Kaiser Aluminum (KALU) 10-Q 21 Apr 20 2020 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2020	Apr. 13, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	1-09447
Entity Registrant Name	KAISER ALUMINUM CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3030279
Entity Address, Address Line One	27422 Portola Parkway
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Foothill Ranch
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92610-2831
City Area Code	(949)
Local Phone Number	614-1740
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	KALU
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		15,789,594
Entity Central Index Key	0000811596
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 307.2	$ 264.3
Short-term investments	39.3	78.7
Receivables:
Trade receivables, net	175.2	167.1
Other	22.6	18.1
Contract assets	47.1	54.6
Inventories	194.6	177.6
Prepaid expenses and other current assets	20.4	19.4
Total current assets	806.4	779.8
Property, plant and equipment, net	630.9	622
Operating lease assets	28.8	25.8
Deferred tax assets, net	2	11.8
Intangible assets, net	28.9	29.6
Goodwill	18.8	18.8
Other assets	37.3	38.4
Total	1,553.1	1,526.2
Current liabilities:
Accounts payable	113.9	92
Accrued salaries, wages and related expenses	28.3	34.4
Other accrued liabilities	56.9	44
Total current liabilities	199.1	170.4
Long-term portion of operating lease liabilities	27.8	25.2
Net liabilities of Salaried VEBA	32.5	32.6
Deferred tax liabilities	4.5	4.5
Long-term liabilities	75.3	67
Long-term debt	492.8	492.6
Total liabilities	832	792.3
Commitments and contingencies
Stockholders' equity:
Preferred stock, 5,000,000 shares authorized at both March 31, 2020 and December 31, 2019; no shares were issued and outstanding at March 31, 2020 and December 31, 2019	0	0
Common stock, par value $0.01, 90,000,000 shares authorized at both March 31, 2020 and at December 31, 2019; 22,624,880 shares issued and 15,789,594 shares outstanding at March 31, 2020; 22,550,827 shares issued and 15,868,304 shares outstanding at December 31, 2019	0.2	0.2
Additional paid in capital	1,060.3	1,062.9
Retained earnings	190.6	172.8
Treasury stock, at cost, 6,835,286 shares at March 31, 2020 and 6,682,523 shares at December 31, 2019, respectively	(475.9)	(463.4)
Accumulated other comprehensive loss	(54.1)	(38.6)
Total stockholders' equity	721.1	733.9
Total	$ 1,553.1	$ 1,526.2

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Stockholders' equity:
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	90,000,000	90,000,000
Common Stock, shares issued	22,624,880	22,550,827
Common stock, shares outstanding	15,789,594	15,868,304
Treasury stock, shares	6,835,286	6,682,523

Statements of Consolidated Inco

Statements of Consolidated Income (Unaudited) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Net sales	$ 369.3	$ 395.2
Costs and expenses:
Cost of products sold, excluding depreciation and amortization and other items	286.6	315.1
Depreciation and amortization	13.2	11.9
Selling, general, administrative, research and development	23.9	25.2
Total costs and expenses	323.7	352.2
Operating income	45.6	43
Other (expense) income:
Interest expense	(6.1)	(5.7)
Other (expense) income, net	(0.8)	0.5
Income before income taxes	38.7	37.8
Income tax provision	(9.6)	(9.8)
Net income	$ 29.1	$ 28
Net income per common share:
Basic (in dollars per share)	$ 1.83	$ 1.74
Diluted (in dollars per share)	$ 1.81	$ 1.71
Weighted-average number of common shares outstanding:
Basic (shares)	15,838	16,108
Diluted (shares)	16,008	16,372

Statements of Consolidated Comp

Statements of Consolidated Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 29.1	$ 28
Other comprehensive (loss) income, net of tax:
Defined benefit pension plan and Salaried VEBA	1.1	1.1
Available for sale securities	(0.2)	(0.2)
Cash flow hedges	(15.9)	8.8
Fair value hedges	(0.5)	0
Other comprehensive (loss) income, net of tax	(15.5)	9.7
Comprehensive income	$ 13.6	$ 37.7

Statements of Consolidated Stoc

Statements of Consolidated Stockholders' Equity (Unaudited) - USD ($) $ in Millions		Total	Common Stock	Additional Paid in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Beginning balance (shares) at Dec. 31, 2018			16,234,603
Beginning balance at Dec. 31, 2018		$ 740.4	$ 0.2	$ 1,059.3	$ 150.2	$ (420.5)	$ (48.8)
Stockholders' Equity [Roll Forward]
Net income		28			28
Other comprehensive income (loss), net of tax		9.7					9.7
Issuance of common shares to employees upon vesting of restricted stock units and performance shares (shares)			122,309
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (shares)			(46,388)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		(5)		(5)
Repurchase of common stock (shares)	[1]		(175,977)
Repurchase of common stock2	[1]	(17.4)				(17.4)
Cash dividends declared3	[2]	(10.2)			(10.2)
Amortization of unearned equity compensation		2.4		2.4
Ending balance (shares) at Mar. 31, 2019			16,134,547
Ending balance at Mar. 31, 2019		$ 747.9	$ 0.2	1,056.7	168	(437.9)	(39.1)
Beginning balance (shares) at Dec. 31, 2019		15,868,304	15,868,304
Beginning balance at Dec. 31, 2019		$ 733.9	$ 0.2	1,062.9	172.8	(463.4)	(38.6)
Stockholders' Equity [Roll Forward]
Net income		29.1			29.1
Other comprehensive income (loss), net of tax		(15.5)					(15.5)
Issuance of common shares to employees upon vesting of restricted stock units and performance shares (shares)			119,598
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (shares)			(45,545)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		(4.3)		(4.3)
Repurchase of common stock (shares)	[3]		(152,763)
Repurchase of common stock2	[3]	(12.5)				(12.5)
Cash dividends declared3	[4]	(11.3)			(11.3)
Amortization of unearned equity compensation		$ 1.7		1.7
Ending balance (shares) at Mar. 31, 2020		15,789,594	15,789,594
Ending balance at Mar. 31, 2020		$ 721.1	$ 0.2	$ 1,060.3	$ 190.6	$ (475.9)	$ (54.1)
[1]	Weighted-average repurchase price (dollars per share) for the quarter ended March 31, 2019 was $98.55 .
[2]	Dividends declared per common share were $0.60 for the quarter ended March 31, 2019 .
[3]	Weighted-average repurchase price (dollars per share) for the quarter ended March 31, 2020 was $81.94 . At March 31, 2020 , $93.1 million remained available to repurchase our common shares pursuant to the stock repurchase program.
[4]	Dividends declared per common share was $0.67 for the quarter ended March 31, 2020 .

Statements of Consolidated St_2

Statements of Consolidated Stockholders' Equity (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Shares available for awards (shares)	380,201
Weighted average repurchase price (in dollars per share)	$ 81.94	$ 98.55
Repurchase amount remaining	$ 93.1
Cash dividends declared (in dollars per share)	$ 0.67	$ 0.60

Statement of Consolidated Cash

Statement of Consolidated Cash Flows (Unaudited) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income		$ 29.1	$ 28
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property, plant and equipment		12.5	11.2
Amortization of definite-lived intangible assets		0.7	0.7
Amortization of debt discount and debt issuance costs		0.3	0.3
Deferred income taxes		14.8	10.4
Non-cash equity compensation		1.7	2.4
Gain on disposition of short-term investments		(0.5)	(0.3)
Loss on disposition of property, plant and equipment		0.2	0
Other non-cash changes in assets and liabilities		1.8	3.6
Changes in operating assets and liabilities:
Trade and other receivables		(12.6)	(12.8)
Contract assets		7.5	(3.5)
Inventories		(17)	(18.8)
Prepaid expenses and other current assets		(2.8)	(3.4)
Accounts payable		21.7	7.4
Accrued liabilities		(2.3)	(0.4)
Annual variable cash contributions to Salaried VEBA		(2.9)	(2.1)
Long-term assets and liabilities, net		0.2	0.1
Net cash provided by operating activities	[1]	52.4	22.8
Cash flows from investing activities
Capital expenditures		(21.1)	(13.6)
Purchase of short-term investments		(39.1)	(18.1)
Proceeds from disposition of short-term investments		78.8	32.7
Net cash provided by investing activities	[1]	18.6	1
Cash flows from financing activities
Repayment of finance lease		(0.4)	(0.3)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		(4.3)	(5)
Repurchase of common stock		(12.5)	(18.5)
Cash dividends and dividend equivalents paid		(11.3)	(10.2)
Net cash used in financing activities	[1]	(28.5)	(34)
Net increase (decrease) in cash, cash equivalents and restricted cash during the period		42.5	(10.2)
Cash, cash equivalents and restricted cash at beginning of period		278.6	139.6
Cash, cash equivalents and restricted cash at end of period		$ 321.1	$ 129.4
[1]	See Note 12 for supplemental cash flow information.

Basis of Presentation and Recen

Basis of Presentation and Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation and Recent Accounting Pronouncements	This Quarterly Report on Form 10-Q (this "Report") should be read in conjunction with the Company's Annual Report on Form 10-K for the year ended December 31, 2019 . Unless the context otherwise requires, references in these notes to interim consolidated financial statements - unaudited to "Kaiser Aluminum Corporation," "we," "us," "our," "the Company" and "our Company" refer collectively to Kaiser Aluminum Corporation and its subsidiaries. Principles of Consolidation and Basis of Presentation. The accompanying unaudited 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") applicable for interim periods and, therefore, do not include all information and footnotes required by GAAP for complete financial statements. In management's opinion, all adjustments (which include normal recurring adjustments) considered necessary for a fair presentation have been included. The results of operations for our interim periods are not necessarily indicative of the results of operations that may be achieved for the entire 2020 fiscal year. The financial information as of December 31, 2019 is derived from our audited consolidated financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2019 . 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. Adoption of New Accounting Pronouncements Accounting Standards Update ("ASU") No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"), was issued in June 2016. Under ASU 2016-13, existing guidance on reporting credit losses for trade and other receivables and available for sale debt securities have been replaced with a new forward-looking "expected loss" model that has resulted in the earlier recognition of allowances for losses. Our adoption of ASU 2016-13 during the quarter ended March 31, 2020 using the modified retrospective transition approach did not result in a material impact on our consolidated financial statements. As part of our assessment of the adequacy of our allowances for credit losses, we consider a number of factors including, but not limited to, customer credit ratings, bankruptcy filings, published or estimated credit default rates, age of receivables, expected loss rates and collateral exposures. ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract ("ASU 2018-15"), was issued in August 2018. Under ASU 2018-15, requirements for capitalizing implementation costs incurred in a hosting arrangement (cloud computing) that is a service contract are to be aligned with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. Our adoption of ASU 2018-15 during the quarter ended March 31, 2020 using the prospective transition approach did not result in a material impact on our consolidated financial statements. Accounting Pronouncements Issued But Not Yet Adopted ASU No. 2019-12, Simplifying the Accounting for Income Taxes ("ASU 2019-12"), was issued in December 2019. Under ASU 2019-12, the accounting for income taxes is simplified by eliminating certain exceptions and implementing additional requirements which result in a more consistent application of ASC 740 Income Taxes . We are currently in the process of evaluating the impact of adopting ASU 2019-12 in 2021, but do not expect it to have a material impact on our consolidated financial statements.

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Balance Sheet Information	Supplemental Balance Sheet Information March 31, 2020 December 31, 2019 (In millions of dollars) Cash and Cash Equivalents Cash and money market funds $ 199.6 $ 28.2 Commercial paper 107.6 236.1 Total $ 307.2 $ 264.3 Trade Receivables, Net Billed trade receivables $ 176.6 $ 168.5 Allowance for doubtful receivables (1.4 ) (1.4 ) Trade receivables, net $ 175.2 $ 167.1 Inventories 1 Finished products $ 43.1 $ 42.6 Work-in-process 89.8 63.5 Raw materials 55.2 65.0 Operating supplies 6.5 6.5 Total $ 194.6 $ 177.6 Property, Plant and Equipment, Net Land and improvements $ 20.8 $ 21.4 Buildings and leasehold improvements 106.8 104.5 Machinery and equipment 821.0 813.5 Construction in progress 44.0 33.2 Property, plant and equipment, gross 992.6 972.6 Accumulated depreciation (364.0 ) (352.2 ) Assets held for sale 2.3 1.6 Property, plant and equipment, net $ 630.9 $ 622.0 Other Accrued Liabilities Uncleared cash disbursements $ 5.7 $ 4.2 Accrued income taxes and taxes payable 10.3 6.2 Accrued annual contribution to Salaried VEBA — 2.9 Accrued interest 2.0 2.3 Short-term environmental accrual – Note 7 4.7 5.5 Other – Note 3 and Note 5 34.2 22.9 Total $ 56.9 $ 44.0 March 31, 2020 December 31, 2019 (In millions of dollars) Long-Term Liabilities Workers' compensation accrual 2 $ 28.5 $ 27.7 Long-term environmental accrual – Note 7 12.3 11.5 Other long-term liabilities 34.5 27.8 Total $ 75.3 $ 67.0 ____________________ 1 At March 31, 2020 and December 31, 2019 , the current cost of our inventory exceeded its stated LIFO value by $1.9 million and $11.9 million , respectively. 2 Our workers' compensation accrual was estimated using a discount rate of 1.00% and 1.75% at March 31, 2020 and December 31, 2019 , respectively. The undiscounted workers' compensation liabilities were estimated at $29.0 million and $29.2 million as of March 31, 2020 and December 31, 2019 , respectively.

Leases

Leases	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Leases	Leases We determine whether an agreement is a lease at inception. We have operating and finance leases for equipment and real estate that primarily have fixed lease payments. Our leases have remaining lease terms of approximately one to 13 years , some of which may include options to extend the lease for up to 20 years , and some of which may include options to terminate the lease within one year . None of our options to extend or terminate are reasonably certain of being exercised, and are therefore not included in our determination of lease assets and liabilities. Short-term leases with an initial term of 12 months or less are not recorded on our Consolidated Balance Sheets. As most of our leases do not provide an implicit rate, we use information available at the lease commencement date in determining an incremental borrowing rate when calculating our operating lease assets and operating lease liabilities. In determining the inputs to the incremental borrowing rate calculation, we make judgments about the value of the leased asset, our credit rating and the lease term, including the probability of our exercising options to extend or terminate the underlying lease. Additionally, we make judgments around contractual asset substitution rights in determining whether a contract contains a lease. We have lease agreements with lease and non-lease components, which are generally accounted for separately. These non-lease components include items such as common area maintenance, taxes and insurance for our real estate leases, as well as maintenance charges related to our equipment leases. We have, however, applied the practical expedient within ASU 2016-02 to not separate lease and non-lease components to our embedded supply system equipment leases and have therefore accounted for both lease and non-lease components in determining the lease assets and liabilities. Many of our equipment leases contain clauses that require us to return the equipment with certain functionality intact. We account for these costs as residual value guarantees when the guarantee becomes probable of being owed. Our lease agreements do not contain any material restrictive covenants. The following table presents lease terms and discount rates as of March 31, 2020 : Finance Leases Operating Leases Weighted-average lease term (in years) 5.7 9.7 Weighted-average discount rate 4.5 % 5.6 % The following table summarizes the classification of lease assets and lease liabilities on our Consolidated Balance Sheet as of the periods presented (in millions of dollars): Leases Classification March 31, 2020 December 31, 2019 Assets Operating lease assets Operating lease assets $ 28.8 $ 25.8 Finance lease assets Property, plant and equipment, net 6.3 6.6 Total lease assets $ 35.1 $ 32.4 Liabilities Current: Operating lease liabilities Other accrued liabilities $ 4.5 $ 3.9 Finance lease liabilities Other accrued liabilities 1.2 1.2 Non-current: Operating lease liabilities Long-term portion of operating lease liabilities 27.8 25.2 Finance lease liabilities Long-term liabilities 5.1 5.4 Total lease liabilities $ 38.6 $ 35.7 The following table summarizes the components of lease cost on our Statements of Consolidated Income for the periods presented (in millions of dollars): Quarter Ended March 31, Lease Cost 2020 2019 Operating lease cost $ 1.8 $ 2.0 Short-term lease cost 0.3 0.3 Finance lease cost: Amortization of leased assets 0.4 0.4 Interest on lease liabilities 0.1 0.1 Total lease cost $ 2.6 $ 2.8 The following table presents the maturity of our lease liabilities as of March 31, 2020 (in millions of dollars): Maturity of Lease Liabilities Finance Leases Operating Leases Remainder of 2020 $ 1.2 $ 4.7 2021 1.4 5.5 2022 1.3 4.7 2023 1.2 4.3 2024 0.6 4.1 2025 0.6 2.2 2026 and thereafter 0.7 16.9 Total minimum lease payments $ 7.0 $ 42.4 Less: interest (0.7 ) (10.1 ) Present value $ 6.3 $ 32.3
Leases	Leases We determine whether an agreement is a lease at inception. We have operating and finance leases for equipment and real estate that primarily have fixed lease payments. Our leases have remaining lease terms of approximately one to 13 years , some of which may include options to extend the lease for up to 20 years , and some of which may include options to terminate the lease within one year . None of our options to extend or terminate are reasonably certain of being exercised, and are therefore not included in our determination of lease assets and liabilities. Short-term leases with an initial term of 12 months or less are not recorded on our Consolidated Balance Sheets. As most of our leases do not provide an implicit rate, we use information available at the lease commencement date in determining an incremental borrowing rate when calculating our operating lease assets and operating lease liabilities. In determining the inputs to the incremental borrowing rate calculation, we make judgments about the value of the leased asset, our credit rating and the lease term, including the probability of our exercising options to extend or terminate the underlying lease. Additionally, we make judgments around contractual asset substitution rights in determining whether a contract contains a lease. We have lease agreements with lease and non-lease components, which are generally accounted for separately. These non-lease components include items such as common area maintenance, taxes and insurance for our real estate leases, as well as maintenance charges related to our equipment leases. We have, however, applied the practical expedient within ASU 2016-02 to not separate lease and non-lease components to our embedded supply system equipment leases and have therefore accounted for both lease and non-lease components in determining the lease assets and liabilities. Many of our equipment leases contain clauses that require us to return the equipment with certain functionality intact. We account for these costs as residual value guarantees when the guarantee becomes probable of being owed. Our lease agreements do not contain any material restrictive covenants. The following table presents lease terms and discount rates as of March 31, 2020 : Finance Leases Operating Leases Weighted-average lease term (in years) 5.7 9.7 Weighted-average discount rate 4.5 % 5.6 % The following table summarizes the classification of lease assets and lease liabilities on our Consolidated Balance Sheet as of the periods presented (in millions of dollars): Leases Classification March 31, 2020 December 31, 2019 Assets Operating lease assets Operating lease assets $ 28.8 $ 25.8 Finance lease assets Property, plant and equipment, net 6.3 6.6 Total lease assets $ 35.1 $ 32.4 Liabilities Current: Operating lease liabilities Other accrued liabilities $ 4.5 $ 3.9 Finance lease liabilities Other accrued liabilities 1.2 1.2 Non-current: Operating lease liabilities Long-term portion of operating lease liabilities 27.8 25.2 Finance lease liabilities Long-term liabilities 5.1 5.4 Total lease liabilities $ 38.6 $ 35.7 The following table summarizes the components of lease cost on our Statements of Consolidated Income for the periods presented (in millions of dollars): Quarter Ended March 31, Lease Cost 2020 2019 Operating lease cost $ 1.8 $ 2.0 Short-term lease cost 0.3 0.3 Finance lease cost: Amortization of leased assets 0.4 0.4 Interest on lease liabilities 0.1 0.1 Total lease cost $ 2.6 $ 2.8 The following table presents the maturity of our lease liabilities as of March 31, 2020 (in millions of dollars): Maturity of Lease Liabilities Finance Leases Operating Leases Remainder of 2020 $ 1.2 $ 4.7 2021 1.4 5.5 2022 1.3 4.7 2023 1.2 4.3 2024 0.6 4.1 2025 0.6 2.2 2026 and thereafter 0.7 16.9 Total minimum lease payments $ 7.0 $ 42.4 Less: interest (0.7 ) (10.1 ) Present value $ 6.3 $ 32.3

Employee Benefits

Employee Benefits	3 Months Ended
	Mar. 31, 2020
Retirement Benefits [Abstract]
Employee Benefits	Employee Benefits 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. Most of our production facilities have similar programs for both hourly and salaried employees. As of March 31, 2020 , we had a liability of $3.7 million recorded within Accrued salaries, wages and related expenses for estimated probable future payments relating to the three month performance period of our 2020 STI Plan. Pension and Similar Benefit Plans. We provide contributions to: (i) defined contribution 401(k) savings plans for salaried employees and certain hourly employees; (ii) a non-qualified, unfunded, unsecured plan of deferred compensation (see " Deferred Compensation Plan " below); (iii) multi-employer pension plans sponsored by the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union, AFL-CIO, CLC, the International Association of Machinists and certain other unions at certain of our production facilities; and (iv) a defined benefit pension plan for salaried employees at our London, Ontario (Canada) facility. Deferred Compensation Plan . We have a non-qualified, unfunded, unsecured plan of deferred compensation for certain 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. 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 held in various investment funds at certain registered investment companies and are accounted for as equity investments with changes in fair value recorded within Other (expense) income, net (see Note 9 ). Assets of our deferred compensation plan are included in Other assets, classified within Level 2 of the fair value hierarchy and are measured and recorded at fair value based on their quoted market prices. The fair value of these assets at March 31, 2020 and December 31, 2019 was $7.6 million and $8.1 million , respectively. Offsetting liabilities relating to the deferred compensation plan are included in Other accrued liabilities and Long-term liabilities. 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"). We have an ongoing obligation with no express termination date to make annual variable cash contributions up to a maximum of $2.9 million to the Salaried VEBA. We paid $2.9 million with respect to 2019 during the quarter ended March 31, 2020. We account for the Salaried VEBA as a defined benefit plan in our financial statements. The following table presents the total (benefit) expense related to all postretirement benefit plans for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Defined contribution plans 1 $ 3.9 $ 3.9 Deferred compensation plan 1 (0.4 ) 0.7 Multiemployer pension plans 1 1.3 1.2 Net periodic postretirement benefit cost relating to Salaried VEBA 2 1.2 1.7 Total $ 6.0 $ 7.5 ____________________ 1 Substantially all of the expense related to employee benefits are in Cost of products sold, excluding depreciation and amortization and other items ("COGS") with the remaining balance in Selling, general, administrative, research and development ("SG&A and R&D"). 2 The current service cost component of Net periodic postretirement benefit cost relating to Salaried VEBA is included within our Statements of Consolidated Income in SG&A and R&D for all periods presented. All other components of Net periodic postretirement benefit cost relating to Salaried VEBA are included within Other (expense) income, net, on our Statements of Consolidated Income. Components of Net Periodic Benefit Cost. Our results of operations included the following impacts associated with our Canadian pension plan and the Salaried VEBA: (i) a charge for service rendered by employees; (ii) a charge for accretion of interest; (iii) a benefit for the expected return on plan assets; (iv) amortization of prior service costs associated with plan amendments; and (v) amortization of net actuarial differences. Net periodic benefit cost related to our Canadian pension plan was not material for the quarters ended March 31, 2020 and March 31, 2019 . The following table presents the components of Net periodic postretirement benefit cost relating to Salaried VEBA for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Salaried VEBA 1 : Interest cost $ 0.6 $ 0.8 Expected return on plan assets (0.7 ) (0.6 ) Amortization of prior service cost 2 1.2 1.4 Amortization of net actuarial loss 0.1 0.1 Total net periodic postretirement benefit cost relating to Salaried VEBA $ 1.2 $ 1.7 ____________________ 1 The service cost 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.

Derivatives, Hedging Programs a

Derivatives, Hedging Programs and Other Financial Instruments	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives, Hedging Programs and Other Financial Instruments	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 cash commitments for equipment purchases denominated in foreign currency. 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 allow for increased responsiveness to changes in market factors. Our derivative activities are overseen by a committee ("Hedging Committee"), which is composed of our chief executive officer, chief operating officer, chief financial officer, chief accounting officer, vice president of metal management, 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 $29.2 million and $7.2 million at March 31, 2020 and December 31, 2019 , respectively, 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. Cash collateral posted from our customers was $2.1 million at March 31, 2020 and $0.2 million at December 31, 2019 . Cash Flow Hedges We designate our aluminum and energy derivatives and our forward swap contracts for zinc and copper ("Alloying Metals") used in our fabrication operations as cash flow hedges. Unrealized gains and losses associated with our cash flow hedges are deferred in Other comprehensive (loss) income, net of tax, and reclassified to COGS when such hedges settle. See Note 8 for the total amount of gain or loss on derivative instruments designated and qualifying as cash flow hedging instruments and fair value hedging instruments that was reported in Accumulated other comprehensive loss ("AOCI"), as well as the related reclassifications into earnings and tax effects. Cumulative gains and losses related to cash flow hedges are reclassified out of AOCI and recorded within COGS when the associated hedged commodity purchases impact earnings. Aluminum Hedges . 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. Alloying Metals Hedges . We are exposed to risk of fluctuating prices for Alloying Metals used as raw materials in our fabrication operations. We, from time to time, in the ordinary course of business, use third-party hedging instruments to mitigate our risk from price fluctuations in Alloying Metals. Energy Hedges . 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. Fair Value Hedges We are exposed to foreign currency exchange risk related to firm-price commitments for equipment purchases from foreign manufacturers. We, from time to time, in the ordinary course of business, use third-party hedging instruments to mitigate our exposure to currency exchange rate fluctuations on these purchases, and designate such hedging instruments as fair value hedges. Gain or loss related to components excluded from the assessment of effectiveness from these fair value hedges is first recognized in AOCI and subsequently reclassified to Depreciation and amortization on a straight-line basis over the term of the hedge. Gain or loss on the hedged item (e.g., equipment purchase firm commitments) and the remaining gain or loss on the fair value hedge is recorded within Depreciation and amortization in the period that the gain or loss occurs. Any difference between the change in the fair value of the excluded component and amounts recognized in income under that systematic and rational method is recognized in AOCI. Notional Amount of Derivative Contracts The following table summarizes our derivative positions at March 31, 2020 : Aluminum Maturity Period (month/year) Notional Amount of Contracts (mmlbs) Fixed price purchase contracts 4/20 through 12/22 115.3 Fixed price sales contracts 4/20 through 11/21 0.8 Midwest premium swap contracts 1 4/20 through 12/22 110.4 Alloying Metals Maturity Period (month/year) Notional Amount of Contracts (mmlbs) Fixed price purchase contracts 4/20 through 12/21 16.9 Natural Gas 2 Maturity Period (month/year) Notional Amount of Contracts (mmbtu) Fixed price purchase contracts 4/20 through 12/24 7,970,000 Electricity 3 Maturity Period (month/year) Notional Amount of Contracts (Mwh) Fixed price purchase contracts 4/20 through 12/22 613,820 Euro Maturity Period (month/year) Notional Amount of Contracts (euro) Fixed price forward contracts 2/21 through 5/22 34,323,380 ____________________ 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 March 31, 2020 , we had derivative and/or physical delivery commitments with energy companies in place to cover exposure to fluctuations in prices for approximately 75% of the expected natural gas purchases for the remainder of 2020 , 76% of the expected natural gas purchases for 2021 , 80% of the expected natural gas purchases for both 2022 and 2023 and 75% of the expected natural gas purchases for 2024 . 3 As of March 31, 2020 , we had derivative and/or physical delivery commitments with energy companies in place to cover exposure to fluctuations in prices for approximately 55% of our expected electricity purchases for both the remainder of 2020 and 2021 and 46% of our expected electricity purchases for 2022 . Loss (Gain) The amount of loss (gain) included on our Statements of Consolidated Income associated with all derivative contracts consisted of the following for the periods presented (in millions of dollars): Quarter Ended 2020 2019 Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded $ 286.6 $ 315.1 Loss (gain) recognized in income related to cash flow hedges: Aluminum 5.7 4.2 Alloying metals 0.6 0.1 Natural gas 0.5 (0.1 ) Electricity 0.2 — Total loss recognized in income related to cash flow hedges $ 7.0 $ 4.2 Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of fair value hedges are recorded $ 13.2 $ 11.9 Loss (gain) recognized in income related to fair value hedges: Foreign exchange contracts 0.2 — Hedged item (0.2 ) — Excluded component amortized from AOCI to income 0.2 — Total loss recognized in income related to fair value hedges $ 0.2 $ — 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. All of our derivative contracts with counterparties are subject to enforceable master netting arrangements. We reflect the fair value of our derivative contracts on a gross basis on our Consolidated Balance Sheets. The following table presents the fair value of our derivative financial instruments as of the periods presented (in millions of dollars): March 31, 2020 December 31, 2019 Derivative Assets Derivative Liabilities Net Amount Derivative Assets Derivative Liabilities Net Amount Cash Flow Hedges: Aluminum – Fixed price purchase contracts $ — $ (14.2 ) $ (14.2 ) $ 1.0 $ (4.1 ) $ (3.1 ) Fixed price sales contracts 0.1 — 0.1 — — — Midwest premium swap contracts — (4.3 ) (4.3 ) — (1.2 ) (1.2 ) Alloying Metals – Fixed price purchase contracts — (5.5 ) (5.5 ) 0.4 (1.5 ) (1.1 ) Natural gas – Fixed price purchase contracts 0.1 (3.0 ) (2.9 ) — (2.8 ) (2.8 ) Electricity – Fixed price purchase contracts 1.6 (2.8 ) (1.2 ) 2.6 (1.6 ) 1.0 March 31, 2020 December 31, 2019 Derivative Assets Derivative Liabilities Net Amount Derivative Assets Derivative Liabilities Net Amount Fair Value Hedges: Foreign currency – Fixed price forward contracts — (1.0 ) (1.0 ) — — — Total $ 1.8 $ (30.8 ) $ (29.0 ) $ 4.0 $ (11.2 ) $ (7.2 ) The following table presents the total amounts of derivative assets and liabilities on our Consolidated Balance Sheets as of the periods presented (in millions of dollars): March 31, 2020 December 31, 2019 Derivative assets: Prepaid expenses and other current assets $ 0.6 $ 2.1 Other assets 1.2 1.9 Total derivative assets $ 1.8 $ 4.0 Derivative liabilities: Other accrued liabilities $ (19.0 ) $ (7.6 ) Long-term liabilities (11.8 ) (3.6 ) Total derivative liabilities $ (30.8 ) $ (11.2 ) Fair Value of Other Financial Instruments Cash and Cash Equivalents. See Note 2 for components of cash and cash equivalents. Available for Sale Securities. We hold debt investment securities that are accounted for as available for sale securities and are presented as cash equivalents and short-term investments on our Consolidated Balance Sheets. The fair value of the debt investment securities, which consist of commercial paper, is determined based on valuation models that use observable market data. All of our short-term investments generally have maturity dates under 12 months , however, due to market conditions existing as of March 31, 2020 , all short-term investments had maturity dates of less than 90 days. We review our debt investment portfolio for credit loss at least quarterly or when there are changes in credit risk or other potential valuation concerns. At March 31, 2020 and December 31, 2019 , the total unrealized loss, net of tax, included in AOCI was immaterial. 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. The following table classifies our other financial assets under the appropriate level of the fair value hierarchy as of March 31, 2020 (in millions of dollars): Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 199.6 $ 107.6 $ — $ 307.2 Short-term investments — 39.3 — 39.3 Total $ 199.6 $ 146.9 $ — $ 346.5 The following table classifies our other financial assets under the appropriate level of the fair value hierarchy as of December 31, 2019 (in millions of dollars): Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 28.2 $ 236.1 $ — $ 264.3 Short-term investments — 78.7 — 78.7 Total $ 28.2 $ 314.8 $ — $ 343.0 All Other Financial Assets and Liabilities.

Debt and Credit Facility

Debt and Credit Facility	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Debt and Credit Facility	Debt and Credit Facility Senior Notes 4.625% Senior Notes. In November 2019, we issued $500.0 million principal amount of 4.625% unsecured senior notes due March 1, 2028 (" 4.625% Senior Notes") at 100% of the principal amount. The unamortized amount of debt issuance costs as of March 31, 2020 was $7.2 million . Interest expense, including amortization of debt issuance costs, relating to the 4.625% Senior Notes was $6.0 million for the quarter ended March 31, 2020 , of which $0.3 million was capitalized as construction in progress. The effective interest rate of the 4.625% Senior Notes was approximately 4.8% per annum, taking into account the amortization of debt issuance costs. The fair value of the outstanding 4.625% Senior Notes, which are Level 1 liabilities, was approximately $438.1 million and $513.5 million at March 31, 2020 and December 31, 2019 , respectively. 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. On December 18, 2019, we redeemed in full all outstanding 5.875% Senior Notes at a redemption price of 104.406% of the principal amount. The effective interest rate of the 5.875% Senior Notes was approximately 6.1% per annum, taking into account the amortization of debt issuance costs. Interest expense, including amortization of debt issuance costs, relating to the 5.875% Senior Notes was $5.7 million for the quarter ended March 31, 2019 net of $0.5 million capitalized as construction in progress. Revolving Credit Facility Our credit agreement with Wells Fargo Bank, National Association, as administrative agent, and the other financial institutions party thereto ("Revolving Credit Facility") provides us with a $375.0 million funding commitment through October 2024. The table below summarizes availability and usage of our Revolving Credit Facility as determined by a borrowing base calculated as of March 31, 2020 (in millions of dollars except for borrowing rate): Revolving Credit Facility borrowing commitment $ 375.0 Borrowing base availability $ 349.2 Less: Outstanding borrowings under Revolving Credit Facility — Less: Outstanding letters of credit under Revolving Credit Facility (7.7 ) Remaining borrowing availability $ 341.5 Borrowing rate (if applicable) 1 3.50 % ____________________ 1 Such borrowing rate, if applicable, represents the interest rate for any overnight borrowings under the Revolving Credit Facility.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
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 5 and Note 6 ). 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 prior to July 6, 2006, 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 Spokane, Washington ("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 an experimental treatment facility and began treatment operations in 2016. As the long-term 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 and cost estimates as the long-term results become available. During 2013, at the request of the Ohio Environmental Protection Agency ("OEPA"), we initiated an investigational study of the Newark, Ohio ("Newark") facility related to historical on-site waste disposal. In the fourth quarter of 2018, we submitted our remedial investigation study to the OEPA, which is subject to their review and approval. Following OEPA approval of the remedial investigational study, we will then prepare the final feasibility study 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 six to 12 months . During 2020, following issuance of information requests under the Comprehensive Environmental Response, Compensation and Liability Act of 1980 ("CERCLA"), to which we responded, United States Environmental Protection Agency ("USEPA") issued a general notice letter to us alleging that we are a potentially responsible party under CERCLA for response and other potential remedial actions concerning property owned by us near our former smelter site in Mead, Spokane County, Washington. On February 21, 2020, we responded to the General Notice letter and are in early discussions with USEPA regarding potential resolution of the matter. At March 31, 2020 , our environmental accrual of $17.0 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, 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 $11.6 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	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The following table presents the changes in the accumulated balances for each component of AOCI for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Defined Benefit Pension Plan and Salaried VEBA: Beginning balance $ (33.2 ) $ (35.6 ) Amortization of net actuarial loss 1 0.1 0.1 Amortization of prior service cost 1 1.2 1.4 Less: income tax expense 2 (0.3 ) (0.4 ) Net amortization reclassified from AOCI to Net income 1.0 1.1 Other comprehensive income, net of tax 1.1 1.1 Ending balance $ (32.1 ) $ (34.5 ) Available for Sale Securities: Beginning balance $ 0.3 $ 0.3 Unrealized gain on available for sale securities 1.3 1.0 Less: income tax expense (0.3 ) (0.3 ) Net unrealized gain on available for sale securities 1.0 0.7 Reclassification of unrealized gain upon sale of available for sale securities 3 (1.5 ) (1.2 ) Less: income tax benefit 2 0.3 0.3 Net gain reclassified from AOCI to Net income (1.2 ) (0.9 ) Other comprehensive loss, net of tax (0.2 ) (0.2 ) Ending balance $ 0.1 $ 0.1 Quarter Ended March 31, 2020 2019 Cash Flow Hedges: Beginning balance $ (5.6 ) $ (13.4 ) Unrealized (loss) gain on cash flow hedges (27.9 ) 7.4 Less: income tax benefit (expense) 6.8 (1.8 ) Net unrealized (loss) gain on cash flow hedges (21.1 ) 5.6 Reclassification of unrealized loss upon settlement of cash flow hedges 4 7.0 4.2 Less: income tax expense 2 (1.8 ) (1.0 ) Net loss reclassified from AOCI to Net income 5.2 3.2 Other comprehensive (loss) income, net of tax (15.9 ) 8.8 Ending balance $ (21.5 ) $ (4.6 ) Fair Value Hedges: Beginning balance $ — $ — Unrealized loss on fair value hedges (0.8 ) — Less: income tax benefit 0.2 — Net unrealized loss on fair value hedges (0.6 ) — Excluded component amortized from OCI to Net income 5 0.2 — Less: income tax expense 2 (0.1 ) — Net loss reclassified from AOCI to Net income 0.1 — Other comprehensive loss, net of tax (0.5 ) — Ending balance $ (0.5 ) $ — Foreign Currency Translation: Beginning balance $ (0.1 ) $ (0.1 ) Other comprehensive income, net of tax — — Ending balance $ (0.1 ) $ (0.1 ) Total AOCI ending balance $ (54.1 ) $ (39.1 ) ____________________ 1 Amounts amortized out of AOCI relating to Salaried VEBA adjustments were included within Other (expense) income, net, 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. 3 Amounts reclassified out of AOCI relating to sales of available for sale securities were included as a component of Other (expense) income, net. We use the specific identification method to determine the amount reclassified out of AOCI. 4 Amounts reclassified out of AOCI relating to cash flow hedges were included as a component of COGS. As of March 31, 2020 , we estimate a net mark-to-market loss before tax of $18.1 million in AOCI will be reclassified into Net income within the next 12 months. 5 Amounts reclassified out of AOCI relating to fair value hedges were included as a component of depreciation expense. As of March 31, 2020 , we estimate a net mark-to-market loss before tax of $0.6 million in AOCI will be reclassified into Net income within the next 12 months.

Other (Expense) Income, Net

Other (Expense) Income, Net	3 Months Ended
	Mar. 31, 2020
Other Income and Expenses [Abstract]
Other (Expense) Income, Net	Other (Expense) Income, Net Other (expense) income, net, consisted of the following for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Interest income $ 0.1 $ 0.2 Net periodic postretirement benefit cost relating to Salaried VEBA (1.2 ) (1.6 ) Realized gain on available for sale securities 1.5 1.2 Unrealized (loss) gain on equity securities (0.6 ) 0.5 All other (expense) income, net (0.6 ) 0.2 Other (expense) income, net $ (0.8 ) $ 0.5

Income Tax Matters

Income Tax Matters	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Tax Matters	Income Tax Matters The provision for in come taxes consisted of the following for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Domestic $ 9.5 $ 9.5 Foreign 0.1 0.3 Total $ 9.6 $ 9.8 The income tax provision for the quarters ended March 31, 2020 and March 31, 2019 was $9.6 million and $9.8 million , respectively, reflecting an effective tax rate of 25% and 26% , respectively. There was no material difference between the effective tax rate and the projected blended statutory tax rate for the quarter ended March 31, 2020 . The difference between the effective tax rate and the projected blended statutory tax rate for the quarter ended March 31, 2019 was primarily due to: (i) an increase of $0.4 million ( 1% of taxable income) related to non-deductible compensation expense and (ii) an increase of $0.7 million ( 2% of taxable income) related to the valuation allowance for certain state net operating losses, partially offset by a decrease of $0.5 million ( 1% of taxable income) for the recognition of excess tax benefits from stock-based compensation. Our gross unrecognized benefits relating to uncertain tax positions were $3.9 million and $4.1 million at March 31, 2020 and December 31, 2019 , respectively, of which, $0.4 million and $0.9 million would be recorded through our income tax provision and thus impact the effective tax rate at March 31, 2020 and December 31, 2019 , respectively, if the gross unrecognized tax benefits were to be recognized. We do not expect our gross unrecognized tax benefits to significantly change within the next 12 months . On March 27, 2020, Congress enacted the Coronavirus Aid, Relief and Economic Security ("CARES") Act to provide certain relief as a result of the Coronavirus Disease 2019 outbreak. We are currently evaluating how provisions in the CARES Act will impact our consolidated financial statements.

Net Income Per Share

Net Income Per Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Net Income per Share	Net Income Per Share Basic net income per share is computed by dividing distributed and undistributed net income allocable to common shares by the weighted-average number of common shares outstanding during the applicable period. The basic weighted-average number of common shares outstanding during the period excludes non-vested share-based payment awards. Diluted net income per share was calculated under the treasury stock method for the quarters ended March 31, 2020 and March 31, 2019 , which in both periods was more dilutive than the two-class method. The following table sets forth the computation of basic and diluted net income per share for the periods presented (in millions of dollars, except share and per share amounts): Quarter Ended March 31, 2020 2019 Numerator: Net income $ 29.1 $ 28.0 Denominator – Weighted-average common shares outstanding (in thousands): Basic 15,838 16,108 Add: dilutive effect of non-vested common shares, restricted stock units and performance shares 1 170 264 Diluted 16,008 16,372 Net income per common share, Basic: $ 1.83 $ 1.74 Net income per common share, Diluted: $ 1.81 $ 1.71 ____________________ 1 During the quarters ended March 31, 2020 and March 31, 2019 , a total of two thousand and four thousand shares, respectively, were excluded from the weighted-average diluted shares computation as their inclusion would have been anti-dilutive.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	3 Months Ended
	Mar. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Quarter Ended March 31, 2020 2019 (In millions of dollars) Interest paid $ 6.1 $ 0.3 Non-cash investing and financing activities (included in Accounts payable): Unpaid purchases of property and equipment $ 4.7 $ 4.7 Stock repurchases not yet settled $ — $ 0.2 Supplemental lease disclosures: Operating lease liabilities arising from obtaining operating lease assets $ 4.2 $ 0.5 Cash paid for amounts included in the measurement of operating lease liabilities $ 1.1 $ 0.9 Finance lease liabilities arising from obtaining finance lease assets $ 0.1 $ — March 31, 2020 March 31, 2019 (In millions of dollars) Components of cash, cash equivalents and restricted cash: Cash and cash equivalents $ 307.2 $ 115.3 Restricted cash included in Prepaid expenses and other current assets 1 — 0.3 Restricted cash included in Other assets 1 13.9 13.8 Total cash, cash equivalents and restricted cash presented on our Statements of Consolidated Cash Flows $ 321.1 $ 129.4 ____________________ 1

Business, Product and Geographi

Business, Product and Geographical Area Information	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Business, Product and Geographical Area Information	Business, Product and Geographical Area Information Our primary line of business is the production of semi-fabricated specialty aluminum mill products, such as aluminum plate and sheet and extruded and drawn products, primarily used in aerospace and high strength ("Aero/HS products"), automotive ("Automotive Extrusions"), general engineering ("GE products") and other industrial ("Other products"). We operate 12 focused production facilities in the United States and one in Canada. Our chief operating decision maker reviews and evaluates our business as a single operating segment. The following table presents Net sales by end market applications and by timing of control transfer for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Net sales: Aero/HS products $ 196.0 $ 198.5 Automotive Extrusions 47.4 53.0 GE products 121.7 130.0 Other products 4.2 13.7 Total net sales $ 369.3 $ 395.2 Timing of revenue recognition: Products transferred at a point in time $ 215.6 $ 223.3 1 Products transferred over time 153.7 171.9 1 Total net sales $ 369.3 $ 395.2 __________________ 1. As corrected from $131.8 million of products transferred at a point in time and $263.4 million of products transferred over time. The following table presents geographic information for income taxes paid for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Income taxes paid: Domestic $ — $ 0.1 Foreign 0.1 0.8 Total income taxes paid $ 0.1 $ 0.9

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Dividend Declaration . On April 14, 2020 , we announced that our Board of Directors declared a cash dividend of $0.67 per common share. As such, we expect to pay approximately $10.7 million (including dividend equivalents) on or about May 15, 2020 to stockholders of record and the holders of certain restricted stock units at the close of business on April 24, 2020 .

Basis of Presentation and Rec_2

Basis of Presentation and Recent Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation. The accompanying unaudited 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") applicable for interim periods and, therefore, do not include all information and footnotes required by GAAP for complete financial statements. In management's opinion, all adjustments (which include normal recurring adjustments) considered necessary for a fair presentation have been included. The results of operations for our interim periods are not necessarily indicative of the results of operations that may be achieved for the entire 2020 fiscal year. The financial information as of December 31, 2019 is derived from our audited consolidated financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2019 .
Use of Estimates in the Preparation of Financial Statements	Use of Estimates in the Preparation of Financial Statements.
New Accounting Pronouncements	Adoption of New Accounting Pronouncements Accounting Standards Update ("ASU") No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"), was issued in June 2016. Under ASU 2016-13, existing guidance on reporting credit losses for trade and other receivables and available for sale debt securities have been replaced with a new forward-looking "expected loss" model that has resulted in the earlier recognition of allowances for losses. Our adoption of ASU 2016-13 during the quarter ended March 31, 2020 using the modified retrospective transition approach did not result in a material impact on our consolidated financial statements. As part of our assessment of the adequacy of our allowances for credit losses, we consider a number of factors including, but not limited to, customer credit ratings, bankruptcy filings, published or estimated credit default rates, age of receivables, expected loss rates and collateral exposures. ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract ("ASU 2018-15"), was issued in August 2018. Under ASU 2018-15, requirements for capitalizing implementation costs incurred in a hosting arrangement (cloud computing) that is a service contract are to be aligned with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. Our adoption of ASU 2018-15 during the quarter ended March 31, 2020 using the prospective transition approach did not result in a material impact on our consolidated financial statements. Accounting Pronouncements Issued But Not Yet Adopted ASU No. 2019-12, Simplifying the Accounting for Income Taxes ("ASU 2019-12"), was issued in December 2019. Under ASU 2019-12, the accounting for income taxes is simplified by eliminating certain exceptions and implementing additional requirements which result in a more consistent application of ASC 740 Income Taxes . We are currently in the process of evaluating the impact of adopting ASU 2019-12 in 2021, but do not expect it to have a material impact on our consolidated financial statements.
Leases	We determine whether an agreement is a lease at inception. We have operating and finance leases for equipment and real estate that primarily have fixed lease payments. Our leases have remaining lease terms of approximately one to 13 years , some of which may include options to extend the lease for up to 20 years , and some of which may include options to terminate the lease within one year . None of our options to extend or terminate are reasonably certain of being exercised, and are therefore not included in our determination of lease assets and liabilities. Short-term leases with an initial term of 12 months or less are not recorded on our Consolidated Balance Sheets. As most of our leases do not provide an implicit rate, we use information available at the lease commencement date in determining an incremental borrowing rate when calculating our operating lease assets and operating lease liabilities. In determining the inputs to the incremental borrowing rate calculation, we make judgments about the value of the leased asset, our credit rating and the lease term, including the probability of our exercising options to extend or terminate the underlying lease. Additionally, we make judgments around contractual asset substitution rights in determining whether a contract contains a lease. We have lease agreements with lease and non-lease components, which are generally accounted for separately. These non-lease components include items such as common area maintenance, taxes and insurance for our real estate leases, as well as maintenance charges related to our equipment leases. We have, however, applied the practical expedient within ASU 2016-02 to not separate lease and non-lease components to our embedded supply system equipment leases and have therefore accounted for both lease and non-lease components in determining the lease assets and liabilities. Many of our equipment leases contain clauses that require us to return the equipment with certain functionality intact. We account for these costs as residual value guarantees when the guarantee becomes probable of being owed. Our lease agreements do not contain any material restrictive covenants.

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Balance Sheet Disclosures	Supplemental Balance Sheet Information March 31, 2020 December 31, 2019 (In millions of dollars) Cash and Cash Equivalents Cash and money market funds $ 199.6 $ 28.2 Commercial paper 107.6 236.1 Total $ 307.2 $ 264.3 Trade Receivables, Net Billed trade receivables $ 176.6 $ 168.5 Allowance for doubtful receivables (1.4 ) (1.4 ) Trade receivables, net $ 175.2 $ 167.1 Inventories 1 Finished products $ 43.1 $ 42.6 Work-in-process 89.8 63.5 Raw materials 55.2 65.0 Operating supplies 6.5 6.5 Total $ 194.6 $ 177.6 Property, Plant and Equipment, Net Land and improvements $ 20.8 $ 21.4 Buildings and leasehold improvements 106.8 104.5 Machinery and equipment 821.0 813.5 Construction in progress 44.0 33.2 Property, plant and equipment, gross 992.6 972.6 Accumulated depreciation (364.0 ) (352.2 ) Assets held for sale 2.3 1.6 Property, plant and equipment, net $ 630.9 $ 622.0 Other Accrued Liabilities Uncleared cash disbursements $ 5.7 $ 4.2 Accrued income taxes and taxes payable 10.3 6.2 Accrued annual contribution to Salaried VEBA — 2.9 Accrued interest 2.0 2.3 Short-term environmental accrual – Note 7 4.7 5.5 Other – Note 3 and Note 5 34.2 22.9 Total $ 56.9 $ 44.0 March 31, 2020 December 31, 2019 (In millions of dollars) Long-Term Liabilities Workers' compensation accrual 2 $ 28.5 $ 27.7 Long-term environmental accrual – Note 7 12.3 11.5 Other long-term liabilities 34.5 27.8 Total $ 75.3 $ 67.0 ____________________ 1 At March 31, 2020 and December 31, 2019 , the current cost of our inventory exceeded its stated LIFO value by $1.9 million and $11.9 million , respectively. 2 Our workers' compensation accrual was estimated using a discount rate of 1.00% and 1.75% at March 31, 2020 and December 31, 2019 , respectively. The undiscounted workers' compensation liabilities were estimated at $29.0 million and $29.2 million as of March 31, 2020 and December 31, 2019 , respectively.

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Schedule of Lease Terms and Discount Rates	The following table presents lease terms and discount rates as of March 31, 2020 : Finance Leases Operating Leases Weighted-average lease term (in years) 5.7 9.7 Weighted-average discount rate 4.5 % 5.6 %
Schedule of Lease Assets and Liabilities	The following table summarizes the classification of lease assets and lease liabilities on our Consolidated Balance Sheet as of the periods presented (in millions of dollars): Leases Classification March 31, 2020 December 31, 2019 Assets Operating lease assets Operating lease assets $ 28.8 $ 25.8 Finance lease assets Property, plant and equipment, net 6.3 6.6 Total lease assets $ 35.1 $ 32.4 Liabilities Current: Operating lease liabilities Other accrued liabilities $ 4.5 $ 3.9 Finance lease liabilities Other accrued liabilities 1.2 1.2 Non-current: Operating lease liabilities Long-term portion of operating lease liabilities 27.8 25.2 Finance lease liabilities Long-term liabilities 5.1 5.4 Total lease liabilities $ 38.6 $ 35.7
Schedule of Lease Cost Classification	The following table summarizes the components of lease cost on our Statements of Consolidated Income for the periods presented (in millions of dollars): Quarter Ended March 31, Lease Cost 2020 2019 Operating lease cost $ 1.8 $ 2.0 Short-term lease cost 0.3 0.3 Finance lease cost: Amortization of leased assets 0.4 0.4 Interest on lease liabilities 0.1 0.1 Total lease cost $ 2.6 $ 2.8
Lease Liability Maturity Schedule	The following table presents the maturity of our lease liabilities as of March 31, 2020 (in millions of dollars): Maturity of Lease Liabilities Finance Leases Operating Leases Remainder of 2020 $ 1.2 $ 4.7 2021 1.4 5.5 2022 1.3 4.7 2023 1.2 4.3 2024 0.6 4.1 2025 0.6 2.2 2026 and thereafter 0.7 16.9 Total minimum lease payments $ 7.0 $ 42.4 Less: interest (0.7 ) (10.1 ) Present value $ 6.3 $ 32.3

Employee Benefits (Tables)

Employee Benefits (Tables)	3 Months Ended
	Mar. 31, 2020
Retirement Benefits [Abstract]
Schedule of Total Expense (Income) Related to Benefit Plans	The following table presents the total (benefit) expense related to all postretirement benefit plans for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Defined contribution plans 1 $ 3.9 $ 3.9 Deferred compensation plan 1 (0.4 ) 0.7 Multiemployer pension plans 1 1.3 1.2 Net periodic postretirement benefit cost relating to Salaried VEBA 2 1.2 1.7 Total $ 6.0 $ 7.5 ____________________ 1 Substantially all of the expense related to employee benefits are in Cost of products sold, excluding depreciation and amortization and other items ("COGS") with the remaining balance in Selling, general, administrative, research and development ("SG&A and R&D"). 2 The current service cost component of Net periodic postretirement benefit cost relating to Salaried VEBA is included within our Statements of Consolidated Income in SG&A and R&D for all periods presented. All other components of Net periodic postretirement benefit cost relating to Salaried VEBA are included within Other (expense) income, net, on our Statements of Consolidated Income.
Schedule of Net Benefit Costs	The following table presents the components of Net periodic postretirement benefit cost relating to Salaried VEBA for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Salaried VEBA 1 : Interest cost $ 0.6 $ 0.8 Expected return on plan assets (0.7 ) (0.6 ) Amortization of prior service cost 2 1.2 1.4 Amortization of net actuarial loss 0.1 0.1 Total net periodic postretirement benefit cost relating to Salaried VEBA $ 1.2 $ 1.7 ____________________ 1 The service cost 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.

Derivatives, Hedging Programs_2

Derivatives, Hedging Programs and Other Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of material derivative positions	The following table summarizes our derivative positions at March 31, 2020 : Aluminum Maturity Period (month/year) Notional Amount of Contracts (mmlbs) Fixed price purchase contracts 4/20 through 12/22 115.3 Fixed price sales contracts 4/20 through 11/21 0.8 Midwest premium swap contracts 1 4/20 through 12/22 110.4 Alloying Metals Maturity Period (month/year) Notional Amount of Contracts (mmlbs) Fixed price purchase contracts 4/20 through 12/21 16.9 Natural Gas 2 Maturity Period (month/year) Notional Amount of Contracts (mmbtu) Fixed price purchase contracts 4/20 through 12/24 7,970,000 Electricity 3 Maturity Period (month/year) Notional Amount of Contracts (Mwh) Fixed price purchase contracts 4/20 through 12/22 613,820 Euro Maturity Period (month/year) Notional Amount of Contracts (euro) Fixed price forward contracts 2/21 through 5/22 34,323,380 ____________________ 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 March 31, 2020 , we had derivative and/or physical delivery commitments with energy companies in place to cover exposure to fluctuations in prices for approximately 75% of the expected natural gas purchases for the remainder of 2020 , 76% of the expected natural gas purchases for 2021 , 80% of the expected natural gas purchases for both 2022 and 2023 and 75% of the expected natural gas purchases for 2024 . 3 As of March 31, 2020 , we had derivative and/or physical delivery commitments with energy companies in place to cover exposure to fluctuations in prices for approximately 55% of our expected electricity purchases for both the remainder of 2020 and 2021 and 46% of our expected electricity purchases for 2022 .
Summary of realized and unrealized gains and losses	The amount of loss (gain) included on our Statements of Consolidated Income associated with all derivative contracts consisted of the following for the periods presented (in millions of dollars): Quarter Ended 2020 2019 Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded $ 286.6 $ 315.1 Loss (gain) recognized in income related to cash flow hedges: Aluminum 5.7 4.2 Alloying metals 0.6 0.1 Natural gas 0.5 (0.1 ) Electricity 0.2 — Total loss recognized in income related to cash flow hedges $ 7.0 $ 4.2 Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of fair value hedges are recorded $ 13.2 $ 11.9 Loss (gain) recognized in income related to fair value hedges: Foreign exchange contracts 0.2 — Hedged item (0.2 ) — Excluded component amortized from AOCI to income 0.2 — Total loss recognized in income related to fair value hedges $ 0.2 $ —
Fair Value of Derivative Assets and Liabilities Measured on Recurring Basis	The following table presents the fair value of our derivative financial instruments as of the periods presented (in millions of dollars): March 31, 2020 December 31, 2019 Derivative Assets Derivative Liabilities Net Amount Derivative Assets Derivative Liabilities Net Amount Cash Flow Hedges: Aluminum – Fixed price purchase contracts $ — $ (14.2 ) $ (14.2 ) $ 1.0 $ (4.1 ) $ (3.1 ) Fixed price sales contracts 0.1 — 0.1 — — — Midwest premium swap contracts — (4.3 ) (4.3 ) — (1.2 ) (1.2 ) Alloying Metals – Fixed price purchase contracts — (5.5 ) (5.5 ) 0.4 (1.5 ) (1.1 ) Natural gas – Fixed price purchase contracts 0.1 (3.0 ) (2.9 ) — (2.8 ) (2.8 ) Electricity – Fixed price purchase contracts 1.6 (2.8 ) (1.2 ) 2.6 (1.6 ) 1.0 March 31, 2020 December 31, 2019 Derivative Assets Derivative Liabilities Net Amount Derivative Assets Derivative Liabilities Net Amount Fair Value Hedges: Foreign currency – Fixed price forward contracts — (1.0 ) (1.0 ) — — — Total $ 1.8 $ (30.8 ) $ (29.0 ) $ 4.0 $ (11.2 ) $ (7.2 ) The following table presents the total amounts of derivative assets and liabilities on our Consolidated Balance Sheets as of the periods presented (in millions of dollars): March 31, 2020 December 31, 2019 Derivative assets: Prepaid expenses and other current assets $ 0.6 $ 2.1 Other assets 1.2 1.9 Total derivative assets $ 1.8 $ 4.0 Derivative liabilities: Other accrued liabilities $ (19.0 ) $ (7.6 ) Long-term liabilities (11.8 ) (3.6 ) Total derivative liabilities $ (30.8 ) $ (11.2 )
Fair Value, Non-Derivative Assets Measured on Recurring Basis	The following table classifies our other financial assets under the appropriate level of the fair value hierarchy as of March 31, 2020 (in millions of dollars): Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 199.6 $ 107.6 $ — $ 307.2 Short-term investments — 39.3 — 39.3 Total $ 199.6 $ 146.9 $ — $ 346.5 The following table classifies our other financial assets under the appropriate level of the fair value hierarchy as of December 31, 2019 (in millions of dollars): Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 28.2 $ 236.1 $ — $ 264.3 Short-term investments — 78.7 — 78.7 Total $ 28.2 $ 314.8 $ — $ 343.0

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table presents the changes in the accumulated balances for each component of AOCI for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Defined Benefit Pension Plan and Salaried VEBA: Beginning balance $ (33.2 ) $ (35.6 ) Amortization of net actuarial loss 1 0.1 0.1 Amortization of prior service cost 1 1.2 1.4 Less: income tax expense 2 (0.3 ) (0.4 ) Net amortization reclassified from AOCI to Net income 1.0 1.1 Other comprehensive income, net of tax 1.1 1.1 Ending balance $ (32.1 ) $ (34.5 ) Available for Sale Securities: Beginning balance $ 0.3 $ 0.3 Unrealized gain on available for sale securities 1.3 1.0 Less: income tax expense (0.3 ) (0.3 ) Net unrealized gain on available for sale securities 1.0 0.7 Reclassification of unrealized gain upon sale of available for sale securities 3 (1.5 ) (1.2 ) Less: income tax benefit 2 0.3 0.3 Net gain reclassified from AOCI to Net income (1.2 ) (0.9 ) Other comprehensive loss, net of tax (0.2 ) (0.2 ) Ending balance $ 0.1 $ 0.1 Quarter Ended March 31, 2020 2019 Cash Flow Hedges: Beginning balance $ (5.6 ) $ (13.4 ) Unrealized (loss) gain on cash flow hedges (27.9 ) 7.4 Less: income tax benefit (expense) 6.8 (1.8 ) Net unrealized (loss) gain on cash flow hedges (21.1 ) 5.6 Reclassification of unrealized loss upon settlement of cash flow hedges 4 7.0 4.2 Less: income tax expense 2 (1.8 ) (1.0 ) Net loss reclassified from AOCI to Net income 5.2 3.2 Other comprehensive (loss) income, net of tax (15.9 ) 8.8 Ending balance $ (21.5 ) $ (4.6 ) Fair Value Hedges: Beginning balance $ — $ — Unrealized loss on fair value hedges (0.8 ) — Less: income tax benefit 0.2 — Net unrealized loss on fair value hedges (0.6 ) — Excluded component amortized from OCI to Net income 5 0.2 — Less: income tax expense 2 (0.1 ) — Net loss reclassified from AOCI to Net income 0.1 — Other comprehensive loss, net of tax (0.5 ) — Ending balance $ (0.5 ) $ — Foreign Currency Translation: Beginning balance $ (0.1 ) $ (0.1 ) Other comprehensive income, net of tax — — Ending balance $ (0.1 ) $ (0.1 ) Total AOCI ending balance $ (54.1 ) $ (39.1 ) ____________________ 1 Amounts amortized out of AOCI relating to Salaried VEBA adjustments were included within Other (expense) income, net, 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. 3 Amounts reclassified out of AOCI relating to sales of available for sale securities were included as a component of Other (expense) income, net. We use the specific identification method to determine the amount reclassified out of AOCI. 4 Amounts reclassified out of AOCI relating to cash flow hedges were included as a component of COGS. As of March 31, 2020 , we estimate a net mark-to-market loss before tax of $18.1 million in AOCI will be reclassified into Net income within the next 12 months. 5 Amounts reclassified out of AOCI relating to fair value hedges were included as a component of depreciation expense. As of March 31, 2020 , we estimate a net mark-to-market loss before tax of $0.6 million in AOCI will be reclassified into Net income within the next 12 months.

Other (Expense) Income, Net (Ta

Other (Expense) Income, Net (Tables)	3 Months Ended
	Mar. 31, 2020
Other Income and Expenses [Abstract]
Other (Expense) Income, Net	Other (expense) income, net, consisted of the following for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Interest income $ 0.1 $ 0.2 Net periodic postretirement benefit cost relating to Salaried VEBA (1.2 ) (1.6 ) Realized gain on available for sale securities 1.5 1.2 Unrealized (loss) gain on equity securities (0.6 ) 0.5 All other (expense) income, net (0.6 ) 0.2 Other (expense) income, net $ (0.8 ) $ 0.5

Income Tax Matters (Tables)

Income Tax Matters (Tables)	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Tax Provision	The provision for in come taxes consisted of the following for the periods presented (in millions of dollars): Quarter Ended March 31, 2020 2019 Domestic $ 9.5 $ 9.5 Foreign 0.1 0.3 Total $ 9.6 $ 9.8

Net Income Per Share (Tables)

Net Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Calculation of basic and diluted earnings per share	The following table sets forth the computation of basic and diluted net income per share for the periods presented (in millions of dollars, except share and per share amounts): Quarter Ended March 31, 2020 2019 Numerator: Net income $ 29.1 $ 28.0 Denominator – Weighted-average common shares outstanding (in thousands): Basic 15,838 16,108 Add: dilutive effect of non-vested common shares, restricted stock units and performance shares 1 170 264 Diluted 16,008 16,372 Net income per common share, Basic: $ 1.83 $ 1.74 Net income per common share, Diluted: $ 1.81 $ 1.71 ____________________ 1 During the quarters ended March 31, 2020 and March 31, 2019 , a total of two thousand and four thousand

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Quarter Ended March 31, 2020 2019 (In millions of dollars) Interest paid $ 6.1 $ 0.3 Non-cash investing and financing activities (included in Accounts payable): Unpaid purchases of property and equipment $ 4.7 $ 4.7 Stock repurchases not yet settled $ — $ 0.2 Supplemental lease disclosures: Operating lease liabilities arising from obtaining operating lease assets $ 4.2 $ 0.5 Cash paid for amounts included in the measurement of operating lease liabilities $ 1.1 $ 0.9 Finance lease liabilities arising from obtaining finance lease assets $ 0.1 $ — March 31, 2020 March 31, 2019 (In millions of dollars) Components of cash, cash equivalents and restricted cash: Cash and cash equivalents $ 307.2 $ 115.3 Restricted cash included in Prepaid expenses and other current assets 1 — 0.3 Restricted cash included in Other assets 1 13.9 13.8 Total cash, cash equivalents and restricted cash presented on our Statements of Consolidated Cash Flows $ 321.1 $ 129.4 ____________________ 1

Business, Product and Geograp_2

Business, Product and Geographical Area Information (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Schedule of net sales by end market segment applications	Quarter Ended March 31, 2020 2019 Net sales: Aero/HS products $ 196.0 $ 198.5 Automotive Extrusions 47.4 53.0 GE products 121.7 130.0 Other products 4.2 13.7 Total net sales $ 369.3 $ 395.2 Timing of revenue recognition: Products transferred at a point in time $ 215.6 $ 223.3 1 Products transferred over time 153.7 171.9 1 Total net sales $ 369.3 $ 395.2
Schedule of income taxes paid by geographical area	Quarter Ended March 31, 2020 2019 Income taxes paid: Domestic $ — $ 0.1 Foreign 0.1 0.8 Total income taxes paid $ 0.1 $ 0.9

Basis of Presentation and Rec_3

Basis of Presentation and Recent Accounting Pronouncements, Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Significant accounting policies
Operating lease assets	$ 28.8		$ 25.8
Operating lease liabilities, current	4.5		3.9
Excess of Replacement or Current Costs over Stated LIFO Value	1.9		11.9
Interest expense capitalized	0.3	$ 0.5
Workers compensation liability	$ 29		$ 29.2
Workers' Compensation Discount, Percent	1.00%		1.75%
Shares available for awards (shares)	380,201
Retained earnings	$ 190.6		$ 172.8
Long-term portion of operating lease liabilities	27.8		$ 25.2
Accrued salaries, wages and related expenses
Significant accounting policies
Accrued salaries, wages and related expenses	$ 3.7

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents
Cash and money market funds	$ 199.6	$ 28.2
Commercial paper	107.6	236.1
Total	307.2	264.3
Trade Receivables – Net
Allowance for doubtful receivables	(1.4)	(1.4)
Trade receivables – net	175.2	167.1
Inventories
Finished products	43.1	42.6
Work-in-process	89.8	63.5
Raw materials	55.2	65
Operating supplies	6.5	6.5
Total	194.6	177.6
Property, Plant and Equipment – Net
Land and improvements	20.8	21.4
Buildings and leasehold improvements	106.8	104.5
Machinery and equipment	821	813.5
Construction in progress	44	33.2
Property, plant and equipment – gross	992.6	972.6
Accumulated depreciation	(364)	(352.2)
Assets held for sale	2.3	1.6
Property, plant and equipment – net	630.9	622
Other Accrued Liabilities
Uncleared cash disbursements	5.7	4.2
Accrued income taxes and taxes payable	10.3	6.2
Accrued annual contribution to Salaried VEBA	0	2.9
Accrued interest	2	2.3
Short-term environmental accrual	4.7	5.5
Other	34.2	22.9
Total	56.9	44
Long-Term Liabilities
Workers’ compensation accruals	28.5	27.7
Long-term environmental accrual	12.3	11.5
Other long-term liabilities	34.5	27.8
Total	75.3	67
Excess of Replacement or Current Costs over Stated LIFO Value	$ 1.9	$ 11.9
Workers' Compensation Discount, Percent	1.00%	1.75%
Workers compensation liability	$ 29	$ 29.2
Billed
Trade Receivables – Net
Trade receivables, gross	$ 176.6	$ 168.5

Leases, Narrative (Details)

Leases, Narrative (Details)	3 Months Ended
	Mar. 31, 2020
Optional extension lease terms	20 years
Lease termination period	1 year
Minimum
Remaining lease terms	1 year
Maximum
Remaining lease terms	13 years

Leases, Weighted Averages (Deta

Leases, Weighted Averages (Details)	Mar. 31, 2020
Leases [Abstract]
Finance Lease, Weighted Average Remaining Lease Term	5 years 8 months 12 days
Operating Lease, Weighted Average Remaining Lease Term	9 years 8 months 12 days
Finance Lease, Weighted Average Discount Rate, Percent	4.50%
Operating Lease, Weighted Average Discount Rate, Percent	5.60%

Leases, Schedule of Lease Asset

Leases, Schedule of Lease Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease assets	$ 28.8	$ 25.8
Finance lease assets	6.3	6.6
Total lease assets	35.1	32.4
Operating lease liabilities, current	4.5	3.9
Finance lease liabilities, current	1.2	1.2
Operating lease liabilities, noncurrent	27.8	25.2
Finance lease liabilities, noncurrent	5.1	5.4
Total lease liabilities	$ 38.6	$ 35.7

Leases, Schedule of Lease Cost

Leases, Schedule of Lease Cost Classification (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Operating lease cost	$ 1.8	$ 2
Short-term lease cost	0.3	0.3
Amortization of leased assets	0.4	0.4
Interest on lease liabilities	0.1	0.1
Total lease cost	$ 2.6	$ 2.8

Leases, Maturity of Lease liabi

Leases, Maturity of Lease liability (Details) $ in Millions	Mar. 31, 2020USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remainder of 2020	$ 4.7
Operating Lease, Liability, Payments, Due Year One	5.5
Lessee, Operating Lease, Liability, Payments, Due Year Two	4.7
Lessee, Operating Lease, Liability, Payments, Due Year Three	4.3
Lessee, Operating Lease, Liability, Payments, Due Year Four	4.1
Lessee, Operating Lease, Liability, Payments, Due Year Five	2.2
2026 and thereafter	16.9
Total minimum lease payments	42.4
Less: interest	(10.1)
Present value	32.3
Finance Lease, Liability, Payment, Due, Rolling Maturity [Abstract]
Remainder of 2020	1.2
Finance Lease, Liability, Payments, Due Year One	1.4
Finance Lease, Liability, Payments, Due Year Two	1.3
Finance Lease, Liability, Payments, Due Year Three	1.2
Finance Lease, Liability, Payments, Due Year Four	0.6
Finance Lease, Liability, Payments, Due Year Five	0.6
2026 and thereafter	0.7
Total minimum lease payments	7
Less: interest	(0.7)
Present value	$ 6.3

Leases, Schedule of Future Mini

Leases, Schedule of Future Minimum Rental Payments (Details) $ in Millions	Mar. 31, 2020USD ($)
Finance Leases
Finance Lease, Liability, Payments, Remainder of Fiscal Year	$ 1.2
Finance Lease, Liability, Payments, Due Year One	1.4
Finance Lease, Liability, Payments, Due Year Two	1.3
Finance Lease, Liability, Payments, Due Year Three	1.2
Finance Lease, Liability, Payments, Due Year Four	0.6
Finance Lease, Liability, Payments, Due Year Five	0.6
Finance Lease, Liability, Payments, Due after Year Five	0.7
Finance Lease, Liability, Payment, Due	7
Finance Lease, Liability, Undiscounted Excess Amount	0.7
Finance Lease, Liability	6.3
Operating Leases
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	4.7
Operating Lease, Liability, Payments, Due Year One	5.5
Lessee, Operating Lease, Liability, Payments, Due Year Two	4.7
Lessee, Operating Lease, Liability, Payments, Due Year Three	4.3
Lessee, Operating Lease, Liability, Payments, Due Year Four	4.1
Lessee, Operating Lease, Liability, Payments, Due Year Five	2.2
Lessee, Operating Lease, Liability, Payments, Due after Year Five	16.9
Lessee, Operating Lease, Liability, Payments, Due	42.4
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	10.1
Operating Lease, Liability	$ 32.3

Employee Benefits Tables (Detai

Employee Benefits Tables (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure
Defined Contribution Plan, Cost	$ 3.9	$ 3.9
Deferred Compensation Arrangement with Individual, Compensation Expense	(0.4)	0.7
Multiemployer Plan, Contributions by Employer	1.3	1.2
Total other employee benefit plans	6	7.5
Postretirement Health Coverage | Salaried VEBA
Defined Benefit Plan Disclosure
Total net periodic postretirement benefit cost relating to Salaried VEBA	1.2	1.7
Salaried VEBA:
Interest cost	0.6	0.8
Expected return on plan assets	(0.7)	(0.6)
Amortization of prior service cost	1.2	1.4
Amortization of net actuarial loss	$ 0.1	$ 0.1

Employee Benefits Narrative (De

Employee Benefits Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Defined Benefit Plan Disclosure
Payment for Other Postretirement Benefits	$ 2.9	$ 2.1
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Defined Benefit Plan Disclosure
Fair value of deferred compensation assets	7.6		$ 8.1
Postretirement Health Coverage | Salaried VEBA
Defined Benefit Plan Disclosure
Maximum contribution threshold	2.9
Payment for Other Postretirement Benefits		$ 2.9
Accrued salaries, wages and related expenses
Defined Benefit Plan Disclosure
Accrued salaries, wages and related expenses	$ 3.7

Derivatives, Hedging Programs_3

Derivatives, Hedging Programs and Other Financial Instruments, Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Collateral posted for net derivatives	$ 0						$ 0
Cash collateral posted from customers	$ 2,100,000						200,000
Maturity period of short-term investments	12 months
Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Derivative net liability	$ 29,200,000						$ 7,200,000
Scenario, Forecast | Natural Gas
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage		75.00%	80.00%	80.00%	76.00%	75.00%
Scenario, Forecast | Electricity
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage				46.00%	55.00%	55.00%

Derivatives, Hedging Programs_4

Derivatives, Hedging Programs and Other Financial Instruments, Material Derivative Positions (Details) mmlbs in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2020MMBTUeuroMWHmmlbs
Foreign Exchange Contract | Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Derivative non-monetary notional amount | euro						34,323,380
Electricity | Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Derivative non-monetary notional amount | MWH						613,820
Aluminum | Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Derivative non-monetary notional amount						115.3
Aluminum | Designated as Hedging Instrument | Sales
Derivative [Line Items]
Derivative non-monetary notional amount						0.8
Midwest premium swap contracts | Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Derivative non-monetary notional amount						110.4
Alloy Metal Hedge | Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Derivative non-monetary notional amount						16.9
Natural Gas | Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Derivative non-monetary notional amount | MMBTU						7,970,000
Scenario, Forecast | Electricity
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage			46.00%	55.00%	55.00%
Scenario, Forecast | Natural Gas
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage	75.00%	80.00%	80.00%	76.00%	75.00%

Derivatives, Hedging Programs_5

Derivatives, Hedging Programs and Other Financial Instruments, Realized and Unrealized Gains (Losses) Table (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments Gain Loss [Line Items]
Cost of products sold, excluding depreciation and amortization and other items	$ 286.6	$ 315.1
Depreciation and amortization	13.2	11.9
Cash Flow Hedges | Cost of Sales | Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Loss (gain) recognized in income related to cash flow hedges:	7	4.2
Cash Flow Hedges | Cost of Sales | Aluminum | Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Loss (gain) recognized in income related to cash flow hedges:	5.7	4.2
Cash Flow Hedges | Cost of Sales | Alloy Metal Hedge | Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Loss (gain) recognized in income related to cash flow hedges:	0.6	0.1
Cash Flow Hedges | Cost of Sales | Natural Gas | Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Loss (gain) recognized in income related to cash flow hedges:	0.5	(0.1)
Cash Flow Hedges | Cost of Sales | Electricity | Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Loss (gain) recognized in income related to cash flow hedges:	0.2	0
Fair Value Hedges | Depreciation and Amortization | Foreign Exchange Contract | Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Loss (gain) recognized in income related to cash flow hedges:	0.2	0
Foreign exchange contracts	0.2	0
Hedged item	(0.2)	0
Excluded component amortized from AOCI to income	$ 0.2	$ 0

Derivatives, Hedging Programs_6

Derivatives, Hedging Programs and Other Financial Instruments, Fair Value Hierarchy Table (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	$ 1.8	$ 4
Derivative liability	(30.8)	(11.2)
Cash and cash equivalents	307.2	264.3
Total	346.5	343
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	199.6	28.2
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	1.8	4
Derivative liability	(30.8)	(11.2)
Derivative Assets (Liabilities), at Fair Value, Net	(29)	(7.2)
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Total	0	0
Designated as Hedging Instrument | Purchase
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	(29.2)	(7.2)
Debt Securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	39.3	78.7
Debt Securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Debt Securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	146.9	314.8
Debt Securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Cash Flow Hedges | Designated as Hedging Instrument | Purchase | Aluminum | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	1
Derivative liability	(14.2)	(4.1)
Derivative Assets (Liabilities), at Fair Value, Net	(14.2)	(3.1)
Cash Flow Hedges | Designated as Hedging Instrument | Purchase | Midwest premium swap contracts | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	(4.3)	(1.2)
Derivative Assets (Liabilities), at Fair Value, Net	(4.3)	(1.2)
Cash Flow Hedges | Designated as Hedging Instrument | Purchase | Alloy Metal Hedge | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0.4
Derivative liability	(5.5)	(1.5)
Derivative Assets (Liabilities), at Fair Value, Net	(5.5)	(1.1)
Cash Flow Hedges | Designated as Hedging Instrument | Purchase | Natural Gas | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0.1	0
Derivative liability	(3)	(2.8)
Derivative Assets (Liabilities), at Fair Value, Net	(2.9)	(2.8)
Cash Flow Hedges | Designated as Hedging Instrument | Purchase | Electricity | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	1.6	2.6
Derivative liability	(2.8)	(1.6)
Derivative Assets (Liabilities), at Fair Value, Net	(1.2)	1
Cash Flow Hedges | Designated as Hedging Instrument | Sales | Aluminum | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0.1	0
Derivative liability	0	0
Derivative Assets (Liabilities), at Fair Value, Net	0.1	0
Fair Value Hedges | Designated as Hedging Instrument | Purchase | Electricity | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	(1)	0
Derivative Assets (Liabilities), at Fair Value, Net	$ (1)	$ 0

Derivatives, Hedging Programs_7

Derivatives, Hedging Programs and Other Financial Instruments, Balance Sheet (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Cash and money market funds	$ 199.6	$ 28.2
Commercial paper	107.6	236.1
Short-term investments	39.3	78.7
Fair Value, Measurements, Recurring
Derivative [Line Items]
Cash and cash equivalents	307.2	264.3
Derivative asset	1.8	4
Derivative liability	(30.8)	(11.2)
Fair Value, Measurements, Recurring | Other Current Liabilities
Derivative [Line Items]
Derivative liability	(19)	(7.6)
Fair Value, Measurements, Recurring | Other Noncurrent Liabilities
Derivative [Line Items]
Derivative liability	(11.8)	(3.6)
Fair Value, Measurements, Recurring | Other Current Assets
Derivative [Line Items]
Derivative asset	0.6	2.1
Fair Value, Measurements, Recurring | Other Assets
Derivative [Line Items]
Derivative asset	1.2	1.9
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Derivative [Line Items]
Cash and money market funds	199.6	28.2
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Derivative [Line Items]
Derivative asset	1.8	4
Derivative liability	(30.8)	(11.2)
Derivative Assets (Liabilities), at Fair Value, Net	(29)	(7.2)
Debt Securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Derivative [Line Items]
Commercial paper	107.6	236.1
Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Derivative liability	$ (29.2)	$ (7.2)

Debt and Credit Facility, Narra

Debt and Credit Facility, Narrative (Details) - USD ($)	Dec. 18, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Nov. 26, 2019	May 15, 2016
Debt Instrument
Interest expense capitalized		$ 300,000	$ 500,000
Senior Notes Due 2028 | Senior Notes
Debt Instrument
Debt principal amount					$ 500,000,000
Debt instrument contractual rate (percent)					4.625%
Debt issuance, percentage of principal amount					100.00%
Unamortized debt issuance cost		7,200,000
Interest expense		$ 6,000,000
Effective interest rate (percent)		4.80%
Fair value of outstanding debt		$ 438,100,000		$ 513,500,000
Senior Notes Due 2024 | Senior Notes
Debt Instrument
Debt principal amount						$ 375,000,000
Debt instrument contractual rate (percent)						5.875%
Debt issuance, percentage of principal amount						100.00%
Interest expense			$ 5,700,000
Effective interest rate (percent)			6.10%
On or after May 15, 2019 | Senior Notes Due 2024 | Senior Notes
Debt Instrument
Debt Instrument, Redemption Price, Percentage	104.406%

Debt and Credit Facility Availa

Debt and Credit Facility Availability and Usage of Revolving Credit Facility (Details) - Revolving Credit Facility	Mar. 31, 2020USD ($)
Line of Credit
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 375,000,000
Line of Credit Facility, Current Borrowing Capacity	349,200,000
Long-term Line of Credit	0
Line of Credit Facility, Remaining Borrowing Capacity	$ 341,500,000
Line of Credit Facility, Interest Rate at Period End	3.50%
Letter of Credit
Line of Credit Facility [Line Items]
Long-term Line of Credit	$ (7,700,000)

Commitments and Contingencies,

Commitments and Contingencies, Environmental (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Environmental Contingency
Environmental accrual	$ 17
Expected period related to remediation expenditures for environmental contingencies period	30 years
Potential increase in environmental costs	$ 11.6
Time period within which Companys recorded estimate of its obligation may change	12 months
Minimum
Environmental Contingency
Period for final feasibility study	6 months
Maximum
Environmental Contingency
Period for final feasibility study	12 months

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 733.9	$ 740.4
Other comprehensive income (loss), net of tax	(15.5)	9.7
Ending balance	721.1	747.9
Estimated net mark-to-market loss before tax within next twelve months - cash flow hedges	18.1
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(33.2)	(35.6)
Less: income tax (expense) benefit	(0.3)	(0.4)
Net loss (gain) reclassified from AOCI to Net income	1	1.1
Other comprehensive income (loss), net of tax	1.1	1.1
Ending balance	(32.1)	(34.5)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of unrealized gain upon sale of available for sale securities and Excluded component amortized from AOCI to net income	0.1	0.1
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of unrealized gain upon sale of available for sale securities and Excluded component amortized from AOCI to net income	1.2	1.4
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0.3	0.3
Unrealized gain (loss) on securities	1.3	1
Less: income tax benefit (expense)	(0.3)	(0.3)
Net unrealized (loss) gain on cash flow hedges	1	0.7
Reclassification of unrealized gain upon sale of available for sale securities and Excluded component amortized from AOCI to net income	(1.5)	(1.2)
Less: income tax (expense) benefit	0.3	0.3
Net loss (gain) reclassified from AOCI to Net income	(1.2)	(0.9)
Other comprehensive income (loss), net of tax	(0.2)	(0.2)
Ending balance	0.1	0.1
AOCI, Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5.6)	(13.4)
Unrealized gain (loss) on securities	(27.9)	7.4
Less: income tax benefit (expense)	6.8	(1.8)
Net unrealized (loss) gain on cash flow hedges	(21.1)	5.6
Reclassification of unrealized gain upon sale of available for sale securities and Excluded component amortized from AOCI to net income	7	4.2
Less: income tax (expense) benefit	(1.8)	(1)
Net loss (gain) reclassified from AOCI to Net income	5.2	3.2
Other comprehensive income (loss), net of tax	(15.9)	8.8
Ending balance	(21.5)	(4.6)
AOCI, Excluded Component of Derivative Qualifying as Fair Value Hedge Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0	0
Unrealized gain (loss) on securities	(0.8)	0
Less: income tax benefit (expense)	0.2	0
Net unrealized (loss) gain on cash flow hedges	(0.6)	0
Reclassification of unrealized gain upon sale of available for sale securities and Excluded component amortized from AOCI to net income	0.2	0
Less: income tax (expense) benefit	(0.1)	0
Net loss (gain) reclassified from AOCI to Net income	0.1	0
Other comprehensive income (loss), net of tax	(0.5)	0
Ending balance	(0.5)	0
AOCI, Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(0.1)	(0.1)
Other comprehensive income (loss), net of tax	0	0
Ending balance	(0.1)	(0.1)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(38.6)	(48.8)
Other comprehensive income (loss), net of tax	(15.5)	9.7
Ending balance	(54.1)	$ (39.1)
Fair Value Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Estimated net mark-to-market loss before tax within next twelve months - fair value hedges	$ 0.6

Other (Expense) Income, Net (De

Other (Expense) Income, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Other Income and Expenses [Abstract]
Interest income	$ 0.1	$ 0.2
Net periodic postretirement benefit cost relating to Salaried VEBA	(1.2)	(1.6)
Realized gain on available for sale securities	1.5	1.2
Unrealized (loss) gain on equity securities	(0.6)	0.5
All other (expense) income, net	(0.6)
All other (expense) income, net		0.2
Other (expense) income, net	$ (0.8)	$ 0.5

Income Tax Matters, Provision T

Income Tax Matters, Provision Table (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Tax Provision
Domestic	$ 9.5	$ 9.5
Foreign	0.1	0.3
Total	$ 9.6	$ 9.8

Income Tax Matters, Narrative (

Income Tax Matters, Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income tax provision	$ 9.6	$ 9.8
Effective tax rate (percent)	25.00%	26.00%
Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-based Payment Arrangement, Amount		$ (0.5)
Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-based Payment Arrangement, Percent		1.00%
Effective tax rate reconciliation, increase (decrease) to the valuation allowance for certain state net operating losses		$ 0.7
Effective tax rate reconciliation, increase (decrease) to the valuation allowance for certain state net operating losses (percent)		2.00%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount		$ 0.4
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent		1.00%
Gross unrecognized tax benefits	$ 3.9		$ 4.1
Gross unrecognized tax benefits that would impact effective tax rate	$ 0.4		$ 0.9

Net Income Per Share (Details)

Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income	$ 29.1	$ 28
Denominator — Weighted-average common shares outstanding (in thousands):
Basic (shares)	15,838	16,108
Add: dilutive effect of non-vested common shares, restricted stock units, performance shares and stock options (shares)	170	264
Diluted (shares)	16,008	16,372
Net income per common share:
Basic (in dollars per share)	$ 1.83	$ 1.74
Earnings per common share, Diluted:
Diluted (in dollars per share)	$ 1.81	$ 1.71

Net Income Per Share, Anti Dilu

Net Income Per Share, Anti Dilution Table (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2	4

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Interest paid	$ 6.1	$ 0.3
Non-cash investing and financing activities (included in Accounts Payable):
Unpaid purchases of property and equipment	4.7	4.7
Stock repurchases not yet settled	0	0.2
Supplemental lease disclosures:
Operating lease liabilities arising from obtaining operating lease assets	4.2	0.5
Cash paid for amounts included in the measurement of operating lease liabilities	1.1	0.9
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	0.1	0
Components of cash, cash equivalents and restricted cash:
Cash and cash equivalents	307.2	115.3	$ 264.3
Restricted cash included in Prepaid expenses and other current assets	0	0.3
Restricted cash included in Other assets	13.9	13.8
Total cash, cash equivalents and restricted cash presented on our Statements of Consolidated Cash Flows	$ 321.1	$ 129.4	$ 278.6	$ 139.6

Business, Product and Geograp_3

Business, Product and Geographical Area Information, Net Sales by End Market Segment Applications (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net Sales:
Net sales	$ 369.3	$ 395.2
Transferred at Point in Time
Net Sales:
Net sales	215.6	223.3
Transferred over Time
Net Sales:
Net sales	153.7	171.9
Aero/HS products
Net Sales:
Net sales	196	198.5
Automotive Extrusions
Net Sales:
Net sales	47.4	53
GE products
Net Sales:
Net sales	121.7	130
Other products
Net Sales:
Net sales	$ 4.2	13.7
Previously Reported [Member] | Transferred at Point in Time
Net Sales:
Revenue from Contract with Customer, Excluding Assessed Tax		131.8
Previously Reported [Member] | Transferred over Time
Net Sales:
Revenue from Contract with Customer, Excluding Assessed Tax		$ 263.4

Business, Product and Geograp_4

Business, Product and Geographical Area Information, Income Taxes Paid by Geographical Area (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information
Income taxes paid	$ 0.1	$ 0.9
Domestic
Segment Reporting Information
Income taxes paid	0	0.1
Foreign
Segment Reporting Information
Income taxes paid	$ 0.1	$ 0.8

Business, Product and Geograp_5

Business, Product and Geographical Area Information, Narrative (Details)	3 Months Ended
	Mar. 31, 2020productionfacilities
Domestic
Segment Reporting Information
Number of production facilities	12
Foreign
Segment Reporting Information
Number of production facilities	1

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 14, 2020	Mar. 31, 2020	Mar. 31, 2019
Subsequent Event [Line Items]
Cash dividends declared (in dollars per share)		$ 0.67	$ 0.60
Subsequent Event
Subsequent Event [Line Items]
Cash dividends declared (in dollars per share)	$ 0.67
Cash dividends declared	$ 10.7