Kaiser Aluminum (KALU) 10-K 23 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Feb. 15, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Kaiser Aluminum Corp
Entity Central Index Key	811,596
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		16,757,781
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1.5

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 51.1	$ 55.2
Short-term investments	183.7	231
Receivables:
Trade receivables, net	165	137.7
Other	15.5	11.9
Inventories	207.9	201.6
Prepaid expenses and other current assets	33.4	18.5
Total current assets	656.6	655.9
Property, plant and equipment, net	571.4	530.9
Deferred tax assets – net	72	159.7
Intangible assets, net	25	26.4
Goodwill	18.8	37.2
Other assets	41.4	33.4
Total	1,385.2	1,443.5
Current liabilities:
Accounts payable	90	75.8
Accrued salaries, wages and related expenses	42.6	49.1
Other accrued liabilities	40.5	40.1
Total current liabilities	173.1	165
Net liabilities of Salaried VEBA	31.9	28.6
Deferred tax liabilities	4.3	3.3
Long-term liabilities	60	73.2
Long-term debt	369.6	368.7
Total liabilities	638.9	638.8
Commitments and contingencies
Stockholders’ equity:
Preferred stock, 5,000,000 shares authorized at both December 31, 2017 and December 31, 2016; no shares were issued and outstanding at December 31, 2017 and December 31, 2016	0	0
Common stock, par value $0.01, 90,000,000 shares authorized at both December 31, 2017 and December 31, 2016; 22,393,537 shares issued and 16,773,586 shares outstanding at December 31, 2017; 22,332,732 shares issued and 17,651,461 shares outstanding at December 31, 2016	0.2	0.2
Additional paid in capital	1,055.9	1,047.4
Retained earnings	85.5	75.2
Treasury stock, at cost, 5,619,951 shares at December 31, 2017 and 4,681,271 shares at December 31, 2016	(358.6)	(281.4)
Accumulated other comprehensive loss	(36.7)	(36.7)
Total stockholders’ equity	746.3	804.7
Total	$ 1,385.2	$ 1,443.5

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	90,000,000	90,000,000
Common Stock, Shares, Issued	22,393,537	22,332,732
Common Stock, Shares, Outstanding	16,773,586	17,651,461
Treasury Stock, Shares	5,619,951	4,681,271
Union VEBA
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred tax liability relating to Union VEBA	$ 0	$ 0

Statements of Consolidated Inco

Statements of Consolidated Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 353.1	$ 332.8	$ 356.3	$ 355.3	$ 331.9	$ 320.6	$ 334.9	$ 343.2	$ 1,397.5	$ 1,330.6	$ 1,391.9
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	282.6	267.2	277.7	277.8	252.4	254.7	250.4	262	1,105.3	1,019.5	1,115.4
Lower of cost or market inventory write-down					0	0	0	4.9	0	4.9	2.6
Unrealized (gain) loss on derivative instruments	(5.4)	(10.8)	11.9	(15.1)	(1.8)	(2)	(10.9)	(4)	(19.4)	(18.7)	3.4
Depreciation and amortization									39.7	36	32.4
Selling, general, administrative, research and development									97.5	105	88.1
Net periodic postretirement benefit cost relating to Salaried VEBA									4.5	3.4	2.4
(Gain) loss on removal of Union VEBA net assets – Note 4									0	(0.1)	493.4
Total selling, general, administrative, research and development									102	108.3	583.9
Goodwill impairment									18.4	0	0
Other operating charges, net									0.8	2.8	0.1
Total costs and expenses									1,246.8	1,152.8	1,737.8
Operating income (loss)	40	39.8	11.4	59.5	45.3	29.8	57.9	44.8	150.7	177.8	(345.9)
Other (expense) income:
Interest expense									(22.2)	(20.3)	(24.1)
Other income (expense), net – Note 11									4.5	(10.3)	(1.8)
Income (loss) before income taxes									133	147.2	(371.8)
Income tax (provision) benefit									(87.6)	(55.5)	135.2
Net income (loss)	$ (15.2)	$ 19.9	$ 4.7	$ 36	$ 24.5	$ 14.9	$ 26	$ 26.3	$ 45.4	$ 91.7	$ (236.6)
Net income (loss) per common share:
Basic (in dollars per share)	$ (0.90)	$ 1.18	$ 0.28	$ 2.07	$ 1.39	$ 0.84	$ 1.45	$ 1.47	$ 2.67	$ 5.15	$ (13.76)
Diluted (in dollars per share)	(0.90)	1.16	0.27	2.04	1.37	0.82	1.43	1.44	$ 2.63	$ 5.09	$ (13.76)
Weighted-average number of common shares outstanding (in thousands):
Basic (in shares)									16,996	17,813	17,201
Diluted (in shares)									17,259	18,033	17,201
Dividends declared per common share (in dollars per share)	$ 0.50	$ 0.50	$ 0.50	$ 0.50	$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 2	$ 1.8	$ 1.6

Statements of Consolidated Comp

Statements of Consolidated Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income (loss)	$ 45.4	$ 91.7	$ (236.6)
Other comprehensive (loss) income, net of tax – Note 10:
Defined benefit pension plan and VEBAs	(1.4)	(5.8)	65.1
Available for sale securities	0.5	0.9	(0.3)
Other	0.9	(0.1)	(0.4)
Other comprehensive (loss) income, net of tax	0	(5)	64.4
Comprehensive income (loss)	$ 45.4	$ 86.7	$ (172.2)

Statement of Consolidated Stock

Statement of Consolidated Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive (Loss) Income
Beginning balance, shares at Dec. 31, 2014		17,607,251
Beginning balance at Dec. 31, 2014	$ 1,015.9	$ 0.2	$ 1,028.5	$ 280.4	$ (197.1)	$ (96.1)
Stockholders' Equity [Roll Forward]
Net income (loss)	(236.6)			(236.6)
Other comprehensive income (loss), net of tax	64.4					64.4
Issuance of non-vested shares to employees		62,285
Issuance of common shares to non-employee directors	0.2		0.2
Issuance of common shares to directors, shares		2,436
Issuance of common shares to employees upon vesting of restricted stock units and performance shares, shares		52,106
Cancellation of employee non-vested shares, shares		(987)
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares, shares		(37,009)
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	$ (2.8)		(2.8)
Repurchase of common stock, shares	(647,520)	(647,520)
Repurchase of common stock	$ (49.4)				(49.4)
Issuance of stock related to warrants, shares		1,015,185
Cash dividends on common stock	(28.1)			(28.1)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	1.3		1.3
Amortization of unearned equity compensation	9.3		9.3
Dividends on unvested equity awards that were canceled	0.2			0.2
Ending balance, shares (Before Cumulative Adjustment) at Dec. 31, 2015		18,053,747
Ending balance (Before Cumulative Adjustment) at Dec. 31, 2015	774.4	$ 0.2	1,036.5	15.9	(246.5)	(31.7)
Ending balance at Dec. 31, 2015						(31.7)
Stockholders' Equity [Roll Forward]
Net income (loss)	91.7			91.7
Other comprehensive income (loss), net of tax	(5)					(5)
Issuance of non-vested shares to employees		9,702
Issuance of common shares to non-employee directors	0.1		0.1
Issuance of common shares to directors, shares		1,474
Issuance of common shares to employees upon vesting of restricted stock units and performance shares, shares		66,810
Issuance of common shares to employees upon option exercises and vesting of restricted stock units and performance shares	1.2		1.2
Cancellation of employee non-vested shares, shares		(379)
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares, shares		(36,055)
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	$ (2.9)		(2.9)
Repurchase of common stock, shares	(443,838)	(443,838)
Repurchase of common stock	$ (34.9)				(34.9)
Cash dividends on common stock	(32.4)			(32.4)
Amortization of unearned equity compensation	11.7		11.7
Dividends on unvested equity awards that were canceled	$ 0.1			0.1
Ending balance, shares (Before Cumulative Adjustment) at Dec. 31, 2016		17,651,461
Ending balance, shares (Restatement Adjustment [Member])		18,053,747
Ending balance, shares at Dec. 31, 2016	17,651,461
Ending balance (Before Cumulative Adjustment) at Dec. 31, 2016	$ 804.7	$ 0.2	1,047.4	75.2	(281.4)	(36.7)
Ending balance (Restatement Adjustment [Member])	775.1	$ 0.2	1,037.3	15.8	(246.5)	(31.7)
Ending balance at Dec. 31, 2016	804.7					(36.7)
Cumulative Effect of New Accounting Principle in Period of Adoption	0.7		0.8	(0.1)
Stockholders' Equity [Roll Forward]
Net income (loss)	45.4			45.4
Issuance of non-vested shares to employees		11,817
Issuance of common shares to non-employee directors	0.2		0.2
Issuance of common shares to directors, shares		2,282
Issuance of common shares to employees upon vesting of restricted stock units and performance shares, shares		103,652
Issuance of common shares to employees upon vesting of restricted stock units and performance shares			0
Cancellation of employee non-vested shares, shares		(451)
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares, shares		(56,495)
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	$ (4.5)		(4.5)
Repurchase of common stock, shares	(938,680)	(938,680)
Repurchase of common stock	$ (77.8)				(77.8)
Cancellation of treasury stock			(0.2)	(0.4)	0.6
Cash dividends on common stock	(35)			(35)
Amortization of unearned equity compensation	$ 13		13
Ending balance, shares at Dec. 31, 2017	16,773,586	16,773,586
Ending balance at Dec. 31, 2017	$ 746.3	$ 0.2	$ 1,055.9	85.5	$ (358.6)	$ (36.7)
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 0.3			$ 0.3

Statement of Consolidated Stoc7

Statement of Consolidated Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Dividends declared per common share (in dollars per share)	$ 0.50	$ 0.50	$ 0.50	$ 0.50	$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 2	$ 1.8	$ 1.6

Statement of Consolidated Cash

Statement of Consolidated Cash Flows $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)		Dec. 31, 2016USD ($)		Dec. 31, 2015USD ($)
Cash flows from operating activities:
Net income (loss)	$ 45.4		$ 91.7		$ (236.6)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation of property, plant and equipment	38.3		34.5		30.8
Amortization of definite-lived intangible assets	1.4		1.5		1.6
Amortization of debt discount and debt issuance costs	1.2		1.1		4.3
Deferred income taxes	89		57.4		(131.7)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	0		0		(1.3)
Non-cash compensation	13.3		11.8		9.5
Lower of cost or market inventory write-down	0		4.9		2.6
Non-cash unrealized (gain) loss on derivative instruments	(19.4)		(18.7)		3.4
Non-cash impairment charges	19.2		2.8		0.1
Loss on repurchase of Senior Notes	0		11.1		2.5
(Gain) loss on disposition of property, plant and equipment	(0.5)		0.2		0.3
Gain on disposition of available for sale securities	(2.3)		0		0
Non-cash defined benefit net periodic benefit cost (income)	4.8		3.7		2.8
Non-cash loss on removal of Union VEBA, net	0		0		(446.7)
Other non-cash changes in assets and liabilities	(3.9)		(1.2)		(0.6)
Changes in operating assets and liabilities:
Trade and other receivables	(30.9)		(26.8)		17.4
Inventories, excluding lower of cost or market write-down	(6.3)		13.1		(7.5)
Prepaid expenses and other current assets	(1.7)		(8)		0.5
Accounts payable	13		3.4		(13.6)
Accrued liabilities	(4.7)		26.2		12.8
Annual variable cash contributions to VEBAs	(20)		(19.5)		(13.7)
Long-term assets and liabilities, net	(2.2)		(26)		28.2
Net cash provided by operating activities	141.5		165.6		159.7
Cash flows from investing activities:
Capital expenditures	(75.5)		(76.1)		(63.1)
Purchase of available for sale securities	(247.5)		(255.3)		(0.5)
Proceeds from disposition of available for sale securities	296.9		55		84
Proceeds from disposal of property, plant and equipment	0.6		0		0
Net cash (used in) provided by investing activities	(25.5)	[1]	(276.4)	[1]	20.4	[1]
Cash flows from financing activities:
Repayment of principal and redemption premium of 8.25% Senior Notes	0		(206)		(30)
Issuance of 5.875% Senior Notes	0		375		0
Repayment of Convertible Notes	0		0		(175)
Proceeds from cash-settled call options related to settlement of Convertible Notes	0		0		94.9
Payment for conversion premium related to settlement of Convertible Notes	0		0		(94.9)
Cash paid for debt issuance costs	0		6.8		0.6
Proceeds from stock option exercises	0		1.2		0
Repayment of capital lease	(0.4)		0		0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	0		0		1.3
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares	(4.5)		(2.9)		(2.8)
Repurchase of common stock	(79.5)		(33.3)		(49.2)
Cash dividends and dividend equivalents paid	(35)		(32.4)		(28.1)
Net cash (used in) provided by financing activities	(119.4)	[1]	94.8	[1]	(284.4)	[1]
Net decrease in cash, cash equivalents and restricted cash during the period	(3.4)		(16)		(104.3)
Cash, cash equivalents and restricted cash at end of period	51.1		55.2		72.5
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 64.3		$ 67.7		$ 83.7
[1]	See Note 14 for supplemental disclosure on non-cash transactions.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies In this Annual Report on Form 10-K (this "Report"), unless the context otherwise requires, references in these notes to consolidated financial statements to "Kaiser Aluminum Corporation," "we," "us," "our," "the Company" and "our Company" refer collectively to Kaiser Aluminum Corporation and its subsidiaries. Organization and Nature of Operations. Kaiser Aluminum Corporation specializes in the production of semi-fabricated specialty aluminum mill products, such as aluminum plate and sheet and extruded and drawn products, for the following end market applications: aerospace and high strength ("Aero/HS products"), automotive applications ("Automotive Extrusions"), general engineering ("GE products") and other industrial ("Other products"). Our business is organized into one operating segment, Fabricated Products. See Note 15 for additional information regarding our reportable segment and business unit. Principles of Consolidation and Basis of Presentation. The consolidated financial statements include the accounts of our 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 ("SEC"). Intercompany balances and transactions are eliminated. Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in accordance with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities known to exist as of the date the financial statements are published and the reported amounts of revenues and expenses during the reporting period. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of our 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 our consolidated financial position and results of operations. Foreign Currency. Certain of our foreign subsidiaries use the local currency as their functional currency; the assets and liabilities of these foreign subsidiaries are translated at exchange rates in effect at the balance sheet date; and our statement of income (loss) is translated at weighted-average monthly rates of exchange prevailing during the year. Resulting translation adjustments are recorded directly to a separate component of stockholders’ equity. Where the U.S. dollar is the functional currency of a foreign facility or subsidiary, re-measurement adjustments are recorded in Other income (expense), net. Fair Value Measurements. We apply the fair value hierarchy established by GAAP for the recognition and measurement of certain financial 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, we utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible and consider counterparty risk in our assessment of fair value. The fair values of financial assets and liabilities are evaluated and measured on a recurring basis. As part of that evaluation process, we review the underlying inputs that are significant to the fair value measurement of financial instruments to determine if a transfer among hierarchy levels is appropriate. We historically have not had significant transfers into or out of each hierarchy level. Financial assets and liabilities that we measure at fair value each period include our derivative instruments and available for sale securities, consisting of debt investment securities and investments related to our deferred compensation plan (see Note 4 ). Additionally, we measure at fair value once each year at December 31 the plan assets of the Salaried VEBA (defined in Note 4 ) and our Canadian defined benefit pension plan. We record our remaining financial assets and liabilities at carrying value. For a majority of our non-financial assets and liabilities, which include goodwill, intangible assets, inventories and property, plant and equipment, we are not required to measure their fair value on a recurring basis. However, if certain triggering events occur (or at least annually for goodwill), an evaluation of the affected non-financial asset or liability will be required, which could result in a reduction to the carrying amount of such asset or liability. Other than the impairment charges discussed below in Property, Plant and Equipment, Net and Goodwill and Intangible Assets, we concluded that none of our other 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 during the years ended December 31, 2017 and December 31, 2016 . Cash and Cash Equivalents. We consider only those short-term, highly liquid investments which, when purchased, have maturities of 90 days or less to be cash equivalents. Our cash equivalents consist primarily of funds in commercial paper, money market funds and other highly liquid investments, which are classified within Level 1 of the fair value hierarchy with the exception of commercial paper, which is classified within Level 2 of the fair value hierarchy (see Note 7 ). Restricted Cash. We are required to keep on deposit certain amounts that are pledged or held as collateral relating to workers’ compensation and other agreements. We account for such deposits as restricted cash (see Note 14 ). From time to time, such restricted funds could be returned to us or we could be required to pledge additional cash. Available for Sale Securities. We account for investments in certain marketable debt securities as available for sale securities. Such securities are recorded at fair value (see Note 7 ), with net unrealized gains and losses, net of income taxes, reflected in Accumulated other comprehensive income (loss) as a component of Stockholders' equity. Realized gains and losses from the sale of marketable debt securities, if any, are determined on a specific identification basis. Debt investment securities with an original maturity of 90 days or less are classified as Cash and cash equivalents (see Note 2 ). Debt investment securities with an original maturity of greater than 90 days are presented as Short-term investments on the Consolidated Balance Sheets. In addition to debt investment securities, we also hold assets in various investment funds managed by a third-party trust in connection with our deferred compensation program (see Note 4 ). Trade Receivables and Allowance for Doubtful Accounts. Trade receivables primarily consist of amounts billed to customers for products sold. Accounts receivable are generally due within 30 to 90 days . For the majority of our receivables, we establish an allowance for doubtful accounts based upon collection experience and other factors. On certain other receivables where we are aware of a specific customer’s inability or reluctance to pay, an allowance for doubtful accounts is established against amounts due, to reduce the net receivable balance to the amount we reasonably expect to collect. However, if circumstances change, our estimate of the recoverability of accounts receivable could be different. Circumstances that could affect our estimates include, but are not limited to, customer credit issues and general economic conditions. Accounts are written off once deemed to be uncollectible. Any subsequent cash collections relating to accounts that have been previously written off are typically recorded as a reduction to total bad debt expense in the period of payment. Write-offs for 2017 , 2016 and 2015 were immaterial to the consolidated financial statements. Inventories. Inventories are stated at the lower of cost or market value. On March 31, 2016, we recorded a lower of cost or market inventory write-down of $4.9 million , as a result of a decrease in our net realizable value of inventory. The net realizable value reflected commitments as of that date from customers to purchase our inventory at prices that exceeded the Midwest Transaction Price ("Midwest Price"), which reflects the primary aluminum supply/demand dynamics in North America, reduced by an approximate normal profit margin. There were no additional lower of cost or market inventory adjustments since the quarter ended March 31, 2016. Finished products, work-in-process and raw material inventories are stated on the last-in, first-out ("LIFO") basis. At December 31, 2017 , the current cost of our inventory exceeded its stated LIFO value by $24.3 million . The stated LIFO value of our inventory represented its net realizable value (less a normal profit margin) and exceeded the current cost of our inventory by $8.5 million at December 31, 2016 . Other inventories are stated on the first-in, first-out basis and consist of operating supplies, which are materials and supplies to be consumed during the production process. 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 our inventories at December 31, 2017 and December 31, 2016 were included in the Fabricated Products segment (see Note 2 for the components of inventories). Replacement Parts. Replacement parts consist of preventative maintenance and capital spare parts, which are stated on the first-in, first-out basis. Replacement parts are recorded within Prepaid expenses and other current assets or Other assets depending on whether or not the expected utilization of the replacement parts is to occur within the current operating cycle. Property, Plant and Equipment, Net. Property, plant and equipment, net is recorded at cost and includes construction in progress (see Note 2 ). Interest related to the construction of qualifying assets is capitalized as part of the construction costs. The amount of interest expense capitalized as construction in progress was $2.2 million , $2.9 million and $1.8 million during 2017 , 2016 and 2015 , respectively. Depreciation is computed using the straight-line method at rates based on the estimated useful lives of the various classes of assets. Capital lease assets and leasehold improvements are depreciated on a straight-line basis over the shorter of the estimated useful lives of the assets or the lease term. The principal estimated useful lives are as follows: Range (in years) Land improvements 3 - 25 Buildings and leasehold improvements 15 - 45 Machinery and equipment 1 - 24 Capital lease assets 3 - 5 Depreciation expense is not included in Cost of products sold, excluding depreciation and amortization and other items , but is included in Depreciation and amortization. Property, plant and equipment are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset or group of assets may not be recoverable. We regularly assess whether events and circumstances with the potential to trigger impairment have occurred and rely on a number of factors, including operating results, business plans, economic projections and anticipated future cash flow, to make such assessments. We use an estimate of the future undiscounted cash flows of the related asset or asset group over the estimated remaining life of such asset(s) in measuring whether the asset(s) are recoverable. Measurement of the amount of impairment, if any, is based on the difference between the carrying value of the asset(s) and the estimated fair value of such asset(s). Fair value is determined through a series of standard valuation techniques. We recorded impairment charges of $0.8 million , $0.2 million and $0.1 million in 2017 , 2016 and 2015 , respectively, to reflect the scrap value of idled assets we determined not to deploy for future use. Asset impairment charges are included in Other operating charges, net in the Statements of Consolidated Income (Loss) and are included in the Fabricated Products segment. We classify assets as held for sale only when an asset is being actively marketed and expected to sell within 12 months. Assets held for sale are initially measured at the lesser of the assets' carrying amount and the fair value less costs to sell. Goodwill and Intangible Assets. Goodwill is tested for impairment during the fourth quarter on an annual basis, as well as on an interim basis, as warranted, at the time of relevant events and changes in circumstances. Intangible assets with definite lives are initially recognized at fair value and subsequently amortized over the estimated useful lives to reflect the pattern in which the economic benefits of the intangible assets are consumed. In the event the pattern cannot be reliably determined, we use a straight-line amortization method. Whenever events or changes in circumstances indicate that the carrying amount of the intangible assets may not be recoverable, the intangible assets are reviewed for impairment. See Note 3 for a discussion of the goodwill impairment charge recorded during 2017 related to the operations at our Chandler, Arizona (Extrusion) facility, as well as the non-cash impairment charge recorded during 2016 related to one of our customer relationship intangible assets. Derivative Financial Instruments. Consistent with guidelines established by management and approved by our Board of Directors, we use derivative financial instruments to mitigate our exposure to changes in the market price of aluminum, alloying metals, and energy and, to a lesser extent, foreign currency exchange rates. We do not use derivative financial instruments for trading or other speculative purposes. Hedging transactions are executed centrally on behalf of all of our operations to minimize transaction costs, monitor consolidated net exposures and respond promptly to changes in market factors. We reflect the fair value of all of our derivative instruments on our Consolidated Balance Sheets (see Note 7 ). The carrying values of hedges settling within one year are included in Prepaid expenses and other current assets or Other accrued liabilities. Carrying values for hedges settling beyond one year are included in Other assets or Long-term liabilities. We do not meet the documentation requirements for hedge (deferral) accounting related to aluminum and energy derivatives. Accordingly, we record unrealized gain or loss associated with these hedges in the Statements of Consolidated Income (Loss) within Unrealized (gain) loss on derivative instruments. As such derivatives settle, we reverse any previously recorded unrealized gain or loss associated with these hedges and record the realized gain or loss within Cost of products sold, excluding depreciation and amortization and other items. Forward swap contracts for zinc and copper ("Alloy Hedges") used in our fabrication operations are designated and qualify as cash flow hedges. Unrealized gain and loss associated with the Alloy Hedges are deferred in Other comprehensive income, net of tax. As Alloy Hedges settle, we reverse any unrealized gain or loss previously recorded within Other comprehensive income, net of tax associated with settling Alloy Hedges and record the realized gain or loss within Cost of products sold, excluding depreciation and amortization and other items. Self Insurance of Workers' Compensation and Employee Healthcare Liabilities . We self-insure the majority of the costs of workers' compensation benefits and employee healthcare benefits and rely on insurance coverage to protect us from large losses on individual claims. Workers' compensation liabilities are based on a combination of estimates for: (i) incurred-but-not-reported claims and (ii) the ultimate expense of incurred claims. Such estimates are based on judgment, using our historical claims data and information and analysis provided by actuarial and claims advisors, our insurance carriers and other professionals. Our undiscounted workers' compensation liabilities were estimated at $24.8 million and $26.8 million at December 31, 2017 and December 31, 2016 , respectively. However, we account for our workers' compensation accrued liability on a discounted basis, using a discount rate of 2.25% at December 31, 2017 and 2.00% at December 31, 2016 . Accrued liabilities for employee healthcare benefits, which are estimates of unpaid incurred medical and prescription drug costs as provided by our healthcare administrators, were $3.5 million and $3.6 million at December 31, 2017 and December 31, 2016 , respectively. Debt Issuance Costs. Costs incurred in connection with debt financing are deferred and amortized over the estimated term of the related borrowing. Such amortization is included in Interest expense and may be capitalized as part of construction in progress (see Note 2 and Note 8 ). Conditional Asset Retirement Obligations ( " CAROs " ). We have CAROs at several of our Fabricated Products facilities. Our CAROs can be separated into two primary categories: (i) legal obligations related to the removal and disposal of asbestos and (ii) asset retirement obligations related to future lease terminations. The majority of our CAROs relate to the first category and consist of incremental costs that would be associated with the removal and disposal of asbestos (all of which is believed to be fully contained and encapsulated within walls, floors, ceilings or piping) of certain of our older facilities if such facilities were to undergo major renovation or be demolished. We estimate incremental costs for special handling, removal and disposal costs of materials that may or will give rise to CAROs and then discount the expected costs back to the current year using a credit-adjusted, risk-free rate. When it is unclear when or if CAROs will be triggered, we use probability weighting for possible timing scenarios to determine the probability-weighted liability amounts that should be recognized in our consolidated financial statements (see Note 9 ). Environmental Contingencies. With respect to environmental loss contingencies, we record a loss contingency whenever a contingency is probable and reasonably estimable (see Note 9 ). Accruals for estimated losses from environmental remediation obligations are generally recognized no later than the completion of the remedial feasibility study. Such accruals are adjusted as information develops or circumstances change. Costs of future expenditures for environmental remediation obligations are not discounted to their present value. Accruals for expected environmental costs are included in Other accrued liabilities or Long-term liabilities, as appropriate (see Note 2 ). Environmental expense relating to continuing operations is included in Cost of products sold, excluding depreciation and amortization and other items in the Statements of Consolidated Income (Loss). Environmental expense relating to non-operating locations is included in Selling, general, administrative, research and development ("SG&A and R&D") in the Statements of Consolidated Income (Loss). Recognition of Sales. Sales are generally recognized on a gross basis when all of the following criteria are met: (i) persuasive evidence of an arrangement exists; (ii) title, ownership and risk of loss has passed to the customer; (iii) the price to the customer is fixed or determinable; and (iv) collection of the resulting receivable is reasonably assured. A provision for estimated sales returns from and allowances to customers is made in the same period as the related revenues are recognized, based on historical experience or the specific identification of an event necessitating a reserve. Shipping and Handling Costs. Shipping and handling costs are recorded as a component of Cost of products sold, excluding depreciation, amortization and other items. Advertising Costs. Advertising costs, which are included in SG&A and R&D, are expensed as incurred. Advertising costs for 2017 , 2016 and 2015 were $0.7 million , $0.4 million and $1.2 million , respectively. Research and Development Costs. Research and development costs, which are included in SG&A and R&D, are expensed as incurred. Research and development costs for 2017 , 2016 and 2015 were $10.0 million , $10.2 million and $9.5 million , respectively. Major Maintenance Activities. All major maintenance costs are accounted for using the direct expensing method. Leases. For leases that contain predetermined fixed escalations of the minimum rent, we recognize the related rent expense on a straight-line basis from the date we take possession of the property to the end of the initial lease term. We record any difference between the straight-line rent amounts and the amount payable under the lease as part of deferred rent in Other accrued liabilities or Long-term liabilities, as appropriate. Deferred rent for all periods presented was not material. Stock-Based Compensation. Stock-based compensation in the form of service-based awards is provided to executive officers, certain employees and non-employee directors and is accounted for at fair value. We measure the cost of services received in exchange for an award of equity instruments based on the grant-date fair value of the award and the number of awards expected to ultimately vest. The grant-date fair value is determined based on the stock price on the date of grant, adjusted for expected dividends or dividend equivalents to be paid during the vesting period. We also grant performance-based awards to executive officers and other key employees. The methodology used to value these performance-based awards is based on the nature of the performance conditions within those awards. Awards that are subject to performance conditions pertaining to total shareholder return are valued on the date of grant using a Monte Carlo valuation model. The key assumptions in applying this model are an expected volatility and a risk-free interest rate. Awards with performance conditions pertaining to our cost performance and awards with performance conditions pertaining to our economic value added performance are valued based on our stock price at the date of grant. For more information on our stock-based compensation, see Note 6 . The cost of service-based awards, including time-vested restricted stock and performance shares, is recognized as an expense over the requisite service period of the award on a straight-line basis. Adjustments to expense related to forfeitures are recorded in the period in which they occur. For performance shares with performance conditions pertaining to our cost performance and economic value added performance, the related expense is updated quarterly by adjusting the estimated number of shares expected to vest based on the most probable outcome of the performance condition (see Note 6 ). Income Taxes. Deferred income taxes reflect the future tax effect of temporary differences between the carrying amount of assets and liabilities for financial and income tax reporting and are measured by applying statutory tax rates in effect for the year during which the differences are expected to reverse. In accordance with Accounting Standards Codification ("ASC") Topic 740, Income Taxes ("ASC 740"), we use a "more likely than not" threshold for recognition of tax attributes that are subject to uncertainties and measure any reserves in respect of such expected benefits based on their probability. Deferred tax assets are reduced by a valuation allowance to the extent it is more likely than not that the deferred tax assets will not be realized (see Note 12 ). New Accounting Pronouncements. Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09") , was issued in May 2014 and requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In August 2015, ASU 2014-09 was amended by ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date , which defers the effective date of ASU 2014-09 by one year for all entities and permits early adoption on a limited basis. ASU 2014-09 was subsequently amended by five additional pronouncements that are applicable to us: (i) ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing ; (ii) ASU No. 2016-11, Revenue Recognition (Topic 605) and Derivatives and Hedging (Topic 815): Rescission of SEC Guidance Because of Accounting Standards Updates 2014-09 and 2014-16 Pursuant to Staff Announcements at the March 3, 2016 EITF Meeting ; (iii) ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients ; (iv) ASU No. 2016-20, Revenue from Contracts with Customers (Topic 606): Technical Corrections and Improvements to Topic 606 ; and (v) ASU No. 2017-14, Income Statement - Reporting Comprehensive Income (Topic 220), Revenue Recognition (Topic 605), and Revenue from Contracts with Customers (Topic 606). The primary change to our accounting policies of adopting ASU 2014-09 and its subsequent amendments discussed above (together "ASC 606") will relate to the timing of revenue recognition. Previously, we recognized revenue upon the transfer of risks and title, which was typically not until the product shipped or reached its destination. We will continue to recognize revenue upon product shipment or delivery under ASC 606 for "point-in-time" sales (under certain contracts). However, upon adopting ASC 606, contract sales for a majority of our Aero/HS products and a substantial portion of our Automotive Extrusions will convert from point-in-time to over-time recognition. On these contract sales, we will accelerate revenue recognition throughout the production process. We do not believe adopting ASC 606 will result in: (i) a change in the number of distinct performance obligations within our contractual arrangements; (ii) a change in our current capitalization and deferral policies; (iii) a change in our accounting for contract acquisition and fulfillment costs; (iv) additional contract liability balances; or (v) the adjustment of the amount of promised consideration from our customers for the effects of significant financing components. Additionally, we plan to account for shipping and handling activities that occur after the customer has obtained control of a product as fulfillment activities (i.e., an expense) rather than as a promised service (i.e., a revenue element). As of December 31, 2017: (i) our review of our customer contracts was complete; (ii) our systems were modified to track information needed to apply ASC 606; and (iii) our employees were trained on the changes to revenue recognition policies and work procedures. We will adopt ASC 606 effective January 1, 2018 by recognizing a cumulative-effect adjustment to increase the 2018 opening balance of Retained earnings for the tax-adjusted gross profit of over-time products that were either in work-in-process, in finished goods or in transit to our customers as of December 31, 2017. We expect our adoption of ASC 606 to result in a cumulative-effect adjustment relating to the early recognition of approximately $55.6 million of Net sales based on the application of guidance to contracts not completed at the date of adoption. The cumulative-effect adjustment will be recorded in our opening balance sheet for the year ended December 31, 2018 as: (i) a Contract asset of $55.6 million ; (ii) a reduction in Inventories of $42.2 million ; (iii) a reduction in Deferred tax assets, net of $3.3 million ; and (iv) an increase in Retained earnings of $10.1 million . We believe the impact of adopting ASC 606 will predominantly relate to the timing of revenue recognition and we do not expect it to have a material impact to our quarter-over-quarter or year-over-year results. However, changes in product mix and the stage of product completion at the end of each quarter could result in some unanticipated variability. ASU No. 2016-02, Leases (Topic 842): Amendments to the Financial Accounting Standards Board Accounting Standards Codification ("ASU 2016-02"), was issued in February 2016. Under ASU 2016-02, lessees will need to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). For income statement purposes, a dual model was retained, requiring leases to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). ASU 2016-02 becomes effective for us in the first quarter of 2019. We are currently assessing the impact and expect the adoption of this ASU in 2019 to have a material impact on our consolidated financial statements. ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"), was issued in August 2017. The amendments under ASU 2017-12 refine and expand hedge accounting requirements for both financial (e.g., interest rate) and commodity risks. Its provisions create more transparency around how economic results are presented, both on the face of the financial statements and in the related notes. It also makes certain targeted improvements to simplify the application of hedge accounting guidance. We do not expect to record a cumulative effect adjustment as a result of early adopting ASU 2017-12 in the first quarter of 2018; however, we plan to designate a significant portion of our commodity hedges as cash flow hedges beginning January 1, 2018. We therefore expect to significantly reduce or eliminate the mark-to-market adjustments that have historically been recorded within Unrealized (gain) loss on derivative instruments. These adjustments will instead be recorded within Accumulated other comprehensive loss beginning in the first quarter of 2018. We do not anticipate any material impact on our consolidated financial statements upon the adoption of the following accounting pronouncements: (i) ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ; (ii) ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ; (iii) ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost ; and (iv) ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. There were no material impacts on our consolidated financial statements resulting from our early adoption in the first quarter of 2017 of the following accounting pronouncements: (i) ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ; (ii) ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash ; and (iii) ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment .

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Balance Sheet Information	Supplemental Balance Sheet Information December 31, 2017 December 31, 2016 (In millions of dollars) Cash and Cash Equivalents Cash and money market funds $ 23.5 $ 37.9 Commercial paper 27.6 17.3 Total $ 51.1 $ 55.2 Trade Receivables, net Billed trade receivables $ 165.9 $ 138.2 Unbilled trade receivables 0.3 0.3 Trade receivables, gross 166.2 138.5 Allowance for doubtful receivables (1.2 ) (0.8 ) Trade receivables, net $ 165.0 $ 137.7 Inventories Finished products $ 63.8 $ 73.8 Work-in-process 78.3 71.7 Raw materials 61.3 51.1 Operating supplies 4.5 5.0 Total $ 207.9 $ 201.6 Property, Plant and Equipment, net Land and improvements $ 21.1 $ 22.7 Buildings and leasehold improvements 92.1 88.6 Machinery and equipment 689.1 615.1 Construction in progress 35.1 34.8 Property, plant and equipment – gross 837.4 761.2 Accumulated depreciation (267.9 ) (230.6 ) Assets held for sale 1.9 0.3 Property, plant and equipment, net $ 571.4 $ 530.9 Other Accrued Liabilities Uncleared cash disbursements $ 7.3 $ 5.8 Accrued income taxes and other taxes payable 6.8 4.3 Accrued annual contribution to VEBAs – Note 4 15.7 20.0 Accrued interest 2.9 2.9 Other 7.8 7.1 Total $ 40.5 $ 40.1 December 31, 2017 December 31, 2016 (In millions of dollars) Long-Term Liabilities Workers’ compensation accruals $ 22.6 $ 25.0 Long-term environmental accrual – Note 9 15.8 15.8 Long-term portion of contingent contribution to Union VEBA – Note 4 — 12.8 Other long-term liabilities 21.6 19.6 Total $ 60.0 $ 73.2 Supplemental Balance Sheet Information December 31, 2017 December 31, 2016 (In millions of dollars) Cash and Cash Equivalents Cash and money market funds $ 23.5 $ 37.9 Commercial paper 27.6 17.3 Total $ 51.1 $ 55.2 Trade Receivables, net Billed trade receivables $ 165.9 $ 138.2 Unbilled trade receivables 0.3 0.3 Trade receivables, gross 166.2 138.5 Allowance for doubtful receivables (1.2 ) (0.8 ) Trade receivables, net $ 165.0 $ 137.7 Inventories Finished products $ 63.8 $ 73.8 Work-in-process 78.3 71.7 Raw materials 61.3 51.1 Operating supplies 4.5 5.0 Total $ 207.9 $ 201.6 Property, Plant and Equipment, net Land and improvements $ 21.1 $ 22.7 Buildings and leasehold improvements 92.1 88.6 Machinery and equipment 689.1 615.1 Construction in progress 35.1 34.8 Property, plant and equipment – gross 837.4 761.2 Accumulated depreciation (267.9 ) (230.6 ) Assets held for sale 1.9 0.3 Property, plant and equipment, net $ 571.4 $ 530.9 Other Accrued Liabilities Uncleared cash disbursements $ 7.3 $ 5.8 Accrued income taxes and other taxes payable 6.8 4.3 Accrued annual contribution to VEBAs – Note 4 15.7 20.0 Accrued interest 2.9 2.9 Other 7.8 7.1 Total $ 40.5 $ 40.1 December 31, 2017 December 31, 2016 (In millions of dollars) Long-Term Liabilities Workers’ compensation accruals $ 22.6 $ 25.0 Long-term environmental accrual – Note 9 15.8 15.8 Long-term portion of contingent contribution to Union VEBA – Note 4 — 12.8 Other long-term liabilities 21.6 19.6 Total $ 60.0 $ 73.2

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill. Goodwill is related to our acquisitions of the Chandler, Arizona (Extrusion) facility and the Florence, Alabama facility and is included in the Fabricated Products segment. The carrying value of our goodwill was $18.8 million as of December 31, 2017 and $37.2 million at both the beginning and the end of the year ended December 31, 2016 . The carrying value as of December 31, 2017 included accumulated impairment of $18.4 million . There was no accumulated impairment reflected in the carrying values at both the beginning and the end of the year ended December 31, 2016 . Several factors identified in a qualitative review in the quarter ended June 30, 2017 indicated that long-term demand for hard alloy extruded shapes produced at the Chandler, Arizona (Extrusion) facility was less than previously assumed. Such factors included: (i) reduced build rates of wide body commercial aircraft; (ii) continued low build rates for business jets; and (iii) additional substitution away from hard alloy extruded shapes in favor of composites, titanium and/or aerospace aluminum plate in the manufacture of commercial aircraft. After testing for goodwill impairment applying Level 3 inputs and a combination of an income approach using the estimated discounted cash flow and a market-based valuation methodology, we impaired the carrying value of the goodwill related to our Chandler, Arizona (Extrusion) facility by $18.4 million as of June 30, 2017. As this goodwill is deductible for income tax purposes, the deferred tax effects were included in the impairment charge and income tax provision. During our annual goodwill impairment test in the quarter ending December 31, 2017 , we performed a quantitative impairment test and determined that no additional impairment of our goodwill was required. Intangible Assets. In 2017 and 2016 , our identifiable intangible assets related to acquired finite-lived customer relationships. Information regarding the gross carrying amount and accumulated amortization of these intangible assets was as follows as of each period presented: December 31, 2017 December 31, 2016 (In millions of dollars) Gross carrying amount $ 34.7 $ 34.7 Accumulated amortization (9.7 ) (8.3 ) Net carrying amount $ 25.0 $ 26.4 We recorded a $2.6 million non-cash impairment charge within Other operating charges, net during the quarter ended September 30, 2016 due to the loss of a customer. We identified no other indicators of impairment associated with the remainder of our intangible assets during the years ended December 31, 2017 , December 31, 2016 or December 31, 2015. Amortization expense relating to definite-lived intangible assets is recorded in the Fabricated Products segment over a weighted-average useful life of 25 years . Such expense was $1.4 million for 2017 , $1.5 million for 2016 , and $1.6 million for 2015 . The expected amortization of intangible assets for each of the next five calendar years is $1.4 million and $18.0 million for years thereafter.

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Employee Benefits	Employee Benefits Employee Plans. Employee benefit plans include: • A defined contribution 401(k) savings plan for hourly bargaining unit employees at nine of our production facilities based on the specific collective bargaining agreement at each facility. For active bargaining unit employees at three of these production facilities, we are required to make fixed rate contributions. For active bargaining unit employees at one of these production facilities, we are required to match certain employee contributions. For active bargaining unit employees at three of these production facilities, we are required to make both fixed rate contributions and concurrent matches. For active bargaining unit employees at two remaining production facilities, we are not required to make any contributions. Fixed rate contributions either: (i) range from (in whole dollars) $800 to $2,400 per employee per year, depending on the employee’s age, or (ii) vary between 2% to 10% of the employees’ compensation depending on their age and years of service for employees hired prior to January 1, 2004 or is a fixed 2% annual contribution for employees hired on or after January 1, 2004. • A defined contribution 401(k) savings plan for salaried and certain hourly employees providing for a concurrent match of up to 4% of certain contributions made by employees plus an annual contribution of between 2% and 10% of their compensation depending on their age and years of service to employees hired prior to January 1, 2004. All new hires on or after January 1, 2004 receive a fixed 2% contribution annually. • A defined benefit plan for salaried employees at our London, Ontario facility, with annual contributions based on each salaried employee’s age and years of service. At December 31, 2017 , approximately 63% of the plan assets were invested in equity securities and 33% of plan assets were invested in fixed income securities. The remaining plan assets were invested in short-term securities. Our investment committee reviews and evaluates the investment portfolio. The asset mix target allocation on the long-term investments is approximately 65% in equity securities, 30% in fixed income securities and 5% in short-term securities. The plan assets of our Canadian pension plan are managed by advisors selected by us, with the investment portfolio subject to periodic review and evaluation by our investment committee. The investment of assets in the Canadian pension plan is based upon the objective of maintaining a diversified portfolio of investments in order to minimize concentration of credit and market risks (such as interest rate, currency, equity price and liquidity risks). The degree of risk and risk tolerance take into account the obligation structure of the plan, the anticipated demand for funds and the maturity profiles required from the investment portfolio in light of these demands. • A non-qualified, unfunded, unsecured plan of deferred compensation for key employees who would otherwise suffer a loss of benefits under our defined contribution plan as a result of the limitations imposed by the Internal Revenue Code of 1986 ("Code"). Despite the plan being an unfunded plan, we make an annual contribution to a rabbi trust to fulfill future funding obligations, as contemplated by the terms of the plan. The assets in the trust are at all times subject to the claims of our general creditors and no participant has a claim to any assets of the trust. Plan participants are eligible to receive distributions from the trust subject to vesting and other eligibility requirements. Assets in the rabbi trust relating to the deferred compensation plan are accounted for as available for sale securities and are included in Other assets on the Consolidated Balance Sheets (see " Fair Value of Plan Assets" below). Liabilities relating to the deferred compensation plan are included in Long-term liabilities on the Consolidated Balance Sheets. • An employment agreement with our chief executive officer extending through July 15, 2020. We also provide certain members of senior management, including each of our named executive officers, with benefits related to terminations of employment in specified circumstances, including in connection with a change in control, by us without cause and by the executive officer with good reason. Salaried VEBA Postretirement Obligation. Certain retirees who retired prior to 2004 and certain employees who were hired prior to February 2002 and have subsequently retired or will retire with the requisite age and service, along with their surviving spouses and eligible dependents, are eligible to participate in a voluntary employees' beneficiary association ("VEBA") that provides healthcare cost, medical cost and long-term care insurance cost reimbursement benefits ("Salaried VEBA"). The Salaried VEBA is managed by trustees who determine the level and type of benefits to offer to its participants and who appoint an independent fiduciary to manage the assets of the Salaried VEBA. The Salaried VEBA trustees are independent of us and not under our control. However, because we have an ongoing obligation with no express termination date to make annual variable cash contributions to the Salaried VEBA, we account for it as a defined benefit plan in our financial statements. Our annual cash contribution payable to the Salaried VEBA varies from a minimum of zero to a maximum of $2.9 million , depending on our annual cash flow. We paid the maximum of $2.9 million to the Salaried VEBA in 2017 and we determined that in 2018 we will also pay the maximum of $2.9 million as our variable cash contribution. Such amount was calculated with respect to the 2017 calendar year and recorded within Other accrued liabilities as of December 31, 2017 (see Note 2 ). It will be paid during the first quarter of 2018. Union VEBA Postretirement Obligation . Certain other eligible retirees represented by certain unions along with their surviving spouses and eligible dependents participate in a separate VEBA ("Union VEBA") that provides healthcare and medical cost reimbursement benefits. We had an obligation to make variable cash contributions to the Union VEBA with respect to periods through September 30, 2017. Our final cash contribution for the nine months ended September 30, 2017, totaling $12.8 million , will be paid during the first quarter of 2018 and was recorded within Other accrued liabilities (see Note 2 ). The variable contribution relating to 2016 in the amount of $17.1 million was paid in 2017. We terminated defined benefit plan accounting with respect to the Union VEBA in 2015, after determining that our obligation to make annual variable contributions to the Union VEBA would expire as of September 2017. This resulted in a non-cash loss of $307.8 million , net of a $184.4 million tax benefit, as we removed the Union VEBA net assets and related deferred tax liabilities from our Consolidated Balance Sheet and accrued amounts estimated to be paid through the expiration of our obligation. Key Assumptions. The following data presents the key assumptions used and the amounts reflected in our consolidated financial statements with respect to our Canadian pension plan and the Salaried VEBA. We use a December 31 measurement date for all of the plans. Assumptions used to determine benefit obligations as of the periods presented were as follows: Canadian Pension Plan Salaried VEBA December 31, 2017 December 31, 2016 December 31, 2017 December 31, 2016 Discount rate 3.40 % 3.80 % 3.20 % 3.60 % Rate of compensation increase 3.00 % 3.00 % — — Key assumptions made in computing the net obligation of the Salaried VEBA and in total include: With respect to Salaried VEBA assets: • Based on the information received from the Salaried VEBA at December 31, 2017 and at December 31, 2016 , the Salaried VEBA assets were invested in various managed proprietary funds. • Our variable payment, if any, is treated as a funding/contribution policy and not counted as a Salaried VEBA asset at December 31 for actuarial purposes. With respect to Salaried VEBA obligations: • The accumulated postretirement benefit obligation ("APBO") for the Salaried VEBA was computed based on the level of benefits being provided by it at December 31, 2017 and December 31, 2016 . • Since the Salaried VEBA was paying a fixed annual amount to its participants at both December 31, 2017 and December 31, 2016 , no future cost trend rate increase has been assumed in computing the APBO for the Salaried VEBA. Assumptions used to determine net periodic benefit cost for the years ended December 31 were: Canadian Pension Plan Salaried VEBA 2017 2016 2015 2017 2016 2015 Discount rate 3.80 % 4.10 % 4.00 % 3.60 % 3.90 % 3.60 % Expected long-term return on plan assets 1 4.45 % 4.45 % 5.10 % 7.75 % 7.75 % 7.75 % Rate of compensation increase 3.00 % 3.00 % 3.00 % — — — _____________________ 1. The expected long-term rate of return assumption for the Salaried VEBA is based on the targeted investment portfolios provided to us by the trustee of the Salaried VEBA. Benefit Obligations and Funded Status. The following table presents the benefit obligations and funded status of our Canadian pension and the Salaried VEBA as of December 31, 2017 and December 31, 2016 and the corresponding amounts that are included in our Consolidated Balance Sheets (in millions of dollars): Canadian Pension Plan Salaried VEBA 2017 2016 2017 2016 Change in benefit obligation: Obligation at beginning of year $ 7.0 $ 6.1 $ 86.8 $ 77.9 Foreign currency translation adjustment 0.5 0.2 — — Service cost 0.3 0.3 — — Interest cost 0.3 0.3 3.0 2.9 Prior service cost 1 — — 7.3 8.4 Actuarial loss (gain) 2 0.6 0.3 (0.5 ) 4.1 Plan participants contributions 0.1 — — — Benefits paid by Company (0.3 ) (0.2 ) — — Benefits paid by Salaried VEBA — — (6.6 ) (6.5 ) Obligation at end of year 3 8.5 7.0 90.0 86.8 Change in plan assets: Fair market value of plan assets at beginning of year 6.1 5.7 58.2 58.9 Foreign currency translation adjustment 0.5 0.2 — — Actual return on assets 0.5 0.1 3.6 2.9 Plan participants contributions 0.1 — — — Company contributions 0.4 0.3 2.9 2.9 Benefits paid by Company (0.3 ) (0.2 ) — — Benefits paid by Salaried VEBA — — (6.6 ) (6.5 ) Fair market value of plan assets at end of year 7.3 6.1 58.1 58.2 Net funded status 4 $ (1.2 ) $ (0.9 ) $ (31.9 ) $ (28.6 ) _____________________________ 1. The prior service cost relating to the Salaried VEBA in both 2017 and 2016 resulted from increases in the annual healthcare reimbursement benefit starting in 2018 and 2017, respectively, for plan participants. 2. The actuarial gain relating to the Salaried VEBA in 2017 was comprised of: (i) a $2.5 million gain due to changes in census information; (ii) a $1.0 million gain due to a change in the projected utilization rate; offset by (iii) a $3.0 million loss due to a change in the discount rate. The actuarial loss relating to the Salaried VEBA in 2016 was comprised of: (i) a $2.3 million loss due to changes in census information; (ii) a $2.2 million loss due to a reduction in the discount rate; offset by (iii) a $0.4 million gain due to a change in the projected utilization rate. 3. For the Canadian pension plan, the benefit obligation is the projected benefit obligation. For the Salaried VEBA, the benefit obligation is the APBO. 4. Net funded status of $31.9 million and $28.6 million relating to the Salaried VEBA at December 31, 2017 and December 31, 2016 , respectively, was presented as Net liabilities of Salaried VEBA on the Consolidated Balance Sheet. The accumulated benefit obligation for the Canadian defined benefit pension plan was $7.9 million and $6.4 million at December 31, 2017 and December 31, 2016 , respectively. We expect to contribute $0.5 million to the Canadian pension plan in 2018 . As of December 31, 2017 , the net benefits expected to be paid in each of the next five fiscal years and in the aggregate for the five fiscal years thereafter are as follows (in millions of dollars): Benefit Payments Due by Period 2018 2019 2020 2021 2022 2023-2027 Canadian pension plan benefit payments $ 0.3 $ 0.3 $ 0.3 $ 0.4 $ 0.3 $ 1.9 Salaried VEBA benefit payments 1 7.5 7.3 7.2 7.0 6.8 30.3 Total net benefits $ 7.8 $ 7.6 $ 7.5 $ 7.4 $ 7.1 $ 32.2 __________________________________ 1. Such amounts are based on benefit amounts and certain key assumptions obtained from the Salaried VEBA. The amount of loss included in the Consolidated Balance Sheets (within Accumulated other comprehensive loss) associated with our Canadian defined benefit pension plan and the Salaried VEBA (before tax) that had not yet been reflected in net periodic benefit cost was as follows at December 31 (in millions of dollars): Canadian Pension Plan Salaried VEBA 2017 2016 2017 2016 Accumulated net actuarial loss $ (1.9 ) $ (1.5 ) $ (17.5 ) $ (18.3 ) Transition assets 0.1 0.1 — — Prior service cost — — (42.7 ) (40.2 ) Cumulative loss reflected in Accumulated other comprehensive loss $ (1.8 ) $ (1.4 ) $ (60.2 ) $ (58.5 ) The amount in Accumulated other comprehensive loss that has not yet been recognized as a component of net periodic postretirement benefit cost at December 31, 2017 that is expected to be recognized in 2018 for the Canadian pension plan was nominal at December 31, 2017 . For the Salaried VEBA, such amounts were $6.2 million at December 31, 2017 . Of the $6.2 million relating to the Salaried VEBA, $5.4 million is related to amortization of prior service cost and $0.8 million is related to amortization of net actuarial loss. See Note 10 for reclassification adjustments of other comprehensive (loss) income that were recognized as components of net periodic benefit cost for 2017 , 2016 and 2015 . Fair Value of Plan Assets. The plan assets of our Canadian pension plan and the Salaried VEBA are measured annually on December 31 and reflected in our Consolidated Balance Sheets at fair value. In determining the fair value of the plan assets at an annual period end, we utilize primarily the results of valuations supplied by the investment advisors responsible for managing the assets of each plan, which we independently review for reasonableness. Valuation of certain Canadian pension plan and Salaried VEBA assets are based on the net asset value ("NAV") of shares held by the plans at year-end using the NAV practical expedient. With respect to the Salaried VEBA, the investment advisors providing the valuations are engaged by the Salaried VEBA trustees. Certain Salaried VEBA plan assets are valued based upon unadjusted quoted market prices in active markets that are accessible at the measurement date for identical, unrestricted assets (e.g., liquid securities listed on an exchange). Such assets are classified within Level 1 of the fair value hierarchy. Valuation of other Salaried VEBA invested plan assets is based on significant observable inputs (e.g., valuations derived from actual market transactions, broker-dealer supplied valuations or correlations between a given U.S. market and a non-U.S. security). Valuation model inputs can generally be verified and valuation techniques do not involve significant judgment. The fair values of such financial instruments are classified within Level 2 of the fair value hierarchy. In addition to the Canadian pension plan and Salaried VEBA, we also hold assets in various investment funds at certain registered investment companies in connection with our deferred compensation program. Such assets are accounted for as available for sale securities within Level 2 of the fair value hierarchy and are measured and recorded at fair value based on their quoted market prices (see Note 1 ). The following table presents the fair value of plan assets, classified under the appropriate level of the fair value hierarchy, as of each period presented (in millions of dollars): Level 1 Level 2 Level 3 Total As of December 31, 2017: Plan Assets in the Fair Value Hierarchy: Salaried VEBA – Cash and money market investments $ 1.3 $ — $ — $ 1.3 Diversified investment funds in registered investment companies 1 10.2 — — 10.2 Total Salaried VEBA assets in the fair value hierarchy 11.5 — — 11.5 Deferred compensation program – Diversified investment funds in registered investment companies 1 — 9.8 — 9.8 Total plan assets in the fair value hierarchy $ 11.5 $ 9.8 $ — $ 21.3 Plan Assets Measured at NAV 2 : Salaried VEBA – Fixed income investment funds in registered investment companies 3 $ 19.4 Salaried VEBA – Equity investment funds in registered investment companies 4 24.3 Canadian pension plan – Diversified investment funds in registered investment companies 1 7.3 Total plan assets at fair value $ 72.3 As of December 31, 2016: Plan Assets in the Fair Value Hierarchy: Salaried VEBA – Cash and money market investments $ 3.3 $ — $ — $ 3.3 Diversified investment funds in registered investment companies 1 12.8 — — 12.8 Total Salaried VEBA assets in the fair value hierarchy 16.1 — — 16.1 Deferred compensation program – Diversified investment funds in registered investment companies 1 — 8.2 — 8.2 Total plan assets in the fair value hierarchy $ 16.1 $ 8.2 $ — $ 24.3 Plan Assets Measured at NAV 2 : Salaried VEBA – Fixed income investment funds in registered investment companies 3 $ 17.9 Salaried VEBA – Equity investment funds in registered investment companies 4 21.3 Canadian pension plan – Diversified investment funds in registered investment companies 1 6.1 Total plan assets at fair value $ 69.6 _________________________ 1. The plan assets are invested in investment funds that hold a diversified portfolio of: (i) U.S and international debt and equity securities; (ii) fixed income securities such as corporate bonds and government bonds; (iii) mortgage-related securities; and (iv) cash and cash equivalents. 2. The market value of these funds has not been categorized in the fair value hierarchy and is being presented in the table above to permit a reconciliation of the fair value hierarchy to the Consolidated Balance Sheets. Equity investment funds measured at fair value using the NAV practical expedient are managed by an investment adviser registered with the SEC under the Investment Advisers Act of 1940 and can be redeemed with five business days notice on the 15th (or last business day prior to the 15th) and on the last business day of each month. A business day is every day that the New York Stock Exchange is open. Diversified investment funds measured at fair value using the NAV practical expedient are unitized mutual funds without externally published net asset values, which can be redeemed daily without restriction. 3. This category represents investments in various fixed income funds with multiple registered investment companies. Such funds invest in diversified portfolios, including: (i) marketable fixed income securities, such as (a) U.S. Treasury and other government and agency securities, (b) municipal bonds, (c) mortgage-backed securities, (d) asset-backed securities, (e) corporate bonds, notes and debentures in various sectors, (f) preferred and common stock, (g) investments in affiliated and other investment companies, (h) short-term investments and other net assets, and (i) repurchase agreements and reverse repurchase agreements; (ii) other commingled investments; (iii) investment grade debt; (iv) fixed income instruments which may be represented by options, future contracts or swap agreements; and (v) cash and cash equivalents. In the prior year, the $17.9 million balance as of December 31, 2016 in the table above was presented within the Level 2 category and has been restated in the current year to properly reflect the balance within the NAV category. 4. This category represents investments in equity funds that invest in portfolios comprised of: (i) equity and equity-related securities of U.S. and non-U.S. issuers across all market capitalizations; (ii) common stock in investment trust funds; and (iii) other short-term investments. Components of Net Periodic Benefit Cost. Our results of operations included the following impacts associated with the Canadian defined benefit plan and the Salaried VEBA: (a) charges for service rendered by employees; (b) a charge for accretion of interest; (c) a benefit for the return on plan assets; and (d) amortization of net gains or losses on assets, prior service costs associated with plan amendments and actuarial differences. The following table presents the components of net periodic benefit cost for the years ended December 31 (in millions of dollars): Canadian Pension Plan Salaried VEBA 2017 2016 2015 2017 2016 2015 Service cost 1 $ 0.3 $ 0.3 $ 0.3 $ — $ — $ — Interest cost 0.3 0.3 0.3 3.0 2.9 2.7 Expected return on plan assets (0.3 ) (0.3 ) (0.3 ) (4.1 ) (4.1 ) (4.3 ) Amortization of prior service cost 2 — — — 4.7 4.1 3.0 Amortization of net actuarial loss — — 0.1 0.9 0.5 1.0 Net periodic benefit cost $ 0.3 $ 0.3 $ 0.4 $ 4.5 $ 3.4 $ 2.4 __________________________ 1. The service cost related to the Salaried VEBA was insignificant for all periods presented. 2. We amortize prior service cost on a straight-line basis over the average remaining years of service to full eligibility for benefits of the active plan participants. The following tables present the total expense (income) related to all benefit plans for the periods presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Included within Fabricated Products: Canadian pension plan $ 0.3 $ 0.3 $ 0.4 Deferred compensation plan 0.4 0.2 0.1 Defined contribution plans 8.1 8.1 7.8 Multiemployer pension plans 1 4.6 4.7 4.4 Total Fabricated Products 2 13.4 13.3 12.7 Included within All Other: Net periodic postretirement benefit cost relating to Salaried VEBA 4.5 3.4 2.4 (Gain) loss on removal of Union VEBA net assets — (0.1 ) 493.4 Deferred compensation plan 1.4 0.7 0.3 Defined contribution plans 0.8 0.8 0.8 Total All Other 3 6.7 4.8 496.9 Total $ 20.1 $ 18.1 $ 509.6 ___________________________ 1. See Note 5 for more information on our multiemployer defined benefit pension plans. 2. Substantially all of the Fabricated Products segment’s charges related to employee benefits were in Cost of products sold, excluding depreciation and amortization and other items with the remaining balance in SG&A and R&D. 3. Expense (income) related to VEBAs is included within the Statements of Consolidated Income (Loss) as Net periodic postretirement benefit cost relating to Salaried VEBA and (Gain) loss on removal of Union VEBA net assets. The remaining balance is reported in SG&A and R&D.

Multiemployer Pension Plans

Multiemployer Pension Plans	12 Months Ended
	Dec. 31, 2017
Multiemployer Plans [Abstract]
Multiemployer Pension Plans Disclosure	Multiemployer Pension Plans Overview. We contribute to multiemployer defined benefit pension plans under the terms of collective bargaining agreements that cover our union-represented employees at certain facilities. At December 31, 2017 , approximately 52% of our total employees were union-represented employees at facilities participating in these multiemployer pension plans. We currently estimate that contributions will range from $3.0 million to $5.0 million per year through 2018 . The risks of participating in these multiemployer plans are different from single-employer plans in the following aspects: • Assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers. • If a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers. • If we choose to stop participating in some of our multiemployer plans, we may be required to pay those plans an amount based on the underfunded status of the plan, referred to as a withdrawal liability. Our participation in multiemployer pension plans for the year ended December 31, 2017 is outlined in the table below: Pension Fund Employer Identification Number Pension Protection Act Zone Status 1 FIP/RP Status Pending/Implemented in 2017 2 Contributions of the Company Surcharge Imposed in 2017 Expiration Date of Collective-Bargaining Agreements 2017 2016 2015 2017 2016 (in millions of dollars) Steelworkers Pension Trust (USW) 3 236648508 Green Green No $ 3.5 $ 3.7 $ 3.5 No Mar 2020 - Nov 2020 Other Funds 4 1.1 1.0 0.9 $ 4.6 $ 4.7 $ 4.4 ________________ 1. The most recent Pension Protection Act zone status available in 2017 and 2016 for the Steelworkers Pension Trust is for the plan's year-end at December 31, 2016 and December 31, 2015 , respectively. The zone status is based on information that we received from the plan and is certified by the plan's actuary. Among other factors, plans in the green zone are at least 80% funded. 2. The "FIP/RP Status Pending/Implemented" column indicates if a Financial Improvement Plan (FIP) or a Rehabilitation Plan (RP) is either pending or has been implemented for the plan under the Pension Protection Act. 3. We are party to three collective bargaining agreements with the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union, AFL-CIO,CLC ("USW") that require contributions to the Steelworkers Pension Trust. As of December 31, 2017 , USW collective bargaining agreements covering employees at the Newark, Ohio ("Newark") and Spokane, Washington ("Trentwood") facilities covered 85% of our USW-represented employees and expire in September 2020. Our monthly contributions per hour worked by each bargaining unit employee at the Newark and Trentwood facilities are (in whole dollars) $1.50 and will increase to $1.75 in 2019. The union contracts covering employees at the Richmond, Virginia facility and Florence, Alabama facility cover 11% and 4% of our USW-represented employees, respectively, and expire in March 2020 and November 2020, respectively. 4. Other Funds consists of plans that are not individually significant. We were not listed in any of the plans' Forms 5500 or the Canada-Wide Industrial Pension Plan financial statements as providing more than 5% of the total contributions for any of the plan years disclosed. At December 31, 2017 , financial statements and Forms 5500 were not available for the plan years ending in 2017 . Further, there were no significant changes to the number of employees covered by our multiemployer plans that would affect the period-to-period comparability of the contributions for the years presented.

Employee Incentive Plans

Employee Incentive Plans	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Incentive Plans	Employee Incentive Plans Short-Term Incentive Plans ("STI Plans") We have annual short-term incentive compensation plans for senior management and certain other employees payable at our election in cash, shares of common stock or a combination of cash and shares of common stock. Amounts earned under STI Plans are based on our adjusted earnings before interest, taxes, depreciation and amortization ("Adjusted EBITDA"), modified for certain safety, quality, delivery, cost and individual performance factors. The Adjusted EBITDA targets are determined based on the return on adjusted net assets of our Fabricated Products business. Most of our production facilities have similar programs for both hourly and salaried employees. As of December 31, 2017 , we had a liability of $17.4 million recorded within Accrued salaries, wages and related expenses for estimated probable future payments relating to the 12-month performance period of our 2017 STI Plans. Long-Term Incentive Programs ("LTI Programs") General . Executive officers and other key employees of the Company, as well as non-employee directors of the Company, are eligible to participate in the Kaiser Aluminum Corporation 2016 Equity and Incentive Compensation Plan ("2016 Plan"). The 2016 Plan was approved by stockholders on May 26, 2016 and replaced and succeeded in its entirety the Kaiser Aluminum Corporation Amended and Restated 2006 Equity and Performance Incentive Plan. At December 31, 2017 , 737,954 shares were available for awards under the 2016 Plan. We issue new shares of our common stock upon vesting under the 2016 Plan. Non-Vested Common Shares and Restricted Stock Units. We grant non-vested common shares to our non-employee directors and non-vested common shares and restricted stock units to our executive officers and other key employees. The restricted stock units have rights similar to the rights of non-vested common shares and each restricted stock unit that becomes vested entitles the recipient to receive one common share or a cash amount equaling the value of one common share. For both non-vested common shares and restricted stock units, the service period is generally one year for non-employee directors and three years for executive officers and other key employees. Performance Shares. In addition to non-vested common shares and restricted stock units, we grant performance shares to executive officers and other key employees. Each performance share that becomes vested and earned entitles the recipient to receive one common share or a cash amount equaling the value of one common share. During the first quarter of 2017, performance shares granted in 2014 under the 2014-2016 LTI Program vested (see " Summary of Activity " below). The number of performance shares that vested resulted in the issuance of common shares was determined based on our total shareholder return ("TSR") compared to the TSR of a specified group of peer companies over a three -year performance period. Performance shares granted in 2015 are subject to performance conditions pertaining to our TSR relative to the TSR of a specified group of peer companies over a three -year performance period ("TSR-Based Performance Shares"). Performance shares granted in 2016 consist of TSR-Based Performance Shares and performance shares subject to performance requirements pertaining to our total controllable cost performance over a three -year performance period ("CP-Based Performance Shares"). Performance shares granted in 2017 consist of TSR-Based Performance Shares, CP-Based Performance Shares and performance shares subject to performance conditions pertaining to our economic value added ("EVA") performance, determined based on our adjusted pre-tax operating income in excess of a capital charge, over a three -year performance period ("EVA-Based Performance Shares"). The number of performance shares under the 2015-2017, 2016-2018 and 2017-2019 LTI Programs that may be earned and result in the issuance of common shares ranges between 0% to 200% of the target number of underlying common shares, which is approximately one-half of the maximum payout. The performance shares granted under the 2015-2017, 2016-2018 and 2017-2019 LTI Programs will vest in 2018, 2019 and 2020, respectively. Inputs and assumptions used in the Monte Carlo simulations to calculate the fair value at grant date of our TSR-Based Performance Shares were as follows: Year Ended December 31, 2017 2016 2015 Grant date fair value $ 97.88 $ 93.02 $ 95.68 Grant date stock price $ 79.69 $ 80.46 $ 75.41 Expected volatility of Kaiser Aluminum 1 22.74 % 17.81 % 19.03 % Expected volatility of peer companies 1 44.19 % 41.22 % 33.73 % Risk-free interest rate 1.54 % 1.01 % 0.98 % Dividend yield 2.50 % 2.24 % 2.12 % _____________________ 1. Expected volatility based on 2.8 years of daily closing share prices from the valuation date to the end of the performance period. Non-Cash Compensation Expense. Non-cash compensation expense relating to all awards is included in SG&A and R&D. Non-cash compensation expense by type of award under LTI Programs was as follows for each period presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Non-vested common shares and restricted stock units $ 5.4 $ 4.7 $ 4.4 TSR-Based Performance Shares 4.8 5.4 4.0 CP-Based Performance Shares 2.7 1.3 — EVA-Based Performance Shares 0.2 0.3 0.9 Total non-cash compensation expense $ 13.1 $ 11.7 $ 9.3 The following table presents the allocation of the charges detailed above, by segment (in millions of dollars): Year Ended December 31, 2017 2016 2015 Fabricated Products $ 5.0 $ 4.2 $ 3.5 All Other 8.1 7.5 5.8 Total non-cash compensation expense $ 13.1 $ 11.7 $ 9.3 Recognized tax benefits relating to non-cash compensation expense were $4.9 million , $4.4 million and $3.5 million for 2017 , 2016 and 2015 , respectively. Unrecognized Gross Compensation Cost Data. The following table presents unrecognized gross compensation cost data by type of award as of December 31, 2017 : Unrecognized Gross Compensation Costs (in millions of dollars) Expected Period (in years) Over Which the Remaining Gross Compensation Costs Will Be Recognized Non-vested common shares and restricted stock units $ 8.1 2.5 TSR-Based Performance Shares $ 4.3 1.6 CP-Based Performance Shares $ 5.2 1.9 EVA-Based Performance Shares $ 0.5 2.2 Summary of Activity. A summary of the activity with respect to non-vested common shares, restricted stock units, TSR-Based Performance Shares, CP-Based Performance Shares and EVA-Based Performance Shares for the year ended December 31, 2017 is as follows: Non-Vested Common Shares Restricted Stock Units TSR-Based Performance Shares CP-Based Performance Shares EVA-Based Performance Shares Shares Weighted-Average Units Weighted-Average Grant-Date Fair Value per Unit Shares Weighted-Average Shares Weighted-Average Shares Weighted-Average Outstanding at December 31, 2016 114,658 $ 69.51 61,800 $ 74.94 394,525 $ 90.30 63,678 $ 80.46 — $ — Granted 1 11,817 86.92 92,275 76.13 65,044 97.88 65,044 79.69 32,504 79.69 Vested (46,689 ) 71.46 (9,570 ) 76.19 (94,082 ) 83.18 — — — — Forfeited 1 (451 ) 69.83 (6,887 ) 77.44 (6,383 ) 95.85 (3,999 ) 79.93 (1,374 ) 79.69 Canceled 1 — — — — (55,288 ) 83.18 — — — — Outstanding at December 31, 2017 79,335 $ 70.96 137,618 $ 75.81 303,816 $ 95.31 124,723 $ 80.08 31,130 $ 79.69 _____________________ 1. For performance shares, the number of shares granted and forfeited are presented at their maximum payout; and the number of shares canceled includes the number of shares that did not vest due to performance results falling below those required for maximum payout. The weighted-average grant-date fair value per share for shares granted by type of award was as follows for each period presented: Year Ended December 31, 2017 2016 2015 Non-vested common shares $ 86.92 $ 86.11 $ 72.09 Restricted stock units $ 76.13 $ 75.29 $ 69.83 TSR-Based Performance Shares $ 97.88 $ 93.02 $ 95.68 CP-Based Performance Shares $ 79.69 $ 80.46 $ — EVA-Based Performance Shares $ 79.69 $ — $ — Stock Options. As of December 31, 2016 , we had 1,543 fully-vested outstanding stock options exercisable to purchase common shares at $80.01 per share, all of which subsequently expired on April 2, 2017. No options were granted during the year ended December 31, 2017 , and no options were outstanding as of December 31, 2017 . Participants may elect to have us 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. We cancel any such shares withheld 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 we withhold these common shares, we are required to remit to the appropriate taxing authorities the fair value of the shares withheld as of the vesting date. During 2017 , 2016 and 2015 , 56,495 , 36,055 and 37,009 common shares, respectively, were withheld and canceled for this purpose. The withholding of common shares by us could be deemed a purchase of the common shares.

Derivative Financial Instrument

Derivative Financial Instruments and Related Hedging Programs	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments and Related Hedging Programs	Derivatives, Hedging Programs and Other Financial Instruments Overview . In conducting our business, we enter into derivative transactions, including forward contracts and options, to limit our exposure to: (i) metal price risk related to our sale of fabricated aluminum products and the purchase of metal used as raw material for our fabrication operations; (ii) energy price risk relating to fluctuating prices of natural gas and electricity used in our production processes; and (iii) foreign currency requirements with respect to our foreign subsidiaries and cash commitments for equipment purchases denominated in foreign currency. Our derivative activities are overseen by a hedging committee ("Hedging Committee"), which is composed of our chief executive officer, chief operating officer, chief financial officer, chief accounting officer, treasurer and other officers and employees selected by the chief executive officer. The Hedging Committee meets regularly to review commodity price exposure, derivative positions and strategy. Management reviews the scope of the Hedging Committee's activities with our Board of Directors. We are exposed to counterparty credit risk on all of our derivative instruments, which we manage by monitoring the credit quality of our counterparties and allocating our hedging positions among multiple counterparties to limit exposure to any single entity. Our counterparties are major investment grade financial institutions or trading companies. Hedging transactions are governed by negotiated reciprocal credit lines, which generally require collateral to be posted above specified credit thresholds. We believe the risk of loss is remote and contained due to counterparty credit quality, our diversification practice and collateral requirements. In a majority of our hedging counterparty agreements, our counterparty offers us a credit line that adjusts up or down, depending on our liquidity. Below specified liquidity thresholds, we may have to post collateral if the fair value of our net liability with such counterparty exceeds our reduced credit line. We manage this risk by allocating hedging transactions among multiple counterparties, using options as part of our hedging activities or both. The aggregate fair value of our derivative instruments that were in a net liability position was insignificant at both December 31, 2017 and December 31, 2016 , and we had no collateral posted as of those dates. Additionally, our firm-price customer sales commitments create incremental customer credit risk related to metal price movements. Under certain circumstances, we mitigate this risk by periodically requiring cash collateral from them, which we classify as deferred revenue and include as a component of Other accrued liabilities. At December 31, 2017 , we had no cash collateral posted from any of our customers. For more information about concentration risks concerning customers and suppliers, see Note 15 . Notional Amount of Derivative Contracts . The following table summarizes our derivative positions at December 31, 2017 : Aluminum Maturity Period (month/year) Notional Amount of contracts (mmlbs) Fixed price purchase contracts 1/18 through 12/21 165.3 Fixed price sales contracts 5/18 through 11/19 1.4 Midwest premium swap contracts 1 1/18 through 12/21 163.9 Alloying Metals Maturity Period (month/year) Notional Amount of contracts (mmlbs) Fixed price purchase contracts 1/18 through 6/18 2.7 Natural Gas 2 Maturity Period (month/year) Notional Amount of contracts (mmbtu) Fixed price purchase contracts 1/18 through 12/20 3,600,000 Electricity 3 Maturity Period (month/year) Notional Amount of contracts (Mwh) Fixed price purchase contracts 1/20 through 12/20 131,760 Euro Maturity Period (month/year) Notional Amount of contracts (euro) Fixed price purchase contracts 1/18 through 4/18 301,304 _________________________ 1. Regional premiums represent the premium over the London Metal Exchange price for primary aluminum which is incurred on our purchases of primary aluminum. 2. As of December 31, 2017 , we had derivative and/or physical delivery commitments with energy companies in place to cover exposure to fluctuations in prices for approximately 70% of the expected natural gas purchases for both 2018 and 2019 , and 55% of the expected natural gas purchases for 2020 . 3. As of December 31, 2017 , we had derivative and/or physical delivery commitments with energy companies in place to cover exposure to fluctuations in prices for approximately 55% of the expected electricity purchases for both 2018 and 2019 , and 46% of the expected electricity purchases for 2020 . Non-Designated Hedges of Operational Risks . Our pricing of fabricated aluminum products is generally intended to lock in a conversion margin (representing the value added from the fabrication process(es)) and to pass through metal price fluctuations to our customers. For some of our higher value added products sold on a spot basis, the pass through of metal price movements can sometimes lag by as much as several months, with a favorable impact to us when metal prices decline and an adverse impact to us when metal prices increase. Additionally, in certain instances, we enter into firm-price arrangements with our customers for stipulated volumes to be delivered in the future. Because we generally purchase primary and secondary aluminum on a floating price basis, the lag in passing through metal price movements to customers on some of our higher value added products sold on a spot basis and the volume that we have committed to sell to our customers under a firm-price arrangement create metal price risk for us. We use third-party hedging instruments to limit exposure to metal price risk related to the metal pass through lag on some of our products and firm-price customer sales contracts. We are exposed to risk of fluctuating prices for natural gas and electricity. We, from time to time, in the ordinary course of business, enter into hedging transactions and/or physical delivery commitments with third parties to mitigate our risk from fluctuations in natural gas and electricity prices. We are also exposed to foreign currency exchange risk related to firm-price agreements for equipment purchases from foreign manufacturers. We use foreign currency forward contracts designed to line up with the timing and amounts of scheduled payments to the foreign equipment manufacturers to mitigate our exposure to currency exchange rate fluctuations on these purchases. Realized and unrealized periodic gains and losses of non-designated foreign currency forward contracts are reflected as a reduction or increase in Other income (expense), net. Designated Alloying Metal Hedges . We enter into agreements with suppliers to purchase alloying metals (zinc and copper) used as raw materials in our fabrication operations at fluctuating prices that we are unable to pass along to our customers. We mitigate our exposure to metal price risk by entering into Alloy Hedges with third-party financial institutions at predetermined/fixed prices at stated delivery dates. Our Alloy Hedges are expected to be highly effective because monthly settlements correspond to forecasted physical purchases of alloying metals by our manufacturing facilities. The effective portion of the fair value on these Alloy Hedges is recorded within Other comprehensive income, net of tax, and is reclassified into the Statements of Consolidated Income (Loss) during the month of settlement to Cost of products sold (see Note 10 ). As of December 31, 2017 , we estimate the net gain of $0.5 million will be reclassified from Accumulated other comprehensive income into Net income within the next 6 months . We incurred no ineffectiveness on these hedges during 2017 . Realized and Unrealized Gain (Loss). Realized and unrealized gain (loss) included on the Statements of Consolidated Income (Loss) associated with all derivative contracts consisted of the following for each period presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Realized (gain) loss: Aluminum $ (20.4 ) $ 2.0 $ 27.3 Natural gas 0.7 5.0 5.4 Alloy Hedges (0.9 ) — — Foreign currency (0.1 ) 0.1 — Electricity — — 1.9 Total realized (gain) loss 1 $ (20.7 ) $ 7.1 $ 34.6 Unrealized (gain) loss: Aluminum $ (20.9 ) $ (10.8 ) $ 4.6 Natural gas 1.4 (7.9 ) 0.5 Electricity 0.1 — (1.7 ) Total unrealized (gain) loss 2 $ (19.4 ) $ (18.7 ) $ 3.4 ______________________ 1. Recorded within Cost of products sold, excluding depreciation, amortization and other items within the Fabricated Products segment. 2. Recorded within Unrealized (gain) loss on derivative instruments within the Fabricated Products segment. Fair Values of Derivative Contracts . The fair values of our derivative contracts are based upon trades in liquid markets. Valuation model inputs can be verified, and valuation techniques do not involve significant judgment. The fair values of such financial instruments are classified within Level 2 of the fair value hierarchy. The following table presents our financial instruments, classified under the appropriate level of the fair value hierarchy, as of the period presented (in millions of dollars): December 31, 2017 Level 1 Level 2 Level 3 Total DERIVATIVE ASSETS: Non-Designated Hedges: Aluminum – Fixed price purchase contracts $ — $ 22.5 $ — $ 22.5 Midwest premium swap contracts — 1.7 — 1.7 Natural gas – Fixed price purchase contracts — 0.2 — 0.2 Designated Hedges: Alloying metals – Fixed price purchase contracts — 0.9 — 0.9 Total derivative assets 1 $ — $ 25.3 $ — $ 25.3 DERIVATIVE LIABILITIES: Non-Designated Hedges: Aluminum – Fixed price sales contracts $ — $ (0.1 ) $ — $ (0.1 ) Midwest premium swap contracts — (0.1 ) — (0.1 ) Natural gas – Fixed price purchase contracts — (0.5 ) — (0.5 ) Electricity – Fixed price purchase contracts — (0.1 ) — (0.1 ) Designated Hedges: Alloying metals – Fixed price purchase contracts — — — — Total derivative liabilities 2 $ — $ (0.8 ) $ — $ (0.8 ) ______________________ 1. Of the $25.3 million in total derivative assets, $18.9 million and $6.4 million were recorded within Prepaid expenses and other current assets and Other assets, respectively. 2. Of the $0.8 million in total derivative liabilities, $0.3 million and $0.5 million were recorded within Other accrued liabilities and Long-term liabilities, respectively. The following table presents our financial instruments, classified under the appropriate level of the fair value hierarchy, as of the period presented (in millions of dollars): December 31, 2016 Level 1 Level 2 Level 3 Total DERIVATIVE ASSETS: Non-Designated Hedges: Aluminum – Fixed price purchase contracts $ — $ 3.3 $ — $ 3.3 Midwest premium swap contracts — 0.9 — 0.9 Natural gas – Fixed price purchase contracts — 1.6 — 1.6 Total derivative assets 1 $ — $ 5.8 $ — $ 5.8 DERIVATIVE LIABILITIES: Non-Designated Hedges: Aluminum – Fixed price purchase contracts $ — $ (1.1 ) $ — $ (1.1 ) Midwest premium swap contracts — (0.2 ) — (0.2 ) Natural gas – Fixed price purchase contracts — (0.4 ) — (0.4 ) Designated Hedges: Alloying Metals – Fixed price purchase contracts — (0.1 ) — (0.1 ) Total derivative liabilities 2 $ — $ (1.8 ) $ — $ (1.8 ) ______________________ 1. Of the $5.8 million in total derivative assets, $5.0 million and $0.8 million were recorded within Prepaid expenses and other current assets and Other assets, respectively. 2. Of the $1.8 million in total derivative liabilities, $0.8 million and $1.0 million were recorded within Other accrued liabilities and Long-term liabilities, respectively. The aggregate fair value of our derivatives recorded on the Consolidated Balance Sheets at December 31, 2017 and December 31, 2016 was a net asset of $24.5 million and net asset of $4.0 million , respectively. The increase in the net asset position during 2017 was primarily due to changes in the underlying commodity and energy prices, as well as settlement of liability positions during the period. Changes in the fair value of our derivative contracts relating to non-designated hedges of operational activities are reflected in Operating income (loss). Offsetting Information . We enter into derivative contracts with counterparties, some of which are subject to enforceable master netting arrangements and some of which are not. We reflect the fair value of our derivative contracts on a gross basis on the Consolidated Balance Sheets. The following tables present offsetting information regarding our derivatives by type of counterparty as of December 31, 2017 (in millions of dollars): Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets Gross Amounts Not Offset in the Consolidated Balance Sheets Net Amount Counterparty (with netting agreements) $ 25.3 $ — $ 25.3 $ 0.8 $ 24.5 Total $ 25.3 $ — $ 25.3 $ 0.8 $ 24.5 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets Gross Amounts Not Offset in the Consolidated Balance Sheets Net Amount Counterparty (with netting agreements) $ (0.8 ) $ — $ (0.8 ) $ (0.8 ) $ — Total $ (0.8 ) $ — $ (0.8 ) $ (0.8 ) $ — The following tables present offsetting information regarding our derivatives by type of counterparty as of December 31, 2016 (in millions of dollars): Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets Gross Amounts Not Offset in the Consolidated Balance Sheets Net Amount Counterparty (with netting agreements) $ 3.3 $ — $ 3.3 $ 1.0 $ 2.3 Counterparty (with partial netting agreements) 2.5 — 2.5 0.7 1.8 Total $ 5.8 $ — $ 5.8 $ 1.7 $ 4.1 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets Gross Amounts Not Offset in the Consolidated Balance Sheets Net Amount Counterparty (with netting agreements) $ (1.0 ) $ — $ (1.0 ) $ (1.0 ) $ — Counterparty (with partial netting agreements) (0.8 ) — (0.8 ) (0.7 ) (0.1 ) Total $ (1.8 ) $ — $ (1.8 ) $ (1.7 ) $ (0.1 ) Fair Value of Other Financial Instruments Available for Sale Securities. We hold debt investment securities that are accounted for as available for sale securities. The fair value of the debt investment securities, which consist of commercial paper, is determined based on valuation models that use observable market data. At December 31, 2017 , all of our short-term investments had maturity dates within 8 months . We review our debt investment portfolio for other-than-temporary impairment at least quarterly or when there are changes in credit risk or other potential valuation concerns. At December 31, 2017 and December 31, 2016 , the total unrealized loss, net of tax, included in Accumulated other comprehensive loss was immaterial and was not other-than-temporarily impaired. We believe that it is probable that the principal and interest will be collected in accordance with the contractual terms, and that the unrealized loss on these securities was due to normal market fluctuations, and not due to increased credit risk or other valuation concerns. The fair value input of our available for sale securities, which are classified within Level 2 of the fair value hierarchy, is calculated based on broker quotes. The amortized cost for available for sale securities approximates their fair value. All Other Financial Assets and Liabilities. We believe that the fair value of our 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. See Note 2 for components of cash and cash equivalents. The following table presents our other financial assets, classified under the appropriate level of the fair value hierarchy, as of December 31, 2017 (in millions of dollars): Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 23.5 $ 27.6 $ — $ 51.1 Short-term investments — 183.7 — 183.7 Total $ 23.5 $ 211.3 $ — $ 234.8 The following table presents our other financial assets, classified under the appropriate level of the fair value hierarchy, as of December 31, 2016 (in millions of dollars): Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 37.9 $ 17.3 $ — $ 55.2 Short-term investments — 231.0 — 231.0 Total $ 37.9 $ 248.3 $ — $ 286.2

Debt and Credit Facility

Debt and Credit Facility	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt and Credit Facility	Debt and Credit Facility Senior Notes 5.875% Senior Notes. In May 2016, we issued $375.0 million principal amount of 5.875% unsecured senior notes due May 15, 2024 ("5.875% Senior Notes") at 100% of the principal amount. The unamortized amount of debt issuance costs as of December 31, 2017 and December 31, 2016 was $5.4 million and $6.3 million , respectively. Interest expense, including amortization of debt issuance costs, relating to the 5.875% Senior Notes was $22.9 million and $14.5 million for the year ended December 31, 2017 and December 31, 2016 , respectively. A portion of the interest relating to the 5.875% Senior Notes was capitalized as construction in progress. The effective interest rate of the 5.875% Senior Notes is approximately 6.1% per annum, taking into account the amortization of debt issuance costs. All outstanding 5.875% Senior Notes are registered and freely transferable. The fair value of the outstanding 5.875% Senior Notes, which are Level 1 liabilities, was approximately $399.9 million and $390.8 million at December 31, 2017 and December 31, 2016 , respectively. The 5.875% Senior Notes are unsecured obligations and are guaranteed by certain of our domestic subsidiaries that own virtually all of our operating assets and through which we conduct the vast majority of our business. See Note 16 for condensed guarantor and non-guarantor financial information. The indenture governing the 5.875% Senior Notes places limitations on our ability to, among other things: (i) incur liens; (ii) consolidate, merge or sell all or substantially all of our and certain of our subsidiaries' assets; (iii) incur or guarantee additional indebtedness; (iv) enter into transactions with affiliates; and (v) make "restricted payments" (as defined in the indenture to include certain loans, investments, dividend payments, share repurchases and prepayments and redemptions and repurchases of certain indebtedness). Many of these limitations also apply to certain of our subsidiaries. Additionally, the indenture limits the ability of certain of our subsidiaries to be subject to consensual restrictions on paying dividends to us, making loans to us, repaying indebtedness owed to us, or transferring assets to us. Certain types and amounts of restricted payments are allowed by various provisions of the indenture. In particular, the indenture provisions permit us to make restricted payments in any amount if, after giving effect to such restricted payments, our "consolidated net indebtedness" as a ratio of "EBITDA" (each term as defined in the indenture) is less than 2.75:1.00 . We may redeem the 5.875% Senior Notes at our option in whole or part at any time on or after May 15, 2019 at a redemption price of 104.406% of the principal amount, declining to 102.938% , 101.469% and 100% of the principal amount on or after May 15, 2020, May 15, 2021 and May 15, 2022, respectively, in each case plus any accrued and unpaid interest. At any time prior to May 15, 2019, we may also redeem some or all of the 5.875% Senior Notes at a redemption price equal to 100% of the principal amount, together with any accrued and unpaid interest, plus a "make-whole premium." Holders of the 5.875% Senior Notes have the right to require us to repurchase the 5.875% Senior Notes at a price equal to 101% of the principal amount plus any accrued and unpaid interest following the occurrence of both: (i) a change of control and (ii) a ratings decline by one or both of the two major rating agencies within 60 days after the earlier of a change of control or the public notice of an upcoming change of control. A change of control includes: (i) certain ownership changes; (ii) certain recapitalizations, mergers and dispositions; (iii) certain changes in the composition of our Board of Directors; and (iv) stockholder approval of any plan or proposal for the liquidation or dissolution of us. We may also be required to offer to repurchase the 5.875% Senior Notes at 100% of the principal amount, plus any accrued and unpaid interest, with the proceeds of certain asset sales. 8.25% Senior Notes. In May 2012, we issued $225.0 million principal amount of 8.25% unsecured senior notes due June 1, 2020 ("8.25% Senior Notes"), of which $197.8 million principal amount remained outstanding at December 31, 2015 . On June 1, 2016, we redeemed in full all remaining 8.25% Senior Notes at a redemption price of 104.125% of the principal amount. Interest expense, including amortization of debt issuance costs, relating to the 8.25% Senior Notes was $7.1 million and $18.8 million for 2016 and 2015 , respectively. A portion of the interest relating to the 8.25% Senior Notes was capitalized as construction in progress. Cash Convertible Senior Notes On April 1, 2015, we settled our 4.5% unsecured cash convertible senior notes ("Convertible Notes"). The net cash outflow was $178.9 million , reflecting principal of $175.0 million and the final coupon payment of $3.9 million . We also paid a conversion premium of $94.9 million to holders of the Convertible Notes, which was completely offset by settlement proceeds of a hedge that we entered into in connection with the issuance of our Convertible Notes. The effective interest rate for the term of the Convertible Notes was approximately 11% , taking into account the amortization of the original issuance discount and debt issuance costs. The following table provides additional information regarding the Convertible Notes (in millions of dollars): Year Ended December 31, 2015 Contractual coupon interest $ 2.0 Amortization of discount 2.4 Amortization of debt issuance costs 0.3 Total interest expense 1 $ 4.7 _______________ 1. A portion of the interest relating to the Convertible Notes was capitalized as construction in progress. Revolving Credit Facility Our credit agreement with JPMorgan Chase Bank, N.A., as administrative agent, and the other financial institutions party thereto ("Revolving Credit Facility") provides us with a $300.0 million funding commitment through December 1, 2020. Joining the Company as borrowers ("Co-Borrowers") are three of our wholly-owned domestic operating subsidiaries: Kaiser Aluminum Investments Company, Kaiser Aluminum Fabricated Products, LLC and Kaiser Aluminum Washington, LLC. The Revolving Credit Facility is secured by a first priority lien on substantially all of the accounts receivable, inventory and certain other related assets and proceeds of the Co-Borrowers, as well as certain machinery and equipment. Under the Revolving Credit Facility, we are able to borrow from time to time an aggregate commitment amount equal to the lesser of $300.0 million and a borrowing base comprised of: (i) 85% of eligible accounts receivable; (ii) the lesser of (a) 75% of eligible inventory and (b) 85% of the net orderly liquidation value of eligible inventory as determined in the most recent inventory appraisal ordered by the administrative agent; and (iii) certain eligible machinery and equipment supporting up to $60.0 million of borrowing availability, reduced by certain reserves, all as specified in the Revolving Credit Facility. Up to a maximum of $20.0 million of availability under the Revolving Credit Facility may be utilized for letters of credit. Borrowings under the Revolving Credit Facility bear interest at a rate equal to either a base prime rate or LIBOR, at our option, plus, in each case, a specified variable percentage determined by reference to the then-remaining borrowing availability under the Revolving Credit Facility. The funding commitment of the Revolving Credit Facility may be increased up to $400.0 million , subject to certain conditions and the agreement of lenders thereunder. We had $300.0 million of total borrowing availability under the Revolving Credit Facility at December 31, 2017 , based on the borrowing base determination then in effect. At December 31, 2017 , there were no borrowings under the Revolving Credit Facility and $8.1 million was used to support outstanding letters of credit, leaving $291.9 million of net borrowing availability. The interest rate applicable to any overnight borrowings under the Revolving Credit Facility would have been 4.75% at December 31, 2017 . Amounts owed under the Revolving Credit Facility may be accelerated upon the occurrence of various events of default including, without limitation, the failure to make principal or interest payments when due and breaches of covenants, representations and warranties set forth therein. The Revolving Credit Facility places limitations on our ability and certain of our subsidiaries to, among other things, grant liens, engage in mergers, sell assets, incur debt, enter into sale and leaseback transactions, make investments, undertake transactions with affiliates, prepay certain debt, pay dividends and repurchase shares. We are allowed to prepay debt, pay dividends and repurchase shares in any amount if, after giving effect to such payment, $52.5 million or more would be available for us to borrow under the Revolving Credit Facility, or if after giving effect to such payment, $45.0 million or more would be available to us to borrow under the Revolving Credit Facility and we maintain a fixed charge coverage ratio at or above 1.15:1.0 . In addition, we are required to maintain a fixed charge coverage ratio on a consolidated basis at or above 1.0:1.0 if borrowing availability under the Revolving Credit Facility is less than $30.0 million .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments. We have a variety of financial commitments, including purchase agreements, forward foreign exchange and forward sales contracts, indebtedness and letters of credit (see Note 7 and Note 8 ). Rental expenses were $7.9 million , $8.5 million and $8.2 million for 2017 , 2016 and 2015 , respectively. There are renewal options in various operating leases subject to certain terms and conditions. Minimum rental commitments under operating leases at December 31, 2017 were as follows (in millions of dollars): Year Ended December 31, 2018 2019 2020 2021 2022 2023 and Thereafter Minimum rental commitments $ 5.7 $ 5.2 $ 3.1 $ 2.5 $ 2.2 $ 21.0 CAROs. The inputs in estimating the fair value of CAROs include: (i) the timing of when any such CARO cash flows may be incurred; (ii) incremental costs associated with special handling or treatment of CARO materials; and (iii) the credit-adjusted risk-free rate applicable at the time additional CARO cash flows are estimated; all of which are considered Level 3 inputs as they involve significant judgment from us. The following table summarizes the activity relating to our CARO liabilities (in millions of dollars): Year Ended December 31, 2017 2016 2015 Beginning balance $ 5.5 $ 4.9 $ 4.8 Liabilities incurred during the period — — — Liabilities settled during the period — (0.1 ) (0.2 ) Accretion expense 0.4 0.5 0.3 Adjustment to accretion expense due to revisions to estimated cash flow and timing of expenditure 1 — 0.2 — Ending balance $ 5.9 $ 5.5 $ 4.9 __________________________________________ 1. The adjustments in 2016 had a de minimis impact on the basic and diluted net income per share for 2016. The estimated fair value of CARO liabilities at December 31, 2017 and December 31, 2016 were based upon the application of a weighted-average credit-adjusted risk-free rate of 8.7% and 8.6% , respectively. CAROs are included in Other accrued liabilities or Long-term liabilities, as appropriate. Environmental Contingencies. We are subject to a number of environmental laws and regulations, to potential fines or penalties assessed for alleged breaches of such laws and regulations and to potential claims based upon such laws and regulations. We are also subject to legacy environmental contingencies related to activities that occurred at operating facilities within Fabricated Products prior to July 6, 2006 while such operating facilities were being operated by a predecessor, which represent the majority of our environmental accruals. The status of these environmental contingencies are discussed below. We have established procedures for regularly evaluating environmental loss contingencies. Our environmental accruals represent our undiscounted estimate of costs reasonably expected to be incurred based on presently enacted laws and regulations, existing requirements, currently available facts, existing technology and our assessment of the likely remediation actions to be taken. We continue to pursue remediation activities, primarily to address the historical use of oils containing polychlorinated biphenyls ("PCBs") at our Trentwood facility. Our remediation efforts are in collaboration with the Washington State Department of Ecology ("Washington State Ecology"), to which we submitted a feasibility study in 2012 of remediation alternatives and from which we received permission to begin certain remediation activities pursuant to a signed work order. As we have finished a number of sections of the work plan, we have received approval from Washington State Ecology on satisfactory completion of those sections. Additionally, in cooperation with Washington State Ecology, to determine the treatability and evaluate the feasibility of removing PCBs from ground water under the Trentwood facility, we constructed a pilot test facility and began treatment operations at the test facility in the first half of 2016. As the success of the new methodology cannot be reasonably determined at this time, it is possible we may need to make upward adjustments to our related accruals as facts and cost estimates regarding the groundwater treatment method and the operation of the treatment facility become available. During 2013, at the request of the Ohio Environmental Protection Agency ("OEPA"), we initiated an investigational study of our Newark facility related to historical on-site waste disposal. Since 2014, we have completed a number of preliminary steps in the preparation of completing the final risk assessment and feasibility study, both of which are subject to review and approval by the OEPA. As work continues and progresses to a final risk assessment and feasibility study, we will establish and update estimates for probable and estimable remediation, 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 . The following table presents the changes in our environmental accrual, which was primarily included in Long-term liabilities (in millions of dollars): Year Ended December 31, 2017 2016 2015 Beginning balance $ 17.2 $ 18.6 $ 19.3 Additional accruals 0.3 0.1 1.3 Less: expenditures (0.9 ) (1.5 ) (2.0 ) Ending balance $ 16.6 $ 17.2 $ 18.6 At December 31, 2017 , our environmental accrual of $16.6 million represented our estimate of the incremental remediation cost based on: (i) proposed alternatives in the final feasibility study related to the Trentwood facility; (ii) currently available facts with respect to our Newark facility; and (iii) facts related to certain other locations owned or formerly owned by us. In accordance with approved and proposed remediation action plans, we expect 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. We believe 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 $12.5 million over the remediation period. It is reasonably possible that our recorded estimate will change in the next 12 months . Other Contingencies. We are party to various lawsuits, claims, investigations and administrative proceedings that arise in connection with past and current operations. We evaluate such matters on a case-by-case basis and our policy is to vigorously contest any such claims we believe are without merit. We accrue 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, we review and adjust 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, we believe that we have sufficiently accrued for such matters and that the ultimate resolution of pending matters will not have a material impact on our consolidated financial position, operating results or liquidity.

Accumulated Other Comprehensive

Accumulated Other Comprehensive (Loss) Income	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Accumulated Other Comprehensive (Loss) Income	Accumulated Other Comprehensive (Loss) Income The following table presents the changes in the accumulated balances for each component of Accumulated other comprehensive (loss) income ("AOCI") for each period presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Defined benefit pension plan and VEBAs: Beginning balance $ (37.1 ) $ (31.3 ) $ (96.4 ) Actuarial loss arising during the period (0.3 ) (5.7 ) (12.9 ) Less: income tax benefit 0.1 2.1 4.9 Net actuarial loss arising during the period (0.2 ) (3.6 ) (8.0 ) Prior service (cost) credit arising during the period (7.3 ) (8.3 ) 6.8 Less: income tax benefit (expense) 2.7 3.1 (2.6 ) Net prior service (cost) credit arising during the period (4.6 ) (5.2 ) 4.2 Amortization of net actuarial loss 1 0.9 0.5 1.1 Amortization of prior service cost 1 4.7 4.1 3.0 Removal of obligation relating to Union VEBA — — 106.6 Less: income tax expense 2 (2.1 ) (1.7 ) (41.8 ) Net amortization and reclassification from AOCI to Net income (loss) 3.5 2.9 68.9 Translation impact on Canadian pension plan AOCI balance (0.1 ) 0.1 — Other comprehensive (loss) income, net of tax (1.4 ) (5.8 ) 65.1 Ending balance $ (38.5 ) $ (37.1 ) $ (31.3 ) Available for sale securities: Beginning balance $ 0.8 $ (0.1 ) $ 0.2 Unrealized gain (loss) on available for sale securities 4.0 1.9 (0.1 ) Less: income tax expense (1.5 ) (0.7 ) — Net gain (loss) on available for sale securities 2.5 1.2 (0.1 ) Gain reclassified from AOCI to Net income (loss) 3 (3.2 ) (0.5 ) (0.4 ) Less: income tax benefit 2 1.2 0.2 0.2 Net gain reclassified from AOCI to Net income (loss) (2.0 ) (0.3 ) (0.2 ) Other comprehensive income (loss), net of tax 0.5 0.9 (0.3 ) Ending balance $ 1.3 $ 0.8 $ (0.1 ) Other: Beginning balance $ (0.4 ) $ (0.3 ) $ 0.1 Unrealized gain (loss) 2.0 (0.2 ) (0.5 ) Less: income tax (expense) benefit (0.7 ) — 0.1 Net gain (loss) 1.3 (0.2 ) (0.4 ) (Gain) loss reclassified from AOCI to Net income (loss) (0.6 ) 0.1 — Less: income tax benefit 2 0.2 — — Net (gain) loss reclassified from AOCI to Net income (loss) (0.4 ) 0.1 — Other comprehensive income (loss), net of tax 0.9 (0.1 ) (0.4 ) Ending balance $ 0.5 $ (0.4 ) $ (0.3 ) Total AOCI ending balance $ (36.7 ) $ (36.7 ) $ (31.7 ) ____________ 1. Amounts amortized out of AOCI relating to Salaried VEBA adjustments were included as a component of Net periodic postretirement benefit cost relating to Salaried VEBA. 2. Income tax amounts reclassified out of AOCI were included as a component of Income tax (provision) benefit. 3. Amounts reclassified out of AOCI relating to sales of available for sale securities were included as a component of Other income (expense), net. We use the specific identification method to determine the amount reclassified out of AOCI.

Other (Expense) Income, Net

Other (Expense) Income, Net	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Other Income, Net	Other Income (Expense), Net Other income (expense), net consisted of the following for each period presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Interest income $ 0.2 $ 0.1 $ 0.4 Realized gain on investments 3.4 0.8 0.8 Loss on extinguishment of debt 1 — (11.1 ) — All other, net 0.9 (0.1 ) (3.0 ) Other income (expense), net $ 4.5 $ (10.3 ) $ (1.8 ) ____________ 1. Represents the loss on extinguishment of our 8.25% Senior Notes during the year ended December 31, 2016 which includes an $8.2 million premium paid to redeem the notes and a $2.9 million write-off of unamortized debt issuance costs associated with the notes.

Income Tax Matters

Income Tax Matters	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Tax Matters	Income Tax Matters Tax (Provision) Benefit . Income (loss) before income taxes by geographic area was as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Domestic $ 127.9 $ 143.6 $ (373.6 ) Foreign 5.1 3.6 1.8 Income (loss) before income taxes $ 133.0 $ 147.2 $ (371.8 ) Income taxes are classified as either domestic or foreign, based on whether payment is made or due to the United States or a foreign country. Certain income classified as foreign is also subject to domestic income taxes. Income tax (provision) benefit consisted of (in millions of dollars): Federal Foreign State Total 2017 Current $ 3.1 $ (0.8 ) $ (1.0 ) $ 1.3 Deferred (82.0 ) (1.0 ) (5.7 ) (88.7 ) Expense applied to increase Retained earnings/ Other comprehensive income (loss) (0.1 ) (0.1 ) — (0.2 ) Income tax provision $ (79.0 ) $ (1.9 ) $ (6.7 ) $ (87.6 ) 2016 Current $ 2.7 $ 0.6 $ (1.5 ) $ 1.8 Deferred (47.8 ) (1.2 ) (4.7 ) (53.7 ) Expense applied to increase Additional paid in capital/ Other comprehensive income (loss) (3.2 ) (0.1 ) (0.3 ) (3.6 ) Income tax provision $ (48.3 ) $ (0.7 ) $ (6.5 ) $ (55.5 ) 2015 Current $ 0.7 $ 2.1 $ 0.4 $ 3.2 Deferred 93.2 (1.2 ) 1.8 93.8 Benefit applied to decrease Additional paid in capital/Other comprehensive income (loss) 33.5 0.4 4.3 38.2 Income tax benefit $ 127.4 $ 1.3 $ 6.5 $ 135.2 A reconciliation between the (provision for) benefit from income taxes and the amount computed by applying the federal statutory income tax rate to Income (loss) before income taxes is as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Amount of federal income tax (provision) benefit based on the statutory rate $ (46.5 ) $ (51.5 ) $ 130.1 (Increase) decrease in federal valuation allowances 0.5 (0.3 ) (0.6 ) Non-deductible compensation (expense) benefit (2.3 ) 0.3 (0.2 ) Non-deductible (expense) — (0.3 ) (0.3 ) State income tax (provision) benefit, net of federal benefit 1 (4.3 ) (4.2 ) 4.2 Foreign income tax (expense) benefit (0.1 ) 0.5 0.1 Foreign undistributed earnings (5.9 ) — — Expiration of statute of limitations — — 1.7 Tax rate change (29.0 ) — — Advance pricing agreement — — (0.2 ) Competent Authority settlement — — 0.4 Income tax (provision) benefit $ (87.6 ) $ (55.5 ) $ 135.2 ___________________________ 1. State income taxes were $4.0 million in 2017 , but were increased by a $2.5 million change in tax rates, and offset by a $2.2 million decrease in the valuation allowance relating to certain state net operating losses. The state income taxes were $4.1 million in 2016 , but were offset by a $0.2 million decrease due to lower tax rates in various states and a $0.3 million increase in the valuation allowance relating to certain state net operating losses. The state income tax benefit was $10.3 million in 2015 , but was offset by a $3.1 million increase due to state tax rate and state law changes and a $3.0 million increase relating to the expiration of certain state net operating losses. Deferred Income Taxes. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and amounts used for income tax purposes. The components of our net deferred income tax assets were as follows (in millions of dollars): Year Ended December 31, 2017 2016 Deferred income tax assets: Loss and credit carryforwards $ 98.7 $ 191.8 VEBAs (see Note 4) 11.6 23.2 Other assets 21.0 39.8 Inventory 9.3 — Valuation allowances (13.0 ) (15.7 ) Total deferred income tax assets 127.6 239.1 Deferred income tax liabilities: Property, plant and equipment (57.7 ) (82.7 ) Undistributed foreign earnings (2.2 ) — Total deferred income tax liabilities (59.9 ) (82.7 ) Net deferred income tax assets 1 $ 67.7 $ 156.4 __________________________ 1. Of the total net deferred income tax assets of $67.7 million , $72.0 million was presented as Deferred tax assets, net and $4.3 million was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2017 . Of the total net deferred income tax assets of $156.4 million , $159.7 million was presented as Deferred tax assets, net and $3.3 million was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2016 . Tax Attributes. At December 31, 2017 , we had $275.1 million of net operating loss ("NOL") carryforwards available to reduce future cash payments for federal income taxes in the United States. H.R.1, commonly referred to as the Tax Cut and Jobs Act ("Tax Act"), allows net operating losses generated prior to December 31, 2017 (including our NOL carryforwards) to be fully deducted against 100% of taxable income until fully utilized or expired (see " Tax Cuts and Jobs Act " below for further discussion of the Tax Act). Our NOL carryforwards expire periodically through 2030. We also had $23.3 million of alternative minimum tax ("AMT") credit carryforwards available to offset regular federal income tax requirements. Since the corporate AMT has been repealed in the Tax Act for tax years beginning after December 31, 2017, our AMT credit carryforwards that have not yet been used are refundable in future years. We will use AMT credits to offset any regular income tax liability in years 2018 through 2020, with 50% of remaining AMT credits refunded in each of the 2018, 2019, and 2020 tax years and all remaining credits refunded in tax year 2021 (see " Tax Cuts and Jobs Act " below for further discussion of the Tax Act). In assessing the realizability of deferred tax assets, management considers whether it is "more likely than not" that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers taxable income in carryback years, the scheduled reversal of deferred tax liabilities, tax planning strategies and projected future taxable income in making this assessment. Due to uncertainties surrounding the realization of some of our deferred tax assets, primarily including state NOL carryforwards sustained during the prior years and expiring tax benefits, we have a valuation allowance against our deferred tax assets. When recognized, the tax benefits relating to any reversal of this valuation allowance will be recorded as a reduction of income tax expense. The (decrease) increase in the valuation allowance was $(2.7) million , $(5.5) million and $2.0 million in 2017 , 2016 and 2015 , respectively. The decrease in the valuation allowance for 2017 was primarily due to the expiration of state NOL carryforwards and the related reversal of their valuation allowances and the utilization of capital losses. The decrease in the valuation allowance for 2016 was primarily due to the expiration of state NOL carryforwards and the related reversal of their valuation allowances. The increase in the valuation allowance in 2015 was primarily due to unutilized state NOL carryforwards and Federal Separate Return Limitation Year losses that were expected to expire. Other . We and our subsidiaries file income tax returns in the U.S. federal jurisdiction and various states and foreign jurisdictions. Our tax returns for certain past years are still subject to examination by taxing authorities and the use of NOL carryforwards in future periods could trigger a review of attributes and other tax matters in years that are not otherwise subject to examination. We have gross unrecognized benefits relating to uncertain tax positions. A reconciliation of changes in the gross unrecognized tax benefits is as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Gross unrecognized tax benefits at beginning of period $ 1.8 $ 1.7 $ 2.2 Gross increases for tax positions of prior years — 0.1 0.1 Gross decreases for tax positions of prior years (0.3 ) — — Gross decrease for tax positions relating to lapse of a statute of limitation — — (0.6 ) Gross unrecognized tax benefits at end of period $ 1.5 $ 1.8 $ 1.7 If and when the $1.5 million , $1.8 million and $1.7 million of gross unrecognized tax benefits at December 31, 2017 , December 31, 2016 and December 31, 2015 , respectively, are recognized, $0.4 million , $0.7 million and $0.6 million will be reflected, respectively, in our income tax provision and thus affect the effective tax rate in future periods. The change during 2017 was primarily due to a change in tax positions. The change in gross unrecognized tax benefits during 2016 was primarily due to a change in tax positions. The change in gross unrecognized tax benefits during 2015 was primarily due to the expiration of statutes. In addition, we recognize interest and penalties related to unrecognized tax benefits in the income tax provision. We had $0.1 million and $0.2 million accrued for interest and penalties at December 31, 2017 and December 31, 2016 , respectively. Of these amounts, none were considered current and, as such, were included in Long-term liabilities on the Consolidated Balance Sheets at December 31, 2017 and December 31, 2016 . We recognized a decrease in interest and penalty of $0.1 million in our tax provision in 2017. There was no change to interest and penalty in 2016 . We recognized decrease in interest and penalty of $1.2 million in our tax provision in 2015 . In connection with the gross unrecognized tax benefits (including interest and penalties) denominated in foreign currency, we incurred a foreign currency translation adjustment in 2015. During 2015 , the foreign currency impact on such liabilities resulted in currency translation adjustments of $0.1 million , which increased Other comprehensive income. We do not expect our gross unrecognized tax benefits to significantly change within the next 12 months . Tax Cuts and Jobs Act . On December 22, 2017, the U.S. government enacted the Tax Act, which makes broad and complex changes to the U.S. tax code, including, but not limited to: (i) reducing the U.S. federal corporate tax rate from 35% to 21% ; (ii) requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries; (iii) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries; (iv) requiring a current inclusion in U.S. federal taxable income of certain earnings of controlled foreign corporations; (v) eliminating the corporate AMT and changing how existing AMT credits can be realized; (vi) creating a new limitation on deductible interest expense; and (vii) changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after December 31, 2017. The SEC staff issued Staff Accounting Bulletin No. 118 ("SAB 118"), which provides guidance on accounting for the tax effects of the Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740 (see Note 1). In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Tax Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. Our accounting for the following elements of the Tax Act is incomplete. However, we were able to make reasonable estimates of certain effects and, therefore, recorded provisional adjustments in the fourth quarter of 2017 as described below. Reduction of US Federal Corporate Tax Rate. The Tax Act reduces the corporate tax rate to 21% , effective January 1, 2018. For certain of our deferred tax assets, we have recorded a provisional decrease of $29.0 million , with a corresponding net increase to deferred income tax expense for the year ended December 31, 2017. While we are able to make a reasonable estimate of the impact of the reduction in corporate rate, our estimate may be affected by other analyses related to the Tax Act, including, but not limited to, our calculation of deemed repatriation of deferred foreign income and the state tax effect of adjustments made to federal temporary differences. Deemed Repatriation Transition Tax. The Deemed Repatriation Transition Tax ("Transition Tax") is a tax on previously untaxed accumulated and current earnings and profits ("E&P") of certain of our foreign subsidiaries. To determine the amount of the Transition Tax, we must determine, in addition to other factors, the amount of post-1986 E&P of the relevant subsidiaries, as well as the amount of non-U.S. income taxes paid on such earnings. We were able to make a reasonable estimate of the Transition Tax and recorded a provisional Transition Tax obligation of $3.7 million . In addition, we have accrued $2.2 million for withholding tax since our earnings in Canada are no longer permanently reinvested. However, we are continuing to gather additional information to more precisely compute the amount of the Transition Tax. Internal Revenue Code Section 162(m). The Tax Act modifies Section 162(m) of the Internal Revenue Code ("Section 162(m)") by: (i) expanding the scope of covered employees to include the chief financial officer; (ii) providing that any individual that becomes a covered employee for a taxable year beginning after December 31, 2016 would remain a covered employee for all future years; and (iii) eliminating the exceptions for commissions and performance-based compensation from the $1.0 million deduction limit. These changes do not apply to compensation stemming from contracts entered into on or before November 2, 2017, unless such contracts were materially modified on or after that date. Compensation agreements entered into and share-based payment awards granted after this date will be subject to the revised terms of Section 162(m). We were able to make a reasonable estimate of the Tax Act modifications to Section 162(m) and recorded a provisional Section 162(m) obligation of $2.3 million . However, we are continuing to gather additional information to more precisely compute the amount of the Section 162(m) limitation.

Net Income (Loss) Per Share and

Net Income (Loss) Per Share and Stockholders' Equity	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Income (Loss) Per Share and Stockholders' Equity	Net Income (Loss) Per Share and Stockholders' Equity Net Income (Loss) Per Share . Basic net income (loss) per share is computed by dividing distributed and undistributed net income (loss) allocable to common shares by the weighted-average number of common shares outstanding during the applicable period. The basic weighted-average number of common shares outstanding during the period excludes unvested share-based payment awards. Diluted net income (loss) per share was calculated under the treasury stock method for 2017 , 2016 and 2015 , which in all years was more dilutive than the two-class method. The following table sets forth the computation of basic and diluted net income (loss) per share for the periods presented (in millions of dollars, except share and per share amounts): Year Ended December 31, 2017 2016 2015 Numerator: Net income (loss) $ 45.4 $ 91.7 $ (236.6 ) Denominator – Weighted-average common shares outstanding (in thousands): Basic 16,996 17,813 17,201 Add: dilutive effect of non-vested common shares, restricted stock units and performance shares 263 220 — Diluted 17,259 18,033 17,201 Net income (loss) per common share, Basic: $ 2.67 $ 5.15 $ (13.76 ) Net income (loss) per common share, Diluted: $ 2.63 $ 5.09 $ (13.76 ) Net-share-settled warrants ("Warrants") relating to approximately 3.7 million notional common shares of our common stock at an exercise price of approximately $60.70 per share were settled during a period from July 1, 2015 through December 18, 2015. In total, we issued 1,015,185 shares of our common stock in connection with the Warrants and paid a de minimis amount in cash to the holders for fractional shares at the end of the settlement period. The following securities were excluded from the weighted-average diluted shares computation for the periods presented as their inclusion would have been anti-dilutive (in thousands of shares): Year Ended December 31, 2017 2016 2015 Non-vested common shares, restricted stock units and performance shares 52 50 302 Warrants — — 639 Total excluded 52 50 941 Dividends . During 2017 , 2016 and 2015 , we paid a total of approximately $35.0 million ( $2.00 per common share), $32.4 million ( $1.80 per common share) and $28.1 million ( $1.60 per common share), respectively, in cash dividends to stockholders, including the holders of restricted stock, and dividend equivalents to the holders of certain restricted stock units and performance shares. Treasury Stock. From time to time, we repurchase shares pursuant to a stock repurchase program authorized by our Board of Directors. Repurchase transactions will occur at such times and prices as management deems appropriate and will be funded with our excess liquidity after giving consideration to, among other things, 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 our Board of Directors at any time. Repurchases of our common stock pursuant to the stock repurchase program is recorded as Treasury stock and consisted of the following for each period presented: Year Ended December 31, 2017 2016 2015 Number of common shares repurchased 938,680 443,838 647,520 Weighted-average repurchase price (dollars per share) $ 82.97 $ 78.59 $ 76.35 Total cost of repurchased common shares (in millions of dollars) $ 77.8 $ 34.9 $ 49.4 At December 31, 2017 and December 31, 2016 , $110.5 million and $88.4 million , respectively, were available to repurchase our common shares pursuant to the stock repurchase program. Preferred Stock . In connection with a tax asset protection rights plan, our Board of Directors declared a dividend, payable April 22, 2016, of one right for each outstanding share of our common stock. In general, if the rights become exercisable, each right would allow its holder to purchase one one-hundredth of a share of our Series A Preferred Stock. The authorized number of shares of Series A Preferred Stock is 900,000 .

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Year Ended December 31, 2017 2016 2015 (in millions of dollars) Interest paid $ 21.1 $ 17.7 $ 22.1 Non-cash investing and financing activities (included in Accounts payable): Unpaid purchases of property and equipment $ 7.4 $ 4.6 $ 10.5 Stock repurchases not yet settled $ 0.1 $ 1.8 $ 0.2 Acquisition of property and equipment through capital leasing arrangements $ 1.2 $ 0.2 $ — December 31, 2017 2016 2015 Components of cash, cash equivalents and restricted cash: Cash and cash equivalents $ 51.1 $ 55.2 $ 72.5 Restricted cash included in Prepaid expenses and other current assets 0.3 0.3 0.3 Restricted cash included in Other assets 12.9 12.2 10.9 Total cash, cash equivalents and restricted cash shown in the Statements of Consolidated Cash Flows $ 64.3 $ 67.7 $ 83.7

Segment and Geographical Area I

Segment and Geographical Area Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment and Geographical Area Information	Segment and Geographical Area Information Our primary line of business is the production of semi-fabricated specialty aluminum products, such as aluminum plate and sheet and extruded and drawn products, primarily used in Aero/HS products, Automotive Extrusions, GE products and Other products. We operate 11 focused production facilities in the United States and one in Canada. Consistent with the manner in which our chief operating decision maker reviews and evaluates our business, the Fabricated Products business is treated as a single operating segment. At December 31, 2017 , approximately 63% of our employees were covered by collective bargaining agreements and approximately 12% of our employees were covered by collective bargaining agreements with expiration dates occurring within one year from December 31, 2017 . In addition to the Fabricated Products segment, we have a business unit, All Other, which provides general and administrative support for our operations. For purposes of segment reporting under GAAP, we treat the Fabricated Products segment as a reportable segment. All Other is not considered a reportable segment. The accounting policies of our Fabricated Products segment are the same as those described in Note 1 . Segment results are evaluated internally by management before any allocation of corporate overhead and without any charge for income taxes, interest expense or other net operating charges. The following tables provide financial information by reporting segment and business unit for each period or as of each period end, as applicable (in millions of dollars): Year Ended December 31, 2017 2016 2015 Net sales: Fabricated Products $ 1,397.5 $ 1,330.6 $ 1,391.9 Segment operating income (loss): Fabricated Products 201.3 229.6 190.8 All Other (50.6 ) (51.8 ) (536.7 ) Total operating income (loss) 150.7 177.8 (345.9 ) Interest expense (22.2 ) (20.3 ) (24.1 ) Other income (expense) , net 4.5 (10.3 ) (1.8 ) Income (loss) before income taxes $ 133.0 $ 147.2 $ (371.8 ) Depreciation and amortization: Fabricated Products $ 39.0 $ 35.4 $ 31.9 All Other 0.7 0.6 0.5 Total depreciation and amortization $ 39.7 $ 36.0 $ 32.4 Capital expenditures: Fabricated Products $ 75.3 $ 75.6 $ 62.4 All Other 0.2 0.5 0.7 Total capital expenditures $ 75.5 $ 76.1 $ 63.1 December 31, 2017 2016 2015 Assets: Fabricated Products $ 1,046.8 $ 969.4 $ 904.7 All Other 1 338.4 474.1 342.2 Total assets $ 1,385.2 $ 1,443.5 $ 1,246.9 __________________ 1. Assets in All Other represent primarily all of our cash, cash equivalents and restricted cash, short-term investments, financial derivative assets, deferred compensation program assets and net deferred income tax assets. Net sales by end market applications for the Fabricated Products segment were as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Net sales: Aero/HS products $ 653.7 $ 675.4 $ 695.5 Automotive Extrusions 217.3 188.8 199.2 GE products 476.2 420.1 426.1 Other products 50.3 46.3 71.1 Total net sales $ 1,397.5 $ 1,330.6 $ 1,391.9 Geographic information for net sales based on country of origin, income taxes paid and long-lived assets were as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Net sales to unaffiliated customers: Fabricated Products – Domestic $ 1,337.3 $ 1,278.6 $ 1,321.3 Foreign 1 60.2 52.0 70.6 Total net sales $ 1,397.5 $ 1,330.6 $ 1,391.9 Income taxes paid: Fabricated Products – Domestic $ 1.2 $ 0.7 $ 0.6 Foreign 0.1 0.5 1.7 Total income taxes paid $ 1.3 $ 1.2 $ 2.3 December 31, 2017 2016 2015 Long-lived assets: 2 Fabricated Products – Domestic $ 536.6 $ 494.7 $ 459.6 Foreign 30.2 31.4 30.9 Total Fabricated Products long-lived assets 566.8 526.1 490.5 All Other – Domestic 4.6 4.8 4.9 Total All Other long-lived assets 4.6 4.8 4.9 Total long-lived assets $ 571.4 $ 530.9 $ 495.4 __________________ 1. Foreign net sales reflect sales shipped from our London, Ontario production facility. 2. Long-lived assets represent Property, plant and equipment, net. The aggregate foreign currency transaction gain (loss) included in determining net income (loss) were immaterial for 2017 , 2016 and 2015 . For the years ended December 31, 2017 , December 31, 2016 and December 31, 2015 , one customer represented 27% , 26% and 25% , respectively, of Fabricated Products Net sales. For the year ended December 31, 2017 , a second customer represented 12% of Fabricated Products Net sales. For each of the years ended December 31, 2016 , and December 31, 2015 , a second customer represented 10% of Fabricated Products Net sales. One individual customer accounted for 22% and another individual customer accounted for 14% of the trade receivables balance at December 31, 2017 . One individual customer accounted for 18% and two individual customers each accounted for 14% of the trade receivables balance at December 31, 2016 . Information for export sales and primary aluminum supply from our major suppliers were as follows: Year Ended December 31, 2017 2016 2015 Percentage of Net sales: Export sales 18 % 19 % 19 % Percentage of total annual primary aluminum supply (lbs): Supply from our top five major suppliers 85 % 84 % 86 % Supply from our largest supplier 36 % 32 % 28 % Supply from our second and third largest suppliers combined 33 % 32 % 36 %

Guarantor and Non-Guarantor Fin

Guarantor and Non-Guarantor Financial Statements (Notes)	12 Months Ended
	Dec. 31, 2017
Guarantor and Non-Guarantor Financial Statement [Abstract]
Guarantor and Non-Guarantor Financial Statements	Condensed Guarantor and Non-Guarantor Financial Information During the quarter ended June 30, 2016, we issued $375.0 million aggregate principal amount of our 5.875% Senior Notes and redeemed in full the remaining principal balance of our 8.25% Senior Notes. The 5.875% Senior Notes were issued by Kaiser Aluminum Corporation ("Parent") pursuant to an indenture dated May 12, 2016 ("Indenture") with Wells Fargo Bank, National Association, as trustee ("Trustee"). The obligations of the Parent under the Indenture are guaranteed by Kaiser Aluminum Investments Company, Kaiser Aluminum Fabricated Products, LLC and Kaiser Aluminum Washington, LLC, ("Guarantor Subsidiaries"). An additional Guarantor Subsidiary, Kaiser Aluminum Alexco, LLC, merged with and into Kaiser Aluminum Fabricated Products, LLC during the first quarter of 2017. All Guarantor Subsidiaries are 100% owned by the Parent. The guarantees are full and unconditional and joint and several but have customary releases in the following situations: (i) the sale of the Guarantor Subsidiary or all of its assets; (ii) the declaration of a Guarantor Subsidiary as an unrestricted subsidiary under the Indenture; (iii) the termination or release of the Guarantor Subsidiary's guarantee of certain other indebtedness; or (iv) our exercise of legal defeasance or covenant defeasance or the discharge of our obligations under the Indenture. The following condensed consolidating financial information as of December 31, 2017 and December 31, 2016 , and for the years ended December 31, 2017 , December 31, 2016 and December 31, 2015 present: (i) the financial position, results of operation and cash flows for each of (a) Parent, (b) the Guarantor Subsidiaries on a combined basis and (c) the Non-Guarantor Subsidiaries on a combined basis; (ii) the "Consolidating Adjustments," which represent the adjustments necessary to eliminate the investments in our subsidiaries, other intercompany balances and other intercompany sales and cost of sales among Parent, the Guarantor Subsidiaries and the Non-Guarantor Subsidiaries; and (iii) the resulting totals, reflecting information for us on a consolidated basis, as reported. The condensed consolidating financial information should be read in conjunction with the consolidated financial statements herein. The "Non-Guarantor Subsidiaries" include Kaiser Aluminum Mill Products, Inc., Kaiser Aluminum Canada Limited, Trochus Insurance Company, DCO Management, LLC (which was dissolved in the fourth quarter of 2016 and ceased to exist as of January 1, 2017), Kaiser Aluminum France, S.A.S. and Kaiser Aluminum Beijing Trading Company. Kaiser Aluminum Mill Products, Inc. was included in the "Guarantor Subsidiaries" under the indenture covering the 8.25% Senior Notes but is not a Guarantor Subsidiary under the Indenture. Historical periods have not been restated to move Kaiser Aluminum Mill Products, Inc. from the Guarantor Subsidiaries category to the Non-Guarantor Subsidiaries category because the impact of this change to the financial position, results of operation and cash flows with respect to the Guarantor Subsidiaries on a combined basis and the Non-Guarantor Subsidiaries on a combined basis is immaterial. CONDENSED CONSOLIDATING BALANCE SHEET (In millions of dollars) December 31, 2017 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated ASSETS Current assets: Cash and cash equivalents $ — $ 48.4 $ 2.7 $ — $ 51.1 Short-term investments — 183.7 — — 183.7 Receivables: Trade receivables, net — 160.1 4.9 — 165.0 Intercompany receivables 22.8 0.1 0.7 (23.6 ) — Other — 14.7 0.8 — 15.5 Inventories — 198.7 9.2 — 207.9 Prepaid expenses and other current assets 0.1 32.9 0.4 — 33.4 Total current assets 22.9 638.6 18.7 (23.6 ) 656.6 Investments in and advances to subsidiaries 1,097.7 48.2 — (1,145.9 ) — Property, plant and equipment, net — 541.2 30.2 — 571.4 Long-term intercompany receivables — — 12.4 (12.4 ) — Deferred tax assets, net — 67.3 — 4.7 72.0 Intangible assets, net — 25.0 — — 25.0 Goodwill — 18.8 — — 18.8 Other assets — 41.4 — — 41.4 Total $ 1,120.6 $ 1,380.5 $ 61.3 $ (1,177.2 ) $ 1,385.2 LIABILITIES AND STOCKHOLDERS’ EQUITY Current liabilities: Accounts payable $ 1.9 $ 81.4 $ 6.7 $ — $ 90.0 Intercompany payable — 23.5 0.1 (23.6 ) — Accrued salaries, wages and related expenses — 41.0 1.6 — 42.6 Other accrued liabilities 2.8 46.2 1.0 (9.5 ) 40.5 Total current liabilities 4.7 192.1 9.4 (33.1 ) 173.1 Net liabilities of Salaried VEBA — 31.9 — — 31.9 Deferred tax liabilities — — 4.3 — 4.3 Long-term intercompany payable — 12.4 — (12.4 ) — Long-term liabilities — 58.0 2.0 — 60.0 Long-term debt 369.6 — — — 369.6 Total liabilities 374.3 294.4 15.7 (45.5 ) 638.9 Total stockholders’ equity 746.3 1,086.1 45.6 (1,131.7 ) 746.3 Total $ 1,120.6 $ 1,380.5 $ 61.3 $ (1,177.2 ) $ 1,385.2 CONDENSED CONSOLIDATING BALANCE SHEET (In millions of dollars) December 31, 2016 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated ASSETS Current assets: Cash and cash equivalents $ — $ 52.9 $ 2.3 $ — $ 55.2 Short-term investments — 231.0 — — 231.0 Receivables: Trade receivables, net — 133.1 4.6 — 137.7 Intercompany receivables 85.8 0.1 0.6 (86.5 ) — Other — 11.4 0.5 — 11.9 Inventories — 197.5 8.0 (3.9 ) 201.6 Prepaid expenses and other current assets 0.1 18.0 0.9 (0.5 ) 18.5 Total current assets 85.9 644.0 16.9 (90.9 ) 655.9 Investments in and advances to subsidiaries 1,012.4 40.1 — (1,052.5 ) — Property, plant and equipment, net — 499.5 31.4 — 530.9 Long-term intercompany receivables 80.2 — 4.9 (85.1 ) — Deferred tax assets, net — 154.9 — 4.8 159.7 Intangible assets, net — 26.4 — — 26.4 Goodwill — 37.2 — — 37.2 Other assets — 33.4 — — 33.4 Total $ 1,178.5 $ 1,435.5 $ 53.2 $ (1,223.7 ) $ 1,443.5 LIABILITIES AND STOCKHOLDERS’ EQUITY Current liabilities: Accounts payable $ 2.2 $ 68.9 $ 4.7 $ — $ 75.8 Intercompany payable — 86.4 0.1 (86.5 ) — Accrued salaries, wages and related expenses — 47.2 1.9 — 49.1 Other accrued liabilities 2.9 52.6 (0.7 ) (14.7 ) 40.1 Total current liabilities 5.1 255.1 6.0 (101.2 ) 165.0 Net liabilities of Salaried VEBA — 28.6 — — 28.6 Deferred tax liabilities — — 3.3 — 3.3 Long-term intercompany payable — 85.1 — (85.1 ) — Long-term liabilities — 70.5 2.7 — 73.2 Long-term debt 368.7 — — — 368.7 Total liabilities 373.8 439.3 12.0 (186.3 ) 638.8 Total stockholders’ equity 804.7 996.2 41.2 (1,037.4 ) 804.7 Total $ 1,178.5 $ 1,435.5 $ 53.2 $ (1,223.7 ) $ 1,443.5 CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (In millions of dollars) Year Ended December 31, 2017 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Net sales $ — $ 1,365.3 $ 115.7 $ (83.5 ) $ 1,397.5 Costs and expenses: Cost of products sold: Cost of products sold, excluding depreciation and amortization and other items — 1,085.5 101.1 (81.3 ) 1,105.3 Unrealized gain on derivative instruments — (19.4 ) — — (19.4 ) Depreciation and amortization — 37.5 2.2 — 39.7 Selling, general, administrative, research and development: Selling, general, administrative, research and development 4.5 88.3 6.9 (2.2 ) 97.5 Net periodic postretirement benefit cost relating to Salaried VEBA — 4.5 — — 4.5 Total selling, general, administrative, research and development 4.5 92.8 6.9 (2.2 ) 102.0 Goodwill impairment — 18.4 — — 18.4 Other operating charges, net — 0.8 — — 0.8 Total costs and expenses 4.5 1,215.6 110.2 (83.5 ) 1,246.8 Operating (loss) income (4.5 ) 149.7 5.5 — 150.7 Other (expense) income: Interest expense (20.7 ) (1.7 ) — 0.2 (22.2 ) Other income, net — 4.0 0.7 (0.2 ) 4.5 (Loss) income before income taxes (25.2 ) 152.0 6.2 — 133.0 Income tax provision — (95.2 ) (1.9 ) 9.5 (87.6 ) Earnings in equity of subsidiaries 70.6 4.3 — (74.9 ) — Net income $ 45.4 $ 61.1 $ 4.3 $ (65.4 ) $ 45.4 Comprehensive income $ 45.4 $ 61.1 $ 4.3 $ (65.4 ) $ 45.4 CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (In millions of dollars) Year Ended December 31, 2016 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Net sales $ — $ 1,301.6 $ 103.4 $ (74.4 ) $ 1,330.6 Costs and expenses: Cost of products sold: Cost of products sold, excluding depreciation and amortization and other items — 1,000.6 90.0 (71.1 ) 1,019.5 Lower of cost or market inventory write-down — 4.9 — — 4.9 Unrealized gain on derivative instruments — (18.7 ) — — (18.7 ) Depreciation and amortization — 34.0 2.0 — 36.0 Selling, general, administrative, research and development: Selling, general, administrative, research and development 4.2 95.0 8.4 (2.6 ) 105.0 Net periodic postretirement benefit cost relating to Salaried VEBA — 3.4 — — 3.4 Gain on removal of Union VEBA net assets — (0.1 ) — — (0.1 ) Total selling, general, administrative, research and development 4.2 98.3 8.4 (2.6 ) 108.3 Other operating charges, net — 2.8 — — 2.8 Total costs and expenses 4.2 1,121.9 100.4 (73.7 ) 1,152.8 Operating (loss) income (4.2 ) 179.7 3.0 (0.7 ) 177.8 Other (expense) income: Interest (expense) income (21.6 ) 1.2 — 0.1 (20.3 ) Other (expense) income, net (11.1 ) 0.9 — (0.1 ) (10.3 ) (Loss) income before income taxes (36.9 ) 181.8 3.0 (0.7 ) 147.2 Income tax provision — (69.0 ) (0.6 ) 14.1 (55.5 ) Earnings in equity of subsidiaries 128.6 1.7 — (130.3 ) — Net income $ 91.7 $ 114.5 $ 2.4 $ (116.9 ) $ 91.7 Comprehensive income $ 86.7 $ 109.8 $ 2.1 $ (111.9 ) $ 86.7 CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE (LOSS) INCOME (In millions of dollars) Year Ended December 31, 2015 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Net sales $ — $ 1,361.6 $ 123.3 $ (93.0 ) $ 1,391.9 Costs and expenses: Cost of products sold: Cost of products sold, excluding depreciation and amortization and other items — 1,095.6 108.4 (88.6 ) 1,115.4 Lower of cost or market inventory write-down — 2.6 — — 2.6 Unrealized loss on derivative instruments — 3.4 — — 3.4 Depreciation and amortization — 31.3 1.1 — 32.4 Selling, general, administrative, research and development: Selling, general, administrative, research and development 4.3 76.5 9.3 (2.0 ) 88.1 Net periodic postretirement benefit income relating to Salaried VEBA — 2.4 — — 2.4 Loss on removal of Union VEBA net assets — 493.4 — — 493.4 Total selling, general, administrative, research and development 4.3 572.3 9.3 (2.0 ) 583.9 Other operating charges, net — 0.1 — — 0.1 Total costs and expenses 4.3 1,705.3 118.8 (90.6 ) 1,737.8 Operating (loss) income (4.3 ) (343.7 ) 4.5 (2.4 ) (345.9 ) Other income (expense): Interest expense (23.5 ) (0.9 ) — 0.3 (24.1 ) Other (expense) income, net (2.5 ) 3.5 (2.5 ) (0.3 ) (1.8 ) (Loss) income before income taxes (30.3 ) (341.1 ) 2.0 (2.4 ) (371.8 ) Income tax benefit — 122.5 1.3 11.4 135.2 (Loss) earnings in equity of subsidiaries (206.3 ) 0.9 — 205.4 — Net (loss) income $ (236.6 ) $ (217.7 ) $ 3.3 $ 214.4 $ (236.6 ) Comprehensive (loss) income $ (172.2 ) $ (153.5 ) $ 3.5 $ 150.0 $ (172.2 ) CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS (In millions of dollars) Year Ended December 31, 2017 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Cash flows from operating activities: Net cash (used in) provided by operating activities $ (24.2 ) $ 156.9 $ 8.8 $ — $ 141.5 Cash flows from investing activities: Capital expenditures — (74.7 ) (0.8 ) — (75.5 ) Purchase of available for sale securities — (247.5 ) — — (247.5 ) Proceeds from disposition of available for sale securities — 296.9 — — 296.9 Proceeds from disposal of property, plant and equipment — 0.6 — — 0.6 Intercompany loans receivable 143.2 — (7.6 ) (135.6 ) — Net cash provided by (used in) investing activities 143.2 (24.7 ) (8.4 ) (135.6 ) (25.5 ) Cash flows from financing activities: Repayment of capital lease — (0.4 ) — — (0.4 ) Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (4.5 ) — — — (4.5 ) Repurchase of common stock (79.5 ) — — — (79.5 ) Cash dividends and dividend equivalents paid (35.0 ) — — — (35.0 ) Intercompany loans payable — (135.6 ) — 135.6 — Net cash used in financing activities (119.0 ) (136.0 ) — 135.6 (119.4 ) Net (decrease) increase in cash and cash equivalents during the period — (3.8 ) 0.4 — (3.4 ) Cash, cash equivalents and restricted cash at beginning of period — 65.1 2.6 — 67.7 Cash, cash equivalents and restricted cash at end of period $ — $ 61.3 $ 3.0 $ — $ 64.3 CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS (In millions of dollars) Year Ended December 31, 2016 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Cash flows from operating activities: Net cash provided by operating activities $ 177.7 $ 178.7 $ 9.2 $ (200.0 ) $ 165.6 Cash flows from investing activities: Capital expenditures — (74.0 ) (2.1 ) — (76.1 ) Purchase of available for sale securities — (255.3 ) — — (255.3 ) Proceeds from disposition of available for sale securities — 55.0 — — 55.0 Intercompany loans receivable 1 (166.0 ) 110.4 (1.3 ) 56.9 — Net cash used in investing activities (166.0 ) (163.9 ) (3.4 ) 56.9 (276.4 ) Cash flows from financing activities: Repayment of principal and redemption premium of 8.25% Senior Notes (206.0 ) — — — (206.0 ) Issuance of 5.875% Senior Notes 375.0 — — — 375.0 Cash paid for debt issuance costs (6.8 ) — — — (6.8 ) Proceeds from stock option exercises 1.2 — — — 1.2 Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (2.9 ) — — — (2.9 ) Repurchase of common stock (33.3 ) — — — (33.3 ) Cash dividends and dividend equivalents paid (32.4 ) — — — (32.4 ) Cash dividends paid to Parent — (200.0 ) — 200.0 — Intercompany loans payable 1 (106.5 ) 167.3 (3.9 ) (56.9 ) — Net cash (used in) provided by financing activities (11.7 ) (32.7 ) (3.9 ) 143.1 94.8 Net (decrease) increase in cash and cash equivalents during the period — (17.9 ) 1.9 — (16.0 ) Cash, cash equivalents and restricted cash at beginning of period — 83.0 0.7 — 83.7 Cash, cash equivalents and restricted cash at end of period $ — $ 65.1 $ 2.6 $ — $ 67.7 ________________ 1 As a result of the Parent's additional liquidity associated with the 5.875% Senior Notes (see Note 8 ), we classify all intercompany receivables and payables as Intercompany loans receivable and Intercompany loans payable, respectively, and therefore categorize changes in these balances within the investing and financing sections, respectively, of the Condensed Consolidating Statement of Cash Flows. CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS (In millions of dollars) Year Ended December 31, 2015 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Cash flows from operating activities: Net cash provided by (used in) operating activities $ 285.7 $ (126.3 ) $ 0.3 $ — $ 159.7 Cash flows from investing activities: Capital expenditures — (47.9 ) (15.2 ) — (63.1 ) Purchase of available for sale securities — (0.5 ) — — (0.5 ) Proceeds from disposition of available for sale securities — 84.0 — — 84.0 Net cash provided by (used in) investing activities — 35.6 (15.2 ) — 20.4 Cash flows from financing activities: Repayment of principal and redemption premium of 8.25% Senior Notes (30.0 ) — — — (30.0 ) Repayment of Convertible Notes (175.0 ) — — — (175.0 ) Proceeds from cash-settled call options related to settlement of Convertible Notes 94.9 — — — 94.9 Payment for conversion premium related to settlement of Convertible Notes (94.9 ) — — — (94.9 ) Cash paid for debt issuance costs (0.6 ) — — — (0.6 ) Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest — 1.3 — — 1.3 Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (2.8 ) — — — (2.8 ) Repurchase of common stock (49.2 ) — — — (49.2 ) Cash dividends and dividend equivalents paid (28.1 ) — — — (28.1 ) Intercompany loans payable — (12.8 ) 12.8 — — Net cash (used in) provided by financing activities (285.7 ) (11.5 ) 12.8 — (284.4 ) Net decrease in cash and cash equivalents during the period — (102.2 ) (2.1 ) — (104.3 ) Cash, cash equivalents and restricted cash at beginning of period — 185.2 2.8 — 188.0 Cash, cash equivalents and restricted cash at end of period $ — $ 83.0 $ 0.7 $ — $ 83.7

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Data [Abstract]
Quarterly Financial Data (Unaudited)	Quarterly Financial Data (Unaudited) The following tables present the unaudited financial data for each of the interim periods in 2017 and 2016 (in millions of dollars, except per share amounts): Quarter Ended 31-Mar Quarter Ended 30-Jun Quarter Ended 30-Sep Quarter Ended 31-Dec 2017 Net sales $ 355.3 $ 356.3 $ 332.8 $ 353.1 Cost of products sold, excluding depreciation, amortization and other items $ 277.8 $ 277.7 $ 267.2 $ 282.6 Unrealized (gain) loss on derivative instruments $ (15.1 ) $ 11.9 $ (10.8 ) $ (5.4 ) Gross profit $ 92.6 $ 66.7 $ 76.4 $ 75.9 Operating income $ 59.5 $ 11.4 $ 39.8 $ 40.0 Net income (loss) 1 $ 36.0 $ 4.7 $ 19.9 $ (15.2 ) Net income (loss) per common share, Basic $ 2.07 $ 0.28 $ 1.18 $ (0.90 ) Net income (loss) per common share, Diluted $ 2.04 $ 0.27 $ 1.16 $ (0.90 ) Dividends declared per common share $ 0.50 $ 0.50 $ 0.50 $ 0.50 ________________ 1 The quarter ended June 30, 2017 reflected an $18.4 million goodwill impairment charge (see Note 3 ). The quarter ended December 31, 2017 included the tax provision effect of $37.2 million due to the Tax Act (see Note 12 ). Quarter Ended 31-Mar Quarter Ended 30-Jun Quarter Ended 30-Sep Quarter Ended 31-Dec 2016 Net sales $ 343.2 $ 334.9 $ 320.6 $ 331.9 Cost of products sold, excluding depreciation, amortization and other items $ 262.0 $ 250.4 $ 254.7 $ 252.4 Lower of cost or market inventory write-down $ 4.9 $ — $ — $ — Unrealized gain on derivative instruments $ (4.0 ) $ (10.9 ) $ (2.0 ) $ (1.8 ) Gross profit $ 80.3 $ 95.4 $ 67.9 $ 81.3 Operating income $ 44.8 $ 57.9 $ 29.8 $ 45.3 Net income $ 26.3 $ 26.0 $ 14.9 $ 24.5 Net income per common share, Basic $ 1.47 $ 1.45 $ 0.84 $ 1.39 Net income per common share, Diluted $ 1.44 $ 1.43 $ 0.82 $ 1.37 Dividends declared per common share $ 0.45 $ 0.45 $ 0.45 $ 0.45

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Dividend Declaration . On January 16, 2018 , we announced that our Board of Directors declared a quarterly cash dividend of $0.55 per common share, or approximately $9.3 million (including dividend equivalents), which was paid on February 15, 2018 to stockholders of record at the close of business on January 26, 2018 .

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation. The consolidated financial statements include the accounts of our 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 ("SEC"). Intercompany balances and transactions are eliminated.
Use of Estimates in the Preparation of Financial Statements	Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in accordance with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities known to exist as of the date the financial statements are published and the reported amounts of revenues and expenses during the reporting period. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of our 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 our consolidated financial position and results of operations.
Foreign Currency	Foreign Currency. Certain of our foreign subsidiaries use the local currency as their functional currency; the assets and liabilities of these foreign subsidiaries are translated at exchange rates in effect at the balance sheet date; and our statement of income (loss) is translated at weighted-average monthly rates of exchange prevailing during the year. Resulting translation adjustments are recorded directly to a separate component of stockholders’ equity. Where the U.S. dollar is the functional currency of a foreign facility or subsidiary, re-measurement adjustments are recorded in Other income (expense), net.
Fair Value Measurement	Fair Value Measurements. We apply the fair value hierarchy established by GAAP for the recognition and measurement of certain financial 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, we utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible and consider counterparty risk in our assessment of fair value. The fair values of financial assets and liabilities are evaluated and measured on a recurring basis. As part of that evaluation process, we review the underlying inputs that are significant to the fair value measurement of financial instruments to determine if a transfer among hierarchy levels is appropriate. We historically have not had significant transfers into or out of each hierarchy level. Financial assets and liabilities that we measure at fair value each period include our derivative instruments and available for sale securities, consisting of debt investment securities and investments related to our deferred compensation plan (see Note 4 ). Additionally, we measure at fair value once each year at December 31 the plan assets of the Salaried VEBA (defined in Note 4 ) and our Canadian defined benefit pension plan. We record our remaining financial assets and liabilities at carrying value. For a majority of our non-financial assets and liabilities, which include goodwill, intangible assets, inventories and property, plant and equipment, we are not required to measure their fair value on a recurring basis. However, if certain triggering events occur (or at least annually for goodwill), an evaluation of the affected non-financial asset or liability will be required, which could result in a reduction to the carrying amount of such asset or liability.
Cash and Cash Equivalents	Cash and Cash Equivalents. We consider only those short-term, highly liquid investments which, when purchased, have maturities of 90 days or less to be cash equivalents. Our cash equivalents consist primarily of funds in commercial paper, money market funds and other highly liquid investments, which are classified within Level 1 of the fair value hierarchy with the exception of commercial paper, which is classified within Level 2 of the fair value hierarchy (see Note 7 ).
Restricted Cash	Restricted Cash. We are required to keep on deposit certain amounts that are pledged or held as collateral relating to workers’ compensation and other agreements. We account for such deposits as restricted cash (see Note 14 ). From time to time, such restricted funds could be returned to us or we could be required to pledge additional cash.
Available for Sale Securities	Available for Sale Securities. We account for investments in certain marketable debt securities as available for sale securities. Such securities are recorded at fair value (see Note 7 ), with net unrealized gains and losses, net of income taxes, reflected in Accumulated other comprehensive income (loss) as a component of Stockholders' equity. Realized gains and losses from the sale of marketable debt securities, if any, are determined on a specific identification basis. Debt investment securities with an original maturity of 90 days or less are classified as Cash and cash equivalents (see Note 2 ). Debt investment securities with an original maturity of greater than 90 days are presented as Short-term investments on the Consolidated Balance Sheets. In addition to debt investment securities, we also hold assets in various investment funds managed by a third-party trust in connection with our deferred compensation program (see Note 4 ).
Trade Receivables and Allowance for Doubtful Accounts	Trade Receivables and Allowance for Doubtful Accounts. Trade receivables primarily consist of amounts billed to customers for products sold. Accounts receivable are generally due within 30 to 90 days . For the majority of our receivables, we establish an allowance for doubtful accounts based upon collection experience and other factors. On certain other receivables where we are aware of a specific customer’s inability or reluctance to pay, an allowance for doubtful accounts is established against amounts due, to reduce the net receivable balance to the amount we reasonably expect to collect. However, if circumstances change, our estimate of the recoverability of accounts receivable could be different. Circumstances that could affect our estimates include, but are not limited to, customer credit issues and general economic conditions. Accounts are written off once deemed to be uncollectible. Any subsequent cash collections relating to accounts that have been previously written off are typically recorded as a reduction to total bad debt expense in the period of payment. Write-offs for 2017 , 2016 and 2015 were immaterial to the consolidated financial statements.
Inventories	Inventories. Inventories are stated at the lower of cost or market value. On March 31, 2016, we recorded a lower of cost or market inventory write-down of $4.9 million , as a result of a decrease in our net realizable value of inventory. The net realizable value reflected commitments as of that date from customers to purchase our inventory at prices that exceeded the Midwest Transaction Price ("Midwest Price"), which reflects the primary aluminum supply/demand dynamics in North America, reduced by an approximate normal profit margin. There were no additional lower of cost or market inventory adjustments since the quarter ended March 31, 2016. Finished products, work-in-process and raw material inventories are stated on the last-in, first-out ("LIFO") basis. At December 31, 2017 , the current cost of our inventory exceeded its stated LIFO value by $24.3 million . The stated LIFO value of our inventory represented its net realizable value (less a normal profit margin) and exceeded the current cost of our inventory by $8.5 million at December 31, 2016 . Other inventories are stated on the first-in, first-out basis and consist of operating supplies, which are materials and supplies to be consumed during the production process. 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 our inventories at December 31, 2017 and December 31, 2016 were included in the Fabricated Products segment (see Note 2 for the components of inventories). Replacement Parts. Replacement parts consist of preventative maintenance and capital spare parts, which are stated on the first-in, first-out basis. Replacement parts are recorded within Prepaid expenses and other current assets or Other assets depending on whether or not the expected utilization of the replacement parts is to occur within the current operating cycle.
Property, Plant and Equipment - Net	Property, Plant and Equipment, Net. Property, plant and equipment, net is recorded at cost and includes construction in progress (see Note 2 ). Interest related to the construction of qualifying assets is capitalized as part of the construction costs. The amount of interest expense capitalized as construction in progress was $2.2 million , $2.9 million and $1.8 million during 2017 , 2016 and 2015 , respectively. Depreciation is computed using the straight-line method at rates based on the estimated useful lives of the various classes of assets. Capital lease assets and leasehold improvements are depreciated on a straight-line basis over the shorter of the estimated useful lives of the assets or the lease term. The principal estimated useful lives are as follows: Range (in years) Land improvements 3 - 25 Buildings and leasehold improvements 15 - 45 Machinery and equipment 1 - 24 Capital lease assets 3 - 5 Depreciation expense is not included in Cost of products sold, excluding depreciation and amortization and other items , but is included in Depreciation and amortization. Property, plant and equipment are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset or group of assets may not be recoverable. We regularly assess whether events and circumstances with the potential to trigger impairment have occurred and rely on a number of factors, including operating results, business plans, economic projections and anticipated future cash flow, to make such assessments. We use an estimate of the future undiscounted cash flows of the related asset or asset group over the estimated remaining life of such asset(s) in measuring whether the asset(s) are recoverable. Measurement of the amount of impairment, if any, is based on the difference between the carrying value of the asset(s) and the estimated fair value of such asset(s). Fair value is determined through a series of standard valuation techniques. We recorded impairment charges of $0.8 million , $0.2 million and $0.1 million in 2017 , 2016 and 2015 , respectively, to reflect the scrap value of idled assets we determined not to deploy for future use. Asset impairment charges are included in Other operating charges, net in the Statements of Consolidated Income (Loss) and are included in the Fabricated Products segment. We classify assets as held for sale only when an asset is being actively marketed and expected to sell within 12 months. Assets held for sale are initially measured at the lesser of the assets' carrying amount and the fair value less costs to sell.
Goodwill and Intangible Assets	Goodwill and Intangible Assets. Goodwill is tested for impairment during the fourth quarter on an annual basis, as well as on an interim basis, as warranted, at the time of relevant events and changes in circumstances. Intangible assets with definite lives are initially recognized at fair value and subsequently amortized over the estimated useful lives to reflect the pattern in which the economic benefits of the intangible assets are consumed. In the event the pattern cannot be reliably determined, we use a straight-line amortization method. Whenever events or changes in circumstances indicate that the carrying amount of the intangible assets may not be recoverable, the intangible assets are reviewed for impairment. See Note 3 for a discussion of the goodwill impairment charge recorded during 2017 related to the operations at our Chandler, Arizona (Extrusion) facility, as well as the non-cash impairment charge recorded during 2016 related to one of our customer relationship intangible assets.
Derivative Financial Instruments	Derivative Financial Instruments. Consistent with guidelines established by management and approved by our Board of Directors, we use derivative financial instruments to mitigate our exposure to changes in the market price of aluminum, alloying metals, and energy and, to a lesser extent, foreign currency exchange rates. We do not use derivative financial instruments for trading or other speculative purposes. Hedging transactions are executed centrally on behalf of all of our operations to minimize transaction costs, monitor consolidated net exposures and respond promptly to changes in market factors. We reflect the fair value of all of our derivative instruments on our Consolidated Balance Sheets (see Note 7 ). The carrying values of hedges settling within one year are included in Prepaid expenses and other current assets or Other accrued liabilities. Carrying values for hedges settling beyond one year are included in Other assets or Long-term liabilities. We do not meet the documentation requirements for hedge (deferral) accounting related to aluminum and energy derivatives. Accordingly, we record unrealized gain or loss associated with these hedges in the Statements of Consolidated Income (Loss) within Unrealized (gain) loss on derivative instruments. As such derivatives settle, we reverse any previously recorded unrealized gain or loss associated with these hedges and record the realized gain or loss within Cost of products sold, excluding depreciation and amortization and other items. Forward swap contracts for zinc and copper ("Alloy Hedges") used in our fabrication operations are designated and qualify as cash flow hedges. Unrealized gain and loss associated with the Alloy Hedges are deferred in Other comprehensive income, net of tax. As Alloy Hedges settle, we reverse any unrealized gain or loss previously recorded within Other comprehensive income, net of tax associated with settling Alloy Hedges and record the realized gain or loss within Cost of products sold, excluding depreciation and amortization and other items.
Self Insurance of Workers' Compensation and Employee Healthcare Liabilities	Self Insurance of Workers' Compensation and Employee Healthcare Liabilities . We self-insure the majority of the costs of workers' compensation benefits and employee healthcare benefits and rely on insurance coverage to protect us from large losses on individual claims. Workers' compensation liabilities are based on a combination of estimates for: (i) incurred-but-not-reported claims and (ii) the ultimate expense of incurred claims. Such estimates are based on judgment, using our historical claims data and information and analysis provided by actuarial and claims advisors, our insurance carriers and other professionals. Our undiscounted workers' compensation liabilities were estimated at $24.8 million and $26.8 million at December 31, 2017 and December 31, 2016 , respectively. However, we account for our workers' compensation accrued liability on a discounted basis, using a discount rate of 2.25% at December 31, 2017 and 2.00% at December 31, 2016 . Accrued liabilities for employee healthcare benefits, which are estimates of unpaid incurred medical and prescription drug costs as provided by our healthcare administrators, were $3.5 million and $3.6 million at December 31, 2017 and December 31, 2016 , respectively.
Deferred Issuance Costs	Debt Issuance Costs. Costs incurred in connection with debt financing are deferred and amortized over the estimated term of the related borrowing. Such amortization is included in Interest expense and may be capitalized as part of construction in progress (see Note 2 and Note 8 ).
Conditional Asset Retirement Obligations ("CAROs")	Conditional Asset Retirement Obligations ( " CAROs " ). We have CAROs at several of our Fabricated Products facilities. Our CAROs can be separated into two primary categories: (i) legal obligations related to the removal and disposal of asbestos and (ii) asset retirement obligations related to future lease terminations. The majority of our CAROs relate to the first category and consist of incremental costs that would be associated with the removal and disposal of asbestos (all of which is believed to be fully contained and encapsulated within walls, floors, ceilings or piping) of certain of our older facilities if such facilities were to undergo major renovation or be demolished. We estimate incremental costs for special handling, removal and disposal costs of materials that may or will give rise to CAROs and then discount the expected costs back to the current year using a credit-adjusted, risk-free rate. When it is unclear when or if CAROs will be triggered, we use probability weighting for possible timing scenarios to determine the probability-weighted liability amounts that should be recognized in our consolidated financial statements (see Note 9 ).
Environmental Contingencies	Environmental Contingencies. With respect to environmental loss contingencies, we record a loss contingency whenever a contingency is probable and reasonably estimable (see Note 9 ). Accruals for estimated losses from environmental remediation obligations are generally recognized no later than the completion of the remedial feasibility study. Such accruals are adjusted as information develops or circumstances change. Costs of future expenditures for environmental remediation obligations are not discounted to their present value. Accruals for expected environmental costs are included in Other accrued liabilities or Long-term liabilities, as appropriate (see Note 2 ). Environmental expense relating to continuing operations is included in Cost of products sold, excluding depreciation and amortization and other items in the Statements of Consolidated Income (Loss). Environmental expense relating to non-operating locations is included in Selling, general, administrative, research and development ("SG&A and R&D") in the Statements of Consolidated Income (Loss).
Recognition of Sales	Recognition of Sales. Sales are generally recognized on a gross basis when all of the following criteria are met: (i) persuasive evidence of an arrangement exists; (ii) title, ownership and risk of loss has passed to the customer; (iii) the price to the customer is fixed or determinable; and (iv) collection of the resulting receivable is reasonably assured. A provision for estimated sales returns from and allowances to customers is made in the same period as the related revenues are recognized, based on historical experience or the specific identification of an event necessitating a reserve.
Shipping and Handling Costs	Shipping and Handling Costs. Shipping and handling costs are recorded as a component of Cost of products sold, excluding depreciation, amortization and other items.
Advertising Costs	Advertising Costs. Advertising costs, which are included in SG&A and R&D, are expensed as incurred. Advertising costs for 2017 , 2016 and 2015 were $0.7 million , $0.4 million and $1.2 million , respectively.
Research and Development Costs	Research and Development Costs. Research and development costs, which are included in SG&A and R&D, are expensed as incurred. Research and development costs for 2017 , 2016 and 2015 were $10.0 million , $10.2 million and $9.5 million , respectively.
Major Maintenance Activities	Major Maintenance Activities. All major maintenance costs are accounted for using the direct expensing method.
Leases	Leases. For leases that contain predetermined fixed escalations of the minimum rent, we recognize the related rent expense on a straight-line basis from the date we take possession of the property to the end of the initial lease term. We record any difference between the straight-line rent amounts and the amount payable under the lease as part of deferred rent in Other accrued liabilities or Long-term liabilities, as appropriate. Deferred rent for all periods presented was not material.
Stock-Based Compensation	Stock-Based Compensation. Stock-based compensation in the form of service-based awards is provided to executive officers, certain employees and non-employee directors and is accounted for at fair value. We measure the cost of services received in exchange for an award of equity instruments based on the grant-date fair value of the award and the number of awards expected to ultimately vest. The grant-date fair value is determined based on the stock price on the date of grant, adjusted for expected dividends or dividend equivalents to be paid during the vesting period. We also grant performance-based awards to executive officers and other key employees. The methodology used to value these performance-based awards is based on the nature of the performance conditions within those awards. Awards that are subject to performance conditions pertaining to total shareholder return are valued on the date of grant using a Monte Carlo valuation model. The key assumptions in applying this model are an expected volatility and a risk-free interest rate. Awards with performance conditions pertaining to our cost performance and awards with performance conditions pertaining to our economic value added performance are valued based on our stock price at the date of grant. For more information on our stock-based compensation, see Note 6 . The cost of service-based awards, including time-vested restricted stock and performance shares, is recognized as an expense over the requisite service period of the award on a straight-line basis. Adjustments to expense related to forfeitures are recorded in the period in which they occur. For performance shares with performance conditions pertaining to our cost performance and economic value added performance, the related expense is updated quarterly by adjusting the estimated number of shares expected to vest based on the most probable outcome of the performance condition (see Note 6 ).
Income Taxes	Income Taxes. Deferred income taxes reflect the future tax effect of temporary differences between the carrying amount of assets and liabilities for financial and income tax reporting and are measured by applying statutory tax rates in effect for the year during which the differences are expected to reverse. In accordance with Accounting Standards Codification ("ASC") Topic 740, Income Taxes ("ASC 740"), we use a "more likely than not" threshold for recognition of tax attributes that are subject to uncertainties and measure any reserves in respect of such expected benefits based on their probability. Deferred tax assets are reduced by a valuation allowance to the extent it is more likely than not that the deferred tax assets will not be realized (see Note 12 ).
New Accounting Pronouncements	New Accounting Pronouncements. Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09") , was issued in May 2014 and requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In August 2015, ASU 2014-09 was amended by ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date , which defers the effective date of ASU 2014-09 by one year for all entities and permits early adoption on a limited basis. ASU 2014-09 was subsequently amended by five additional pronouncements that are applicable to us: (i) ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing ; (ii) ASU No. 2016-11, Revenue Recognition (Topic 605) and Derivatives and Hedging (Topic 815): Rescission of SEC Guidance Because of Accounting Standards Updates 2014-09 and 2014-16 Pursuant to Staff Announcements at the March 3, 2016 EITF Meeting ; (iii) ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients ; (iv) ASU No. 2016-20, Revenue from Contracts with Customers (Topic 606): Technical Corrections and Improvements to Topic 606 ; and (v) ASU No. 2017-14, Income Statement - Reporting Comprehensive Income (Topic 220), Revenue Recognition (Topic 605), and Revenue from Contracts with Customers (Topic 606). The primary change to our accounting policies of adopting ASU 2014-09 and its subsequent amendments discussed above (together "ASC 606") will relate to the timing of revenue recognition. Previously, we recognized revenue upon the transfer of risks and title, which was typically not until the product shipped or reached its destination. We will continue to recognize revenue upon product shipment or delivery under ASC 606 for "point-in-time" sales (under certain contracts). However, upon adopting ASC 606, contract sales for a majority of our Aero/HS products and a substantial portion of our Automotive Extrusions will convert from point-in-time to over-time recognition. On these contract sales, we will accelerate revenue recognition throughout the production process. We do not believe adopting ASC 606 will result in: (i) a change in the number of distinct performance obligations within our contractual arrangements; (ii) a change in our current capitalization and deferral policies; (iii) a change in our accounting for contract acquisition and fulfillment costs; (iv) additional contract liability balances; or (v) the adjustment of the amount of promised consideration from our customers for the effects of significant financing components. Additionally, we plan to account for shipping and handling activities that occur after the customer has obtained control of a product as fulfillment activities (i.e., an expense) rather than as a promised service (i.e., a revenue element). As of December 31, 2017: (i) our review of our customer contracts was complete; (ii) our systems were modified to track information needed to apply ASC 606; and (iii) our employees were trained on the changes to revenue recognition policies and work procedures. We will adopt ASC 606 effective January 1, 2018 by recognizing a cumulative-effect adjustment to increase the 2018 opening balance of Retained earnings for the tax-adjusted gross profit of over-time products that were either in work-in-process, in finished goods or in transit to our customers as of December 31, 2017. We expect our adoption of ASC 606 to result in a cumulative-effect adjustment relating to the early recognition of approximately $55.6 million of Net sales based on the application of guidance to contracts not completed at the date of adoption. The cumulative-effect adjustment will be recorded in our opening balance sheet for the year ended December 31, 2018 as: (i) a Contract asset of $55.6 million ; (ii) a reduction in Inventories of $42.2 million ; (iii) a reduction in Deferred tax assets, net of $3.3 million ; and (iv) an increase in Retained earnings of $10.1 million . We believe the impact of adopting ASC 606 will predominantly relate to the timing of revenue recognition and we do not expect it to have a material impact to our quarter-over-quarter or year-over-year results. However, changes in product mix and the stage of product completion at the end of each quarter could result in some unanticipated variability. ASU No. 2016-02, Leases (Topic 842): Amendments to the Financial Accounting Standards Board Accounting Standards Codification ("ASU 2016-02"), was issued in February 2016. Under ASU 2016-02, lessees will need to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). For income statement purposes, a dual model was retained, requiring leases to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). ASU 2016-02 becomes effective for us in the first quarter of 2019. We are currently assessing the impact and expect the adoption of this ASU in 2019 to have a material impact on our consolidated financial statements. ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"), was issued in August 2017. The amendments under ASU 2017-12 refine and expand hedge accounting requirements for both financial (e.g., interest rate) and commodity risks. Its provisions create more transparency around how economic results are presented, both on the face of the financial statements and in the related notes. It also makes certain targeted improvements to simplify the application of hedge accounting guidance. We do not expect to record a cumulative effect adjustment as a result of early adopting ASU 2017-12 in the first quarter of 2018; however, we plan to designate a significant portion of our commodity hedges as cash flow hedges beginning January 1, 2018. We therefore expect to significantly reduce or eliminate the mark-to-market adjustments that have historically been recorded within Unrealized (gain) loss on derivative instruments. These adjustments will instead be recorded within Accumulated other comprehensive loss beginning in the first quarter of 2018. We do not anticipate any material impact on our consolidated financial statements upon the adoption of the following accounting pronouncements: (i) ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ; (ii) ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ; (iii) ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost ; and (iv) ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. There were no material impacts on our consolidated financial statements resulting from our early adoption in the first quarter of 2017 of the following accounting pronouncements: (i) ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ; (ii) ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash ; and (iii) ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment .

Supplemental Balance Sheet In28

Supplemental Balance Sheet Information Supplemental Balance Sheet Information (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Balance Sheet Disclosures	Supplemental Balance Sheet Information December 31, 2017 December 31, 2016 (In millions of dollars) Cash and Cash Equivalents Cash and money market funds $ 23.5 $ 37.9 Commercial paper 27.6 17.3 Total $ 51.1 $ 55.2 Trade Receivables, net Billed trade receivables $ 165.9 $ 138.2 Unbilled trade receivables 0.3 0.3 Trade receivables, gross 166.2 138.5 Allowance for doubtful receivables (1.2 ) (0.8 ) Trade receivables, net $ 165.0 $ 137.7 Inventories Finished products $ 63.8 $ 73.8 Work-in-process 78.3 71.7 Raw materials 61.3 51.1 Operating supplies 4.5 5.0 Total $ 207.9 $ 201.6 Property, Plant and Equipment, net Land and improvements $ 21.1 $ 22.7 Buildings and leasehold improvements 92.1 88.6 Machinery and equipment 689.1 615.1 Construction in progress 35.1 34.8 Property, plant and equipment – gross 837.4 761.2 Accumulated depreciation (267.9 ) (230.6 ) Assets held for sale 1.9 0.3 Property, plant and equipment, net $ 571.4 $ 530.9 Other Accrued Liabilities Uncleared cash disbursements $ 7.3 $ 5.8 Accrued income taxes and other taxes payable 6.8 4.3 Accrued annual contribution to VEBAs – Note 4 15.7 20.0 Accrued interest 2.9 2.9 Other 7.8 7.1 Total $ 40.5 $ 40.1 December 31, 2017 December 31, 2016 (In millions of dollars) Long-Term Liabilities Workers’ compensation accruals $ 22.6 $ 25.0 Long-term environmental accrual – Note 9 15.8 15.8 Long-term portion of contingent contribution to Union VEBA – Note 4 — 12.8 Other long-term liabilities 21.6 19.6 Total $ 60.0 $ 73.2 Supplemental Balance Sheet Information December 31, 2017 December 31, 2016 (In millions of dollars) Cash and Cash Equivalents Cash and money market funds $ 23.5 $ 37.9 Commercial paper 27.6 17.3 Total $ 51.1 $ 55.2 Trade Receivables, net Billed trade receivables $ 165.9 $ 138.2 Unbilled trade receivables 0.3 0.3 Trade receivables, gross 166.2 138.5 Allowance for doubtful receivables (1.2 ) (0.8 ) Trade receivables, net $ 165.0 $ 137.7 Inventories Finished products $ 63.8 $ 73.8 Work-in-process 78.3 71.7 Raw materials 61.3 51.1 Operating supplies 4.5 5.0 Total $ 207.9 $ 201.6 Property, Plant and Equipment, net Land and improvements $ 21.1 $ 22.7 Buildings and leasehold improvements 92.1 88.6 Machinery and equipment 689.1 615.1 Construction in progress 35.1 34.8 Property, plant and equipment – gross 837.4 761.2 Accumulated depreciation (267.9 ) (230.6 ) Assets held for sale 1.9 0.3 Property, plant and equipment, net $ 571.4 $ 530.9 Other Accrued Liabilities Uncleared cash disbursements $ 7.3 $ 5.8 Accrued income taxes and other taxes payable 6.8 4.3 Accrued annual contribution to VEBAs – Note 4 15.7 20.0 Accrued interest 2.9 2.9 Other 7.8 7.1 Total $ 40.5 $ 40.1 December 31, 2017 December 31, 2016 (In millions of dollars) Long-Term Liabilities Workers’ compensation accruals $ 22.6 $ 25.0 Long-term environmental accrual – Note 9 15.8 15.8 Long-term portion of contingent contribution to Union VEBA – Note 4 — 12.8 Other long-term liabilities 21.6 19.6 Total $ 60.0 $ 73.2

Goodwill and Intangible Assets

Goodwill and Intangible Assets Finite Lived Intangibles (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	Information regarding the gross carrying amount and accumulated amortization of these intangible assets was as follows as of each period presented: December 31, 2017 December 31, 2016 (In millions of dollars) Gross carrying amount $ 34.7 $ 34.7 Accumulated amortization (9.7 ) (8.3 ) Net carrying amount $ 25.0 $ 26.4

Employee Benefits (Tables)

Employee Benefits (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Schedule of Assumptions Used for Benefit Obligation	Assumptions used to determine benefit obligations as of the periods presented were as follows: Canadian Pension Plan Salaried VEBA December 31, 2017 December 31, 2016 December 31, 2017 December 31, 2016 Discount rate 3.40 % 3.80 % 3.20 % 3.60 % Rate of compensation increase 3.00 % 3.00 % — —
Schedule of Assumptions Used to Determine Net Periodic Benefit Cost (Income)	Assumptions used to determine net periodic benefit cost for the years ended December 31 were: Canadian Pension Plan Salaried VEBA 2017 2016 2015 2017 2016 2015 Discount rate 3.80 % 4.10 % 4.00 % 3.60 % 3.90 % 3.60 % Expected long-term return on plan assets 1 4.45 % 4.45 % 5.10 % 7.75 % 7.75 % 7.75 % Rate of compensation increase 3.00 % 3.00 % 3.00 % — — — _____________________ 1. The expected long-term rate of return assumption for the Salaried VEBA is based on the targeted investment portfolios provided to us by the trustee of the Salaried VEBA.
Schedule of Changes in Benefit Obligations	The following table presents the benefit obligations and funded status of our Canadian pension and the Salaried VEBA as of December 31, 2017 and December 31, 2016 and the corresponding amounts that are included in our Consolidated Balance Sheets (in millions of dollars): Canadian Pension Plan Salaried VEBA 2017 2016 2017 2016 Change in benefit obligation: Obligation at beginning of year $ 7.0 $ 6.1 $ 86.8 $ 77.9 Foreign currency translation adjustment 0.5 0.2 — — Service cost 0.3 0.3 — — Interest cost 0.3 0.3 3.0 2.9 Prior service cost 1 — — 7.3 8.4 Actuarial loss (gain) 2 0.6 0.3 (0.5 ) 4.1 Plan participants contributions 0.1 — — — Benefits paid by Company (0.3 ) (0.2 ) — — Benefits paid by Salaried VEBA — — (6.6 ) (6.5 ) Obligation at end of year 3 8.5 7.0 90.0 86.8 Change in plan assets: Fair market value of plan assets at beginning of year 6.1 5.7 58.2 58.9 Foreign currency translation adjustment 0.5 0.2 — — Actual return on assets 0.5 0.1 3.6 2.9 Plan participants contributions 0.1 — — — Company contributions 0.4 0.3 2.9 2.9 Benefits paid by Company (0.3 ) (0.2 ) — — Benefits paid by Salaried VEBA — — (6.6 ) (6.5 ) Fair market value of plan assets at end of year 7.3 6.1 58.1 58.2 Net funded status 4 $ (1.2 ) $ (0.9 ) $ (31.9 ) $ (28.6 ) _____________________________ 1. The prior service cost relating to the Salaried VEBA in both 2017 and 2016 resulted from increases in the annual healthcare reimbursement benefit starting in 2018 and 2017, respectively, for plan participants. 2. The actuarial gain relating to the Salaried VEBA in 2017 was comprised of: (i) a $2.5 million gain due to changes in census information; (ii) a $1.0 million gain due to a change in the projected utilization rate; offset by (iii) a $3.0 million loss due to a change in the discount rate. The actuarial loss relating to the Salaried VEBA in 2016 was comprised of: (i) a $2.3 million loss due to changes in census information; (ii) a $2.2 million loss due to a reduction in the discount rate; offset by (iii) a $0.4 million gain due to a change in the projected utilization rate. 3. For the Canadian pension plan, the benefit obligation is the projected benefit obligation. For the Salaried VEBA, the benefit obligation is the APBO. 4. Net funded status of $31.9 million and $28.6 million relating to the Salaried VEBA at December 31, 2017 and December 31, 2016 , respectively, was presented as Net liabilities of Salaried VEBA on the Consolidated Balance Sheet.
Schedule of Changes in Plan Assets	The following table presents the benefit obligations and funded status of our Canadian pension and the Salaried VEBA as of December 31, 2017 and December 31, 2016 and the corresponding amounts that are included in our Consolidated Balance Sheets (in millions of dollars): Canadian Pension Plan Salaried VEBA 2017 2016 2017 2016 Change in benefit obligation: Obligation at beginning of year $ 7.0 $ 6.1 $ 86.8 $ 77.9 Foreign currency translation adjustment 0.5 0.2 — — Service cost 0.3 0.3 — — Interest cost 0.3 0.3 3.0 2.9 Prior service cost 1 — — 7.3 8.4 Actuarial loss (gain) 2 0.6 0.3 (0.5 ) 4.1 Plan participants contributions 0.1 — — — Benefits paid by Company (0.3 ) (0.2 ) — — Benefits paid by Salaried VEBA — — (6.6 ) (6.5 ) Obligation at end of year 3 8.5 7.0 90.0 86.8 Change in plan assets: Fair market value of plan assets at beginning of year 6.1 5.7 58.2 58.9 Foreign currency translation adjustment 0.5 0.2 — — Actual return on assets 0.5 0.1 3.6 2.9 Plan participants contributions 0.1 — — — Company contributions 0.4 0.3 2.9 2.9 Benefits paid by Company (0.3 ) (0.2 ) — — Benefits paid by Salaried VEBA — — (6.6 ) (6.5 ) Fair market value of plan assets at end of year 7.3 6.1 58.1 58.2 Net funded status 4 $ (1.2 ) $ (0.9 ) $ (31.9 ) $ (28.6 ) _____________________________ 1. The prior service cost relating to the Salaried VEBA in both 2017 and 2016 resulted from increases in the annual healthcare reimbursement benefit starting in 2018 and 2017, respectively, for plan participants. 2. The actuarial gain relating to the Salaried VEBA in 2017 was comprised of: (i) a $2.5 million gain due to changes in census information; (ii) a $1.0 million gain due to a change in the projected utilization rate; offset by (iii) a $3.0 million loss due to a change in the discount rate. The actuarial loss relating to the Salaried VEBA in 2016 was comprised of: (i) a $2.3 million loss due to changes in census information; (ii) a $2.2 million loss due to a reduction in the discount rate; offset by (iii) a $0.4 million gain due to a change in the projected utilization rate. 3. For the Canadian pension plan, the benefit obligation is the projected benefit obligation. For the Salaried VEBA, the benefit obligation is the APBO. 4. Net funded status of $31.9 million and $28.6 million relating to the Salaried VEBA at December 31, 2017 and December 31, 2016 , respectively, was presented as Net liabilities of Salaried VEBA on the Consolidated Balance Sheet.
Schedule of Expected Benefit Payments	As of December 31, 2017 , the net benefits expected to be paid in each of the next five fiscal years and in the aggregate for the five fiscal years thereafter are as follows (in millions of dollars): Benefit Payments Due by Period 2018 2019 2020 2021 2022 2023-2027 Canadian pension plan benefit payments $ 0.3 $ 0.3 $ 0.3 $ 0.4 $ 0.3 $ 1.9 Salaried VEBA benefit payments 1 7.5 7.3 7.2 7.0 6.8 30.3 Total net benefits $ 7.8 $ 7.6 $ 7.5 $ 7.4 $ 7.1 $ 32.2 __________________________________ 1. Such amounts are based on benefit amounts and certain key assumptions obtained from the Salaried VEBA.
Schedule of Net Periodic Benefit Cost Not yet Recognized	The amount of loss included in the Consolidated Balance Sheets (within Accumulated other comprehensive loss) associated with our Canadian defined benefit pension plan and the Salaried VEBA (before tax) that had not yet been reflected in net periodic benefit cost was as follows at December 31 (in millions of dollars): Canadian Pension Plan Salaried VEBA 2017 2016 2017 2016 Accumulated net actuarial loss $ (1.9 ) $ (1.5 ) $ (17.5 ) $ (18.3 ) Transition assets 0.1 0.1 — — Prior service cost — — (42.7 ) (40.2 ) Cumulative loss reflected in Accumulated other comprehensive loss $ (1.8 ) $ (1.4 ) $ (60.2 ) $ (58.5 )
Schedule of Defined Benefit Plans Disclosures [Table Text Block]	fair value of plan assets, classified under the appropriate level of the fair value hierarchy, as of each period presented (in millions of dollars): Level 1 Level 2 Level 3 Total As of December 31, 2017: Plan Assets in the Fair Value Hierarchy: Salaried VEBA – Cash and money market investments $ 1.3 $ — $ — $ 1.3 Diversified investment funds in registered investment companies 1 10.2 — — 10.2 Total Salaried VEBA assets in the fair value hierarchy 11.5 — — 11.5 Deferred compensation program – Diversified investment funds in registered investment companies 1 — 9.8 — 9.8 Total plan assets in the fair value hierarchy $ 11.5 $ 9.8 $ — $ 21.3 Plan Assets Measured at NAV 2 : Salaried VEBA – Fixed income investment funds in registered investment companies 3 $ 19.4 Salaried VEBA – Equity investment funds in registered investment companies 4 24.3 Canadian pension plan – Diversified investment funds in registered investment companies 1 7.3 Total plan assets at fair value $ 72.3 As of December 31, 2016: Plan Assets in the Fair Value Hierarchy: Salaried VEBA – Cash and money market investments $ 3.3 $ — $ — $ 3.3 Diversified investment funds in registered investment companies 1 12.8 — — 12.8 Total Salaried VEBA assets in the fair value hierarchy 16.1 — — 16.1 Deferred compensation program – Diversified investment funds in registered investment companies 1 — 8.2 — 8.2 Total plan assets in the fair value hierarchy $ 16.1 $ 8.2 $ — $ 24.3 Plan Assets Measured at NAV 2 : Salaried VEBA – Fixed income investment funds in registered investment companies 3 $ 17.9 Salaried VEBA – Equity investment funds in registered investment companies 4 21.3 Canadian pension plan – Diversified investment funds in registered investment companies 1 6.1 Total plan assets at fair value $ 69.6 _________________________ 1. The plan assets are invested in investment funds that hold a diversified portfolio of: (i) U.S and international debt and equity securities; (ii) fixed income securities such as corporate bonds and government bonds; (iii) mortgage-related securities; and (iv) cash and cash equivalents. 2. The market value of these funds has not been categorized in the fair value hierarchy and is being presented in the table above to permit a reconciliation of the fair value hierarchy to the Consolidated Balance Sheets. Equity investment funds measured at fair value using the NAV practical expedient are managed by an investment adviser registered with the SEC under the Investment Advisers Act of 1940 and can be redeemed with five business days notice on the 15th (or last business day prior to the 15th) and on the last business day of each month. A business day is every day that the New York Stock Exchange is open. Diversified investment funds measured at fair value using the NAV practical expedient are unitized mutual funds without externally published net asset values, which can be redeemed daily without restriction. 3. This category represents investments in various fixed income funds with multiple registered investment companies. Such funds invest in diversified portfolios, including: (i) marketable fixed income securities, such as (a) U.S. Treasury and other government and agency securities, (b) municipal bonds, (c) mortgage-backed securities, (d) asset-backed securities, (e) corporate bonds, notes and debentures in various sectors, (f) preferred and common stock, (g) investments in affiliated and other investment companies, (h) short-term investments and other net assets, and (i) repurchase agreements and reverse repurchase agreements; (ii) other commingled investments; (iii) investment grade debt; (iv) fixed income instruments which may be represented by options, future contracts or swap agreements; and (v) cash and cash equivalents. In the prior year, the $17.9 million balance as of December 31, 2016 in the table above was presented within the Level 2 category and has been restated in the current year to properly reflect the balance within the NAV category. 4. This category represents investments in equity funds that invest in portfolios comprised of: (i) equity and equity-related securities of U.S. and non-U.S. issuers across all market capitalizations; (ii) common stock in investment trust funds; and (iii) other short-term investments.
Schedule of Net Periodic Benefit Costs (Income)	The following table presents the components of net periodic benefit cost for the years ended December 31 (in millions of dollars): Canadian Pension Plan Salaried VEBA 2017 2016 2015 2017 2016 2015 Service cost 1 $ 0.3 $ 0.3 $ 0.3 $ — $ — $ — Interest cost 0.3 0.3 0.3 3.0 2.9 2.7 Expected return on plan assets (0.3 ) (0.3 ) (0.3 ) (4.1 ) (4.1 ) (4.3 ) Amortization of prior service cost 2 — — — 4.7 4.1 3.0 Amortization of net actuarial loss — — 0.1 0.9 0.5 1.0 Net periodic benefit cost $ 0.3 $ 0.3 $ 0.4 $ 4.5 $ 3.4 $ 2.4 __________________________ 1. The service cost related to the Salaried VEBA was insignificant for all periods presented. 2. We amortize prior service cost on a straight-line basis over the average remaining years of service to full eligibility for benefits of the active plan participants.
Schedule of Income (Charges) Related to All Benefit Plans	The following tables present the total expense (income) related to all benefit plans for the periods presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Included within Fabricated Products: Canadian pension plan $ 0.3 $ 0.3 $ 0.4 Deferred compensation plan 0.4 0.2 0.1 Defined contribution plans 8.1 8.1 7.8 Multiemployer pension plans 1 4.6 4.7 4.4 Total Fabricated Products 2 13.4 13.3 12.7 Included within All Other: Net periodic postretirement benefit cost relating to Salaried VEBA 4.5 3.4 2.4 (Gain) loss on removal of Union VEBA net assets — (0.1 ) 493.4 Deferred compensation plan 1.4 0.7 0.3 Defined contribution plans 0.8 0.8 0.8 Total All Other 3 6.7 4.8 496.9 Total $ 20.1 $ 18.1 $ 509.6 ___________________________ 1. See Note 5 for more information on our multiemployer defined benefit pension plans. 2. Substantially all of the Fabricated Products segment’s charges related to employee benefits were in Cost of products sold, excluding depreciation and amortization and other items with the remaining balance in SG&A and R&D. 3. Expense (income) related to VEBAs is included within the Statements of Consolidated Income (Loss) as Net periodic postretirement benefit cost relating to Salaried VEBA and (Gain) loss on removal of Union VEBA net assets. The remaining balance is reported in SG&A and R&D.

Multiemployer Pension Plans (Ta

Multiemployer Pension Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Multiemployer Plans [Abstract]
Multiemployer Pension Plan Description and Contributions	participation in multiemployer pension plans for the year ended December 31, 2017 is outlined in the table below: Pension Fund Employer Identification Number Pension Protection Act Zone Status 1 FIP/RP Status Pending/Implemented in 2017 2 Contributions of the Company Surcharge Imposed in 2017 Expiration Date of Collective-Bargaining Agreements 2017 2016 2015 2017 2016 (in millions of dollars) Steelworkers Pension Trust (USW) 3 236648508 Green Green No $ 3.5 $ 3.7 $ 3.5 No Mar 2020 - Nov 2020 Other Funds 4 1.1 1.0 0.9 $ 4.6 $ 4.7 $ 4.4 ________________ 1. The most recent Pension Protection Act zone status available in 2017 and 2016 for the Steelworkers Pension Trust is for the plan's year-end at December 31, 2016 and December 31, 2015 , respectively. The zone status is based on information that we received from the plan and is certified by the plan's actuary. Among other factors, plans in the green zone are at least 80% funded. 2. The "FIP/RP Status Pending/Implemented" column indicates if a Financial Improvement Plan (FIP) or a Rehabilitation Plan (RP) is either pending or has been implemented for the plan under the Pension Protection Act. 3. We are party to three collective bargaining agreements with the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union, AFL-CIO,CLC ("USW") that require contributions to the Steelworkers Pension Trust. As of December 31, 2017 , USW collective bargaining agreements covering employees at the Newark, Ohio ("Newark") and Spokane, Washington ("Trentwood") facilities covered 85% of our USW-represented employees and expire in September 2020. Our monthly contributions per hour worked by each bargaining unit employee at the Newark and Trentwood facilities are (in whole dollars) $1.50 and will increase to $1.75 in 2019. The union contracts covering employees at the Richmond, Virginia facility and Florence, Alabama facility cover 11% and 4% of our USW-represented employees, respectively, and expire in March 2020 and November 2020, respectively. 4. Other Funds consists of plans that are not individually significant.

Employee Incentive Plans (Table

Employee Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	Inputs and assumptions used in the Monte Carlo simulations to calculate the fair value at grant date of our TSR-Based Performance Shares were as follows: Year Ended December 31, 2017 2016 2015 Grant date fair value $ 97.88 $ 93.02 $ 95.68 Grant date stock price $ 79.69 $ 80.46 $ 75.41 Expected volatility of Kaiser Aluminum 1 22.74 % 17.81 % 19.03 % Expected volatility of peer companies 1 44.19 % 41.22 % 33.73 % Risk-free interest rate 1.54 % 1.01 % 0.98 % Dividend yield 2.50 % 2.24 % 2.12 % _____________________ 1. Expected volatility based on 2.8 years of daily closing share prices from the valuation date to the end of the performance period.
Non-cash compensation expense	Non-cash compensation expense by type of award under LTI Programs was as follows for each period presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Non-vested common shares and restricted stock units $ 5.4 $ 4.7 $ 4.4 TSR-Based Performance Shares 4.8 5.4 4.0 CP-Based Performance Shares 2.7 1.3 — EVA-Based Performance Shares 0.2 0.3 0.9 Total non-cash compensation expense $ 13.1 $ 11.7 $ 9.3 The following table presents the allocation of the charges detailed above, by segment (in millions of dollars): Year Ended December 31, 2017 2016 2015 Fabricated Products $ 5.0 $ 4.2 $ 3.5 All Other 8.1 7.5 5.8 Total non-cash compensation expense $ 13.1 $ 11.7 $ 9.3
Unrecognized gross compensation cost data	Unrecognized Gross Compensation Cost Data. The following table presents unrecognized gross compensation cost data by type of award as of December 31, 2017 : Unrecognized Gross Compensation Costs (in millions of dollars) Expected Period (in years) Over Which the Remaining Gross Compensation Costs Will Be Recognized Non-vested common shares and restricted stock units $ 8.1 2.5 TSR-Based Performance Shares $ 4.3 1.6 CP-Based Performance Shares $ 5.2 1.9 EVA-Based Performance Shares $ 0.5 2.2
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, TSR-Based Performance Shares, CP-Based Performance Shares and EVA-Based Performance Shares for the year ended December 31, 2017 is as follows: Non-Vested Common Shares Restricted Stock Units TSR-Based Performance Shares CP-Based Performance Shares EVA-Based Performance Shares Shares Weighted-Average Units Weighted-Average Grant-Date Fair Value per Unit Shares Weighted-Average Shares Weighted-Average Shares Weighted-Average Outstanding at December 31, 2016 114,658 $ 69.51 61,800 $ 74.94 394,525 $ 90.30 63,678 $ 80.46 — $ — Granted 1 11,817 86.92 92,275 76.13 65,044 97.88 65,044 79.69 32,504 79.69 Vested (46,689 ) 71.46 (9,570 ) 76.19 (94,082 ) 83.18 — — — — Forfeited 1 (451 ) 69.83 (6,887 ) 77.44 (6,383 ) 95.85 (3,999 ) 79.93 (1,374 ) 79.69 Canceled 1 — — — — (55,288 ) 83.18 — — — — Outstanding at December 31, 2017 79,335 $ 70.96 137,618 $ 75.81 303,816 $ 95.31 124,723 $ 80.08 31,130 $ 79.69 _____________________ 1. For performance shares, the number of shares granted and forfeited are presented at their maximum payout; and the number of shares canceled includes the number of shares that did not vest due to performance results falling below those required for maximum payout.
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	The weighted-average grant-date fair value per share for shares granted by type of award was as follows for each period presented: Year Ended December 31, 2017 2016 2015 Non-vested common shares $ 86.92 $ 86.11 $ 72.09 Restricted stock units $ 76.13 $ 75.29 $ 69.83 TSR-Based Performance Shares $ 97.88 $ 93.02 $ 95.68 CP-Based Performance Shares $ 79.69 $ 80.46 $ — EVA-Based Performance Shares $ 79.69 $ — $ —

Derivative Financial Instrume33

Derivative Financial Instruments and Related Hedging Programs (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of material derivative positions	The following table summarizes our derivative positions at December 31, 2017 : Aluminum Maturity Period (month/year) Notional Amount of contracts (mmlbs) Fixed price purchase contracts 1/18 through 12/21 165.3 Fixed price sales contracts 5/18 through 11/19 1.4 Midwest premium swap contracts 1 1/18 through 12/21 163.9 Alloying Metals Maturity Period (month/year) Notional Amount of contracts (mmlbs) Fixed price purchase contracts 1/18 through 6/18 2.7 Natural Gas 2 Maturity Period (month/year) Notional Amount of contracts (mmbtu) Fixed price purchase contracts 1/18 through 12/20 3,600,000 Electricity 3 Maturity Period (month/year) Notional Amount of contracts (Mwh) Fixed price purchase contracts 1/20 through 12/20 131,760 Euro Maturity Period (month/year) Notional Amount of contracts (euro) Fixed price purchase contracts 1/18 through 4/18 301,304 _________________________ 1. Regional premiums represent the premium over the London Metal Exchange price for primary aluminum which is incurred on our purchases of primary aluminum. 2. As of December 31, 2017 , we had derivative and/or physical delivery commitments with energy companies in place to cover exposure to fluctuations in prices for approximately 70% of the expected natural gas purchases for both 2018 and 2019 , and 55% of the expected natural gas purchases for 2020 .
Summary of realized and unrealized gains and losses	Realized and unrealized gain (loss) included on the Statements of Consolidated Income (Loss) associated with all derivative contracts consisted of the following for each period presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Realized (gain) loss: Aluminum $ (20.4 ) $ 2.0 $ 27.3 Natural gas 0.7 5.0 5.4 Alloy Hedges (0.9 ) — — Foreign currency (0.1 ) 0.1 — Electricity — — 1.9 Total realized (gain) loss 1 $ (20.7 ) $ 7.1 $ 34.6 Unrealized (gain) loss: Aluminum $ (20.9 ) $ (10.8 ) $ 4.6 Natural gas 1.4 (7.9 ) 0.5 Electricity 0.1 — (1.7 ) Total unrealized (gain) loss 2 $ (19.4 ) $ (18.7 ) $ 3.4 ______________________ 1. Recorded within Cost of products sold, excluding depreciation, amortization and other items within the Fabricated Products segment. 2. Recorded within Unrealized (gain) loss on derivative instruments within the Fabricated Products segment.
Fair Value, Measurement Inputs, Disclosure	The following table presents our financial instruments, classified under the appropriate level of the fair value hierarchy, as of the period presented (in millions of dollars): December 31, 2016 Level 1 Level 2 Level 3 Total DERIVATIVE ASSETS: Non-Designated Hedges: Aluminum – Fixed price purchase contracts $ — $ 3.3 $ — $ 3.3 Midwest premium swap contracts — 0.9 — 0.9 Natural gas – Fixed price purchase contracts — 1.6 — 1.6 Total derivative assets 1 $ — $ 5.8 $ — $ 5.8 DERIVATIVE LIABILITIES: Non-Designated Hedges: Aluminum – Fixed price purchase contracts $ — $ (1.1 ) $ — $ (1.1 ) Midwest premium swap contracts — (0.2 ) — (0.2 ) Natural gas – Fixed price purchase contracts — (0.4 ) — (0.4 ) Designated Hedges: Alloying Metals – Fixed price purchase contracts — (0.1 ) — (0.1 ) Total derivative liabilities 2 $ — $ (1.8 ) $ — $ (1.8 ) The following table presents our financial instruments, classified under the appropriate level of the fair value hierarchy, as of the period presented (in millions of dollars): December 31, 2017 Level 1 Level 2 Level 3 Total DERIVATIVE ASSETS: Non-Designated Hedges: Aluminum – Fixed price purchase contracts $ — $ 22.5 $ — $ 22.5 Midwest premium swap contracts — 1.7 — 1.7 Natural gas – Fixed price purchase contracts — 0.2 — 0.2 Designated Hedges: Alloying metals – Fixed price purchase contracts — 0.9 — 0.9 Total derivative assets 1 $ — $ 25.3 $ — $ 25.3 DERIVATIVE LIABILITIES: Non-Designated Hedges: Aluminum – Fixed price sales contracts $ — $ (0.1 ) $ — $ (0.1 ) Midwest premium swap contracts — (0.1 ) — (0.1 ) Natural gas – Fixed price purchase contracts — (0.5 ) — (0.5 ) Electricity – Fixed price purchase contracts — (0.1 ) — (0.1 ) Designated Hedges: Alloying metals – Fixed price purchase contracts — — — — Total derivative liabilities 2 $ — $ (0.8 ) $ — $ (0.8 )
Schedule of Offsetting Derivative Instruments by Counterparty	The following tables present offsetting information regarding our derivatives by type of counterparty as of December 31, 2017 (in millions of dollars): Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets Gross Amounts Not Offset in the Consolidated Balance Sheets Net Amount Counterparty (with netting agreements) $ 25.3 $ — $ 25.3 $ 0.8 $ 24.5 Total $ 25.3 $ — $ 25.3 $ 0.8 $ 24.5 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets Gross Amounts Not Offset in the Consolidated Balance Sheets Net Amount Counterparty (with netting agreements) $ (0.8 ) $ — $ (0.8 ) $ (0.8 ) $ — Total $ (0.8 ) $ — $ (0.8 ) $ (0.8 ) $ — The following tables present offsetting information regarding our derivatives by type of counterparty as of December 31, 2016 (in millions of dollars): Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets Gross Amounts Not Offset in the Consolidated Balance Sheets Net Amount Counterparty (with netting agreements) $ 3.3 $ — $ 3.3 $ 1.0 $ 2.3 Counterparty (with partial netting agreements) 2.5 — 2.5 0.7 1.8 Total $ 5.8 $ — $ 5.8 $ 1.7 $ 4.1 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets Gross Amounts Not Offset in the Consolidated Balance Sheets Net Amount Counterparty (with netting agreements) $ (1.0 ) $ — $ (1.0 ) $ (1.0 ) $ — Counterparty (with partial netting agreements) (0.8 ) — (0.8 ) (0.7 ) (0.1 ) Total $ (1.8 ) $ — $ (1.8 ) $ (1.7 ) $ (0.1 )
Fair Value, Assets Measured on Recurring Basis	The following table presents our other financial assets, classified under the appropriate level of the fair value hierarchy, as of December 31, 2016 (in millions of dollars): Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 37.9 $ 17.3 $ — $ 55.2 Short-term investments — 231.0 — 231.0 Total $ 37.9 $ 248.3 $ — $ 286.2 The following table presents our other financial assets, classified under the appropriate level of the fair value hierarchy, as of December 31, 2017 (in millions of dollars): Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 23.5 $ 27.6 $ — $ 51.1 Short-term investments — 183.7 — 183.7 Total $ 23.5 $ 211.3 $ — $ 234.8

Debt and Credit Facility (Table

Debt and Credit Facility (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Interest Incurred on Convertible Debt	The following table provides additional information regarding the Convertible Notes (in millions of dollars): Year Ended December 31, 2015 Contractual coupon interest $ 2.0 Amortization of discount 2.4 Amortization of debt issuance costs 0.3 Total interest expense 1 $ 4.7 _______________ 1. A portion of the interest relating to the Convertible Notes was capitalized as construction in progress.

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum rental payments	Minimum rental commitments under operating leases at December 31, 2017 were as follows (in millions of dollars): Year Ended December 31, 2018 2019 2020 2021 2022 2023 and Thereafter Minimum rental commitments $ 5.7 $ 5.2 $ 3.1 $ 2.5 $ 2.2 $ 21.0
Summary of activities relating to the Company's CARO liabilities	The following table summarizes the activity relating to our CARO liabilities (in millions of dollars): Year Ended December 31, 2017 2016 2015 Beginning balance $ 5.5 $ 4.9 $ 4.8 Liabilities incurred during the period — — — Liabilities settled during the period — (0.1 ) (0.2 ) Accretion expense 0.4 0.5 0.3 Adjustment to accretion expense due to revisions to estimated cash flow and timing of expenditure 1 — 0.2 — Ending balance $ 5.9 $ 5.5 $ 4.9 __________________________________________ 1. The adjustments in 2016 had a de minimis impact on the basic and diluted net income per share for 2016.
Schedule of changes in environmental contingencies	Year Ended December 31, 2017 2016 2015 Beginning balance $ 17.2 $ 18.6 $ 19.3 Additional accruals 0.3 0.1 1.3 Less: expenditures (0.9 ) (1.5 ) (2.0 ) Ending balance $ 16.6 $ 17.2 $ 18.6

Accumulated Other Comprehensi36

Accumulated Other Comprehensive (Loss) Income (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Schedule of Accumulated Other Comprehensive (Loss) Income	The following table presents the changes in the accumulated balances for each component of Accumulated other comprehensive (loss) income ("AOCI") for each period presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Defined benefit pension plan and VEBAs: Beginning balance $ (37.1 ) $ (31.3 ) $ (96.4 ) Actuarial loss arising during the period (0.3 ) (5.7 ) (12.9 ) Less: income tax benefit 0.1 2.1 4.9 Net actuarial loss arising during the period (0.2 ) (3.6 ) (8.0 ) Prior service (cost) credit arising during the period (7.3 ) (8.3 ) 6.8 Less: income tax benefit (expense) 2.7 3.1 (2.6 ) Net prior service (cost) credit arising during the period (4.6 ) (5.2 ) 4.2 Amortization of net actuarial loss 1 0.9 0.5 1.1 Amortization of prior service cost 1 4.7 4.1 3.0 Removal of obligation relating to Union VEBA — — 106.6 Less: income tax expense 2 (2.1 ) (1.7 ) (41.8 ) Net amortization and reclassification from AOCI to Net income (loss) 3.5 2.9 68.9 Translation impact on Canadian pension plan AOCI balance (0.1 ) 0.1 — Other comprehensive (loss) income, net of tax (1.4 ) (5.8 ) 65.1 Ending balance $ (38.5 ) $ (37.1 ) $ (31.3 ) Available for sale securities: Beginning balance $ 0.8 $ (0.1 ) $ 0.2 Unrealized gain (loss) on available for sale securities 4.0 1.9 (0.1 ) Less: income tax expense (1.5 ) (0.7 ) — Net gain (loss) on available for sale securities 2.5 1.2 (0.1 ) Gain reclassified from AOCI to Net income (loss) 3 (3.2 ) (0.5 ) (0.4 ) Less: income tax benefit 2 1.2 0.2 0.2 Net gain reclassified from AOCI to Net income (loss) (2.0 ) (0.3 ) (0.2 ) Other comprehensive income (loss), net of tax 0.5 0.9 (0.3 ) Ending balance $ 1.3 $ 0.8 $ (0.1 ) Other: Beginning balance $ (0.4 ) $ (0.3 ) $ 0.1 Unrealized gain (loss) 2.0 (0.2 ) (0.5 ) Less: income tax (expense) benefit (0.7 ) — 0.1 Net gain (loss) 1.3 (0.2 ) (0.4 ) (Gain) loss reclassified from AOCI to Net income (loss) (0.6 ) 0.1 — Less: income tax benefit 2 0.2 — — Net (gain) loss reclassified from AOCI to Net income (loss) (0.4 ) 0.1 — Other comprehensive income (loss), net of tax 0.9 (0.1 ) (0.4 ) Ending balance $ 0.5 $ (0.4 ) $ (0.3 ) Total AOCI ending balance $ (36.7 ) $ (36.7 ) $ (31.7 ) ____________ 1. Amounts amortized out of AOCI relating to Salaried VEBA adjustments were included as a component of Net periodic postretirement benefit cost relating to Salaried VEBA. 2. Income tax amounts reclassified out of AOCI were included as a component of Income tax (provision) benefit. 3. Amounts reclassified out of AOCI relating to sales of available for sale securities were included as a component of Other income (expense), net. We use the specific identification method to determine the amount reclassified out of AOCI.

Other (Expense) Income, Net (Ta

Other (Expense) Income, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Other Income (Expense), Net	Other income (expense), net consisted of the following for each period presented (in millions of dollars): Year Ended December 31, 2017 2016 2015 Interest income $ 0.2 $ 0.1 $ 0.4 Realized gain on investments 3.4 0.8 0.8 Loss on extinguishment of debt 1 — (11.1 ) — All other, net 0.9 (0.1 ) (3.0 ) Other income (expense), net $ 4.5 $ (10.3 ) $ (1.8 ) ____________ 1. Represents the loss on extinguishment of our 8.25% Senior Notes during the year ended December 31, 2016 which includes an $8.2 million premium paid to redeem the notes and a $2.9 million write-off of unamortized debt issuance costs associated with the notes.

Income Tax Matters (Tables)

Income Tax Matters (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income before income taxes by geographic area	Tax (Provision) Benefit . Income (loss) before income taxes by geographic area was as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Domestic $ 127.9 $ 143.6 $ (373.6 ) Foreign 5.1 3.6 1.8 Income (loss) before income taxes $ 133.0 $ 147.2 $ (371.8 )
Tax Provision	Income tax (provision) benefit consisted of (in millions of dollars): Federal Foreign State Total 2017 Current $ 3.1 $ (0.8 ) $ (1.0 ) $ 1.3 Deferred (82.0 ) (1.0 ) (5.7 ) (88.7 ) Expense applied to increase Retained earnings/ Other comprehensive income (loss) (0.1 ) (0.1 ) — (0.2 ) Income tax provision $ (79.0 ) $ (1.9 ) $ (6.7 ) $ (87.6 ) 2016 Current $ 2.7 $ 0.6 $ (1.5 ) $ 1.8 Deferred (47.8 ) (1.2 ) (4.7 ) (53.7 ) Expense applied to increase Additional paid in capital/ Other comprehensive income (loss) (3.2 ) (0.1 ) (0.3 ) (3.6 ) Income tax provision $ (48.3 ) $ (0.7 ) $ (6.5 ) $ (55.5 ) 2015 Current $ 0.7 $ 2.1 $ 0.4 $ 3.2 Deferred 93.2 (1.2 ) 1.8 93.8 Benefit applied to decrease Additional paid in capital/Other comprehensive income (loss) 33.5 0.4 4.3 38.2 Income tax benefit $ 127.4 $ 1.3 $ 6.5 $ 135.2
Reconciliation of income tax provision based on effective income tax rate and statutory tax rate	A reconciliation between the (provision for) benefit from income taxes and the amount computed by applying the federal statutory income tax rate to Income (loss) before income taxes is as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Amount of federal income tax (provision) benefit based on the statutory rate $ (46.5 ) $ (51.5 ) $ 130.1 (Increase) decrease in federal valuation allowances 0.5 (0.3 ) (0.6 ) Non-deductible compensation (expense) benefit (2.3 ) 0.3 (0.2 ) Non-deductible (expense) — (0.3 ) (0.3 ) State income tax (provision) benefit, net of federal benefit 1 (4.3 ) (4.2 ) 4.2 Foreign income tax (expense) benefit (0.1 ) 0.5 0.1 Foreign undistributed earnings (5.9 ) — — Expiration of statute of limitations — — 1.7 Tax rate change (29.0 ) — — Advance pricing agreement — — (0.2 ) Competent Authority settlement — — 0.4 Income tax (provision) benefit $ (87.6 ) $ (55.5 ) $ 135.2 ___________________________ 1. State income taxes were $4.0 million in 2017 , but were increased by a $2.5 million change in tax rates, and offset by a $2.2 million decrease in the valuation allowance relating to certain state net operating losses. The state income taxes were $4.1 million in 2016 , but were offset by a $0.2 million decrease due to lower tax rates in various states and a $0.3 million increase in the valuation allowance relating to certain state net operating losses. The state income tax benefit was $10.3 million in 2015 , but was offset by a $3.1 million increase due to state tax rate and state law changes and a $3.0 million increase relating to the expiration of certain state net operating losses.
Deferred tax assets and liabilities	Deferred Income Taxes. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and amounts used for income tax purposes. The components of our net deferred income tax assets were as follows (in millions of dollars): Year Ended December 31, 2017 2016 Deferred income tax assets: Loss and credit carryforwards $ 98.7 $ 191.8 VEBAs (see Note 4) 11.6 23.2 Other assets 21.0 39.8 Inventory 9.3 — Valuation allowances (13.0 ) (15.7 ) Total deferred income tax assets 127.6 239.1 Deferred income tax liabilities: Property, plant and equipment (57.7 ) (82.7 ) Undistributed foreign earnings (2.2 ) — Total deferred income tax liabilities (59.9 ) (82.7 ) Net deferred income tax assets 1 $ 67.7 $ 156.4 __________________________ 1. Of the total net deferred income tax assets of $67.7 million , $72.0 million was presented as Deferred tax assets, net and $4.3 million was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2017 . Of the total net deferred income tax assets of $156.4 million , $159.7 million was presented as Deferred tax assets, net and $3.3 million was presented as Deferred tax liabilities on the Consolidated Balance Sheet as of December 31, 2016 .
Reconciliation of changes in the gross unrecognized tax benefits	We have gross unrecognized benefits relating to uncertain tax positions. A reconciliation of changes in the gross unrecognized tax benefits is as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Gross unrecognized tax benefits at beginning of period $ 1.8 $ 1.7 $ 2.2 Gross increases for tax positions of prior years — 0.1 0.1 Gross decreases for tax positions of prior years (0.3 ) — — Gross decrease for tax positions relating to lapse of a statute of limitation — — (0.6 ) Gross unrecognized tax benefits at end of period $ 1.5 $ 1.8 $ 1.7

Net Income (Loss) Per Share a39

Net Income (Loss) Per Share and Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Calculation of basic and diluted earnings per share	asic and diluted net income (loss) per share for the periods presented (in millions of dollars, except share and per share amounts): Year Ended December 31, 2017 2016 2015 Numerator: Net income (loss) $ 45.4 $ 91.7 $ (236.6 ) Denominator – Weighted-average common shares outstanding (in thousands): Basic 16,996 17,813 17,201 Add: dilutive effect of non-vested common shares, restricted stock units and performance shares 263 220 — Diluted 17,259 18,033 17,201 Net income (loss) per common share, Basic: $ 2.67 $ 5.15 $ (13.76 ) Net income (loss) per common share, Diluted: $ 2.63 $ 5.09 $ (13.76 )
Schedule of securities excluded from weighted-average diluted shares	The following securities were excluded from the weighted-average diluted shares computation for the periods presented as their inclusion would have been anti-dilutive (in thousands of shares): Year Ended December 31, 2017 2016 2015 Non-vested common shares, restricted stock units and performance shares 52 50 302 Warrants — — 639 Total excluded 52 50 941
Treasury Stock	Repurchases of our common stock pursuant to the stock repurchase program is recorded as Treasury stock and consisted of the following for each period presented: Year Ended December 31, 2017 2016 2015 Number of common shares repurchased 938,680 443,838 647,520 Weighted-average repurchase price (dollars per share) $ 82.97 $ 78.59 $ 76.35 Total cost of repurchased common shares (in millions of dollars) $ 77.8 $ 34.9 $ 49.4

Supplemental Cash Flow Inform40

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Year Ended December 31, 2017 2016 2015 (in millions of dollars) Interest paid $ 21.1 $ 17.7 $ 22.1 Non-cash investing and financing activities (included in Accounts payable): Unpaid purchases of property and equipment $ 7.4 $ 4.6 $ 10.5 Stock repurchases not yet settled $ 0.1 $ 1.8 $ 0.2 Acquisition of property and equipment through capital leasing arrangements $ 1.2 $ 0.2 $ — December 31, 2017 2016 2015 Components of cash, cash equivalents and restricted cash: Cash and cash equivalents $ 51.1 $ 55.2 $ 72.5 Restricted cash included in Prepaid expenses and other current assets 0.3 0.3 0.3 Restricted cash included in Other assets 12.9 12.2 10.9 Total cash, cash equivalents and restricted cash shown in the Statements of Consolidated Cash Flows $ 64.3 $ 67.7 $ 83.7

Segment and Geographical Area41

Segment and Geographical Area Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Summary of financial information by operating segment	The following tables provide financial information by reporting segment and business unit for each period or as of each period end, as applicable (in millions of dollars): Year Ended December 31, 2017 2016 2015 Net sales: Fabricated Products $ 1,397.5 $ 1,330.6 $ 1,391.9 Segment operating income (loss): Fabricated Products 201.3 229.6 190.8 All Other (50.6 ) (51.8 ) (536.7 ) Total operating income (loss) 150.7 177.8 (345.9 ) Interest expense (22.2 ) (20.3 ) (24.1 ) Other income (expense) , net 4.5 (10.3 ) (1.8 ) Income (loss) before income taxes $ 133.0 $ 147.2 $ (371.8 ) Depreciation and amortization: Fabricated Products $ 39.0 $ 35.4 $ 31.9 All Other 0.7 0.6 0.5 Total depreciation and amortization $ 39.7 $ 36.0 $ 32.4 Capital expenditures: Fabricated Products $ 75.3 $ 75.6 $ 62.4 All Other 0.2 0.5 0.7 Total capital expenditures $ 75.5 $ 76.1 $ 63.1 December 31, 2017 2016 2015 Assets: Fabricated Products $ 1,046.8 $ 969.4 $ 904.7 All Other 1 338.4 474.1 342.2 Total assets $ 1,385.2 $ 1,443.5 $ 1,246.9 __________________ 1. Assets in All Other represent primarily all of our cash, cash equivalents and restricted cash, short-term investments, financial derivative assets, deferred compensation program assets and net deferred income tax assets.
Schedule of net sales by end market segment applications	Net sales by end market applications for the Fabricated Products segment were as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Net sales: Aero/HS products $ 653.7 $ 675.4 $ 695.5 Automotive Extrusions 217.3 188.8 199.2 GE products 476.2 420.1 426.1 Other products 50.3 46.3 71.1 Total net sales $ 1,397.5 $ 1,330.6 $ 1,391.9
Schedule of net sales, income taxes paid, and long-lived assets, by geographical area	Geographic information for net sales based on country of origin, income taxes paid and long-lived assets were as follows (in millions of dollars): Year Ended December 31, 2017 2016 2015 Net sales to unaffiliated customers: Fabricated Products – Domestic $ 1,337.3 $ 1,278.6 $ 1,321.3 Foreign 1 60.2 52.0 70.6 Total net sales $ 1,397.5 $ 1,330.6 $ 1,391.9 Income taxes paid: Fabricated Products – Domestic $ 1.2 $ 0.7 $ 0.6 Foreign 0.1 0.5 1.7 Total income taxes paid $ 1.3 $ 1.2 $ 2.3 December 31, 2017 2016 2015 Long-lived assets: 2 Fabricated Products – Domestic $ 536.6 $ 494.7 $ 459.6 Foreign 30.2 31.4 30.9 Total Fabricated Products long-lived assets 566.8 526.1 490.5 All Other – Domestic 4.6 4.8 4.9 Total All Other long-lived assets 4.6 4.8 4.9 Total long-lived assets $ 571.4 $ 530.9 $ 495.4 __________________ 1. Foreign net sales reflect sales shipped from our London, Ontario production facility. 2. Long-lived assets represent Property, plant and equipment, net.
Schedules of Concentration of Risk, by Risk Factor	Information for export sales and primary aluminum supply from our major suppliers were as follows: Year Ended December 31, 2017 2016 2015 Percentage of Net sales: Export sales 18 % 19 % 19 % Percentage of total annual primary aluminum supply (lbs): Supply from our top five major suppliers 85 % 84 % 86 % Supply from our largest supplier 36 % 32 % 28 % Supply from our second and third largest suppliers combined 33 % 32 % 36 %

Guarantor and Non-Guarantor F42

Guarantor and Non-Guarantor Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2017
Guarantor and Non-Guarantor Financial Statement [Abstract]
Schedule of Condensed Financial Statements	CONDENSED CONSOLIDATING BALANCE SHEET (In millions of dollars) December 31, 2017 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated ASSETS Current assets: Cash and cash equivalents $ — $ 48.4 $ 2.7 $ — $ 51.1 Short-term investments — 183.7 — — 183.7 Receivables: Trade receivables, net — 160.1 4.9 — 165.0 Intercompany receivables 22.8 0.1 0.7 (23.6 ) — Other — 14.7 0.8 — 15.5 Inventories — 198.7 9.2 — 207.9 Prepaid expenses and other current assets 0.1 32.9 0.4 — 33.4 Total current assets 22.9 638.6 18.7 (23.6 ) 656.6 Investments in and advances to subsidiaries 1,097.7 48.2 — (1,145.9 ) — Property, plant and equipment, net — 541.2 30.2 — 571.4 Long-term intercompany receivables — — 12.4 (12.4 ) — Deferred tax assets, net — 67.3 — 4.7 72.0 Intangible assets, net — 25.0 — — 25.0 Goodwill — 18.8 — — 18.8 Other assets — 41.4 — — 41.4 Total $ 1,120.6 $ 1,380.5 $ 61.3 $ (1,177.2 ) $ 1,385.2 LIABILITIES AND STOCKHOLDERS’ EQUITY Current liabilities: Accounts payable $ 1.9 $ 81.4 $ 6.7 $ — $ 90.0 Intercompany payable — 23.5 0.1 (23.6 ) — Accrued salaries, wages and related expenses — 41.0 1.6 — 42.6 Other accrued liabilities 2.8 46.2 1.0 (9.5 ) 40.5 Total current liabilities 4.7 192.1 9.4 (33.1 ) 173.1 Net liabilities of Salaried VEBA — 31.9 — — 31.9 Deferred tax liabilities — — 4.3 — 4.3 Long-term intercompany payable — 12.4 — (12.4 ) — Long-term liabilities — 58.0 2.0 — 60.0 Long-term debt 369.6 — — — 369.6 Total liabilities 374.3 294.4 15.7 (45.5 ) 638.9 Total stockholders’ equity 746.3 1,086.1 45.6 (1,131.7 ) 746.3 Total $ 1,120.6 $ 1,380.5 $ 61.3 $ (1,177.2 ) $ 1,385.2 CONDENSED CONSOLIDATING BALANCE SHEET (In millions of dollars) December 31, 2016 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated ASSETS Current assets: Cash and cash equivalents $ — $ 52.9 $ 2.3 $ — $ 55.2 Short-term investments — 231.0 — — 231.0 Receivables: Trade receivables, net — 133.1 4.6 — 137.7 Intercompany receivables 85.8 0.1 0.6 (86.5 ) — Other — 11.4 0.5 — 11.9 Inventories — 197.5 8.0 (3.9 ) 201.6 Prepaid expenses and other current assets 0.1 18.0 0.9 (0.5 ) 18.5 Total current assets 85.9 644.0 16.9 (90.9 ) 655.9 Investments in and advances to subsidiaries 1,012.4 40.1 — (1,052.5 ) — Property, plant and equipment, net — 499.5 31.4 — 530.9 Long-term intercompany receivables 80.2 — 4.9 (85.1 ) — Deferred tax assets, net — 154.9 — 4.8 159.7 Intangible assets, net — 26.4 — — 26.4 Goodwill — 37.2 — — 37.2 Other assets — 33.4 — — 33.4 Total $ 1,178.5 $ 1,435.5 $ 53.2 $ (1,223.7 ) $ 1,443.5 LIABILITIES AND STOCKHOLDERS’ EQUITY Current liabilities: Accounts payable $ 2.2 $ 68.9 $ 4.7 $ — $ 75.8 Intercompany payable — 86.4 0.1 (86.5 ) — Accrued salaries, wages and related expenses — 47.2 1.9 — 49.1 Other accrued liabilities 2.9 52.6 (0.7 ) (14.7 ) 40.1 Total current liabilities 5.1 255.1 6.0 (101.2 ) 165.0 Net liabilities of Salaried VEBA — 28.6 — — 28.6 Deferred tax liabilities — — 3.3 — 3.3 Long-term intercompany payable — 85.1 — (85.1 ) — Long-term liabilities — 70.5 2.7 — 73.2 Long-term debt 368.7 — — — 368.7 Total liabilities 373.8 439.3 12.0 (186.3 ) 638.8 Total stockholders’ equity 804.7 996.2 41.2 (1,037.4 ) 804.7 Total $ 1,178.5 $ 1,435.5 $ 53.2 $ (1,223.7 ) $ 1,443.5 CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (In millions of dollars) Year Ended December 31, 2017 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Net sales $ — $ 1,365.3 $ 115.7 $ (83.5 ) $ 1,397.5 Costs and expenses: Cost of products sold: Cost of products sold, excluding depreciation and amortization and other items — 1,085.5 101.1 (81.3 ) 1,105.3 Unrealized gain on derivative instruments — (19.4 ) — — (19.4 ) Depreciation and amortization — 37.5 2.2 — 39.7 Selling, general, administrative, research and development: Selling, general, administrative, research and development 4.5 88.3 6.9 (2.2 ) 97.5 Net periodic postretirement benefit cost relating to Salaried VEBA — 4.5 — — 4.5 Total selling, general, administrative, research and development 4.5 92.8 6.9 (2.2 ) 102.0 Goodwill impairment — 18.4 — — 18.4 Other operating charges, net — 0.8 — — 0.8 Total costs and expenses 4.5 1,215.6 110.2 (83.5 ) 1,246.8 Operating (loss) income (4.5 ) 149.7 5.5 — 150.7 Other (expense) income: Interest expense (20.7 ) (1.7 ) — 0.2 (22.2 ) Other income, net — 4.0 0.7 (0.2 ) 4.5 (Loss) income before income taxes (25.2 ) 152.0 6.2 — 133.0 Income tax provision — (95.2 ) (1.9 ) 9.5 (87.6 ) Earnings in equity of subsidiaries 70.6 4.3 — (74.9 ) — Net income $ 45.4 $ 61.1 $ 4.3 $ (65.4 ) $ 45.4 Comprehensive income $ 45.4 $ 61.1 $ 4.3 $ (65.4 ) $ 45.4 CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (In millions of dollars) Year Ended December 31, 2016 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Net sales $ — $ 1,301.6 $ 103.4 $ (74.4 ) $ 1,330.6 Costs and expenses: Cost of products sold: Cost of products sold, excluding depreciation and amortization and other items — 1,000.6 90.0 (71.1 ) 1,019.5 Lower of cost or market inventory write-down — 4.9 — — 4.9 Unrealized gain on derivative instruments — (18.7 ) — — (18.7 ) Depreciation and amortization — 34.0 2.0 — 36.0 Selling, general, administrative, research and development: Selling, general, administrative, research and development 4.2 95.0 8.4 (2.6 ) 105.0 Net periodic postretirement benefit cost relating to Salaried VEBA — 3.4 — — 3.4 Gain on removal of Union VEBA net assets — (0.1 ) — — (0.1 ) Total selling, general, administrative, research and development 4.2 98.3 8.4 (2.6 ) 108.3 Other operating charges, net — 2.8 — — 2.8 Total costs and expenses 4.2 1,121.9 100.4 (73.7 ) 1,152.8 Operating (loss) income (4.2 ) 179.7 3.0 (0.7 ) 177.8 Other (expense) income: Interest (expense) income (21.6 ) 1.2 — 0.1 (20.3 ) Other (expense) income, net (11.1 ) 0.9 — (0.1 ) (10.3 ) (Loss) income before income taxes (36.9 ) 181.8 3.0 (0.7 ) 147.2 Income tax provision — (69.0 ) (0.6 ) 14.1 (55.5 ) Earnings in equity of subsidiaries 128.6 1.7 — (130.3 ) — Net income $ 91.7 $ 114.5 $ 2.4 $ (116.9 ) $ 91.7 Comprehensive income $ 86.7 $ 109.8 $ 2.1 $ (111.9 ) $ 86.7 CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE (LOSS) INCOME (In millions of dollars) Year Ended December 31, 2015 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Net sales $ — $ 1,361.6 $ 123.3 $ (93.0 ) $ 1,391.9 Costs and expenses: Cost of products sold: Cost of products sold, excluding depreciation and amortization and other items — 1,095.6 108.4 (88.6 ) 1,115.4 Lower of cost or market inventory write-down — 2.6 — — 2.6 Unrealized loss on derivative instruments — 3.4 — — 3.4 Depreciation and amortization — 31.3 1.1 — 32.4 Selling, general, administrative, research and development: Selling, general, administrative, research and development 4.3 76.5 9.3 (2.0 ) 88.1 Net periodic postretirement benefit income relating to Salaried VEBA — 2.4 — — 2.4 Loss on removal of Union VEBA net assets — 493.4 — — 493.4 Total selling, general, administrative, research and development 4.3 572.3 9.3 (2.0 ) 583.9 Other operating charges, net — 0.1 — — 0.1 Total costs and expenses 4.3 1,705.3 118.8 (90.6 ) 1,737.8 Operating (loss) income (4.3 ) (343.7 ) 4.5 (2.4 ) (345.9 ) Other income (expense): Interest expense (23.5 ) (0.9 ) — 0.3 (24.1 ) Other (expense) income, net (2.5 ) 3.5 (2.5 ) (0.3 ) (1.8 ) (Loss) income before income taxes (30.3 ) (341.1 ) 2.0 (2.4 ) (371.8 ) Income tax benefit — 122.5 1.3 11.4 135.2 (Loss) earnings in equity of subsidiaries (206.3 ) 0.9 — 205.4 — Net (loss) income $ (236.6 ) $ (217.7 ) $ 3.3 $ 214.4 $ (236.6 ) Comprehensive (loss) income $ (172.2 ) $ (153.5 ) $ 3.5 $ 150.0 $ (172.2 ) CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS (In millions of dollars) Year Ended December 31, 2017 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Cash flows from operating activities: Net cash (used in) provided by operating activities $ (24.2 ) $ 156.9 $ 8.8 $ — $ 141.5 Cash flows from investing activities: Capital expenditures — (74.7 ) (0.8 ) — (75.5 ) Purchase of available for sale securities — (247.5 ) — — (247.5 ) Proceeds from disposition of available for sale securities — 296.9 — — 296.9 Proceeds from disposal of property, plant and equipment — 0.6 — — 0.6 Intercompany loans receivable 143.2 — (7.6 ) (135.6 ) — Net cash provided by (used in) investing activities 143.2 (24.7 ) (8.4 ) (135.6 ) (25.5 ) Cash flows from financing activities: Repayment of capital lease — (0.4 ) — — (0.4 ) Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (4.5 ) — — — (4.5 ) Repurchase of common stock (79.5 ) — — — (79.5 ) Cash dividends and dividend equivalents paid (35.0 ) — — — (35.0 ) Intercompany loans payable — (135.6 ) — 135.6 — Net cash used in financing activities (119.0 ) (136.0 ) — 135.6 (119.4 ) Net (decrease) increase in cash and cash equivalents during the period — (3.8 ) 0.4 — (3.4 ) Cash, cash equivalents and restricted cash at beginning of period — 65.1 2.6 — 67.7 Cash, cash equivalents and restricted cash at end of period $ — $ 61.3 $ 3.0 $ — $ 64.3 CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS (In millions of dollars) Year Ended December 31, 2016 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Cash flows from operating activities: Net cash provided by operating activities $ 177.7 $ 178.7 $ 9.2 $ (200.0 ) $ 165.6 Cash flows from investing activities: Capital expenditures — (74.0 ) (2.1 ) — (76.1 ) Purchase of available for sale securities — (255.3 ) — — (255.3 ) Proceeds from disposition of available for sale securities — 55.0 — — 55.0 Intercompany loans receivable 1 (166.0 ) 110.4 (1.3 ) 56.9 — Net cash used in investing activities (166.0 ) (163.9 ) (3.4 ) 56.9 (276.4 ) Cash flows from financing activities: Repayment of principal and redemption premium of 8.25% Senior Notes (206.0 ) — — — (206.0 ) Issuance of 5.875% Senior Notes 375.0 — — — 375.0 Cash paid for debt issuance costs (6.8 ) — — — (6.8 ) Proceeds from stock option exercises 1.2 — — — 1.2 Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (2.9 ) — — — (2.9 ) Repurchase of common stock (33.3 ) — — — (33.3 ) Cash dividends and dividend equivalents paid (32.4 ) — — — (32.4 ) Cash dividends paid to Parent — (200.0 ) — 200.0 — Intercompany loans payable 1 (106.5 ) 167.3 (3.9 ) (56.9 ) — Net cash (used in) provided by financing activities (11.7 ) (32.7 ) (3.9 ) 143.1 94.8 Net (decrease) increase in cash and cash equivalents during the period — (17.9 ) 1.9 — (16.0 ) Cash, cash equivalents and restricted cash at beginning of period — 83.0 0.7 — 83.7 Cash, cash equivalents and restricted cash at end of period $ — $ 65.1 $ 2.6 $ — $ 67.7 ________________ 1 As a result of the Parent's additional liquidity associated with the 5.875% Senior Notes (see Note 8 ), we classify all intercompany receivables and payables as Intercompany loans receivable and Intercompany loans payable, respectively, and therefore categorize changes in these balances within the investing and financing sections, respectively, of the Condensed Consolidating Statement of Cash Flows. CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS (In millions of dollars) Year Ended December 31, 2015 Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Consolidated Cash flows from operating activities: Net cash provided by (used in) operating activities $ 285.7 $ (126.3 ) $ 0.3 $ — $ 159.7 Cash flows from investing activities: Capital expenditures — (47.9 ) (15.2 ) — (63.1 ) Purchase of available for sale securities — (0.5 ) — — (0.5 ) Proceeds from disposition of available for sale securities — 84.0 — — 84.0 Net cash provided by (used in) investing activities — 35.6 (15.2 ) — 20.4 Cash flows from financing activities: Repayment of principal and redemption premium of 8.25% Senior Notes (30.0 ) — — — (30.0 ) Repayment of Convertible Notes (175.0 ) — — — (175.0 ) Proceeds from cash-settled call options related to settlement of Convertible Notes 94.9 — — — 94.9 Payment for conversion premium related to settlement of Convertible Notes (94.9 ) — — — (94.9 ) Cash paid for debt issuance costs (0.6 ) — — — (0.6 ) Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest — 1.3 — — 1.3 Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (2.8 ) — — — (2.8 ) Repurchase of common stock (49.2 ) — — — (49.2 ) Cash dividends and dividend equivalents paid (28.1 ) — — — (28.1 ) Intercompany loans payable — (12.8 ) 12.8 — — Net cash (used in) provided by financing activities (285.7 ) (11.5 ) 12.8 — (284.4 ) Net decrease in cash and cash equivalents during the period — (102.2 ) (2.1 ) — (104.3 ) Cash, cash equivalents and restricted cash at beginning of period — 185.2 2.8 — 188.0 Cash, cash equivalents and restricted cash at end of period $ — $ 83.0 $ 0.7 $ — $ 83.7

Quarterly Financial Data (Una43

Quarterly Financial Data (Unaudited) Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Data [Abstract]
Schedule of Quarterly Financial Data	The following tables present the unaudited financial data for each of the interim periods in 2017 and 2016 (in millions of dollars, except per share amounts): Quarter Ended 31-Mar Quarter Ended 30-Jun Quarter Ended 30-Sep Quarter Ended 31-Dec 2017 Net sales $ 355.3 $ 356.3 $ 332.8 $ 353.1 Cost of products sold, excluding depreciation, amortization and other items $ 277.8 $ 277.7 $ 267.2 $ 282.6 Unrealized (gain) loss on derivative instruments $ (15.1 ) $ 11.9 $ (10.8 ) $ (5.4 ) Gross profit $ 92.6 $ 66.7 $ 76.4 $ 75.9 Operating income $ 59.5 $ 11.4 $ 39.8 $ 40.0 Net income (loss) 1 $ 36.0 $ 4.7 $ 19.9 $ (15.2 ) Net income (loss) per common share, Basic $ 2.07 $ 0.28 $ 1.18 $ (0.90 ) Net income (loss) per common share, Diluted $ 2.04 $ 0.27 $ 1.16 $ (0.90 ) Dividends declared per common share $ 0.50 $ 0.50 $ 0.50 $ 0.50 ________________ 1 The quarter ended June 30, 2017 reflected an $18.4 million goodwill impairment charge (see Note 3 ). The quarter ended December 31, 2017 included the tax provision effect of $37.2 million due to the Tax Act (see Note 12 ). Quarter Ended 31-Mar Quarter Ended 30-Jun Quarter Ended 30-Sep Quarter Ended 31-Dec 2016 Net sales $ 343.2 $ 334.9 $ 320.6 $ 331.9 Cost of products sold, excluding depreciation, amortization and other items $ 262.0 $ 250.4 $ 254.7 $ 252.4 Lower of cost or market inventory write-down $ 4.9 $ — $ — $ — Unrealized gain on derivative instruments $ (4.0 ) $ (10.9 ) $ (2.0 ) $ (1.8 ) Gross profit $ 80.3 $ 95.4 $ 67.9 $ 81.3 Operating income $ 44.8 $ 57.9 $ 29.8 $ 45.3 Net income $ 26.3 $ 26.0 $ 14.9 $ 24.5 Net income per common share, Basic $ 1.47 $ 1.45 $ 0.84 $ 1.39 Net income per common share, Diluted $ 1.44 $ 1.43 $ 0.82 $ 1.37 Dividends declared per common share $ 0.45 $ 0.45 $ 0.45 $ 0.45

Summary of Significant Accoun44

Summary of Significant Accounting Policies, Narrative (Details) $ in Millions	Jan. 01, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Accounting policies additional disclosures
Number of operating segments | segment										1
Advertising costs										$ 0.7	$ 0.4	$ 1.2
Research and development costs										10	10.2	9.5
Lower of cost or market inventory write-down						$ 0	$ 0	$ 0	$ 4.9	0	4.9	2.6
Excess of current cost over the stated LIFO value of inventory		$ 24.3				(8.5)				24.3	(8.5)
Non-cash impairment charges										19.2	2.8	0.1
Impairment of the carrying value of goodwill		18.4				0				18.4	0	0
Undiscounted workers' compensation liabilities										$ 24.8	$ 26.8
Discount rate used in estimating liabilities for worker compensation claims										2.25%	2.00%
Accrued employee healthcare benefits		3.5				3.6				$ 3.5	$ 3.6
Cumulative effect adjustment to Net sales		353.1	$ 332.8	$ 356.3	$ 355.3	331.9	$ 320.6	$ 334.9	$ 343.2	1,397.5	1,330.6	$ 1,391.9
Reduction in inventories		(207.9)				(201.6)				(207.9)	(201.6)
Reduction in deferred tax assets, net		(67.7)				(156.4)				(67.7)	(156.4)
Increase in retained earnings		$ 85.5				$ 75.2				$ 85.5	$ 75.2
Minimum
Accounting policies additional disclosures
Period over which accounts receivable is due, days										30 days
Number of days in maturity for debt investment securities to be classified as short-term investments										90 days
Maximum
Accounting policies additional disclosures
Period over which accounts receivable is due, days										90 days
Number of days to maturity for debt investment securities to be classified as cash and cash equivalents										90 days
Cumulative effect adjustment | Scenario, Forecast | Cumulative effect adjustment of ASU 2014-09
Accounting policies additional disclosures
Cumulative effect adjustment to Net sales	$ 55.6
Contract asset	55.6
Reduction in inventories	42.2
Reduction in deferred tax assets, net	3.3
Increase in retained earnings	$ 10.1

Summary of Significant Accoun45

Summary of Significant Accounting Policies, Narrative, Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment
Interest expense capitalized as construction in progress	$ 2.2	$ 2.9	$ 1.8
Depreciation expense	38.3	34.5	30.8
Non-cash impairment charges	19.2	2.8	0.1
Fabricated Products | Idled equipment
Property, Plant and Equipment
Non-cash impairment charges	$ 0.8	$ 0.2	$ 0.1
Minimum | Land improvements
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	3 years
Minimum | Buildings and leasehold improvements
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	15 years
Minimum | Machinery and equipment
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	1 year
Minimum | Capital lease assets
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	3 years
Maximum | Land improvements
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	25 years
Maximum | Buildings and leasehold improvements
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	45 years
Maximum | Machinery and equipment
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	24 years
Maximum | Capital lease assets
Property, Plant and Equipment
Property, plant and equipment useful lives (in years)	5 years

Supplemental Balance Sheet In46

Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents
Cash and money market funds	$ 23.5	$ 37.9
Commercial paper	27.6	17.3
Total	51.1	55.2
Trade Receivables - Net
Billed trade receivables	165.9	138.2
Unbilled trade receivables	0.3	0.3
Trade receivables, gross	166.2	138.5
Allowance for doubtful receivables	(1.2)	(0.8)
Trade receivables - net	165	137.7
Inventories
Finished products	63.8	73.8
Work-in-process	78.3	71.7
Raw materials	61.3	51.1
Operating supplies	4.5	5
Total	207.9	201.6
Property, Plant and Equipment - Net
Land and improvements	21.1	22.7
Buildings and leasehold improvements	92.1	88.6
Machinery and equipment	689.1	615.1
Construction in progress	35.1	34.8
Property, plant and equipment - gross	837.4	761.2
Accumulated depreciation	(267.9)	(230.6)
Assets held for sale	1.9	0.3
Property, plant and equipment - net	571.4	530.9
Other Accrued Liabilities
Uncleared cash disbursements	7.3	5.8
Accrued income taxes and taxes payable	6.8	4.3
Accrued annual contribution to VEBAs – Note 4	15.7	20
Accrued interest	2.9	2.9
Other	7.8	7.1
Total	40.5	40.1
Long-Term Liabilities
Workers’ compensation accruals	22.6	25
Long-term environmental accrual – Note 9	15.8	15.8
Long-term portion of contingent contribution to Union VEBA	0	12.8
Other long-term liabilities	21.6	19.6
Total	$ 60	$ 73.2

Goodwill and Intangible Assets,

Goodwill and Intangible Assets, Goodwill (Details) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill
Goodwill		$ 18,800,000	$ 37,200,000
Impairment of the carrying value of goodwill		18,400,000	0	$ 0
Goodwill impairment		18,400,000	0	0
Goodwill impairment		0
Fabricated Products
Goodwill
Goodwill		18,800,000	$ 37,200,000	$ 37,200,000
Goodwill impairment	$ (18,400,000)	$ (18,400,000)

Goodwill and Intangible Asset48

Goodwill and Intangible Assets, Identifiable Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Identifiable intangible assets
Net book value		$ 25	$ 26.4
Impairment of Intangible Assets	$ 2.6
Amortization of definite-lived intangible assets		1.4	1.5	$ 1.6
Impairment of the carrying value of goodwill		18.4	0	$ 0
Expected amortization of intangible assets for the next five years
2,018		1.4
2,019		1.4
2,020		1.4
2,021		1.4
2,022		1.4
Expected amortization of intangible assets, after 2022		18
Customer relationships
Identifiable intangible assets
Original cost		34.7	34.7
Accumulated amortization		(9.7)	(8.3)
Net book value		$ 25	$ 26.4

Employee Benefits Employee Bene

Employee Benefits Employee Benefits, Assumptions used to determine benefit obligations (Details)	Dec. 31, 2017	Dec. 31, 2016
Salaried VEBA
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.20%	3.60%
Canadian pension plan | Canadian pension plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.40%	3.80%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	3.00%	3.00%

Employee Benefits Employee Be50

Employee Benefits Employee Benefits, Assumptions used to determine net periodic benefit cost (income) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Salaried VEBA
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	3.60%	3.90%	3.60%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	7.75%	7.75%	7.75%
Canadian pension plan | Canadian pension plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	3.80%	4.10%	4.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	4.45%	4.45%	5.10%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	3.00%	3.00%	3.00%

Employee Benefits Employee Be51

Employee Benefits Employee Benefits, Benefit obligations and funded status of our Canadian pension and the VEBAs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Change in plan assets:
Fair value of plan assets at beginning of year	$ 69.6
Fair value of plan assets at end of year	72.3	$ 69.6
Accrued Annual Veba Contribution	15.7	20
Net liabilities of Salaried VEBA	31.9	28.6
Long-term portion of contingent contribution to Union VEBA	0	12.8
VEBAs
Change in benefit obligation:
Obligation at beginning of year	86.8	77.9
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)	0	0
Defined Benefit Plan, Service Cost	0	0
Defined Benefit Plan, Interest Cost	3	2.9
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment	7.3	8.4
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	0.5	(4.1)
Benefits paid by VEBA	(6.6)	(6.5)
Obligation at end of year	90	86.8
Change in plan assets:
Fair value of plan assets at beginning of year	58.2	58.9
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	3.6	2.9
Defined Benefit Plan, Plan Assets, Contributions by Employer	2.9	2.9
Benefits paid by VEBA	(6.6)	(6.5)
Fair value of plan assets at end of year	58.1	58.2
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(31.9)	(28.6)
Salaried VEBA
Change in plan assets:
Actuarial (gain) loss due to projected lower benefit utilization	(1)	(0.4)
Actuarial (Gain) Loss Due To Change In Discount Rate	3	2.2
Actuarial (Gain) Loss Due To Changes In Census Data	(2.5)	2.3
Accrued Annual Veba Contribution	2.9	2.9
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(31.9)	(28.6)
Union VEBA
Change in plan assets:
Accrued Annual Veba Contribution	12.8	17.1
Canadian pension plan
Change in plan assets:
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	0.1	0
Canadian pension plan | Canadian pension plan
Change in benefit obligation:
Obligation at beginning of year	7	6.1
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)	0.5	0.2
Defined Benefit Plan, Service Cost at Balance Sheet Exchange Rate	0.3	0.3
Defined Benefit Plan, Interest Cost at Balance Sheet Exchange Rate	0.3	0.3
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	(0.6)	(0.3)
Obligation at end of year	8.5	7
Change in plan assets:
Fair value of plan assets at beginning of year	6.1	5.7
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	0.5	0.2
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	0.5	0.1
Defined Benefit Plan, Plan Assets, Contributions by Employer	0.4	0.3
Fair value of plan assets at end of year	7.3	6.1
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(1.2)	(0.9)
Defined Benefit Plan, Plan Assets, Benefits Paid	$ 0.3	$ 0.2

Employee Benefits Employee Be52

Employee Benefits Employee Benefits, Net assets (liabilities) of each VEBA (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 72.3	$ 69.6
Salaried VEBA
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ (31.9)	$ (28.6)

Employee Benefits Employee Be53

Employee Benefits Employee Benefits, Net benefits expected to be paid in each of the next five fiscal years (Details) $ in Millions	Dec. 31, 2017USD ($)
Defined Benefit Plan Disclosure [Line Items]
2,016	$ 7.8
2,017	7.6
2,018	7.5
2,019	7.4
2,020	7.1
2020-2023	32.2
VEBAs
Defined Benefit Plan Disclosure [Line Items]
2,016	7.5
2,017	7.3
2,018	7.2
2,019	7
2,020	6.8
2020-2023	30.3
Canadian pension plan | Canadian pension plan
Defined Benefit Plan Disclosure [Line Items]
2,016	0.3
2,017	0.3
2,018	0.3
2,019	0.4
2,020	0.3
2020-2023	$ 1.9

Employee Benefits Employee Be54

Employee Benefits Employee Benefits, Amount of loss recognized in accumulated other comprehensive loss (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Salaried VEBA
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	$ (17.5)	$ (18.3)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax	42.7	40.2
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	60.2	58.5
Canadian pension plan | Canadian pension plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	(1.9)	(1.5)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Transition Asset (Obligation), before Tax	0.1	0.1
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	$ 1.8	$ 1.4

Employee Benefits, Net Periodic

Employee Benefits, Net Periodic Benefit Costs and Charges Relating To Other Benefit Plans(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Periodic Benefit Costs and Charges Relating to Other Benefit Plans
Non-cash net periodic benefit income	$ 4.8	$ 3.7	$ 2.8
Total	20.1	18.1	509.6
Fabricated Products
Net Periodic Benefit Costs and Charges Relating to Other Benefit Plans
Deferred Compensation Arrangement with Individual, Compensation Expense	0.4	0.2	0.1
Defined contribution plans	8.1	8.1	7.8
Total	13.4	13.3	12.7
All Other
Net Periodic Benefit Costs and Charges Relating to Other Benefit Plans
Deferred Compensation Arrangement with Individual, Compensation Expense	1.4	0.7	0.3
Defined contribution plans	0.8	0.8	0.8
Total	6.7	4.8	496.9
VEBAs | All Other
Net Periodic Benefit Costs and Charges Relating to Other Benefit Plans
Non-cash net periodic benefit income	$ 4.5	$ 3.4	$ 2.4

Employee Benefits Employee Be56

Employee Benefits Employee Benefits, Components of net periodic benefit cost (income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 4.8	$ 3.7	$ 2.8
VEBAs
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	0	0
Defined Benefit Plan, Interest Cost	3	2.9
All Other | VEBAs
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	0	0	0
Defined Benefit Plan, Interest Cost	3	2.9	2.7
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	4.1	4.1	4.3
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	4.7	4.1	3
Defined Benefit Plan, Amortization of Gain (Loss)	(0.9)	(0.5)	(1)
Net periodic benefit cost	4.5	3.4	2.4
Canadian pension plan | Fabricated Products | Canadian pension plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	0.3	0.3	0.3
Defined Benefit Plan, Interest Cost	0.3	0.3	0.3
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	0.3	0.3	0.3
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	0
Defined Benefit Plan, Amortization of Gain (Loss)	0	0	(0.1)
Net periodic benefit cost	$ 0.3	$ 0.3	$ 0.4

Employee Benefits, Total charge

Employee Benefits, Total charges (income) related to all benefit plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
(Gain) loss on removal of Union VEBA net assets – Note 4	$ 0	$ (0.1)	$ 493.4
Components of Net Periodic Benefit Cost (Income)
Net periodic benefit cost	4.8	3.7	2.8
Contributions of the Company	4.6	4.7	4.4
Defined Benefit Plan Net Periodic Benefit Cost And Charges Relating To Other Benefit Plans	20.1	18.1	509.6
Fabricated Products
Components of Net Periodic Benefit Cost (Income)
Deferred Compensation Arrangement with Individual, Compensation Expense	0.4	0.2	0.1
Defined Contribution Plan, Cost	8.1	8.1	7.8
Defined Benefit Plan Net Periodic Benefit Cost And Charges Relating To Other Benefit Plans	13.4	13.3	12.7
All Other
Components of Net Periodic Benefit Cost (Income)
Deferred Compensation Arrangement with Individual, Compensation Expense	1.4	0.7	0.3
Defined Contribution Plan, Cost	0.8	0.8	0.8
Defined Benefit Plan Net Periodic Benefit Cost And Charges Relating To Other Benefit Plans	6.7	4.8	496.9
All Other | VEBAs
Components of Net Periodic Benefit Cost (Income)
Net periodic benefit cost	4.5	3.4	2.4
Canadian pension plan | Fabricated Products | Canadian pension plan
Components of Net Periodic Benefit Cost (Income)
Net periodic benefit cost	$ 0.3	$ 0.3	$ 0.4

Employee Benefits, Defined Cont

Employee Benefits, Defined Contribution Plans Narrative (Details) - Defined Contribution Plan	12 Months Ended
	Dec. 31, 2017USD ($)productionfacilities
Hourly bargaining unit employees
Defined Contribution Plan Disclosure [Line Items]
Number of production facilities	9
Hourly bargaining unit employees | Fixed rate contributions
Defined Contribution Plan Disclosure [Line Items]
Number of production facilities	3
Hourly bargaining unit employees | Concurrent match
Defined Contribution Plan Disclosure [Line Items]
Number of production facilities	1
Hourly bargaining unit employees | Fixed rate and concurrent match
Defined Contribution Plan Disclosure [Line Items]
Number of production facilities	3
Hourly bargaining unit employees | No contributions required
Defined Contribution Plan Disclosure [Line Items]
Number of production facilities	2
Salaried and certain hourly employee | Concurrent match
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan employer concurrent match percentage	4.00%
Hired on or after January 1, 2004 | Hourly bargaining unit employees | Fixed rate contributions
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan annual employer contribution percentage	2.00%
Hired on or after January 1, 2004 | Salaried and certain hourly employee | Fixed rate contributions
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan annual employer contribution percentage	2.00%
Minimum | Hourly bargaining unit employees | Fixed rate contributions
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount | $	$ 800
Minimum | Hired prior to January 1, 2004 | Hourly bargaining unit employees | Fixed rate contributions
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan annual employer contribution percentage	2.00%
Minimum | Hired prior to January 1, 2004 | Salaried and certain hourly employee | Fixed rate contributions
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan annual employer contribution percentage	2.00%
Maximum | Hourly bargaining unit employees | Fixed rate contributions
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount | $	$ 2,400
Maximum | Salaried and certain hourly employee
Defined Contribution Plan Disclosure [Line Items]
Estimated annual contribution to pension and other postretirement benefit plans | $	$ 2,900,000
Maximum | Hired prior to January 1, 2004 | Hourly bargaining unit employees | Fixed rate contributions
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan annual employer contribution percentage	10.00%
Maximum | Hired prior to January 1, 2004 | Salaried and certain hourly employee | Fixed rate contributions
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan annual employer contribution percentage	10.00%

Employee Benefits Employee Be59

Employee Benefits Employee Benefits, Defined Benefit Plans Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accrued Annual Veba Contribution		$ 15.7	$ 20
Long-term portion of contingent contribution to Union VEBA		0	12.8
Defined Benefit Plan, Fair Value of Plan Assets		72.3	69.6
(Gain) loss on removal of Union VEBA net assets – Note 4		0	(0.1)	$ 493.4
Union VEBA
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accrued Annual Veba Contribution		12.8	17.1
Loss on settlement of Union VEBA - net of tax	$ 307.8
Income tax benefit on removal of Union VEBA net assets	$ 184.4
Salaried VEBA
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accrued Annual Veba Contribution		2.9	2.9
Defined Benefit Plan, Expected Amortization of Prior Service Cost (Credit), Next Fiscal Year		5.4
Defined Benefit Plan, Expected Amortization, Next Fiscal Year		6.2
Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year		0.8
VEBAs
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation		90	86.8	77.9
Defined Benefit Plan, Fair Value of Plan Assets		58.1	58.2	58.9
Salaried and certain hourly employee | Canadian pension plan | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated annual contribution to pension and other postretirement benefit plans		2.9
Canadian pension plan | Canadian pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation		8.5	7	6.1
Defined Benefit Plan, Fair Value of Plan Assets		7.3	6.1	$ 5.7
Defined Benefit Plan, Accumulated Benefit Obligation		7.9	$ 6.4
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		$ 0.5
London Ontario Facility | Canadian pension plan | Canadian pension plan | Fixed Income Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations		33.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		30.00%
London Ontario Facility | Canadian pension plan | Canadian pension plan | Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations		63.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		65.00%

Employee Benefits Fair Value of

Employee Benefits Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 72.3	$ 69.6
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	21.3	24.3
Deferred Compensation Plan Assets	9.8	8.2
Fair Value, Measurements, Recurring [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.5	16.1
Deferred Compensation Plan Assets	0	0
Fair Value, Measurements, Recurring [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	9.8	8.2
Deferred Compensation Plan Assets	9.8	8.2
Fair Value, Measurements, Recurring [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Deferred Compensation Plan Assets	0	0
Salaried VEBA | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.5	16.1
Salaried VEBA | Fair Value, Measurements, Recurring [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.5	16.1
Salaried VEBA | Fair Value, Measurements, Recurring [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Salaried VEBA | Fair Value, Measurements, Recurring [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Salaried VEBA | Diversified Investment Funds in Registered Investment Companies [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	10.2	12.8
Salaried VEBA | Diversified Investment Funds in Registered Investment Companies [Member] | Fair Value, Measurements, Recurring [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	10.2	12.8
Salaried VEBA | Diversified Investment Funds in Registered Investment Companies [Member] | Fair Value, Measurements, Recurring [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Salaried VEBA | Diversified Investment Funds in Registered Investment Companies [Member] | Fair Value, Measurements, Recurring [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Salaried VEBA | Equity Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	24.3	21.3
Salaried VEBA | Fixed Income Funds [Member] | Fair Value, Measurements, Recurring [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	19.4	17.9
Salaried VEBA | Cash and Cash Equivalents [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1.3	3.3
Salaried VEBA | Cash and Cash Equivalents [Member] | Fair Value, Measurements, Recurring [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1.3	3.3
Salaried VEBA | Cash and Cash Equivalents [Member] | Fair Value, Measurements, Recurring [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Salaried VEBA | Cash and Cash Equivalents [Member] | Fair Value, Measurements, Recurring [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Canadian pension plan | Diversified Investment Funds in Registered Investment Companies [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 7.3	$ 6.1

Multiemployer Pension Plans (De

Multiemployer Pension Plans (Details)	12 Months Ended
	Dec. 31, 2017USD ($)agreements	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Multiemployer Pension Plan Disclosure
Percentage of employees participating in multiemployer pension plans to total employees	52.00%
Contributions of the Company	$ 4,600,000	$ 4,700,000	$ 4,400,000
Company's contributions to the multiemployer plans is less than	5.00%
USW Plan
Multiemployer Pension Plan Disclosure
Employer Identification Number	236,648,508
Pension Protection Act Zone Status	Green	Green
FIP/RP Status Pending/Implemented in Current Year	No
Contributions of the Company	$ 3,500,000	$ 3,700,000	3,500,000
Surcharge Imposed in 2017	No
Expiration Date of Collective-Bargaining Agreement, First	Mar. 31, 2020
Expiration Date of Collective-Bargaining Agreement, Last	Nov. 30, 2020
Number of collective-bargaining agreements | agreements	3
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities
Multiemployer Pension Plan Disclosure
Percentage of employees covered by bargaining agreement	85.00%
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities | Starting July 2015
Multiemployer Pension Plan Disclosure
Monthly contributions per hour worked by each bargaining unit employee	$ 1.50
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities | Ending in July Two Thousand Nineteen
Multiemployer Pension Plan Disclosure
Monthly contributions per hour worked by each bargaining unit employee	$ 1.75
USW Plan | Richmond (Bellwood), Virginia Facility
Multiemployer Pension Plan Disclosure
Percentage of employees covered by bargaining agreement	11.00%
USW Plan | Florence, Alabama Facility
Multiemployer Pension Plan Disclosure
Percentage of employees covered by bargaining agreement	4.00%
Other Funds
Multiemployer Pension Plan Disclosure
Contributions of the Company	$ 1,100,000	$ 1,000,000	$ 900,000
Multiemployer Plans, Pension | Minimum
Multiemployer Pension Plan Disclosure
Estimated annual contribution to pension and other postretirement benefit plans	3,000,000
Multiemployer Plans, Pension | Maximum
Multiemployer Pension Plan Disclosure
Estimated annual contribution to pension and other postretirement benefit plans	$ 5,000,000

Employee Incentive Plans, Short

Employee Incentive Plans, Short Term Incentive Plans (Details) $ in Millions	Dec. 31, 2017USD ($)
Short Term Incentive Plans
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Accrued Bonuses	$ 17.4

Employee Incentive Plans Inputs

Employee Incentive Plans Inputs and Assumptions Used in Monte Carlo Simulations (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of awards remaining	2 years 10 months
TSR-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value	$ 97.88	$ 93.02	$ 95.68
Grant date stock price	$ 79.69	$ 80.46	$ 75.41
Expected volatility of Kaiser Aluminum	22.74%	17.81%	19.03%
Expected volatility of peer companies	44.19%	41.22%	33.73%
Risk-free interest rate	1.54%	1.01%	0.98%
Dividend yield	2.50%	2.24%	2.12%

Employee Incentive Plans Employ

Employee Incentive Plans Employee Incentive Plans, Compensation expense under LTI programs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 13.1	$ 11.7	$ 9.3
Restricted Stock And Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	5.4	4.7	4.4
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 8.1
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 6 months
TSR-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 4.8	5.4	4
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 4.3
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 7 months
Cost Performance-Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 2.7	1.3	0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 5.2
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 11 months
EVA-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 0.2	0.3	0.9
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 0.5
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 2 months
Fabricated Products
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 5	4.2	3.5
All Other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 8.1	$ 7.5	$ 5.8

Employee Incentive Plans Empl65

Employee Incentive Plans Employee Incentive Plans, Summary of Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding Beginning Balance, Shares/Units	114,658
Outstanding Beginning Balance, Weighted-Average Grant-Date Fair Value per Share	$ 69.51
Granted, shares/units	11,817
Granted, Weighted-Average Grant-Date Fair Value per Share	$ 86.92	$ 86.11	$ 72.09
Vested, shares/units	(46,689)
Vested, Weighted-Average Grant-Date Fair Value per Share	$ 71.46
Forfeited, shares/units	(451)
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$ 69.83
Canceled, shares/units	0
Canceled, Weighted-Average Grant-Date Fair Value per Share	$ 0
Outstanding Ending Balance, Shares/Units	79,335	114,658
Outstanding Ending Balance, Weighted-Average Grant-Date Fair Value per Share	$ 70.96	$ 69.51
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding Beginning Balance, Shares/Units	61,800
Outstanding Beginning Balance, Weighted-Average Grant-Date Fair Value per Share	$ 74.94
Granted, shares/units	92,275
Granted, Weighted-Average Grant-Date Fair Value per Share	$ 76.13	$ 75.29	69.83
Vested, shares/units	(9,570)
Vested, Weighted-Average Grant-Date Fair Value per Share	$ 76.19
Forfeited, shares/units	(6,887)
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$ 77.44
Canceled, shares/units	0
Canceled, Weighted-Average Grant-Date Fair Value per Share	$ 0
Outstanding Ending Balance, Shares/Units	137,618	61,800
Outstanding Ending Balance, Weighted-Average Grant-Date Fair Value per Share	$ 75.81	$ 74.94
TSR-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding Beginning Balance, Shares/Units	394,525
Outstanding Beginning Balance, Weighted-Average Grant-Date Fair Value per Share	$ 90.30
Granted, shares/units	65,044
Granted, Weighted-Average Grant-Date Fair Value per Share	$ 97.88	$ 93.02	95.68
Vested, shares/units	(94,082)
Vested, Weighted-Average Grant-Date Fair Value per Share	$ 83.18
Forfeited, shares/units	(6,383)
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$ 95.85
Canceled, shares/units	(55,288)
Canceled, Weighted-Average Grant-Date Fair Value per Share	$ 83.18
Outstanding Ending Balance, Shares/Units	303,816	394,525
Outstanding Ending Balance, Weighted-Average Grant-Date Fair Value per Share	$ 95.31	$ 90.30
Cost Performance-Based Shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding Beginning Balance, Shares/Units	63,678
Outstanding Beginning Balance, Weighted-Average Grant-Date Fair Value per Share	$ 80.46
Granted, shares/units	65,044
Granted, Weighted-Average Grant-Date Fair Value per Share	$ 79.69	$ 80.46	0
Vested, shares/units	0
Vested, Weighted-Average Grant-Date Fair Value per Share	$ 0
Forfeited, shares/units	(3,999)
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$ 79.93
Canceled, shares/units	0
Canceled, Weighted-Average Grant-Date Fair Value per Share	$ 0
Outstanding Ending Balance, Shares/Units	124,723	63,678
Outstanding Ending Balance, Weighted-Average Grant-Date Fair Value per Share	$ 80.08	$ 80.46
EVA-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding Beginning Balance, Shares/Units	0
Outstanding Beginning Balance, Weighted-Average Grant-Date Fair Value per Share	$ 0
Granted, shares/units	32,504
Granted, Weighted-Average Grant-Date Fair Value per Share	$ 79.69	$ 0	$ 0
Vested, shares/units	0
Vested, Weighted-Average Grant-Date Fair Value per Share	$ 0
Forfeited, shares/units	(1,374)
Forfeited, Weighted-Average Grant-Date Fair Value per Share	$ 79.69
Canceled, shares/units	0
Canceled, Weighted-Average Grant-Date Fair Value per Share	$ 0
Outstanding Ending Balance, Shares/Units	31,130	0
Outstanding Ending Balance, Weighted-Average Grant-Date Fair Value per Share	$ 79.69	$ 0

Employee Incentive Plans Empl66

Employee Incentive Plans Employee Incentive Plans, Weighted Average Grant Date Fair Value (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted-Average Grant-Date Fair Value per Share	$ 86.92	$ 86.11	$ 72.09
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted-Average Grant-Date Fair Value per Share	76.13	75.29	69.83
TSR-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted-Average Grant-Date Fair Value per Share	97.88	93.02	95.68
CP-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted-Average Grant-Date Fair Value per Share	79.69	80.46	0
EVA-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted-Average Grant-Date Fair Value per Share	$ 79.69	$ 0	$ 0

Employee Incentive Plans, Narra

Employee Incentive Plans, Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common shares available for additional awards under Equity Incentive Plan	737,954
Recognized tax benefit relating to non-cash compensation expense	$ 4.9	$ 4.4	$ 3.5
Fully-vested options outstanding	0	1,543
Exercise price of options to purchase common stock		$ 80.01
Stock options granted	0
Shares Paid for Tax Withholding for Share Based Compensation	56,495	36,055	37,009
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common share received by the employee on vesting of restricted stock unit	1
TSR-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
TSR-Based Performance Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	0.00%
TSR-Based Performance Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	200.00%

Derivative Financial Instrume68

Derivative Financial Instruments and Related Hedging Programs, Notional Quantity Table (Details) mmlbs in Millions	Dec. 31, 2017EUR (€)mmlbsMMBTU
Not Designated as Hedging Instrument | Aluminum | Purchase
Derivative [Line Items]
Derivative Notional Amount (Non-Monetary)	165.3
Not Designated as Hedging Instrument | Aluminum | Sale
Derivative [Line Items]
Derivative Notional Amount (Non-Monetary)	1.4
Not Designated as Hedging Instrument | Midwest premium swap contracts | Purchase
Derivative [Line Items]
Derivative Notional Amount (Non-Monetary)	163.9
Not Designated as Hedging Instrument | Natural Gas Member | Purchase
Derivative [Line Items]
Derivative Notional Amount (Non-Monetary) | MMBTU	3,600,000
Not Designated as Hedging Instrument | Electricity | Purchase
Derivative [Line Items]
Derivative Notional Amount (Non-Monetary) | MMBTU	131,760
Not Designated as Hedging Instrument | Foreign Exchange Contract | Purchase
Derivative [Line Items]
Derivative, Notional Amount (Monetary) | €	€ 301,304
Designated as Hedging Instrument | Alloy Metal Hedge | Purchase
Derivative [Line Items]
Derivative Notional Amount (Non-Monetary)	2.7

Derivative Financial Instrume69

Derivative Financial Instruments and Related Hedging Programs, Realized and Unrealized Gains and Losses Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments Gain Loss [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 19.4	$ 18.7	$ (3.4)
Operational Risk Hedges | Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Unrealized Gain (Loss) on Derivatives	(19.4)	(18.7)	3.4
Cost of Sales | Aluminum | Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Realized (losses) gains	20.4	(2)	(27.3)
Cost of Sales | Natural Gas | Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Realized (losses) gains	(0.7)	(5)	(5.4)
Cost of Sales | Alloy Metal Hedge | Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Realized (losses) gains	(0.9)	0	0
Cost of Sales | Electricity | Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Realized (losses) gains	0	0	(1.9)
Cost of Sales | Operational Risk Hedges | Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Realized (losses) gains	20.7	(7.1)	(34.6)
Other Operating Income (Expense) | Foreign Exchange Contract | Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Realized (losses) gains	0.1	(0.1)	0
Gain (Loss) on Derivative Instruments | Aluminum | Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Unrealized Gain (Loss) on Derivatives	(20.9)	(10.8)	4.6
Gain (Loss) on Derivative Instruments | Natural Gas | Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Unrealized Gain (Loss) on Derivatives	1.4	(7.9)	0.5
Gain (Loss) on Derivative Instruments | Electricity | Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 0.1	$ 0	$ (1.7)

Derivative Financial Instrume70

Derivative Financial Instruments and Related Hedging Programs, Fair Value Hierarchy Table (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	$ (25.3)	$ (5.8)
Derivative Liability	(0.8)	(1.8)
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	51.1	55.2
Derivative Asset	(25.3)	(5.8)
Derivative Liability	(0.8)	(1.8)
Other Assets, Fair Value Disclosure	234.8	286.2
Fair Value, Measurements, Recurring [Member] | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	183.7	231
Fair Value, Measurements, Recurring [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	23.5	37.9
Derivative Asset	0	0
Derivative Liability	0	0
Other Assets, Fair Value Disclosure	23.5	37.9
Fair Value, Measurements, Recurring [Member] | Level 1 | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	27.6	17.3
Derivative Asset	(25.3)	(5.8)
Derivative Liability	(0.8)	(1.8)
Other Assets, Fair Value Disclosure	211.3	248.3
Fair Value, Measurements, Recurring [Member] | Level 2 | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	183.7	231
Fair Value, Measurements, Recurring [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Derivative Asset	0	0
Derivative Liability	0	0
Other Assets, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Aluminum Member
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0.9
Derivative Liability		(0.2)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Aluminum Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	(22.5)	(3.3)
Derivative Liability		(1.1)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Aluminum Member | Short
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	(0.1)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Midwest premium swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	(1.7)
Derivative Liability	(0.1)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Natural Gas Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	(0.2)	(1.6)
Derivative Liability	(0.5)	(0.4)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Electricity Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	(0.1)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 1 | Aluminum Member
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0
Derivative Liability		0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 1 | Aluminum Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability		0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 1 | Aluminum Member | Short
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 1 | Midwest premium swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0
Derivative Liability	0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 1 | Natural Gas Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability	0	0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 1 | Electricity Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 2 | Aluminum Member
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0.9
Derivative Liability		0.2
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 2 | Aluminum Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	(22.5)	(3.3)
Derivative Liability		(1.1)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 2 | Aluminum Member | Short
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	(0.1)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 2 | Midwest premium swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	(1.7)
Derivative Liability	(0.1)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 2 | Natural Gas Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	(0.2)	(1.6)
Derivative Liability	(0.5)	(0.4)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 2 | Electricity Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	(0.1)
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 3 | Aluminum Member
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0
Derivative Liability		0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 3 | Aluminum Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability		0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 3 | Aluminum Member | Short
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 3 | Midwest premium swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0
Derivative Liability	0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 3 | Natural Gas Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability	0	0
Not Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 3 | Electricity Member | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	0
Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Alloy Metal Hedge | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	(0.9)
Derivative Liability	0	(0.1)
Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 1 | Alloy Metal Hedge | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0
Derivative Liability	0	0
Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 2 | Alloy Metal Hedge | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	(0.9)
Derivative Liability	0	(0.1)
Designated as Hedging Instrument | Fair Value, Measurements, Recurring [Member] | Level 3 | Alloy Metal Hedge | Long
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0
Derivative Liability	0	0
Other Current Liabilities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	(0.3)	(0.8)
Other Noncurrent Liabilities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	(0.5)	(1)
Other Current Assets [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	(18.9)	(5)
Other Assets [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	$ (6.4)	$ (0.8)

Derivative Financial Instrume71

Derivative Financial Instruments and Related Hedging Programs, Offsetting of Derivative Instruments by Counterparty (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Assets	$ 25.3	$ 5.8
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	25.3	5.8
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0.8	1.7
Net Amount	24.5	4.1
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Liabilities	(0.8)	(1.8)
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	(0.8)	(1.8)
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	(0.8)	(1.7)
Net Amount	0	(0.1)
Counterparty (with netting agreements)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Assets	25.3	3.3
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	25.3	3.3
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0.8	1
Net Amount	24.5	2.3
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Liabilities	(0.8)	(1)
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	(0.8)	(1)
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	(0.8)	(1)
Net Amount	$ 0	0
Counterparty (with partial netting agreements)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Assets		2.5
Gross Amounts Offset in the Consolidated Balance Sheets		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets		2.5
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments		0.7
Net Amount		1.8
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross Amounts of Recognized Liabilities		(0.8)
Gross Amounts Offset in the Consolidated Balance Sheets		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets		(0.8)
Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments		(0.7)
Net Amount		$ (0.1)

Derivative Financial Instrume72

Derivative Financial Instruments and Related Hedging Programs, Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2020	Dec. 31, 2018
Derivative [Line Items]
Margin deposits with counterparties	$ 0
Customer Deposits, Current	0
Derivative Asset	25,300,000	$ 5,800,000
Derivative Instruments in Hedges, at Fair Value, Net	$ 24,500,000	4,000,000
Debt Instrument, Term	8 months
Alloy Metal Hedge | Designated as Hedging Instrument
Derivative [Line Items]
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net	$ 0
Maximum | Alloy Metal Hedge | Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Derivative, Remaining Maturity	6 months
Scenario, Forecast | Natural Gas Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage				55.00%	70.00%
Scenario, Forecast | Electricity Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage				46.00%	55.00%
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
Derivative [Line Items]
OCI, before Reclassifications, before Tax, Attributable to Parent	$ 2,000,000	$ (200,000)	$ (500,000)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Alloy Metal Hedge
Derivative [Line Items]
OCI, before Reclassifications, before Tax, Attributable to Parent	$ (500,000)

Debt and Credit Facility, Addit

Debt and Credit Facility, Additional Information Regarding Convertible Notes (Details) - Convertible Notes Payable - Convertible Notes - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument
Contractual coupon interest		$ 2
Amortization of discount		2.4
Amortization of debt issuance costs		$ 0.3
Total interest expense	$ 4.7

Debt and Credit Facility, Narra

Debt and Credit Facility, Narrative (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jun. 01, 2016USD ($)	May 15, 2016USD ($)	May 23, 2012USD ($)	Mar. 31, 2010USD ($)
Debt Instrument
Loss on Repurchase of Debt Instrument		$ 0	$ (11,100,000)	$ (2,500,000)
Long-term debt		369,600,000	368,700,000
Repayments of Unsecured Debt		0	206,000,000	30,000,000
Senior Notes Due 2024 | Senior Notes
Debt Instrument
Principal amount of notes						$ 375,000,000
Interest rate						5.875%
Percentage of principal amount issued						100.00%
Unamortized Debt Issuance Expense		5,400,000	6,300,000
Interest Expense including amortization of deferred financing cost		$ 22,900,000	14,500,000
Effective interest rate		6.10%
Debt Instrument, Fair Value Disclosure		$ 399,900,000	390,800,000
Senior Notes Due 2024 | Senior Notes | Change in control
Debt Instrument
Debt Instrument, Redemption Price, Percentage		101.00%
Senior Notes Due 2020 | Senior Notes
Debt Instrument
Principal amount of notes							$ 225,000,000
Interest rate							8.25%
Interest Expense including amortization of deferred financing cost			$ 7,100,000	$ 18,800,000
Long-term debt					$ 197,800,000
Convertible Notes | Convertible Notes Payable
Debt Instrument
Principal amount of notes								$ 175,000,000
Interest rate								4.50%
Effective interest rate			11.00%
Debt Instrument, Periodic Payment			$ 3,900,000
Debt Instrument, Convertible, If-converted Value in Excess of Principal			94,900,000
Net cash outflow in convertible debt settlement			$ 178,900,000
Revolving Credit Facility | Line of Credit
Debt Instrument
Maximum borrowing capacity		$ 300,000,000
Percentage of eligible accounts receivable for borrowing base		85.00%
Percentage of eligible inventory for borrowing base		75.00%
Percentage of net orderly liquidation value of eligible inventory		85.00%
Maximum amount of eligible machinery and equipment for borrowing base		$ 60,000,000
Line of Credit Facility, Possible Future Maximum Borrowing Capacity		400,000,000
Available borrowing capacity		300,000,000
Outstanding line of credit		0
Remaining available borrowing capacity		$ 291,900,000
Interest on Revolving Credit Facility		4.75%
Minimum Amount of Available Borrowing to Maintain		$ 52,500,000
Revolving Credit Facility | Line of Credit | Borrowing Availability Under $45.0 Million
Debt Instrument
Line of Credit, Ability to Make Restricted Actions, Available Borrowing Necessary After Action with Fixed Charge Coverage Ratio		$ 45,000,000
Fixed Charge Coverage Ratio		1.15
Revolving Credit Facility | Line of Credit | Borrowing Availability Under $30.0 Million
Debt Instrument
Fixed Charge Coverage Ratio		1
Line of Credit, Minimum Borrowing Availability Threshold to Maintain Fixed Charge Coverage Ratio		$ 30,000,000
Revolving Credit Facility | Letter of Credit
Debt Instrument
Maximum borrowing capacity		20,000,000
Outstanding line of credit		$ (8,100,000)
On or after June 1, 2016 | Senior Notes Due 2020 | Senior Notes
Debt Instrument
Debt Instrument, Redemption Price, Percentage	104.125%
On or after May 15, 2019 | Senior Notes Due 2024 | Senior Notes
Debt Instrument
Debt Instrument, Redemption Price, Percentage		104.406%
On or after May 15, 2020 | Senior Notes Due 2024 | Senior Notes
Debt Instrument
Debt Instrument, Redemption Price, Percentage		102.938%
On or after May 15, 2021 | Senior Notes Due 2024 | Senior Notes
Debt Instrument
Debt Instrument, Redemption Price, Percentage		101.469%
On or after May 15, 2022 | Senior Notes Due 2024 | Senior Notes
Debt Instrument
Debt Instrument, Redemption Price, Percentage		100.00%
Any time prior to May 15, 2019 | Senior Notes Due 2024 | Senior Notes
Debt Instrument
Debt Instrument, Redemption Price, Percentage		100.00%
Upon receipt of the proceeds of certain asset sales | Senior Notes Due 2024 | Senior Notes
Debt Instrument
Debt Instrument, Redemption Price, Percentage		100.00%

Commitments and Contingencies,

Commitments and Contingencies, Minimum Commitments (Details) $ in Millions	Dec. 31, 2017USD ($)
Minimum rental commitments
2,018	$ 5.7
2,019	5.2
2,020	3.1
2,021	2.5
2,022	2.2
2023 and Thereafter	$ 21

Commitments and Contingencies76

Commitments and Contingencies, Rollforward of CARO Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Weighted Average Discount Rate, Percent	10.00%	10.00%
Asset Retirement Obligation, Roll Forward
Beginning balance	$ 5.5	$ 4.9	$ 4.8
Liabilities incurred during the period	0	0	0
Liabilities settled during the period	0	(0.1)	(0.2)
Accretion expense	0.4	0.5	0.3
Adjustment to accretion expense due to revisions to estimated cash flow and timing of expenditure1	0	0.2	0
Ending balance	$ 5.9	$ 5.5	$ 4.9

Commitments and Contingencies77

Commitments and Contingencies Commitments and Contingencies, Changes in Environmental Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	$ 12.5
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	17.2	$ 18.6	$ 19.3
Additional accruals	0.3	0.1	1.3
Less: expenditures	0.9	1.5	2
Ending balance	$ 16.6	$ 17.2	$ 18.6

Commitments and Contingencies78

Commitments and Contingencies, Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accrual for Environmental Loss Contingencies, Gross, Fiscal Year Maturity
Rental expense	$ 7.9	$ 8.5	$ 8.2
Environmental accrual	$ 16.6	$ 17.2	$ 18.6	$ 19.3
Expected period related to remediation expenditures for environmental contingencies	30 years
Estimated environmental contingency loss exposure in excess of current accrual	$ 12.5
Time period within which Company's recorded estimate of its obligation may change	12 months
Minimum
Accrual for Environmental Loss Contingencies, Gross, Fiscal Year Maturity
Period for feasibility study completion	18 months
Maximum
Accrual for Environmental Loss Contingencies, Gross, Fiscal Year Maturity
Period for feasibility study completion	24 months

Accumulated Other Comprehensi79

Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 804.7		$ 1,015.9
Other comprehensive income (loss), net of tax		$ (5)	64.4
Ending balance	746.3	804.7
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(37.1)	(31.3)	(96.4)
Reclassification from AOCI, Current Period, Tax	2.1	1.7	41.8
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	3.5	2.9	68.9
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)	(0.1)	0.1	0
Other comprehensive income (loss), net of tax	(1.4)	(5.8)	65.1
Ending balance	(38.5)	(37.1)	(31.3)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI, before Reclassifications, before Tax, Attributable to Parent	(0.3)	(5.7)	(12.9)
Other Comprehensive Income (Loss) before Reclassifications, Tax	(0.1)	(2.1)	(4.9)
OCI, before Reclassifications, Net of Tax, Attributable to Parent	(0.2)	(3.6)	(8)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	0.9	0.5	1.1
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI, before Reclassifications, before Tax, Attributable to Parent	(7.3)	(8.3)	6.8
Other Comprehensive Income (Loss) before Reclassifications, Tax	(2.7)	(3.1)	2.6
OCI, before Reclassifications, Net of Tax, Attributable to Parent	(4.6)	(5.2)	4.2
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	4.7	4.1	3
Accumulated Defined Benefit Plans Adjustment, Removal Of Obligation Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	0	0	106.6
Accumulated Net Investment Gain (Loss) Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0.8	(0.1)	0.2
OCI, before Reclassifications, before Tax, Attributable to Parent	4	1.9	(0.1)
Other Comprehensive Income (Loss) before Reclassifications, Tax	1.5	0.7	0
OCI, before Reclassifications, Net of Tax, Attributable to Parent	2.5	1.2	(0.1)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	(3.2)	(0.5)	(0.4)
Reclassification from AOCI, Current Period, Tax	(1.2)	(0.2)	(0.2)
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	(2)	(0.3)	(0.2)
Other comprehensive income (loss), net of tax	0.5	0.9	(0.3)
Ending balance	1.3	0.8	(0.1)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(0.4)	(0.3)	0.1
OCI, before Reclassifications, before Tax, Attributable to Parent	2	(0.2)	(0.5)
Other Comprehensive Income (Loss) before Reclassifications, Tax	0.7	0	(0.1)
OCI, before Reclassifications, Net of Tax, Attributable to Parent	1.3	(0.2)	(0.4)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	(0.6)	0.1	0
Reclassification from AOCI, Current Period, Tax	(0.2)	0	0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	(0.4)	0.1	0
Other comprehensive income (loss), net of tax	0.9	(0.1)	(0.4)
Ending balance	0.5	(0.4)	(0.3)
AOCI Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(36.7)	(31.7)	(96.1)
Other comprehensive income (loss), net of tax		(5)	64.4
Ending balance	$ (36.7)	$ (36.7)	$ (31.7)

Other (Expense) Income, Net (De

Other (Expense) Income, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument, Redemption
Interest income	$ 0.2	$ 0.1	$ 0.4
Realized gain on investments	3.4	0.8	0.8
Loss on extinguishment of debt	0	(11.1)	0
All other, net	0.9	(0.1)	(3)
Other income (expense), net	$ 4.5	(10.3)	$ (1.8)
Senior Notes | Senior Notes Due 2020
Debt Instrument, Redemption
Redemption Premium		8.2
Write off of Deferred Debt Issuance Cost		$ 2.9

Income Tax Matters Income Tax M

Income Tax Matters Income Tax Matters, Income Before Income Taxes Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ 127.9	$ 143.6	$ (373.6)
Foreign	5.1	3.6	1.8
Income (loss) before income taxes	$ 133	$ 147.2	$ (371.8)

Income Tax Matters, Income Tax

Income Tax Matters, Income Tax Benefit (Provision) Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal income tax (expense) benefit
Current federal tax (expense) benefit	$ 3.1	$ 2.7	$ 0.7
Deferred federal income tax (expense) benefit	(82)	(47.8)	93.2
Federal benefit (expense) applied to increase (decrease) Additional capital/Other comprehensive income	(0.1)	(3.2)	33.5
Federal income tax (expense) benefit	(79)	(48.3)	127.4
Foreign income tax (expense) benefit
Current foreign tax (expense) benefit	(0.8)	0.6	2.1
Deferred foreign income tax (expense) benefit	(1)	(1.2)	(1.2)
Foreign benefit (expense) applied to increase (decrease) Additional capital/Other comprehensive income	(0.1)	(0.1)	0.4
Foreign income tax (expense) benefit	(1.9)	(0.7)	1.3
State income tax (expense) benefit
Current state tax (expense) benefit	(1)	(1.5)	0.4
Deferred state income tax (expense) benefit	(5.7)	(4.7)	1.8
State benefit (expense) applied to increase (decrease) additional capital/Other comprehensive income	0	(0.3)	4.3
State income tax (expense) benefit	(6.7)	(6.5)	6.5
Total income tax (expense) benefit
Current income tax (expense) benefit	1.3	1.8	3.2
Deferred income tax (expense) benefit	(88.7)	(53.7)	93.8
Benefit (expense) applied to increase (decrease) Additional capital/Other comprehensive income	(0.2)	(3.6)	38.2
Income tax (provision) benefit	$ (87.6)	$ (55.5)	$ 135.2

Income Tax Matters, Reconciliat

Income Tax Matters, Reconciliation Between Income Tax Provision and Statutory Income Tax Provision Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation between income tax provision and statutory income tax provision:
Amount of federal income tax (provision) benefit based on the statutory rate	$ (46.5)	$ (51.5)	$ 130.1
(Increase) decrease in federal valuation allowances	0.5	(0.3)	(0.6)
Non-deductible compensation (expense) benefit	(2.3)	0.3	(0.2)
Non-deductible (expense)	0	(0.3)	(0.3)
State income taxes, net of federal benefit	(4.3)	(4.2)	4.2
Foreign income tax (expense) benefit	(0.1)	0.5	0.1
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount	(5.9)	0	0
Expiration of statute of limitations	0	0	1.7
Effective Income Tax Rate Reconciliation, Tax Settlement, Foreign, Amount	29	0	0
Advance pricing agreement	0	0	(0.2)
Competent Authority settlement	0	0	0.4
Income tax (provision) benefit	(87.6)	(55.5)	135.2
State and Local Jurisdiction [Member]
Reconciliation between income tax provision and statutory income tax provision:
(Increase) decrease in federal valuation allowances	2.2	(0.3)
State and tax expense (benefit) before adjustments	4	4.1	(10.3)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ (2.5)	$ 0.2	(3.1)
Increase (decrease) in state income tax expense (benefit) due to expiring net operating losses			$ (3)

Income Tax Matters, Components

Income Tax Matters, Components of Deferred Tax Assets and Liabilities Table (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax assets:
Loss and credit carryforwards	$ 98.7	$ 191.8
VEBAs (see Note 4)	11.6	23.2
Other assets	21	39.8
Inventory	9.3	0
Valuation allowances	(13)	(15.7)
Total deferred income tax assets	127.6	239.1
Deferred income tax liabilities:
Property, plant and equipment	(57.7)	(82.7)
Undistributed foreign earnings	(2.2)	0
Total deferred income tax liabilities	(59.9)	(82.7)
Net deferred income tax assets	67.7	156.4
Net deferred income tax assets, long term	72	159.7
Deferred tax liability, long term	$ (4.3)	$ (3.3)

Income Tax Matters, Reconcili85

Income Tax Matters, Reconciliation of Changes in the Gross Unrecognized Tax Benefits Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of changes in the gross unrecognized tax benefits:
Gross unrecognized tax benefits at beginning of period	$ 1.8	$ 1.7	$ 2.2
Gross increases for tax positions of prior years	0	0.1	0.1
Gross decreases for tax positions of prior years	(0.3)	0	0
Gross decrease for tax positions relating to lapse of a statute of limitation	0	0	(0.6)
Gross unrecognized tax benefits at end of period	$ 1.5	$ 1.8	$ 1.7

Income Tax Matters Income Tax86

Income Tax Matters Income Tax Matters Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Operating Loss Carryforwards	$ 275,100,000	$ 275,100,000
Tax Credit Carryforward, Amount	23,300,000	23,300,000
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		(2,700,000)	$ (5,500,000)	$ 2,000,000
Unrecognized Tax Benefits	1,500,000	1,500,000	1,800,000	1,700,000	$ 2,200,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	400,000	400,000	700,000	600,000
Accrued interest and penalties on unrecognized tax benefits	100,000	100,000	200,000
Accrued interest and penalties on unrecognized tax benefits, current	0	0
(Decrease) increase in interest and penalty	(100,000)	(100,000)	$ 0	(1,200,000)
Foreign currency impact on gross unrecognized tax benefit (including interest and penalties) which increased (decreased) Other comprehensive income (loss)				$ 100,000
Provisional decrease in deferred tax assets	29,000,000
Provisional Transition Tax obligation	3,700,000
Accrued witholding taxes due to Canadian earnings deemed no longer permanently reinvested	2,200,000	2,200,000
Provisional Section 162(m) obligation	$ 2,300,000	$ 2,300,000

Net Income (Loss) Per Share a87

Net Income (Loss) Per Share and Stockholders' Equity, Calculation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net income (loss)	$ (15.2)	$ 19.9	$ 4.7	$ 36	$ 24.5	$ 14.9	$ 26	$ 26.3	$ 45.4	$ 91.7	$ (236.6)
Denominator – Weighted-average common shares outstanding (in thousands):
Basic (in shares)									16,996	17,813	17,201
Add: dilutive effect of non-vested common shares, restricted stock units and performance shares									263	220	0
Diluted (in shares)									17,259	18,033	17,201
Net (loss) income per common share, Basic (in dollars per share)	$ (0.90)	$ 1.18	$ 0.28	$ 2.07	$ 1.39	$ 0.84	$ 1.45	$ 1.47	$ 2.67	$ 5.15	$ (13.76)
Net (loss) income per common share, Diluted (in dollars per share	$ (0.90)	$ 1.16	$ 0.27	$ 2.04	$ 1.37	$ 0.82	$ 1.43	$ 1.44	$ 2.63	$ 5.09	$ (13.76)

Net Income (Loss) Per Share a88

Net Income (Loss) Per Share and Stockholders' Equity Net Income (Loss) Per Share and Stockholders' Equity, Anti-Dilution Table (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total excluded	52	50	941
Non-vested common shares, restricted stock units and performance shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total excluded	52	50	302
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total excluded	0	0	639

Net Income (Loss) Per Share a89

Net Income (Loss) Per Share and Stockholders' Equity Net Income (Loss) Per Share and Stockholders' Equity, Share Repurchases (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Number of common shares repurchased (shares)	938,680	443,838	647,520
Weighted-average repurchase price (dollars per share)	$ 82.97	$ 78.59	$ 76.35
Total cost of repurchased common shares	$ 77.8	$ 34.9	$ 49.4

Net Income (Loss) Per Share a90

Net Income (Loss) Per Share and Stockholders' Equity, Narrative (Details) $ / shares in Units, $ in Millions	Apr. 07, 2016	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Apr. 22, 2016shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares				$ 60.70
Payment of cash dividends to stockholders | $		$ 35	$ 32.4	$ 28.1
Payment of quarterly cash dividends | $ / shares		$ 2	$ 1.80	$ 1.60
Repurchase of common shares pursuant to an authorization from the Board, shares		938,680	443,838	647,520
Weighted-average price of repurchases of common shares | $ / shares		$ 82.97	$ 78.59	$ 76.35
Repurchase of common shares pursuant to an authorization from the Board, value | $		$ 77.8	$ 34.9	$ 49.4
Common shares available for additional share repurchase | $		$ 110.5	$ 88.4
Preferred Stock, Shares Authorized		5,000,000	5,000,000
Convertible Notes | Convertible Notes Payable
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock Issued During Period, Shares, Other			1,015,185
Warrant Transactions
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of common shares underlying the Warrants outstanding				3,700,000
Series A Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred Stock, Rights Conversion Ratio into Preferred Stock	1
Preferred Stock, Shares Authorized					900,000

Supplemental Cash Flow Inform91

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental disclosure of cash flow information:
Interest paid	$ 21.1	$ 17.7	$ 22.1
Non-cash investing and financing activities (included in Accounts payable):
Unpaid purchases of property and equipment	7.4	4.6	10.5
Stock repurchases not yet settled (accrued in accounts payable)	0.1	1.8	0.2
Acquisition of property and equipment through capital leasing arrangements	1.2	0.2	0
Cash and cash equivalents	51.1	55.2	72.5
Restricted cash included in Prepaid expenses and other current assets	0.3	0.3	0.3
Restricted cash included in Other assets	12.9	12.2	10.9
Total cash, cash equivalents and restricted cash shown in the Statements of Consolidated Cash Flows	$ 64.3	$ 67.7	$ 83.7	$ 188

Segment and Geographical Area92

Segment and Geographical Area Information, Summary of financial information by operating segment (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information
Impairment of Intangible Assets						$ 2.6
Net Sales:
Net sales	$ 353.1	$ 332.8	$ 356.3	$ 355.3	$ 331.9	320.6	$ 334.9	$ 343.2	$ 1,397.5	$ 1,330.6	$ 1,391.9
Segment Operating Income (Loss):
Total operating income (loss)	40	$ 39.8	$ 11.4	$ 59.5	45.3	$ 29.8	$ 57.9	$ 44.8	150.7	177.8	(345.9)
Interest expense									(22.2)	(20.3)	(24.1)
Other income, net									4.5	(10.3)	(1.8)
Income (loss) before income taxes									133	147.2	(371.8)
Depreciation and Amortization:
Depreciation and amortization									39.7	36	32.4
Capital expenditures:
Capital expenditures									75.5	76.1	63.1
Segment assets:
Total	1,385.2				1,443.5				1,385.2	1,443.5	1,246.9
Fabricated Products
Net Sales:
Net sales									1,397.5	1,330.6	1,391.9
Segment Operating Income (Loss):
Total operating income (loss)									201.3	229.6	190.8
Depreciation and Amortization:
Depreciation and amortization									39	35.4	31.9
Capital expenditures:
Capital expenditures									75.3	75.6	62.4
Segment assets:
Total	1,046.8				969.4				1,046.8	969.4	904.7
All Other
Segment Operating Income (Loss):
Total operating income (loss)									(50.6)	(51.8)	(536.7)
Depreciation and Amortization:
Depreciation and amortization									0.7	0.6	0.5
Capital expenditures:
Capital expenditures									0.2	0.5	0.7
Segment assets:
Total	$ 338.4				$ 474.1				$ 338.4	$ 474.1	$ 342.2

Segment and Geographical Area93

Segment and Geographical Area Information, Schedule of net sales by end market segment applications (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue from External Customer
Net sales	$ 353.1	$ 332.8	$ 356.3	$ 355.3	$ 331.9	$ 320.6	$ 334.9	$ 343.2	$ 1,397.5	$ 1,330.6	$ 1,391.9
Aero/HS products
Revenue from External Customer
Net sales									653.7	675.4	695.5
Automotive Extrusions
Revenue from External Customer
Net sales									217.3	188.8	199.2
GE products
Revenue from External Customer
Net sales									476.2	420.1	426.1
Other products
Revenue from External Customer
Net sales									$ 50.3	$ 46.3	$ 71.1

Segment and Geographical Area94

Segment and Geographical Area Information Segment and Geographical Area Information, Schedule of net sales, income taxes paid, and long-lived assets, by geographical area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Net sales to unaffiliated customers	$ 353.1	$ 332.8	$ 356.3	$ 355.3	$ 331.9	$ 320.6	$ 334.9	$ 343.2	$ 1,397.5	$ 1,330.6	$ 1,391.9
Income taxes paid									1.3	1.2	2.3
Long-lived assets	571.4				530.9				571.4	530.9	495.4
Fabricated Products
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Net sales to unaffiliated customers									1,397.5	1,330.6	1,391.9
Long-lived assets	566.8				526.1				566.8	526.1	490.5
Fabricated Products | United States
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Net sales to unaffiliated customers									1,337.3	1,278.6	1,321.3
Income taxes paid									1.2	0.7	0.6
Long-lived assets	536.6				494.7				536.6	494.7	459.6
Fabricated Products | Canada
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Net sales to unaffiliated customers									60.2	52	70.6
Income taxes paid									0.1	0.5	1.7
Long-lived assets	30.2				31.4				30.2	31.4	30.9
All Other
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Long-lived assets	4.6				4.8				4.6	4.8	4.9
All Other | United States
Revenues from External Customers, Income Taxes Paid, and Long-Lived Assets
Long-lived assets	$ 4.6				$ 4.8				$ 4.6	$ 4.8	$ 4.9

Segment and Geographical Area95

Segment and Geographical Area Information Segment and Geographical Area Information, Schedules of Concentration of Risk, by Risk Factor (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Export sales | Net sales
Concentration Risk
Concentration risk, percentage	18.00%	19.00%	19.00%
Supplier concentration risk | Aluminum | Top five major suppliers
Concentration Risk
Concentration risk, percentage	85.00%	84.00%	86.00%
Supplier concentration risk | Aluminum | Largest supplier
Concentration Risk
Concentration risk, percentage	36.00%	32.00%	28.00%
Supplier concentration risk | Aluminum | Second and third largest suppliers
Concentration Risk
Concentration risk, percentage	33.00%	32.00%	36.00%

Segment and Geographical Area96

Segment and Geographical Area Information, Narrative (Details)	12 Months Ended
	Dec. 31, 2017productionfacilitiescustomer	Dec. 31, 2016customer	Dec. 31, 2015customer
Segment Reporting Information
Percentage of Employees Covered by Collective Bargaining Agreements	63.00%
Percentage of Employees Covered by Collective Bargaining Agreements Expiring Within One Year	12.00%
United States
Segment Reporting Information
Number of production facilities | productionfacilities	11
Canada
Segment Reporting Information
Number of production facilities | productionfacilities	1
Customer Concentration Risk | Net sales | Largest Customer | Fabricated Products
Segment Reporting Information
Concentration risk, percentage	27.00%	26.00%	25.00%
Number of Customers | customer	1	1	1
Customer Concentration Risk | Net sales | Second Largest Customer | Fabricated Products
Segment Reporting Information
Concentration risk, percentage	12.00%	10.00%	10.00%
Customer Concentration Risk | Trade Receivables | Largest Customer
Segment Reporting Information
Concentration risk, percentage	22.00%	18.00%
Customer Concentration Risk | Trade Receivables | Second Largest Customer
Segment Reporting Information
Concentration risk, percentage	14.00%
Customer Concentration Risk | Trade Receivables | Second Largest Customer | Fabricated Products
Segment Reporting Information
Number of Customers | customer	2

Guarantor and Non-Guarantor F97

Guarantor and Non-Guarantor Financial Statements (Details) - USD ($)		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 01, 2016	May 15, 2016	Dec. 31, 2014	May 23, 2012
Condensed Financial Statements [Line Items]
Ownership interest by parent		100.00%								100.00%
Current assets:
Cash and cash equivalents		$ 51,100,000				$ 55,200,000				$ 51,100,000	$ 55,200,000	$ 72,500,000
Short-term investments		183,700,000				231,000,000				183,700,000	231,000,000
Receivables:
Trade, less allowance for doubtful receivables		165,000,000				137,700,000				165,000,000	137,700,000
Intercompany receivables		0				0				0	0
Other		15,500,000				11,900,000				15,500,000	11,900,000
Inventories		207,900,000				201,600,000				207,900,000	201,600,000
Prepaid expenses and other current assets		33,400,000				18,500,000				33,400,000	18,500,000
Total current assets		656,600,000				655,900,000				656,600,000	655,900,000
Investments in and advances to unconsolidated affiliates		0				0				0	0
Property, plant and equipment, net		571,400,000				530,900,000				571,400,000	530,900,000
Long-term intercompany receivables		0				0				0	0
Deferred tax assets — net		72,000,000				159,700,000				72,000,000	159,700,000
Intangible assets, net		25,000,000				26,400,000				25,000,000	26,400,000
Goodwill		18,800,000				37,200,000				18,800,000	37,200,000
Other assets		41,400,000				33,400,000				41,400,000	33,400,000
Total		1,385,200,000				1,443,500,000				1,385,200,000	1,443,500,000	1,246,900,000
Current liabilities:
Accounts payable		90,000,000				75,800,000				90,000,000	75,800,000
Intercompany payable		0				0				0	0
Accrued salaries, wages and related expenses		42,600,000				49,100,000				42,600,000	49,100,000
Other accrued liabilities		40,500,000				40,100,000				40,500,000	40,100,000
Total current liabilities		173,100,000				165,000,000				173,100,000	165,000,000
Net liabilities of Salaried VEBA		31,900,000				28,600,000				31,900,000	28,600,000
Deferred tax liabilities		4,300,000				3,300,000				4,300,000	3,300,000
Long-term intercompany payable		0				0				0	0
Long-term liabilities		60,000,000				73,200,000				60,000,000	73,200,000
Long-term debt		369,600,000				368,700,000				369,600,000	368,700,000
Total liabilities		638,900,000				638,800,000				638,900,000	638,800,000
Total stockholders’ equity		746,300,000				804,700,000				746,300,000	804,700,000				$ 1,015,900,000
Total		1,385,200,000				1,443,500,000				1,385,200,000	1,443,500,000
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales		353,100,000	$ 332,800,000	$ 356,300,000	$ 355,300,000	331,900,000	$ 320,600,000	$ 334,900,000	$ 343,200,000	1,397,500,000	1,330,600,000	1,391,900,000
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items		282,600,000	267,200,000	277,700,000	277,800,000	252,400,000	254,700,000	250,400,000	262,000,000	1,105,300,000	1,019,500,000	1,115,400,000
Lower of cost or market inventory write-down						0	0	0	4,900,000	0	4,900,000	2,600,000
Unrealized (gain) loss on derivative instruments		(5,400,000)	(10,800,000)	11,900,000	(15,100,000)	(1,800,000)	(2,000,000)	(10,900,000)	(4,000,000)	(19,400,000)	(18,700,000)	3,400,000
Depreciation and amortization										39,700,000	36,000,000	32,400,000
Selling, general, administrative, research and development										97,500,000	105,000,000	88,100,000
Net periodic postretirement benefit cost relating to Salaried VEBA										4,500,000	3,400,000	2,400,000
(Gain) loss on removal of Union VEBA net assets – Note 4										0	(100,000)	493,400,000
Total selling, administrative, research and development and general										102,000,000	108,300,000	583,900,000
Goodwill impairment										18,400,000	0	0
Other operating charges, net										800,000	2,800,000	100,000
Total costs and expenses										1,246,800,000	1,152,800,000	1,737,800,000
Operating (loss) income		40,000,000	39,800,000	11,400,000	59,500,000	45,300,000	29,800,000	57,900,000	44,800,000	150,700,000	177,800,000	(345,900,000)
Interest expense										(22,200,000)	(20,300,000)	(24,100,000)
Other (expense) income:
Other income, net										4,500,000	(10,300,000)	(1,800,000)
(Loss) income before income taxes										133,000,000	147,200,000	(371,800,000)
Income tax provision										(87,600,000)	(55,500,000)	135,200,000
Earnings in equity of subsidiaries										0	0	0
Net income (loss)		(15,200,000)	$ 19,900,000	$ 4,700,000	36,000,000	24,500,000	$ 14,900,000	$ 26,000,000	26,300,000	45,400,000	91,700,000	(236,600,000)
Comprehensive (loss) income										45,400,000	86,700,000	(172,200,000)
Cash flows from operating activities:
Net cash (used in) provided by operating activities										141,500,000	165,600,000	159,700,000
Cash flows from investing activities:
Capital expenditures										(75,500,000)	(76,100,000)	(63,100,000)
Purchase of available for sale securities										(247,500,000)	(255,300,000)	(500,000)
Proceeds from disposition of available for sale securities										296,900,000	55,000,000	84,000,000
Proceeds from disposal of property, plant and equipment										600,000	0	0
Intercompany loans receivable										0	0
Net cash (used in) provided by investing activities	[1]									(25,500,000)	(276,400,000)	20,400,000
Repayment of principal and redemption premium of 8.25% Senior Notes										0	(206,000,000)	(30,000,000)
Issuance of 5.875% Senior Notes										0	375,000,000	0
Repayment of Convertible Notes										0	0	(175,000,000)
Proceeds from cash-settled call options related to settlement of Convertible Notes										0	0	94,900,000
Payment for conversion premium related to settlement of Convertible Notes										0	0	(94,900,000)
Cash paid for debt issuance costs										0	(6,800,000)	(600,000)
Proceeds from stock option exercises										0	1,200,000	0
Repayment of capital lease										400,000	0	0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest										0	0	1,300,000
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares										(4,500,000)	(2,900,000)	(2,800,000)
Repurchase of common stock										(79,500,000)	(33,300,000)	(49,200,000)
Cash dividends and dividend equivalents paid										(35,000,000)	(32,400,000)	(28,100,000)
Cash dividends paid to Parent											0
Intercompany loans payable										0	0	0
Net cash (used in) provided by financing activities	[1]									(119,400,000)	94,800,000	(284,400,000)
Net decrease in cash, cash equivalents and restricted cash during the period										(3,400,000)	(16,000,000)	(104,300,000)
Cash, cash equivalents and restricted cash at beginning of period					67,700,000				83,700,000	67,700,000	83,700,000	188,000,000
Cash, cash equivalents and restricted cash at end of period		64,300,000				67,700,000				64,300,000	67,700,000	83,700,000
Consolidating Adjustments
Current assets:
Cash and cash equivalents		0				0				0	0
Short-term investments		0				0				0	0
Receivables:
Trade, less allowance for doubtful receivables		0				0				0	0
Intercompany receivables		(23,600,000)				(86,500,000)				(23,600,000)	(86,500,000)
Other		0				0				0	0
Inventories		0				(3,900,000)				0	(3,900,000)
Prepaid expenses and other current assets		0				(500,000)				0	(500,000)
Total current assets		(23,600,000)				(90,900,000)				(23,600,000)	(90,900,000)
Investments in and advances to unconsolidated affiliates		(1,145,900,000)				(1,052,500,000)				(1,145,900,000)	(1,052,500,000)
Property, plant and equipment, net		0				0				0	0
Long-term intercompany receivables		(12,400,000)				(85,100,000)				(12,400,000)	(85,100,000)
Deferred tax assets — net		4,700,000				4,800,000				4,700,000	4,800,000
Intangible assets, net		0				0				0	0
Goodwill		0				0				0	0
Other assets		0				0				0	0
Total		(1,177,200,000)				(1,223,700,000)				(1,177,200,000)	(1,223,700,000)
Current liabilities:
Accounts payable		0				0				0	0
Intercompany payable		(23,600,000)				(86,500,000)				(23,600,000)	(86,500,000)
Accrued salaries, wages and related expenses		0				0				0	0
Other accrued liabilities		(9,500,000)				(14,700,000)				(9,500,000)	(14,700,000)
Total current liabilities		(33,100,000)				(101,200,000)				(33,100,000)	(101,200,000)
Net liabilities of Salaried VEBA		0				0				0	0
Deferred tax liabilities		0				0				0	0
Long-term intercompany payable		(12,400,000)				(85,100,000)				(12,400,000)	(85,100,000)
Long-term liabilities		0				0				0	0
Long-term debt		0				0				0	0
Total liabilities		(45,500,000)				(186,300,000)				(45,500,000)	(186,300,000)
Total stockholders’ equity		(1,131,700,000)				(1,037,400,000)				(1,131,700,000)	(1,037,400,000)
Total		(1,177,200,000)				(1,223,700,000)				(1,177,200,000)	(1,223,700,000)
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales										(83,500,000)	(74,400,000)	(93,000,000)
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items										(81,300,000)	(71,100,000)	(88,600,000)
Lower of cost or market inventory write-down											0	0
Unrealized (gain) loss on derivative instruments										0	0	0
Depreciation and amortization										0	0	0
Selling, general, administrative, research and development										(2,200,000)	(2,600,000)	(2,000,000)
Net periodic postretirement benefit cost relating to Salaried VEBA										0	0	0
(Gain) loss on removal of Union VEBA net assets – Note 4											0	0
Total selling, administrative, research and development and general										(2,200,000)	(2,600,000)	(2,000,000)
Goodwill impairment										0
Other operating charges, net										0	0	0
Total costs and expenses										(83,500,000)	(73,700,000)	(90,600,000)
Operating (loss) income										0	(700,000)	(2,400,000)
Interest expense										200,000	100,000	300,000
Other (expense) income:
Other income, net										(200,000)	(100,000)	(300,000)
(Loss) income before income taxes										0	(700,000)	(2,400,000)
Income tax provision										9,500,000	14,100,000	11,400,000
Earnings in equity of subsidiaries										(74,900,000)	(130,300,000)	205,400,000
Net income (loss)										(65,400,000)	(116,900,000)	214,400,000
Comprehensive (loss) income										(65,400,000)	(111,900,000)	150,000,000
Cash flows from operating activities:
Net cash (used in) provided by operating activities										0	(200,000,000)	0
Cash flows from investing activities:
Capital expenditures										0	0	0
Purchase of available for sale securities										0	0	0
Proceeds from disposition of available for sale securities										0	0	0
Proceeds from disposal of property, plant and equipment										0
Intercompany loans receivable										(135,600,000)	56,900,000
Net cash (used in) provided by investing activities										(135,600,000)	56,900,000	0
Repayment of principal and redemption premium of 8.25% Senior Notes											0	0
Issuance of 5.875% Senior Notes											0
Repayment of Convertible Notes												0
Proceeds from cash-settled call options related to settlement of Convertible Notes												0
Payment for conversion premium related to settlement of Convertible Notes												0
Cash paid for debt issuance costs											0	0
Proceeds from stock option exercises											0
Repayment of capital lease										0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest												0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares										0	0	0
Repurchase of common stock										0	0	0
Cash dividends and dividend equivalents paid										0	0	0
Cash dividends paid to Parent											200,000,000
Intercompany loans payable										135,600,000	(56,900,000)	0
Net cash (used in) provided by financing activities										135,600,000	143,100,000	0
Net decrease in cash, cash equivalents and restricted cash during the period										0	0	0
Cash, cash equivalents and restricted cash at beginning of period					0				0	0	0	0
Cash, cash equivalents and restricted cash at end of period		0				0				0	0	0
Parent Company [Member]
Current assets:
Cash and cash equivalents		0				0				0	0
Short-term investments		0				0				0	0
Receivables:
Trade, less allowance for doubtful receivables		0				0				0	0
Intercompany receivables		22,800,000				85,800,000				22,800,000	85,800,000
Other		0				0				0	0
Inventories		0				0				0	0
Prepaid expenses and other current assets		100,000				100,000				100,000	100,000
Total current assets		22,900,000				85,900,000				22,900,000	85,900,000
Investments in and advances to unconsolidated affiliates		1,097,700,000				1,012,400,000				1,097,700,000	1,012,400,000
Property, plant and equipment, net		0				0				0	0
Long-term intercompany receivables		0				80,200,000				0	80,200,000
Deferred tax assets — net		0				0				0	0
Intangible assets, net		0				0				0	0
Goodwill		0				0				0	0
Other assets		0				0				0	0
Total		1,120,600,000				1,178,500,000				1,120,600,000	1,178,500,000
Current liabilities:
Accounts payable		1,900,000				2,200,000				1,900,000	2,200,000
Intercompany payable		0				0				0	0
Accrued salaries, wages and related expenses		0				0				0	0
Other accrued liabilities		2,800,000				2,900,000				2,800,000	2,900,000
Total current liabilities		4,700,000				5,100,000				4,700,000	5,100,000
Net liabilities of Salaried VEBA		0				0				0	0
Deferred tax liabilities		0				0				0	0
Long-term intercompany payable		0				0				0	0
Long-term liabilities		0				0				0	0
Long-term debt		369,600,000				368,700,000				369,600,000	368,700,000
Total liabilities		374,300,000				373,800,000				374,300,000	373,800,000
Total stockholders’ equity		746,300,000				804,700,000				746,300,000	804,700,000
Total		1,120,600,000				1,178,500,000				1,120,600,000	1,178,500,000
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales										0	0	0
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items										0	0	0
Lower of cost or market inventory write-down											0	0
Unrealized (gain) loss on derivative instruments										0	0	0
Depreciation and amortization										0	0	0
Selling, general, administrative, research and development										4,500,000	4,200,000	4,300,000
Net periodic postretirement benefit cost relating to Salaried VEBA										0	0	0
(Gain) loss on removal of Union VEBA net assets – Note 4											0	0
Total selling, administrative, research and development and general										4,500,000	4,200,000	4,300,000
Goodwill impairment										0
Other operating charges, net										0	0	0
Total costs and expenses										4,500,000	4,200,000	4,300,000
Operating (loss) income										(4,500,000)	(4,200,000)	(4,300,000)
Interest expense										(20,700,000)	(21,600,000)	(23,500,000)
Other (expense) income:
Other income, net										0	(11,100,000)	(2,500,000)
(Loss) income before income taxes										(25,200,000)	(36,900,000)	(30,300,000)
Income tax provision										0	0	0
Earnings in equity of subsidiaries										70,600,000	128,600,000	(206,300,000)
Net income (loss)										45,400,000	91,700,000	(236,600,000)
Comprehensive (loss) income										45,400,000	86,700,000	(172,200,000)
Cash flows from operating activities:
Net cash (used in) provided by operating activities										(24,200,000)	177,700,000	285,700,000
Cash flows from investing activities:
Capital expenditures										0	0	0
Purchase of available for sale securities										0	0	0
Proceeds from disposition of available for sale securities										0	0	0
Proceeds from disposal of property, plant and equipment										0
Intercompany loans receivable										143,200,000	(166,000,000)
Net cash (used in) provided by investing activities										143,200,000	(166,000,000)	0
Repayment of principal and redemption premium of 8.25% Senior Notes											(206,000,000)	(30,000,000)
Issuance of 5.875% Senior Notes											375,000,000
Repayment of Convertible Notes												(175,000,000)
Proceeds from cash-settled call options related to settlement of Convertible Notes												94,900,000
Payment for conversion premium related to settlement of Convertible Notes												(94,900,000)
Cash paid for debt issuance costs											(6,800,000)	(600,000)
Proceeds from stock option exercises											1,200,000
Repayment of capital lease										0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest												0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares										(4,500,000)	(2,900,000)	(2,800,000)
Repurchase of common stock										(79,500,000)	(33,300,000)	(49,200,000)
Cash dividends and dividend equivalents paid										(35,000,000)	(32,400,000)	(28,100,000)
Cash dividends paid to Parent											0
Intercompany loans payable										0	(106,500,000)	0
Net cash (used in) provided by financing activities										(119,000,000)	(11,700,000)	(285,700,000)
Net decrease in cash, cash equivalents and restricted cash during the period										0	0	0
Cash, cash equivalents and restricted cash at beginning of period					0				0	0	0	0
Cash, cash equivalents and restricted cash at end of period		0				0				0	0	0
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents		48,400,000				52,900,000				48,400,000	52,900,000
Short-term investments		183,700,000				231,000,000				183,700,000	231,000,000
Receivables:
Trade, less allowance for doubtful receivables		160,100,000				133,100,000				160,100,000	133,100,000
Intercompany receivables		100,000				100,000				100,000	100,000
Other		14,700,000				11,400,000				14,700,000	11,400,000
Inventories		198,700,000				197,500,000				198,700,000	197,500,000
Prepaid expenses and other current assets		32,900,000				18,000,000				32,900,000	18,000,000
Total current assets		638,600,000				644,000,000				638,600,000	644,000,000
Investments in and advances to unconsolidated affiliates		48,200,000				40,100,000				48,200,000	40,100,000
Property, plant and equipment, net		541,200,000				499,500,000				541,200,000	499,500,000
Long-term intercompany receivables		0				0				0	0
Deferred tax assets — net		67,300,000				154,900,000				67,300,000	154,900,000
Intangible assets, net		25,000,000				26,400,000				25,000,000	26,400,000
Goodwill		18,800,000				37,200,000				18,800,000	37,200,000
Other assets		41,400,000				33,400,000				41,400,000	33,400,000
Total		1,380,500,000				1,435,500,000				1,380,500,000	1,435,500,000
Current liabilities:
Accounts payable		81,400,000				68,900,000				81,400,000	68,900,000
Intercompany payable		23,500,000				86,400,000				23,500,000	86,400,000
Accrued salaries, wages and related expenses		41,000,000				47,200,000				41,000,000	47,200,000
Other accrued liabilities		46,200,000				52,600,000				46,200,000	52,600,000
Total current liabilities		192,100,000				255,100,000				192,100,000	255,100,000
Net liabilities of Salaried VEBA		31,900,000				28,600,000				31,900,000	28,600,000
Deferred tax liabilities		0				0				0	0
Long-term intercompany payable		12,400,000				85,100,000				12,400,000	85,100,000
Long-term liabilities		58,000,000				70,500,000				58,000,000	70,500,000
Long-term debt		0				0				0	0
Total liabilities		294,400,000				439,300,000				294,400,000	439,300,000
Total stockholders’ equity		1,086,100,000				996,200,000				1,086,100,000	996,200,000
Total		1,380,500,000				1,435,500,000				1,380,500,000	1,435,500,000
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales										1,365,300,000	1,301,600,000	1,361,600,000
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items										1,085,500,000	1,000,600,000	1,095,600,000
Lower of cost or market inventory write-down											4,900,000	2,600,000
Unrealized (gain) loss on derivative instruments										(19,400,000)	(18,700,000)	3,400,000
Depreciation and amortization										37,500,000	34,000,000	31,300,000
Selling, general, administrative, research and development										88,300,000	95,000,000	76,500,000
Net periodic postretirement benefit cost relating to Salaried VEBA										4,500,000	3,400,000	2,400,000
(Gain) loss on removal of Union VEBA net assets – Note 4											(100,000)	493,400,000
Total selling, administrative, research and development and general										92,800,000	98,300,000	572,300,000
Goodwill impairment										18,400,000
Other operating charges, net										800,000	2,800,000	100,000
Total costs and expenses										1,215,600,000	1,121,900,000	1,705,300,000
Operating (loss) income										149,700,000	179,700,000	(343,700,000)
Interest expense										(1,700,000)	1,200,000	(900,000)
Other (expense) income:
Other income, net										4,000,000	900,000	3,500,000
(Loss) income before income taxes										152,000,000	181,800,000	(341,100,000)
Income tax provision										(95,200,000)	(69,000,000)	122,500,000
Earnings in equity of subsidiaries										4,300,000	1,700,000	900,000
Net income (loss)										61,100,000	114,500,000	(217,700,000)
Comprehensive (loss) income										61,100,000	109,800,000	(153,500,000)
Cash flows from operating activities:
Net cash (used in) provided by operating activities										156,900,000	178,700,000	(126,300,000)
Cash flows from investing activities:
Capital expenditures										(74,700,000)	(74,000,000)	(47,900,000)
Purchase of available for sale securities										(247,500,000)	(255,300,000)	(500,000)
Proceeds from disposition of available for sale securities										296,900,000	55,000,000	84,000,000
Proceeds from disposal of property, plant and equipment										600,000
Intercompany loans receivable										0	110,400,000
Net cash (used in) provided by investing activities										(24,700,000)	(163,900,000)	35,600,000
Repayment of principal and redemption premium of 8.25% Senior Notes											0	0
Issuance of 5.875% Senior Notes											0
Repayment of Convertible Notes												0
Proceeds from cash-settled call options related to settlement of Convertible Notes												0
Payment for conversion premium related to settlement of Convertible Notes												0
Cash paid for debt issuance costs											0	0
Proceeds from stock option exercises											0
Repayment of capital lease										400,000
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest												1,300,000
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares										0	0	0
Repurchase of common stock										0	0	0
Cash dividends and dividend equivalents paid										0	0	0
Cash dividends paid to Parent											(200,000,000)
Intercompany loans payable										(135,600,000)	167,300,000	(12,800,000)
Net cash (used in) provided by financing activities										(136,000,000)	(32,700,000)	(11,500,000)
Net decrease in cash, cash equivalents and restricted cash during the period										(3,800,000)	(17,900,000)	(102,200,000)
Cash, cash equivalents and restricted cash at beginning of period					65,100,000				83,000,000	65,100,000	83,000,000	185,200,000
Cash, cash equivalents and restricted cash at end of period		61,300,000				65,100,000				61,300,000	65,100,000	83,000,000
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents		2,700,000				2,300,000				2,700,000	2,300,000
Short-term investments		0				0				0	0
Receivables:
Trade, less allowance for doubtful receivables		4,900,000				4,600,000				4,900,000	4,600,000
Intercompany receivables		700,000				600,000				700,000	600,000
Other		800,000				500,000				800,000	500,000
Inventories		9,200,000				8,000,000				9,200,000	8,000,000
Prepaid expenses and other current assets		400,000				900,000				400,000	900,000
Total current assets		18,700,000				16,900,000				18,700,000	16,900,000
Investments in and advances to unconsolidated affiliates		0				0				0	0
Property, plant and equipment, net		30,200,000				31,400,000				30,200,000	31,400,000
Long-term intercompany receivables		12,400,000				4,900,000				12,400,000	4,900,000
Deferred tax assets — net		0				0				0	0
Intangible assets, net		0				0				0	0
Goodwill		0				0				0	0
Other assets		0				0				0	0
Total		61,300,000				53,200,000				61,300,000	53,200,000
Current liabilities:
Accounts payable		6,700,000				4,700,000				6,700,000	4,700,000
Intercompany payable		100,000				100,000				100,000	100,000
Accrued salaries, wages and related expenses		1,600,000				1,900,000				1,600,000	1,900,000
Other accrued liabilities		1,000,000				(700,000)				1,000,000	(700,000)
Total current liabilities		9,400,000				6,000,000				9,400,000	6,000,000
Net liabilities of Salaried VEBA		0				0				0	0
Deferred tax liabilities		4,300,000				3,300,000				4,300,000	3,300,000
Long-term intercompany payable		0				0				0	0
Long-term liabilities		2,000,000				2,700,000				2,000,000	2,700,000
Long-term debt		0				0				0	0
Total liabilities		15,700,000				12,000,000				15,700,000	12,000,000
Total stockholders’ equity		45,600,000				41,200,000				45,600,000	41,200,000
Total		61,300,000				53,200,000				61,300,000	53,200,000
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales										115,700,000	103,400,000	123,300,000
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items										101,100,000	90,000,000	108,400,000
Lower of cost or market inventory write-down											0	0
Unrealized (gain) loss on derivative instruments										0	0	0
Depreciation and amortization										2,200,000	2,000,000	1,100,000
Selling, general, administrative, research and development										6,900,000	8,400,000	9,300,000
Net periodic postretirement benefit cost relating to Salaried VEBA										0	0	0
(Gain) loss on removal of Union VEBA net assets – Note 4											0	0
Total selling, administrative, research and development and general										6,900,000	8,400,000	9,300,000
Goodwill impairment										0
Other operating charges, net										0	0	0
Total costs and expenses										110,200,000	100,400,000	118,800,000
Operating (loss) income										5,500,000	3,000,000	4,500,000
Interest expense										0	0	0
Other (expense) income:
Other income, net										700,000	0	(2,500,000)
(Loss) income before income taxes										6,200,000	3,000,000	2,000,000
Income tax provision										(1,900,000)	(600,000)	1,300,000
Earnings in equity of subsidiaries										0	0	0
Net income (loss)										4,300,000	2,400,000	3,300,000
Comprehensive (loss) income										4,300,000	2,100,000	3,500,000
Cash flows from operating activities:
Net cash (used in) provided by operating activities										8,800,000	9,200,000	300,000
Cash flows from investing activities:
Capital expenditures										(800,000)	(2,100,000)	(15,200,000)
Purchase of available for sale securities										0	0	0
Proceeds from disposition of available for sale securities										0	0	0
Proceeds from disposal of property, plant and equipment										0
Intercompany loans receivable										(7,600,000)	(1,300,000)
Net cash (used in) provided by investing activities										(8,400,000)	(3,400,000)	(15,200,000)
Repayment of principal and redemption premium of 8.25% Senior Notes											0	0
Issuance of 5.875% Senior Notes											0
Repayment of Convertible Notes												0
Proceeds from cash-settled call options related to settlement of Convertible Notes												0
Payment for conversion premium related to settlement of Convertible Notes												0
Cash paid for debt issuance costs											0	0
Proceeds from stock option exercises											0
Repayment of capital lease										0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest												0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares										0	0	0
Repurchase of common stock										0	0	0
Cash dividends and dividend equivalents paid										0	0	0
Cash dividends paid to Parent											0
Intercompany loans payable										0	(3,900,000)	12,800,000
Net cash (used in) provided by financing activities										0	(3,900,000)	12,800,000
Net decrease in cash, cash equivalents and restricted cash during the period										400,000	1,900,000	(2,100,000)
Cash, cash equivalents and restricted cash at beginning of period					$ 2,600,000				$ 700,000	2,600,000	700,000	2,800,000
Cash, cash equivalents and restricted cash at end of period		$ 3,000,000				$ 2,600,000				$ 3,000,000	$ 2,600,000	$ 700,000
Senior Notes | Senior Notes Due 2024
Condensed Financial Statements [Line Items]
Principal amount of notes														$ 375,000,000
Debt Instrument, Interest Rate, Stated Percentage														5.875%
Senior Notes | Senior Notes Due 2020
Condensed Financial Statements [Line Items]
Principal amount of notes																$ 225,000,000
Debt Instrument, Interest Rate, Stated Percentage																8.25%
Current liabilities:
Long-term debt													$ 197,800,000
[1]	See Note 14 for supplemental disclosure on non-cash transactions.

Quarterly Financial Data (Detai

Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill impairment									$ 18.4	$ 0	$ 0
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)	$ (37.2)
Net sales	353.1	$ 332.8	$ 356.3	$ 355.3	$ 331.9	$ 320.6	$ 334.9	$ 343.2	1,397.5	1,330.6	1,391.9
Cost of products sold, excluding depreciation and amortization and other items	282.6	267.2	277.7	277.8	252.4	254.7	250.4	262	1,105.3	1,019.5	1,115.4
Lower of cost or market inventory write-down					0	0	0	4.9	0	4.9	2.6
Unrealized (gain) loss on derivative instruments	(5.4)	(10.8)	11.9	(15.1)	(1.8)	(2)	(10.9)	(4)	(19.4)	(18.7)	3.4
Gross Profit	75.9	76.4	66.7	92.6	81.3	67.9	95.4	80.3
Operating income	40	39.8	11.4	59.5	45.3	29.8	57.9	44.8	150.7	177.8	(345.9)
Net income (loss)	$ (15.2)	$ 19.9	$ 4.7	$ 36	$ 24.5	$ 14.9	$ 26	$ 26.3	$ 45.4	$ 91.7	$ (236.6)
Net income (loss) per common share:
Basic (in dollars per share)	$ (0.90)	$ 1.18	$ 0.28	$ 2.07	$ 1.39	$ 0.84	$ 1.45	$ 1.47	$ 2.67	$ 5.15	$ (13.76)
Net Income (loss) per common share, Diluted:
Diluted (in dollars per share)	(0.90)	1.16	0.27	2.04	1.37	0.82	1.43	1.44	2.63	5.09	(13.76)
Dividends declared per common share (in dollars per share)	$ 0.50	$ 0.50	$ 0.50	$ 0.50	$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 2	$ 1.8	$ 1.6
Fabricated Products
Goodwill impairment			$ (18.4)						$ (18.4)
Net sales									1,397.5	$ 1,330.6	$ 1,391.9
Operating income									$ 201.3	$ 229.6	$ 190.8

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 16, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Dividends declared per common share (in dollars per share)		$ 0.50	$ 0.50	$ 0.50	$ 0.50	$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 2	$ 1.8	$ 1.6
Subsequent Event
Subsequent Event [Line Items]
Dividends declared per common share (in dollars per share)	$ 0.55
Dividends	$ 9.3