:
	Derivative instruments:
	Aluminum -
	Fixed priced purchase contracts	$	—		$	(1.8	)	$	—	$	(1.8	)
	Natural Gas -
	Fixed priced purchase contracts	—			(0.8		)	—		(0.8		)
	Electricity -
	Fixed priced 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	(260.0		)	—			—		(260.0		)
Total Liabilities	$	(515.4	)	$	(86.1	)	$	—	$	(601.5	)
Reconciliation of activity for financial instruments classified as Level 3	'
	The following table presents a reconciliation of activity for the Midwest premium derivative contracts on a net basis:
		Level 3
	Balance at December 31, 2013	$	1.1
	Total realized/unrealized gains included in:
	Cost of goods sold excluding depreciation and amortization and other items and Unrealized losses (gains) on derivative instruments	1.8
	Transactions involving Level 3 derivative contracts:
	Purchases	0.4
	Sales	—
	Issuances	—
	Settlements	(0.7		)
	Transactions involving Level 3 derivatives — net	(0.3		)
	Transfers in and (or) out of Level 3 valuation hierarchy	—
	Balance at March 31, 2014	$	2.6
	Total gains included in Unrealized losses (gains) on derivative instruments, attributable to the change in unrealized gains/losses relating to derivative contracts held at March 31, 2014:	$	2.1

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Calculation of basic and diluted earnings per share	'
	Basic and diluted earnings per share were calculated as follows, for each period presented:
		Quarter Ended
		March 31,
		2014		2013
	Numerator:
	Net income	$	15.8	$	33.5
	Denominator — Weighted-average common shares outstanding (in thousands):
	Basic1	17,921		19,143
	Add: dilutive effect of non-vested common shares, restricted stock units, performance shares and market-based shares	122		131
	Add: dilutive effect of warrants	471		92
	Diluted2	18,514		19,366
	Earnings per common share, Basic:
	Net income per share	$	0.88	$	1.75
	Earnings per common share, Diluted:
	Net income per share	$	0.85	$	1.73
	______________________
	1	The basic weighted-average number of common shares outstanding during the period excludes non-vested common shares, restricted stock units, performance shares and market-based shares.
	2	The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Summary of financial information by operating segment	'
	The following tables provide financial information by reporting segment for each period or as of each period-end, as applicable. For periods or period-ends prior to March 31, 2014, All Other also included activity relating to Anglesey Aluminum Limited (“Anglesey”). The Company sold its non-controlling interest in Anglesey during the quarter ended December 31, 2013.
		Quarter Ended
		March 31,
		2014			2013
	Net sales:
	Fabricated Products	$	335.1		$	337.4
	Segment operating income (loss):
	Fabricated Products 1,2	$	35.4		$	55.2
	All Other3	(3.3		)	(5.2		)
	Total operating income	$	32.1		$	50
	Interest expense	(8.8		)	(9.3		)
	Other income, net	1.9			1
	Income before income taxes	$	25.2		$	41.7
	Depreciation and amortization:
	Fabricated Products	$	7.2		$	6.9
	All Other	0.2			0.1
	Total depreciation and amortization	$	7.4		$	7
	Capital expenditures:
	Fabricated Products	$	15.3		$	8.9
	All Other	0.1			0.4
	Total capital expenditures	$	15.4		$	9.3
	Income taxes paid:
	Fabricated Products —
	United States	$	0.1		$	0.4
	Canada	0.6			0.3
	Total income taxes paid	$	0.7		$	0.7
	______________________
	1.	Operating results in the Fabricated Products segment for the quarter ended March 31, 2014 included a charge of $1.8 as a result of decrementing a prior year, higher cost LIFO layer.
	2.	Fabricated Products segment results include non-cash mark-to-market gains (losses) on primary aluminum, natural gas, electricity and foreign currency hedging activities totaling $2.0 and $(0.7) for the quarters ended March 31, 2014 and March 31, 2013, respectively. For further discussion regarding mark-to-market matters, see Note 8.
	3.	Operating results in All Other include VEBA net periodic pension benefit income of $5.6 for both quarters ended March 31, 2014 and March 31, 2013, respectively.
		March 31, 2014			December 31, 2013
	Assets:
	Fabricated Products	$	853.7		$	852.5
	All Other1	912.3			918.4
	Total assets	$	1,766.00		$	1,770.90
	_____________________
	1.	Assets in All Other represent primarily all of the Company’s cash and cash equivalents, short-term investments, financial derivative assets, net assets of VEBA(s) (see Note 5) and net deferred income tax assets.
Schedule of net sales by end market segment applications	'
	Net sales by product categories, which are based on end market applications, for the Fabricated Products segment are as follows:
		Quarter Ended
		March 31,
		2014			2013
	Net sales:
	Aero/HS products	$	163.6		$	179.6
	GE products	112.2			105.8
	Automotive Extrusions	40.8			30.8
	Other products	18.5			21.2
	Total net sales	$	335.1		$	337.4

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2014
Supplemental Cash Flow Elements [Abstract]	'
Supplemental Cash Flow Information	'
		Quarter Ended
		March 31,
		2014		2013
	Supplemental disclosure of cash flow information:
	Interest paid	$	0.4	$	0.4
	Income taxes paid	$	0.7	$	0.7
	Supplemental disclosure of non-cash transactions:
	Stock repurchases not yet settled (accrued in accounts payable)	$	—	$	1.5
	Non-cash capital expenditures	$	3.4	$	2.7
	Capital leases acquired	$	—	$	0.1

Other_Income_Expense_Net_Table

Other Income (Expense), Net (Tables)	3 Months Ended
	Mar. 31, 2014
Other Income and Expenses [Abstract]	'
Other Income (Expense), Net	'
	Other income (expense), net consisted of the following, for each period presented:
		Quarter Ended
		March 31,
		2014		2013
	Interest income	$	0.3	$	0.1
	Unrealized gains on financial derivatives1	0.9		0.4
	Realized gains on investments	0.2		0.5
	All other, net	0.5		—
	Other non-operating income, net	$	1.9	$	1
	______________________
	1	See “Hedges Relating to the Convertible Notes” in Note 8 for discussion of such instruments.

Other_Comprehensive_Income_Tab

Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]	'
Other Comprehensive Income	'
	The following table presents the tax effect allocated to each component of Other comprehensive income for each period presented:
		Before-Tax			Income Tax			Net-of-Tax
		Amount			(Expense) Benefit3			Amount
	Quarter Ended March 31, 2014
	VEBAs:
	Reclassification adjustments
	Amortization of net actuarial gain1	$	(0.3	)	$	0.1		$	(0.2	)
	Amortization of prior service cost1	2.8			(1.0		)	1.8
	Other comprehensive income relating to VEBAs	2.5			(0.9		)	1.6
	Available for sale securities
	Unrealized gains on available for sale securities	0.1			—			0.1
	Reclassification adjustments
	Reclassification of unrealized gain upon sale of available for sale securities2	(0.1		)	—			(0.1		)
	Other comprehensive income relating to available for sale securities	—			—			—
	Foreign currency translation adjustment	0.2			—			0.2
	Cumulative tax rate adjustment	—			(0.9		)	(0.9		)
	Other comprehensive income	$	2.7		$	(1.8	)	$	0.9
	Quarter Ended March 31, 2013
	VEBAs:
	Reclassification adjustments
	Amortization of net actuarial loss1	$	0.3		$	(0.1	)	$	0.2
	Amortization of prior service cost1	1.1			(0.4		)	0.7
	Other comprehensive income relating to VEBAs	1.4			(0.5		)	0.9
	Available for sale securities
	Unrealized gains on available for sale securities	0.3			(0.1		)	0.2
	Reclassification Adjustments
	Reclassification of unrealized gain upon sale of available for sale securities2	(0.4		)	0.1			(0.3		)
	Other comprehensive loss relating to available for sale securities	(0.1		)	—			(0.1		)
	Foreign currency translation adjustment	0.4			—			0.4
	Other comprehensive income	$	1.7		$	(0.5	)	$	1.2
	________________
	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 (expense) income, 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.

Guarantor_and_NonGuarantor_Fin1

Guarantor and Non-Guarantor Financial Statements (Tables)	3 Months Ended
	Mar. 31, 2014
Guarantor and Non-Guarantor Financial Statement [Abstract]	'
Schedule of Condensed Financial Statements	'
	CONDENSED CONSOLIDATING BALANCE SHEET
	Quarter Ended March 31, 2014
		Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	ASSETS
	Current assets:
	Cash and cash equivalents	$	5		$	174.3		$	6.3		$	—		$	185.6
	Short-term investments	—			104.5			—			—			104.5
	Receivables:
	Trade, less allowance for doubtful receivables	—			119.5			4			—			123.5
	Intercompany receivables	32.2			25.4			0.7			(58.3		)	—
	Other	—			5.9			5.8			—			11.7
	Inventories	—			198			5.8			(0.7		)	203.1
	Prepaid expenses and other current assets	0.1			48			0.5			—			48.6
	Total current assets	37.3			675.6			23.1			(59.0		)	677
	Investments in and advances to subsidiaries	1,466.50			26.9			—			(1,493.4		)	—
	Property, plant, and equipment — net	—			421.6			15.1			—			436.7
	Long-term intercompany receivables	—			1.1			10.6			(11.7		)	—
	Net asset of VEBAs	—			414.1			—			—			414.1
	Deferred tax assets — net	—			50.2			—			9			59.2
	Intangible assets — net	—			33.3			—			—			33.3
	Goodwill	—			37.2			—			—			37.2
	Other assets	90.1			18.3			0.1			—			108.5
	Total	$	1,593.90		$	1,678.30		$	48.9		$	(1,555.1	)	$	1,766.00
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Current liabilities:
	Accounts payable	$	0.4		$	66.6		$	5.3		$	—		$	72.3
	Intercompany payable	22.8			36.9			1.9			(61.6		)	—
	Accrued salaries, wages, and related expenses	—			29.9			3.3			—			33.2
	Other accrued liabilities	10.1			25.8			1.2			—			37.1
	Short-term capital lease	—			0.2			—			—			0.2
	Total current liabilities	33.3			159.4			11.7			(61.6		)	142.8
	Deferred tax liability	—			—			1.2			—			1.2
	Long-term intercompany payable	1			10.7			—			(11.7		)	—
	Long-term liabilities	86.6			51.3			11.1			—			149
	Long-term debt	390.7			—			—			—			390.7
	Total liabilities	511.6			221.4			24			(73.3		)	683.7
	Total stockholders’ equity	1,082.30			1,456.90			24.9			(1,481.8		)	1,082.30
	Total	$	1,593.90		$	1,678.30		$	48.9		$	(1,555.1	)	$	1,766.00
	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, less allowance for doubtful receivables	—			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 asset 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 liability	—			—			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 COMPREHESIVE INCOME
Quarter Ended March 31, 2014
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	327.1		$	33.1		$	(25.1	)	$	335.1
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			278.9			28.4			(24.4		)	282.9
Unrealized gains on derivative instruments	—			(2.0		)	—			—			(2.0		)
Depreciation and amortization	—			7.1			0.3			—			7.4
Selling, administrative, research and development, and general:
Selling, administrative, research and development, and general	1			16.6			3.3			(0.6		)	20.3
Net periodic pension benefit income relating to VEBAs	—			(5.6		)	—			—			(5.6		)
Total selling, administrative, research and development, and general	1			11			3.3			(0.6		)	14.7
Total costs and expenses	1			295			32			(25.0		)	303
Operating (loss) income	(1.0		)	32.1			1.1			(0.1		)	32.1
Other (expense) income:
Interest (expense) income	(9.3		)	0.4			—			0.1			(8.8		)
Other income, net	1			1.2			(0.2		)	(0.1		)	1.9
(Loss) income before income taxes	(9.3		)	33.7			0.9			(0.1		)	25.2
Income tax provision	—			(12.6		)	(0.3		)	3.5			(9.4		)
Earnings in equity of subsidiaries	25.1			0.4			—			(25.5		)	—
Net income	$	15.8		$	21.5		$	0.6		$	(22.1	)	$	15.8
Comprehensive income	$	16.7		$	22.2		$	0.8		$	(23.0	)	$	16.7
CONDENSED CONSOLIDATING STATEMENT OF COMPREHESIVE INCOME
Quarter Ended March 31, 2013
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Net sales	$	—		$	331.8		$	30.4		$	(24.8	)	$	337.4
Costs and expenses:
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	—			259.7			27			(23.1		)	263.6
Unrealized losses on derivative instruments	—			0.7			—			—			0.7
Depreciation and amortization	—			6.7			0.3			—			7
Selling, administrative, research and development, and general
Selling, administrative, research and development and general	0.4			20.4			2.4			(1.5		)	21.7
Net periodic pension benefit income relating to VEBAs	—			(5.6		)	—			—			(5.6		)
Total selling, administrative, research and development, and general	0.4			14.8			2.4			(1.5		)	16.1
Total costs and expenses	0.4			281.9			29.7			(24.6		)	287.4
Operating (loss) income	(0.4		)	49.9			0.7			(0.2		)	50
Other (expense) income:
Interest expense	(9.1		)	(0.3		)	—			0.1			(9.3		)
Other income, net	0.4			0.6			0.1			(0.1		)	1
(Loss) income before income taxes	(9.1		)	50.2			0.8			(0.2		)	41.7
Income tax (provision) benefit	—			(19.0		)	7.2			3.6			(8.2		)
Earnings in equity of subsidiaries	42.6			7.8			—			(50.4		)	—
Net income	$	33.5		$	39		$	8		$	(47.0	)	$	33.5
Comprehensive income	$	34.7		$	39.8		$	8.4		$	(48.2	)	$	34.7
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Quarter Ended March 31, 2014
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$	(11.0	)	$	35.8		$	2.3		$	—		$	27.1
Cash flows from investing activities:
Capital expenditures	—			(15.4		)	—			—			(15.4		)
Proceeds from disposition of available for sale securities	—			25			—			—			25
Net cash provided by investing activities	—			9.6			—			—			9.6
Cash flows from financing activities:
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	—			0.7			—			—			0.7
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	(2.2		)	—			—			—			(2.2		)
Cash dividend paid to stockholders	(6.4		)	—			—			—			(6.4		)
Repurchase of common stock	(12.7		)	—			—			—			(12.7		)
Intercompany loan	32.3			(29.5		)	(2.8		)	—			—
Net cash provided by (used in) financing activities	11			(28.8		)	(2.8		)	—			(20.6		)
Net increase (decrease) in cash and cash equivalents during the period	—			16.6			(0.5		)	—			16.1
Cash and cash equivalents at beginning of period	5			157.7			6.8			—			169.5
Cash and cash equivalents at end of period	$	5		$	174.3		$	6.3		$	—		$	185.6
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Quarter Ended March 31, 2013
	Parent			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$	(0.5	)	$	5.4		$	1.4		$	—		$	6.3
Cash flows from investing activities:
Capital expenditures	—			(9.0		)	(0.3		)	—			(9.3		)
Purchase of available for sale securities	—			(85.6		)	—			—			(85.6		)
Proceeds from disposition of available for sale securities	—			85.2			—			—			85.2
Net cash used in investing activities	—			(9.4		)	(0.3		)	—			(9.7		)
Cash flows from financing activities:
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	(2.2		)	—			—			—			(2.2		)
Cash dividend paid to stockholders	(5.9		)	—			—			—			(5.9		)
Repurchase of common stock	(14.7		)	—			—			—			(14.7		)
Intercompany loan	23.3			(21.2		)	(2.1		)	—			—
Net cash provided by (used in) financing activities	0.5			(20.4		)	(2.1		)	—			(22.0		)
Net decrease in cash and cash equivalents during the period	—			(24.4		)	(1.0		)	—			(25.4		)
Cash and cash equivalents at beginning of period	5			266			2.4			—			273.4
Cash and cash equivalents at end of period	$	5		$	241.6		$	1.4		$	—		$	248

Summary_of_Significant_Account2

Summary of Significant Accounting Policies, Textuals (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
		Fabricated Products	Fabricated Products
Significant accounting policies [Line Items]	'	'	'
Charge relating to decrement of a prior year, higher cost LIFO layer	$1.80	'	'
Excess of current cost over the stated LIFO value of inventory	'	$11.10	$0.40

Summary_of_Significant_Account3

Summary of Significant Accounting Policies, Textuals, Property, Plant and Equipment (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Property, Plant and Equipment	'	'
Interest expense capitalized as construction in progress	$1.10	$0.40
Depreciation expense	7	6.6
Fabricated Products	'	'
Property, Plant and Equipment	'	'
Depreciation expense	$6.80	$6.50

Supplemental_Balance_Sheet_Inf2

Supplemental Balance Sheet Information (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Cash and Cash Equivalents.	'	'	'	'
Cash and money market funds	$68.50	$57.70	'	'
Commercial paper	117.1	111.8	'	'
Total	185.6	169.5	248	273.4
Trade Receivables.	'	'	'	'
Trade receivables, gross	124.3	120.6	'	'
Allowance for doubtful receivables	-0.8	-0.8	'	'
Trade receivables, net	123.5	119.8	'	'
Inventories.	'	'	'	'
Finished products	65.9	72.5	'	'
Work-in-process	66.9	75.9	'	'
Raw materials	51.5	47.2	'	'
Operating supplies and repair and maintenance parts	18.8	18.8	'	'
Total	203.1	214.4	'	'
Prepaid Expenses and Other Current Assets.	'	'	'	'
Current derivative assets – Notes 8 and 9	4.1	2	'	'
Current deferred tax assets	36.7	36.7	'	'
Short-term restricted cash	0.3	0.3	'	'
Prepaid taxes	2.8	0	'	'
Prepaid expenses	4.7	5.2	'	'
Total	48.6	44.2	'	'
Property, Plant and Equipment - Net.	'	'	'	'
Land and improvements	22.8	22.6	'	'
Buildings and leasehold improvements	54.2	53	'	'
Machinery and equipment	455.3	425.6	'	'
Construction in progress	49.3	66	'	'
Property, plant and equipment, gross	581.6	567.2	'	'
Accumulated depreciation	-144.9	-137.9	'	'
Total	436.7	429.3	'	'
Other Assets.	'	'	'	'
Derivative assets – Notes 8 and 9	84.2	79.8	'	'
Restricted cash	9.3	9.3	'	'
Deferred financing costs	8.2	8.9	'	'
Deferred compensation plan assets	6.6	6.5	'	'
Other	0.2	0.3	'	'
Total	108.5	104.8	'	'
Other Accrued Liabilities.	'	'	'	'
Current derivative liabilities – Notes 8 and 9	2	1.8	'	'
Uncleared cash disbursements	10.5	9.6	'	'
Accrued income taxes and taxes payable	7.6	4.3	'	'
Accrued annual VEBA contribution	0	16	'	'
Short-term environmental accrual – Note 7	3.6	2.8	'	'
Accrued interest	10.3	3.7	'	'
Other	3.1	6.6	'	'
Total	37.1	44.8	'	'
Long-term Liabilities.	'	'	'	'
Derivative liabilities – Notes 8 and 9	87.7	84.3	'	'
Income tax liabilities	4.9	5	'	'
Workers’ compensation accruals	23.4	23.3	'	'
Long-term environmental accrual – Note 7	18.9	20	'	'
Long-term asset retirement obligations	4.1	4	'	'
Deferred compensation liability	7.2	7	'	'
Long-term capital lease	0.1	0.1	'	'
Other long-term liabilities	2.7	2.7	'	'
Total	149	146.4	'	'
Long-term Debt. — Note 3	'	'	'	'
Senior notes	225	225	'	'
Cash convertible senior notes	165.7	163.5	'	'
Total	390.7	388.5	'	'
Billed	'	'	'	'
Trade Receivables.	'	'	'	'
Trade receivables, gross	124.1	120.2	'	'
Unbilled	'	'	'	'
Trade Receivables.	'	'	'	'
Trade receivables, gross	$0.20	$0.40	'	'

LongTerm_Debt_and_Credit_Facil2

Long-Term Debt and Credit Facility, Textuals (Details) (USD $)

3 Months Ended

3 Months Ended

3 Months Ended

Share data in Millions, except Per Share data, unless otherwise specified

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 29, 2010

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2013

23-May-12

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Convertible Notes

Convertible Notes

Call Options

Warrant Transactions

Warrant Transactions

Senior Notes

Senior Notes

Senior Notes

Revolving Credit Facility

Line of Credit

Letter of Credit

Minimum

Days

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair Value Assumptions, Expected Dividend Payments

'

'

'

'

'

'

'

'

'

'

'

'

'

$0.24

[1]

Long-term debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Principal amount of notes

'

'

'

$175,000,000

'

'

'

'

'

$225,000,000

'

'

'

'

Interest rate

'

'

'

4.50%

'

'

'

'

'

8.25%

'

'

'

'

Interest expense including amortization of deferred financing costs

'

'

'

'

'

'

'

4,800,000

4,800,000

'

'

'

'

'

Payment of quarterly cash dividends

$0.35

$0.30

'

'

'

'

'

'

'

'

'

'

'

$0.24

Conversion rate of common stock shares per $1,000 of principal amount

'

'

20.8234

'

'

'

'

'

'

'

'

'

'

'

Principal amount in conversion feature

'

'

1,000

'

'

'

'

'

'

'

'

'

'

'

Conversion price per share of note

'

'

$48.02

'

'

'

'

'

'

'

'

'

'

'

Threshold percentage of stock price trigger for conversion

'

'

130.00%

'

'

'

'

'

'

'

'

'

'

'

Trading days threshold for conversion

'

'

20

'

'

'

'

'

'

'

'

'

'

'

Consecutive trading days threshold for conversion

'

'

'30 days

'

'

'

'

'

'

'

'

'

'

'

Common stock sold related to option counterparties net-share-settled warrants

'

'

'

'

'

3.6

3.6

'

'

'

'

'

'

'

Exercise price per share of Call Options

'

'

'

'

$48.02

'

'

'

'

'

'

'

'

'

Exercise price per share of Warrants

'

'

'

'

'

60.98

61.25

'

'

'

'

'

'

'

Line of Credit Facility

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum borrowing capacity

'

'

'

'

'

'

'

'

'

'

300,000,000

'

'

'

Available borrowing capacity

'

'

'

'

'

'

'

'

'

'

263,400,000

'

'

'

Outstanding line of credit

'

'

'

'

'

'

'

'

'

'

'

0

7,000,000

'

Remaining available borrowing capacity

'

'

'

'

'

'

'

'

'

'

$256,400,000

'

'

'

Interest on Revolving Credit Facility

'

'

'

'

'

'

'

'

'

'

4.00%

'

'

'

[1]

The quarterly dividend in the first quarter of 2014 was $0.35 per share, but the model assumes a discrete $0.24 per share quarterly dividend as was paid at the inception of the Call Options. Quarterly dividends in excess of $0.24 per share do not affect the Call Options’ value due to anti-dilution adjustments.

LongTerm_Debt_and_Credit_Facil3

Long-Term Debt and Credit Facility, Carrying Amount Table (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Principal amount, carrying amount and interest expense of notes	'		'		'
Carrying amount, net of discount	$165.70		'		$163.50
Convertible Notes	'		'		'
Principal amount, carrying amount and interest expense of notes	'		'		'
Principal amount	175		'		175
Less: unamortized issuance discount	-9.3		'		-11.5
Carrying amount, net of discount	165.7		'		163.5
Contractual coupon interest	2		2		'
Amortization of discount	2.1		1.9		'
Amortization of deferred financing costs	0.3		0.3		'
Total interest expense	$4.40	[1]	$4.20	[1]	'
[1]	A portion of the interest relating to the Convertible Notes is capitalized as Construction in progress.

Income_Tax_Matters_Provision_T

Income Tax Matters, Provision Table (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Tax Provision	'	'
Domestic	$9.10	$15.40
Foreign	0.3	-7.2
Total	$9.40	$8.20

Income_Tax_Matters_Textuals_De

Income Tax Matters, Textuals (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2013	Dec. 31, 2013
Income Tax Examination [Line Items]	'	'	'	'
Income tax provision	$9.40	'	$8.20	'
Effective tax rate	37.40%	'	19.70%	'
Cash tax benefit from settlement of tax audit	'	'	7.6	'
Cash received from settlement of tax audit	7.2	'	'	'
Cash tax benefit from advance pricing agreement	'	2.8	'	'
Gross unrecognized tax benefits	3.7	'	'	3.8
Gross unrecognized tax benefits that would impact effective tax rate	2.6	'	'	2.7
Reduction in gross unrecognized tax benefits	1.5	'	'	'
Period which gross unrecognized tax benefits are expected to be reduced	'12 months	'	'	'
Audit settlement with the Canada Revenue Agency Competent Authority	'	'	'	'
Income Tax Examination [Line Items]	'	'	'	'
Decrease in unrecognized tax benefits due to an audit settlement with the Canada Revenue Agency Competent Authority	'	'	($7.50)	'
Decrease in effective tax rate, percent	'	'	-17.90%	'

Employee_Benefits_Defined_Bene

Employee Benefits, Defined Benefit Plans (Details) (USD $)

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

In Millions, unless otherwise specified

VEBAs

VEBAs

Union VEBA

Union VEBA

Salaried VEBA

Variable cash contribution

Variable cash contribution

Variable cash contribution

Variable cash contribution

Variable cash contribution

Maximum

trustrees

Company Appointed

VEBAs

VEBAs

VEBAs

VEBAs

VEBAs

trustrees

Maximum

Annual Cash Flows up to $20 Million

Annual Cash Flows in Excess of $20 Million

VEBA Postretirement Medical Obligations

'

'

'

'

'

'

'

'

'

'

'

'

Number of trustees

'

'

'

'

4

2

'

'

'

'

'

'

Administrative expenses of the VEBAs

'

'

'

$0.30

'

'

'

'

'

'

'

'

Postretirement medical plan contribution obligation percentage

'

'

'

'

'

'

'

'

'

'

10.00%

20.00%

Cash flow in determining VEBA obligation

'

'

20

'

'

'

'

'

'

'

'

'

Variable cash contribution obligation to VEBAs

'

'

'

'

'

'

'

'

'

20

'

'

Percent allocation of total contribution between VEBAs

'

'

'

'

85.50%

'

14.50%

'

'

'

'

'

Accrued Annual Veba Contribution

$0

$16

'

'

'

'

'

$16

$20

'

'

'

Employee_Benefits_Net_Periodic

Employee Benefits, Net Periodic Benefit Costs and Charges Relating To All Other Employee Benefit Plans(Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
VEBAs:	'	'
Total net periodic pension benefit income relating to VEBAs	($5.60)	($5.60)
Deferred compensation plan	0.2	0.4
Defined contribution plans	4	4
Multiemployer pension plans	0.9	0.8
Total	-0.5	-0.4
Fabricated Products	'	'
VEBAs:	'	'
Total	4.6	4.6
All Other	'	'
VEBAs:	'	'
Total	-5.1	-5
VEBAs	'	'
VEBAs:	'	'
Service cost	0.6	0.6
Interest cost	4.1	3.6
Expected return on plan assets	-12.8	-11.2
Amortization of prior service cost	2.8	1.1
Amortization of net actuarial (gain) loss	-0.3	0.3
Total net periodic pension benefit income relating to VEBAs	($5.60)	($5.60)

Employee_Incentive_Plans_Short

Employee Incentive Plans, Short Term Incentive Plans (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Compensation charges associated with STI Plans	'	'
EVA measurement period	'1 year	'
Costs recorded in connection with STI plans	$2.40	$4.10
Fabricated Products	'	'
Compensation charges associated with STI Plans	'	'
Costs recorded in connection with STI plans	1.9	2.9
All Other	'	'
Compensation charges associated with STI Plans	'	'
Costs recorded in connection with STI plans	0.5	1.2
Cost of products sold, excluding depreciation and amortization and other items	'	'
Compensation charges associated with STI Plans	'	'
Costs recorded in connection with STI plans	1.1	1.1
Selling, administrative, research and development, and general	'	'
Compensation charges associated with STI Plans	'	'
Costs recorded in connection with STI plans	$1.30	$3

Employee_Incentive_Plans_Long_

Employee Incentive Plans, Long term Incentive Plans (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
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	761,462	'	'
Non-cash compensation expense	$2	$2.60	'
Stock Options	'	'	'
Fully-vested options outstanding	20,791	'	20,791
Exercise price of options to purchase common stock	$80.01	'	$80.01
Remaining contractual life of options outstanding	'3 years	'	'3 years 3 months
Grant date fair value of options outstanding	$39.90	'	$39.90
Stock options granted	0	'	'
Stock options forfeited	0	'	'
Stock options exercised	0	'	'
Vested Stock	'	'	'
Common shares withheld and canceled	30,869	35,838	'
Fabricated Products	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Non-cash compensation expense	1	0.6	'
All Other	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Non-cash compensation expense	1	2	'
Service-based non-vested common shares and restricted stock units	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Non-cash compensation expense	1.1	1.7	'
Unrecognized gross compensation costs, by award type	6.6	'	'
Expected period (in years) over which the remaining gross compensation costs will be recognized, by award type	'2 years 1 month 6 days	'	'
Performance shares	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Performance award vesting period, years	'3 years	'	'
Non-cash compensation expense	0.5	0.9	'
Unrecognized gross compensation costs, by award type	3.7	'	'
Expected period (in years) over which the remaining gross compensation costs will be recognized, by award type	'1 year 8 months 12 days	'	'
Summary of Activity	'	'	'
Outstanding at December 31, 2013, Shares	562,554	'	'
Outstanding at December 31, 2013, Weighted-Average Grant-Date Fair Value per Share	$49.26	'	'
Granted, shares	0	167,312	'
Granted, Weighted-Average Grant-Date Fair Value per Share	$0	$57.54	'
Vested, shares	-41,212	-32,312	'
Vested, Weighted-Average Grant-Date Fair Value per Share	$46.65	$34.13	'
Forfeited, shares	-1,111	'	'
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$50.51	'	'
Canceled, Shares	-138,051	'	'
Canceled, Weighted-Average Grant-Date Fair Value per Share	$46.65	'	'
Outstanding at March 31, 2014, Shares	382,180	'	'
Outstanding at March 31, 2014, Weighted-Average Grant-Date Fair Value per Share	$50.49	'	'
Market-based shares	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Non-cash compensation expense	0.4	0	'
Unrecognized gross compensation costs, by award type	$6.30	'	'
Expected period (in years) over which the remaining gross compensation costs will be recognized, by award type	'2 years 10 months 10 days	'	'
Summary of Activity	'	'	'
Outstanding at December 31, 2013, Shares	0	'	'
Outstanding at December 31, 2013, Weighted-Average Grant-Date Fair Value per Share	$0	'	'
Granted, shares	160,868	'	'
Granted, Weighted-Average Grant-Date Fair Value per Share	$83.18	'	'
Vested, shares	0	'	'
Vested, Weighted-Average Grant-Date Fair Value per Share	$0	'	'
Forfeited, shares	0	'	'
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$0	'	'
Canceled, Shares	0	'	'
Canceled, Weighted-Average Grant-Date Fair Value per Share	$0	'	'
Outstanding at March 31, 2014, Shares	160,868	'	'
Outstanding at March 31, 2014, Weighted-Average Grant-Date Fair Value per Share	$83.18	'	'
Non-vested common shares	'	'	'
Summary of Activity	'	'	'
Outstanding at December 31, 2013, Shares	143,967	'	'
Outstanding at December 31, 2013, Weighted-Average Grant-Date Fair Value per Share	$51.09	'	'
Granted, shares	55,613	57,190	'
Granted, Weighted-Average Grant-Date Fair Value per Share	$67.42	$57.54	'
Vested, shares	-43,640	-65,646	'
Vested, Weighted-Average Grant-Date Fair Value per Share	$48.61	$40.29	'
Forfeited, shares	-323	'	'
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$52.32	'	'
Canceled, Shares	0	'	'
Canceled, Weighted-Average Grant-Date Fair Value per Share	$0	'	'
Outstanding at March 31, 2014, Shares	155,617	'	'
Outstanding at March 31, 2014, Weighted-Average Grant-Date Fair Value per Share	$57.62	'	'
Restricted stock units (RSUs)	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Number of common shares received by the employee on vesting of restricted stock unit	1	'	'
Summary of Activity	'	'	'
Outstanding at December 31, 2013, Shares	5,472	'	'
Outstanding at December 31, 2013, Weighted-Average Grant-Date Fair Value per Share	$51.03	'	'
Granted, shares	2,235	2,333	'
Granted, Weighted-Average Grant-Date Fair Value per Share	$67.42	$57.54	'
Vested, shares	-2,350	-2,311	'
Vested, Weighted-Average Grant-Date Fair Value per Share	$46.83	$42.74	'
Forfeited, shares	0	'	'
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$0	'	'
Canceled, Shares	0	'	'
Canceled, Weighted-Average Grant-Date Fair Value per Share	$0	'	'
Outstanding at March 31, 2014, Shares	5,357	'	'
Outstanding at March 31, 2014, Weighted-Average Grant-Date Fair Value per Share	$59.71	'	'

Commitments_and_Contingencies_

Commitments and Contingencies, Textuals (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2013
In Millions, unless otherwise specified		Minimum	Maximum
Commitments and contingencies	'	'	'
Period for Ohio Environmental Protection Agency feasibility study completion	'	'18 months	'24 months
Environmental accrual	$22.50	'	'
Expected period the Company expects remedictations actions will be taken	'30 years	'	'
Potential increase in environmental costs	$24.90	'	'

Derivative_Financial_Instrumen2

Derivative Financial Instruments and Related Hedging Programs, Hedging Discussion (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2014	Mar. 29, 2010
	mmlbs	mmlbs		Remainder of 2014	2015	Convertible Notes
				mmlbs	mmlbs
Derivative Financial Instruments and Related Hedging Programs (Textuals) [Abstract]	'	'	'	'	'	'
Aggregate fair value of derivative instruments that contain credit-risk-related contingency features that were in a net liability position	$1.30	'	$1.60	'	'	'
Total fabricated products shipments containing fixed price terms	34.4	29.8	'	'	'	'
Firm price customer sales contracts containing price risk on anticipated purchases of primary aluminum	'	'	'	62.3	2.6	'
Principal amount of notes	'	'	'	'	'	$175

Derivative_Financial_Instrumen3

Derivative Financial Instruments and Related Hedging Programs, Realized and Unrealized Gains (Losses) Table (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Summary Of Realized And Unrealized Gains (Losses)	'	'
Unrealized gains (losses)	$2.90	($0.30)
Not Designated as Hedging Instrument	'	'
Summary Of Realized And Unrealized Gains (Losses)	'	'
Realized (losses) gains	2	-0.7
Unrealized gains (losses)	2.9	-0.3
Aluminum | Not Designated as Hedging Instrument	'	'
Summary Of Realized And Unrealized Gains (Losses)	'	'
Realized (losses) gains	0.8	0
Unrealized gains (losses)	1.7	-4.4
Natural Gas | Not Designated as Hedging Instrument	'	'
Summary Of Realized And Unrealized Gains (Losses)	'	'
Realized (losses) gains	0.7	-0.7
Unrealized gains (losses)	0.8	2.7
Electricity | Not Designated as Hedging Instrument	'	'
Summary Of Realized And Unrealized Gains (Losses)	'	'
Realized (losses) gains	0.5	0
Unrealized gains (losses)	-0.5	1.2
Foreign Currency | Not Designated as Hedging Instrument	'	'
Summary Of Realized And Unrealized Gains (Losses)	'	'
Unrealized gains (losses)	0	-0.2
Hedges Relating to the Convertible Notes | Call Options | Not Designated as Hedging Instrument	'	'
Summary Of Realized And Unrealized Gains (Losses)	'	'
Unrealized gains (losses)	4.4	6
Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature | Not Designated as Hedging Instrument	'	'
Summary Of Realized And Unrealized Gains (Losses)	'	'
Unrealized gains (losses)	($3.50)	($5.60)

Derivative_Financial_Instrumen4

Derivative Financial Instruments and Related Hedging Programs, Notional Quantity Table (Details) (GBP £)	Mar. 31, 2014
Remainder of 2014	'
Summary of material derivative positions	'
Percentage of natural gas purchases for which the Company's exposure to fluctuations in gas prices had been substantially reduced	89.00%
2015	'
Summary of material derivative positions	'
Percentage of natural gas purchases for which the Company's exposure to fluctuations in gas prices had been substantially 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 had been substantially reduced	18.00%
Not Designated as Hedging Instrument | Aluminum | Fixed priced contracts | Purchase	'
Summary of material derivative positions	'
Notional amount of contracts	54
Not Designated as Hedging Instrument | Aluminum | Fixed priced contracts | Sales	'
Summary of material derivative positions	'
Notional amount of contracts	0.4
Not Designated as Hedging Instrument | Aluminum | Midwest premium swap contracts | Purchase	'
Summary of material derivative positions	'
Notional amount of contracts	52.4	[1]
Not Designated as Hedging Instrument | Natural Gas | Fixed priced contracts | Purchase	'
Summary of material derivative positions	'
Notional amount of contracts	6,120,000	[2]
Not Designated as Hedging Instrument | Electricity | Fixed priced contracts | Purchase	'
Summary of material derivative positions	'
Notional amount of contracts	340,225
Not Designated as Hedging Instrument | Foreign Currency | Fixed priced contracts | Purchase | GBP	'
Summary of material derivative positions	'
Notional amount of contracts, currency	44,106
Not Designated as Hedging Instrument | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature	'
Summary of material derivative positions	'
Notional amount of contracts	3,644,095	[3]
Not Designated as Hedging Instrument | Hedges Relating to the Convertible Notes | Call Options	'
Summary of material derivative positions	'
Notional amount of contracts	3,644,095	[3]
[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 March 31, 2014, the Company’s exposure to fluctuations in natural gas prices had been substantially reduced for approximately 89%, 73% and 18% of the expected natural gas purchases for the remainder of 2014, 2015 and 2016, respectively.
[3]	The Bifurcated Conversion Feature represents the cash conversion feature of the Convertible Notes. The Call Options 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 Call Options is derived from a notional number of shares of the Company’s common stock, the Call Options may only be settled in cash.

Derivative_Financial_Instrumen5

Derivative Financial Instruments and Related Hedging Programs, Offsetting of Derivative Instruments by Counterparty (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Derivative Assets and Collateral Held by Counterparty	'		'
Gross Amounts of Recognized Assets	$88.30		$81.80
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	88.3		81.8
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	1.8		1.2
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	0		0
Net Amount	86.5		80.6
Derivative Liabilities and Collateral Held by Counterparty	'		'
Gross Amounts of Recognized Liabilities	-89.7		-86.1
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	-89.7		-86.1
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	-1.8		-1.2
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Net Amount	-87.9		-84.9
Counterparty (with Netting Agreements)	'		'
Derivative Assets and Collateral Held by Counterparty	'		'
Gross Amounts of Recognized Assets	1.4		1
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	1.4		1
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	1.2		0.8
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	0		0
Net Amount	0.2		0.2
Derivative Liabilities and Collateral Held by Counterparty	'		'
Gross Amounts of Recognized Liabilities	-1.9		-1.6
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	-1.9		-1.6
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	-1.2		-0.8
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Net Amount	-0.7		-0.8
Counterparty (without Netting Agreements)	'		'
Derivative Assets and Collateral Held by Counterparty	'		'
Gross Amounts of Recognized Assets	85.7	[1]	80.4	[1]
Gross Amounts Offset in the Consolidated Balance Sheets	0	[1]	0	[1]
Net Amounts of Assets Presented in the Consolidated Balance Sheets	85.7	[1]	80.4	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0	[1]	0	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	0	[1]	0	[1]
Net Amount	85.7	[1]	80.4	[1]
Derivative Liabilities and Collateral Held by Counterparty	'		'
Gross Amounts of Recognized Liabilities	-86.9	[1]	-83.2	[1]
Gross Amounts Offset in the Consolidated Balance Sheets	0	[1]	0	[1]
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	-86.9	[1]	-83.2	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0	[1]	0	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0	[1]	0	[1]
Net Amount	-86.9	[1]	-83.2	[1]
Counterparty (with partial Netting Agreements)	'		'
Derivative Assets and Collateral Held by Counterparty	'		'
Gross Amounts of Recognized Assets	1.2		0.4
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	1.2		0.4
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0.6		0.4
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	0		0
Net Amount	0.6		0
Derivative Liabilities and Collateral Held by Counterparty	'		'
Gross Amounts of Recognized Liabilities	-0.9		-1.3
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	-0.9		-1.3
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	-0.6		-0.4
Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Net Amount	($0.30)		($0.90)
[1]	Such amounts include the fair value of the Bifurcated Conversion Feature and Call Options at March 31, 2014 (see Note 9).

Fair_Value_Measurements_Call_O

Fair Value Measurements, Call Option FV Assumption Table (Details) (USD $)	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
	basispoints
Fair Value Disclosures [Abstract]	'		'
The Company’s stock price	$71.42		'
Risk-free interest rate	0.13%	[1]	'
Credit spread (basis points)	154	[2]	'
Expected volatility rate	17.00%	[3]	'
Cash dividends paid per share	$0.35		$0.30
Constant Maturity Treasury rate	'1 year		'
[1]	The risk-free rate was based on the one-year Constant Maturity Treasury rate on March 31, 2014.
[2]	The credit spread is based on the Company’s long-term credit rating of BB- issued by Standard & Poor’s and a senior unsecured credit rating of Ba3 issued by Moody’s.
[3]	The volatility rate was based on both observed volatility, which is based on the Company’s historical stock price, and implied volatility from the Company’s traded options. Such volatility was further adjusted to take into consideration market participant risk tolerance.

Fair_Value_Measurements_Fair_V

Fair Value Measurements Fair Value Measurements, Textual (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
			Minimum	Maximum	Derivative	Derivative
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'	'	'
Net liability	'	'	'	'	$1.40	$4.30
Unrealized gains (losses)	$2.90	($0.30)	'	'	'	'
Commercial paper maturity period	'	'	'4 months	'12 months	'	'

Fair_Value_Measurements_Fair_V1

Fair Value Measurements, Fair Value Hierarchy Table (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Financial Assets:	'	'
Derivative Assets	$88.30	$81.80
Deferred compensation plan assets	6.6	6.5
Financial Liabilities:	'	'
Derivative Liabilities	-89.7	-86.1
Recurring	'	'
Financial Assets:	'	'
Cash and cash equivalents	185.6	169.5
Short-term investments	104.5	129.5
Deferred compensation plan assets	6.6	6.5
Total Assets	385	387.3
Financial Liabilities:	'	'
Convertible Notes	-266.2	-260
Total Liabilities	-611.3	-601.5
Recurring | Senior Notes	'	'
Financial Liabilities:	'	'
Senior Notes	-255.4	-255.4
Recurring | Aluminum | Midwest premium swap contracts	'	'
Financial Assets:	'	'
Derivative Assets	2.6	1.1
Recurring | Aluminum | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0.2	0.1
Financial Liabilities:	'	'
Derivative Liabilities	-1.7	-1.8
Recurring | Aluminum | Fixed priced contracts | Sales	'	'
Financial Assets:	'	'
Derivative Assets	0.1	'
Recurring | Natural Gas | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	1.1	0.5
Financial Liabilities:	'	'
Derivative Liabilities	-0.5	-0.8
Recurring | Electricity | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0.4	0.5
Financial Liabilities:	'	'
Derivative Liabilities	-0.9	-0.4
Recurring | Foreign Currency | Fixed priced contracts | Purchase | Euro	'	'
Financial Assets:	'	'
Derivative Assets	'	0.1
Recurring | Hedges Relating to the Convertible Notes | Call Options	'	'
Financial Assets:	'	'
Derivative Assets	83.9	79.5
Recurring | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature	'	'
Financial Liabilities:	'	'
Derivative Liabilities	-86.6	-83.1
Recurring | Level 1	'	'
Financial Assets:	'	'
Cash and cash equivalents	68.5	57.7
Short-term investments	0	0
Deferred compensation plan assets	0	0
Total Assets	68.5	57.7
Financial Liabilities:	'	'
Convertible Notes	-266.2	-260
Total Liabilities	-521.6	-515.4
Recurring | Level 1 | Senior Notes	'	'
Financial Liabilities:	'	'
Senior Notes	-255.4	-255.4
Recurring | Level 1 | Aluminum | Midwest premium swap contracts	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Recurring | Level 1 | Aluminum | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Financial Liabilities:	'	'
Derivative Liabilities	0	0
Recurring | Level 1 | Aluminum | Fixed priced contracts | Sales	'	'
Financial Assets:	'	'
Derivative Assets	0	'
Recurring | Level 1 | Natural Gas | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Financial Liabilities:	'	'
Derivative Liabilities	0	0
Recurring | Level 1 | Electricity | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Financial Liabilities:	'	'
Derivative Liabilities	0	0
Recurring | Level 1 | Foreign Currency | Fixed priced contracts | Purchase | Euro	'	'
Financial Assets:	'	'
Derivative Assets	'	0
Recurring | Level 1 | Hedges Relating to the Convertible Notes | Call Options	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Recurring | Level 1 | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature	'	'
Financial Liabilities:	'	'
Derivative Liabilities	0	0
Recurring | Level 2	'	'
Financial Assets:	'	'
Cash and cash equivalents	117.1	111.8
Short-term investments	104.5	129.5
Deferred compensation plan assets	6.6	6.5
Total Assets	313.9	328.5
Financial Liabilities:	'	'
Convertible Notes	0	0
Total Liabilities	-89.7	-86.1
Recurring | Level 2 | Senior Notes	'	'
Financial Liabilities:	'	'
Senior Notes	0	0
Recurring | Level 2 | Aluminum | Midwest premium swap contracts	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Recurring | Level 2 | Aluminum | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0.2	0.1
Financial Liabilities:	'	'
Derivative Liabilities	-1.7	-1.8
Recurring | Level 2 | Aluminum | Fixed priced contracts | Sales	'	'
Financial Assets:	'	'
Derivative Assets	0.1	'
Recurring | Level 2 | Natural Gas | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	1.1	0.5
Financial Liabilities:	'	'
Derivative Liabilities	-0.5	-0.8
Recurring | Level 2 | Electricity | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0.4	0.5
Financial Liabilities:	'	'
Derivative Liabilities	-0.9	-0.4
Recurring | Level 2 | Foreign Currency | Fixed priced contracts | Purchase | Euro	'	'
Financial Assets:	'	'
Derivative Assets	'	0.1
Recurring | Level 2 | Hedges Relating to the Convertible Notes | Call Options	'	'
Financial Assets:	'	'
Derivative Assets	83.9	79.5
Recurring | Level 2 | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature	'	'
Financial Liabilities:	'	'
Derivative Liabilities	-86.6	-83.1
Recurring | Level 3	'	'
Financial Assets:	'	'
Cash and cash equivalents	0	0
Short-term investments	0	0
Deferred compensation plan assets	0	0
Total Assets	2.6	1.1
Financial Liabilities:	'	'
Convertible Notes	0	0
Total Liabilities	0	0
Recurring | Level 3 | Senior Notes	'	'
Financial Liabilities:	'	'
Senior Notes	0	0
Recurring | Level 3 | Aluminum | Midwest premium swap contracts	'	'
Financial Assets:	'	'
Derivative Assets	2.6	1.1
Recurring | Level 3 | Aluminum | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Financial Liabilities:	'	'
Derivative Liabilities	0	0
Recurring | Level 3 | Aluminum | Fixed priced contracts | Sales	'	'
Financial Assets:	'	'
Derivative Assets	0	'
Recurring | Level 3 | Natural Gas | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Financial Liabilities:	'	'
Derivative Liabilities	0	0
Recurring | Level 3 | Electricity | Fixed priced contracts | Purchase	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Financial Liabilities:	'	'
Derivative Liabilities	0	0
Recurring | Level 3 | Foreign Currency | Fixed priced contracts | Purchase | Euro	'	'
Financial Assets:	'	'
Derivative Assets	'	0
Recurring | Level 3 | Hedges Relating to the Convertible Notes | Call Options	'	'
Financial Assets:	'	'
Derivative Assets	0	0
Recurring | Level 3 | Hedges Relating to the Convertible Notes | Bifurcated Conversion Feature	'	'
Financial Liabilities:	'	'
Derivative Liabilities	$0	$0

Fair_Value_Measurements_Level_

Fair Value Measurements, Level 3 Fair Value Input Reconciliation Table (Details) (Derivative, Midwest premium swap contracts, USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Derivative | Midwest premium swap contracts	'
Reconciliation of activity for financial instruments classified as Level 3:	'
Balance at December 31, 2013	$1.10
Total realized/unrealized gains included in:	'
Cost of goods sold excluding depreciation and amortization and other items and Unrealized losses (gains) on derivative instruments	1.8
Transactions involving Level 3 derivative contracts:	'
Purchases	0.4
Sales	0
Issuances	0
Settlements	-0.7
Transactions involving Level 3 derivatives — net	-0.3
Transfers in and (or) out of Level 3 valuation hierarchy	0
Balance at March 31, 2014	2.6
Total gains included in Unrealized losses (gains) on derivative instruments, attributable to the change in unrealized gains/losses relating to derivative contracts held at March 31, 2014:	$2.10

Earnings_Per_Share_Calculation

Earnings Per Share, Calculation of EPS (Details) (USD $)	3 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Numerator:	'		'
Net income	$15.80		$33.50
Denominator — Weighted-average common shares outstanding (in thousands):	'		'
Basic	17,921	[1]	19,143	[1]
Add: dilutive effect of non-vested common shares, restricted stock units, performance shares and market-based shares	122		131
Add: dilutive effect of warrants	471		92
Diluted	18,514	[2]	19,366	[2]
Earnings per common share, Basic:	'		'
Net income per share	$0.88		$1.75
Earnings per common share, Diluted:	'		'
Net income per share	$0.85		$1.73
[1]	The basic weighted-average number of common shares outstanding during the period excludes non-vested common shares, restricted stock units, performance shares and market-based shares.
[2]	The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.

Earnings_Per_Share_Textuals_De

Earnings Per Share, Textuals (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Potential dilutive effect of options and Warrants	'	'	'
Options outstanding to purchase common shares	20,791	'	20,791
Average exercise price per share	$80.01	'	$80.01
Potential dilutive effect of options outstanding	0	0	'
Dividends	'	'	'
Cash dividends paid	$6.40	$5.90	'
Cash dividends paid per share	$0.35	$0.30	'
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]	'	'	'
Common share amount available for additional share repurchase	104.9	'	117.6
Repurchase of common stock, shares	184,400	259,596	'
Weighted-average price per share of common stock repurchased	$69.07	$62.62	'
Repurchase of common stock	$12.70	$16.20	'
Warrant Transactions	'	'	'
Potential dilutive effect of options and Warrants	'	'	'
Number of common shares underlying the Warrants outstanding	3,600,000	3,600,000	'
Average exercise price of common shares underlying Warrants	60.98	61.25	'

Segment_Information_Textuals_D

Segment Information, Textuals (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]	'	'
Charge relating to decrement of a prior year, higher cost LIFO layer	$1.80	'
Unrealized gains (losses) on derivatives	2.9	-0.3
VEBA net periodic pension benefit income	5.6	5.6
Fabricated Products	'	'
Segment Reporting Information [Line Items]	'	'
Unrealized gains (losses) on derivatives	2	-0.7
United States	'	'
Segment Reporting Information [Line Items]	'	'
Number of production facilities	11	'
Canada	'	'
Segment Reporting Information [Line Items]	'	'
Number of production facilities	1	'
VEBAs	'	'
Segment Reporting Information [Line Items]	'	'
VEBA net periodic pension benefit income	$5.60	$5.60

Segment_Information_Financial_

Segment Information, Financial Information by Reporting Segment Table (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Net sales:	'		'		'
Net Sales	$335.10		$337.40		'
Segment operating income (loss):	'		'		'
Operating income (loss)	32.1		50		'
Interest expense	-8.8		-9.3		'
Other income, net	1.9		1		'
Income before income taxes	25.2		41.7		'
Depreciation and amortization:	'		'		'
Depreciation and amortization	7.4		7		'
Capital expenditures:	'		'		'
Capital expenditures	15.4		9.3		'
Income taxes paid:	'		'		'
Income taxes paid	0.7		0.7		'
Assets:	'		'		'
Assets	1,766		'		1,770.90
Fabricated Products	'		'		'
Net sales:	'		'		'
Net Sales	335.1		337.4		'
Segment operating income (loss):	'		'		'
Operating income (loss)	35.4	[1],[2]	55.2	[1],[2]	'
Depreciation and amortization:	'		'		'
Depreciation and amortization	7.2		6.9		'
Capital expenditures:	'		'		'
Capital expenditures	15.3		8.9		'
Assets:	'		'		'
Assets	853.7		'		852.5
Fabricated Products | United States	'		'		'
Income taxes paid:	'		'		'
Income taxes paid	0.1		0.4		'
Fabricated Products | Canada	'		'		'
Income taxes paid:	'		'		'
Income taxes paid	0.6		0.3		'
All Other	'		'		'
Segment operating income (loss):	'		'		'
Operating income (loss)	-3.3	[3]	-5.2	[3]	'
Depreciation and amortization:	'		'		'
Depreciation and amortization	0.2		0.1		'
Capital expenditures:	'		'		'
Capital expenditures	0.1		0.4		'
Assets:	'		'		'
Assets	$912.30	[4]	'		$918.40	[4]
[1]	Fabricated Products segment results include non-cash mark-to-market gains (losses) on primary aluminum, natural gas, electricity and foreign currency hedging activities totaling $2.0 and $(0.7) for the quarters ended March 31, 2014 and March 31, 2013, respectively. For further discussion regarding mark-to-market matters, see Note 8.
[2]	Operating results in the Fabricated Products segment for the quarter ended March 31, 2014 included a charge of $1.8 as a result of decrementing a prior year, higher cost LIFO layer.
[3]	Operating results in All Other include VEBA net periodic pension benefit income of $5.6 for both quarters ended March 31, 2014 and March 31, 2013, 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 VEBA(s) (see Note 5) and net deferred income tax assets.

Segment_Information_Net_Sales_

Segment Information, Net Sales by Product Categories (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Net Sales:	'	'
Net sales	$335.10	$337.40
Aero/HS products	'	'
Net Sales:	'	'
Net sales	163.6	179.6
GE products	'	'
Net Sales:	'	'
Net sales	112.2	105.8
Automotive Extrusions	'	'
Net Sales:	'	'
Net sales	40.8	30.8
Other products	'	'
Net Sales:	'	'
Net sales	$18.50	$21.20

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Supplemental disclosure of cash flow information:	'	'
Interest paid	$0.40	$0.40
Income taxes paid	0.7	0.7
Supplemental disclosure of non-cash transactions:	'	'
Stock repurchases not yet settled (accrued in accounts payable)	0	1.5
Non-cash capital expenditures	3.4	2.7
Capital leases acquired	$0	$0.10

Other_Income_Expense_Net_Detai

Other Income (Expense), Net (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Other Income (Expense), Net	'		'
Interest income	$0.30		$0.10
Unrealized gains on financial derivatives	0.9	[1]	0.4	[1]
Realized gains on investments	0.2		0.5
All other, net	0.5		0
Other non-operating income, net	$1.90		$1
[1]	See “Hedges Relating to the Convertible Notes” in Note 8 for discussion of such instruments.

Other_Comprehensive_Income_Det

Other Comprehensive Income (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Reclassification adjustments, before tax:	'	'
Amortization of net actuarial (gain) loss, before tax	($0.30)	$0.30
Amortization of prior service cost, before tax	2.8	1.1
Other comprehensive income relating to VEBAs, before tax	2.5	1.4
Available for sale securities	'	'
Unrealized gain on available for sale securities, before tax	0.1	0.3
Reclassification adjustments, before tax:	'	'
Reclassification of unrealized gain upon sale of available for sale securities, before tax	-0.1	-0.4
Other comprehensive income (loss) relating to available for sale securities, before tax	0	-0.1
Foreign currency translation adjustment, before tax	0.2	0.4
Cumulative tax rate adjustment, before tax	0	'
Other comprehensive income, before tax	2.7	1.7
Reclassification adjustments, income tax (expense) benefit:	'	'
Amortization of net actuarial (gain) loss, income tax (expense) benefit	0.1	-0.1
Amortization of prior service cost, income tax (expense) benefit	-1	-0.4
Other comprehensive income relating to VEBAs, income tax (expense) benefit	-0.9	-0.5
Available for sale securities	'	'
Unrealized gain on available for sale securities, Income tax (expense) benefit	0	-0.1
Reclassification adjustments, income tax (expense) benefit:	'	'
Reclassification of unrealized gain upon sale of available for sale securities, income tax (expense) benefit	0	0.1
Other comprehensive income (loss) relating to available for sale securities, income tax (expense)	0	0
Foreign currency translation adjustment, income tax (expense) benefit	0	0
Cumulative tax rate adjustment, tax	-0.9	'
Other comprehensive income, Income tax (expense) benefit	-1.8	-0.5
Reclassification adjustments, net of tax:	'	'
Amortization of net actuarial (gain) loss relating to VEBAs, net of tax	-0.2	0.2
Amortization of prior service cost relating to VEBAs, net of tax	1.8	0.7
Other comprehensive income relating to VEBAs, net of tax	1.6	0.9
Available for sale securities	'	'
Unrealized gain on available for sale securities, net of tax	0.1	0.2
Reclassification adjustments, net of tax:	'	'
Reclassification of unrealized gain upon sale of available for sale securities, net of tax	-0.1	-0.3
Other comprehensive income (loss) relating to available for sale securities, net of tax	0	-0.1
Foreign currency translation adjustment, net of tax	0.2	0.4
Cumulative tax rate adjustment, net of tax	-0.9	'
Other comprehensive income, net of tax	$0.90	$1.20

Guarantor_and_NonGuarantor_Fin2

Guarantor and Non-Guarantor Financial Statements (Details) (USD $)	3 Months Ended			3 Months Ended			3 Months Ended			3 Months Ended			3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	23-May-12
				Parent	Parent	Parent	Guarantor Subsidiaries	Guarantor Subsidiaries	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Consolidating Adjustments	Consolidating Adjustments	Consolidating Adjustments	Senior Notes
Condensed Financial Statements [Line Items]	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Principal amount of notes	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	$225
Ownership interest by parent	100.00%	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Current assets:	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Cash and cash equivalents	185.6	248	'	5	5	'	174.3	241.6	'	6.3	1.4	'	0	0	'	'
Short-term investments	104.5	'	129.5	0	'	0	104.5	'	129.5	0	'	0	0	'	0	'
Receivables:	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Trade, less allowance for doubtful receivables	123.5	'	119.8	0	'	0	119.5	'	117.7	4	'	2.1	0	'	0	'
Intercompany receivables	0	'	0	32.2	'	0	25.4	'	0.1	0.7	'	0.2	-58.3	'	-0.3	'
Other	11.7	'	13.4	0	'	0	5.9	'	5.3	5.8	'	8.1	0	'	0	'
Inventories	203.1	'	214.4	0	'	0	198	'	208.6	5.8	'	6.4	-0.7	'	-0.6	'
Prepaid expenses and other current assets	48.6	'	44.2	0.1	'	0.1	48	'	43.7	0.5	'	0.4	0	'	0	'
Total current assets	677	'	690.8	37.3	'	5.1	675.6	'	662.6	23.1	'	24	-59	'	-0.9	'
Investments in and advances to subsidiaries	0	'	0	1,466.50	'	1,437.90	26.9	'	26.5	0	'	0	-1,493.40	'	-1,464.40	'
Property, plant, and equipment – net	436.7	'	429.3	0	'	0	421.6	'	414	15.1	'	15.3	0	'	0	'
Long-term intercompany receivables	0	'	0	0	'	31.3	1.1	'	1.6	10.6	'	9.5	-11.7	'	-42.4	'
Net asset of VEBAs	414.1	'	406	0	'	0	414.1	'	406	0	'	0	0	'	0	'
Deferred tax assets — net	59.2	'	69.1	0	'	0	50.2	'	60.2	0	'	0	9	'	8.9	'
Intangible assets – net	33.3	'	33.7	0	'	0	33.3	'	33.7	0	'	0	0	'	0	'
Goodwill	37.2	'	37.2	0	'	0	37.2	'	37.2	0	'	0	0	'	0	'
Other assets	108.5	'	104.8	90.1	'	86.2	18.3	'	18.5	0.1	'	0.1	0	'	0	'
Total	1,766	'	1,770.90	1,593.90	'	1,560.50	1,678.30	'	1,660.30	48.9	'	48.9	-1,555.10	'	-1,498.80	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Accounts payable	72.3	'	62.9	0.4	'	1.1	66.6	'	56.3	5.3	'	5.5	0	'	0	'
Intercompany payable	0	'	0	22.8	'	0	36.9	'	13.9	1.9	'	0.1	-61.6	'	-14	'
Accrued salaries, wages, and related expenses	33.2	'	42.7	0	'	0	29.9	'	39.3	3.3	'	3.4	0	'	0	'
Other accrued liabilities	37.1	'	44.8	10.1	'	3.5	25.8	'	39.9	1.2	'	1.4	0	'	0	'
Short-term capital lease	0.2	'	0.2	0	'	0	0.2	'	0.2	0	'	0	0	'	0	'
Total current liabilities	142.8	'	150.6	33.3	'	4.6	159.4	'	149.6	11.7	'	10.4	-61.6	'	-14	'
Deferred tax liability	1.2	'	1.2	0	'	0	0	'	0	1.2	'	1.2	0	'	0	'
Long-term intercompany payable	0	'	0	1	'	0	10.7	'	40.7	0	'	1.7	-11.7	'	-42.4	'
Long-term liabilities	149	'	146.4	86.6	'	83.2	51.3	'	52	11.1	'	11.2	0	'	0	'
Long-term debt	390.7	'	388.5	390.7	'	388.5	0	'	0	0	'	0	0	'	0	'
Total liabilities	683.7	'	686.7	511.6	'	476.3	221.4	'	242.3	24	'	24.5	-73.3	'	-56.4	'
Total stockholders’ equity	1,082.30	'	1,084.20	1,082.30	'	1,084.20	1,456.90	'	1,418	24.9	'	24.4	-1,481.80	'	-1,442.40	'
Total	1,766	'	1,770.90	1,593.90	'	1,560.50	1,678.30	'	1,660.30	48.9	'	48.9	-1,555.10	'	-1,498.80	'
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Net sales	335.1	337.4	'	0	0	'	327.1	331.8	'	33.1	30.4	'	-25.1	-24.8	'	'
Cost of products sold:	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Cost of products sold, excluding depreciation and amortization and other items	282.9	263.6	'	0	0	'	278.9	259.7	'	28.4	27	'	-24.4	-23.1	'	'
Unrealized (gains) losses on derivative instruments	-2	0.7	'	0	0	'	-2	0.7	'	0	0	'	0	0	'	'
Depreciation and amortization	7.4	7	'	0	0	'	7.1	6.7	'	0.3	0.3	'	0	0	'	'
Selling, administrative, research and development, and general	20.3	21.7	'	1	0.4	'	16.6	20.4	'	3.3	2.4	'	-0.6	-1.5	'	'
Net periodic pension benefit income relating to VEBAs	-5.6	-5.6	'	0	0	'	-5.6	-5.6	'	0	0	'	0	0	'	'
Total selling, administrative, research and development, and general	14.7	16.1	'	1	0.4	'	11	14.8	'	3.3	2.4	'	-0.6	-1.5	'	'
Total costs and expenses	303	287.4	'	1	0.4	'	295	281.9	'	32	29.7	'	-25	-24.6	'	'
Operating (loss) income	32.1	50	'	-1	-0.4	'	32.1	49.9	'	1.1	0.7	'	-0.1	-0.2	'	'
Other (expense) income:	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Interest (expense) income	-8.8	-9.3	'	-9.3	-9.1	'	0.4	-0.3	'	0	0	'	0.1	0.1	'	'
Other income, net	1.9	1	'	1	0.4	'	1.2	0.6	'	-0.2	0.1	'	-0.1	-0.1	'	'
(Loss) income before income taxes	25.2	41.7	'	-9.3	-9.1	'	33.7	50.2	'	0.9	0.8	'	-0.1	-0.2	'	'
Income tax (provision) benefit	-9.4	-8.2	'	0	0	'	-12.6	-19	'	-0.3	7.2	'	3.5	3.6	'	'
Earnings in equity of subsidiaries	0	0	'	25.1	42.6	'	0.4	7.8	'	0	0	'	-25.5	-50.4	'	'
Net income	15.8	33.5	'	15.8	33.5	'	21.5	39	'	0.6	8	'	-22.1	-47	'	'
Comprehensive income	16.7	34.7	'	16.7	34.7	'	22.2	39.8	'	0.8	8.4	'	-23	-48.2	'	'
Cash flows from operating activities:	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Net cash (used in) provided by operating activities	27.1	6.3	'	-11	-0.5	'	35.8	5.4	'	2.3	1.4	'	0	0	'	'
Cash flows from investing activities:	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Capital expenditures	-15.4	-9.3	'	0	0	'	-15.4	-9	'	0	-0.3	'	0	0	'	'
Purchase of available for sale securities	0	-85.6	'	'	0	'	'	-85.6	'	'	0	'	'	0	'	'
Proceeds from disposition of available for sale securities	25	85.2	'	0	0	'	25	85.2	'	0	0	'	0	0	'	'
Net cash provided by (used in) investing activities	9.6	-9.7	'	0	0	'	9.6	-9.4	'	0	-0.3	'	0	0	'	'
Cash flows from financing activities:	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	0.7	0.8	'	0	0	'	0.7	0.8	'	0	0	'	0	0	'	'
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	-2.2	-2.2	'	-2.2	-2.2	'	0	0	'	0	0	'	0	0	'	'
Cash dividend paid to stockholders	-6.4	-5.9	'	-6.4	-5.9	'	0	0	'	0	0	'	0	0	'	'
Repurchase of common stock	-12.7	-14.7	'	-12.7	-14.7	'	0	0	'	0	0	'	0	0	'	'
Intercompany loan	0	0	'	32.3	23.3	'	-29.5	-21.2	'	-2.8	-2.1	'	0	0	'	'
Net cash provided by (used in) financing activities	-20.6	-22	'	11	0.5	'	-28.8	-20.4	'	-2.8	-2.1	'	0	0	'	'
Net increase (decrease) in cash and cash equivalents during the period	16.1	-25.4	'	0	0	'	16.6	-24.4	'	-0.5	-1	'	0	0	'	'
Cash and cash equivalents at beginning of period	169.5	273.4	'	5	5	'	157.7	266	'	6.8	2.4	'	0	0	'	'
Cash and cash equivalents at end of period	$185.60	$248	'	$5	$5	'	$174.30	$241.60	'	$6.30	$1.40	'	$0	$0	'	'

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	3 Months Ended		12 Months Ended	1 Months Ended	3 Months Ended	1 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Apr. 22, 2014	Mar. 31, 2014	Apr. 22, 2014	Mar. 31, 2014	Apr. 22, 2014	Mar. 31, 2014	Mar. 31, 2013	Apr. 22, 2014
				Subsequent Event	Convertible Notes	Convertible Notes	Call Options	Call Options	Warrants	Warrants	Warrants
						Subsequent Event		Subsequent Event			Subsequent Event
Subsequent Events (Textuals) [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Cash dividend declared per common share	'	'	'	$0.35	'	'	'	'	'	'	'
Cash dividends declared	'	'	'	$6,400,000	'	'	'	'	'	'	'
Conversion rate of common stock shares per $1,000 of principal amount	'	'	'	'	20.8234	20.8549	'	'	'	'	'
Principal amount in conversion feature	'	'	'	'	1,000	1,000	'	'	'	'	'
Conversion price per share of note	'	'	'	'	$48.02	$47.95	'	'	'	'	'
Exercise price per share of Call Options	'	'	'	'	'	'	$48.02	$47.95	'	'	'
Exercise price per share of Warrants	'	'	'	'	'	'	'	'	60.98	61.25	60.89
Repurchase of common stock, shares	184,400	259,596	'	'	'	'	'	'	'	'	'
Weighted-average price per share of common stock repurchased	$69.07	$62.62	'	'	'	'	'	'	'	'	'
Common share amount available for additional share repurchase	$104,900,000	'	$117,600,000	'	'	'	'	'	'	'	'