Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	Apr. 22, 2019
Document Information [Line Items]
Entity Registrant Name	Kaiser Aluminum Corp
Entity Central Index Key	0000811596
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		16,123,168

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 115.3	$ 125.6
Short-term investments	22.3	36.7
Receivables:
Trade receivables, net	195.8	179.8
Other	22.4	25.6
Contract assets	58.4	54.9
Inventories	233.9	215.1
Prepaid expenses and other current assets	23.0	18.9
Total current assets	671.1	656.6
Property, plant and equipment, net	610.9	611.8
Operating lease assets	27.4	0.0
Deferred tax assets, net	22.4	35.9
Intangible assets, net	31.7	32.4
Goodwill	44.0	44.0
Other assets	40.3	38.6
Total	1,447.8	1,419.3
Current liabilities:
Accounts payable	124.4	121.4
Accrued salaries, wages and related expenses	28.2	40.1
Other accrued liabilities	51.6	44.0
Total current liabilities	204.2	205.5
Long-term portion of operating lease liabilities	26.6	0.0
Net liabilities of Salaried VEBA	32.5	32.4
Deferred tax liabilities	4.2	4.2
Long-term liabilities	61.8	66.4
Long-term debt	370.6	370.4
Total liabilities	699.9	678.9
Commitments and contingencies
Stockholders' equity:
Preferred stock, 5,000,000 shares authorized at both March 31, 2019 and December 31, 2018; no shares were issued and outstanding at March 31, 2019 and December 31, 2018	0.0	0.0
Common stock, par value $0.01, 90,000,000 shares authorized at both March 31, 2019 and at December 31, 2018; 22,547,626 shares issued and 16,134,547 shares outstanding at March 31, 2019; 22,471,705 shares issued and 16,234,603 shares outstanding at December 31, 2018	0.2	0.2
Additional paid in capital	1,056.7	1,059.3
Retained earnings	168.0	150.2
Treasury stock, at cost, 6,413,079 shares at March 31, 2019 and 6,237,102 shares at December 31, 2018, respectively	(437.9)	(420.5)
Accumulated other comprehensive loss	(39.1)	(48.8)
Total stockholders' equity	747.9	740.4
Total	$ 1,447.8	$ 1,419.3

Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
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	22,547,626	22,471,705
Common stock, shares outstanding	16,134,547	16,234,603
Treasury stock, shares	6,413,079	6,237,102

Statements of Consolidated Income (Unaudited) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenues	$ 395.2	$ 388.0
Costs and expenses:
Cost of products sold, excluding depreciation and amortization and other items	315.1	316.7
Depreciation and amortization	11.9	10.5
Selling, general, administrative, research and development	25.2	23.6
Other operating charges, net	0.0	0.1
Total costs and expenses	352.2	350.9
Operating income	43.0	37.1
Other income (expense):
Interest expense	(5.7)	(5.6)
Other income, net	0.5	0.1
Income before income taxes	37.8	31.6
Income tax provision	(9.8)	(5.9)
Net income	$ 28.0	$ 25.7
Net income per common share:
Basic (in dollars per share)	$ 1.74	$ 1.54
Diluted (in dollars per share)	$ 1.71	$ 1.51
Weighted-average number of common shares outstanding (in thousands):
Basic (shares)	16,108	16,707
Diluted (shares)	16,372	17,031

Statements of Consolidated Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 28.0	$ 25.7
Other Comprehensive Income (Loss), Net of Tax
Defined benefit pension plan and Salaried VEBA	1.1	1.2
Available for sale securities	(0.2)	(0.2)
Cash flow hedges	8.8	(9.3)
Other comprehensive income (loss), net of tax	9.7	(8.3)
Comprehensive income	$ 37.7	$ 17.4

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Statement of Consolidated Stockholders' Equity (Unaudited) - USD ($)
$ in Millions

Total

Common Stock

Additional Paid in Capital

Retained Earnings

Treasury Stock

Accumulated Other Comprehensive Loss

Stockholders' Equity [Roll Forward]

Cumulative-effect adjustment

$ 10.1

$ 10.5

$ 0.0

$ (0.4)

Adjusted balance

756.4

$ 0.2

$ 1,055.9

96.0

(358.6)

(37.1)

Beginning balance (shares) at Dec. 31, 2017

16,773,586

Beginning balance at Dec. 31, 2017

746.3

$ 0.2

1,055.9

85.5

(358.6)

(36.7)

Stockholders' Equity [Roll Forward]

Net income

25.7

Other comprehensive income, net of tax

(8.3)

Issuance of common shares to employees upon vesting of restricted stock units and performance shares (shares)

135,134

Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares (shares)

(68,029)

Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares

$ (6.9)

(6.9)

Repurchase of common stock (shares)

(58,155)

Repurchase of common stock

$ (6.1)

(6.1)

Cash dividends on common stock and restricted shares and dividend equivalents on restricted stock units and performance shares1

^[1]

(10.0)

Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition

2.8

Ending balance (shares) at Mar. 31, 2018

16,782,536

Ending balance at Mar. 31, 2018

$ 753.6

$ 0.2

1,051.8

111.7

(364.7)

(45.4)

Stockholders' Equity [Roll Forward]

Cash dividends declared (in dollars per share)

$ 0.55

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

28.0

Other comprehensive income, net of tax

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

$ (5.0)

(5.0)

Repurchase of common stock (shares)

(175,977)

Repurchase of common stock

$ (17.4)

(17.4)

Cash dividends on common stock and restricted shares and dividend equivalents on restricted stock units and performance shares1

^[2]

(10.2)

Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition

$ 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

$ 168.0

$ (437.9)

$ (39.1)

Stockholders' Equity [Roll Forward]

Cash dividends declared (in dollars per share)

$ 0.60

[1]	Dividends declared per common share were $0.55 during the quarter ended March 31, 2018.
[2]	Dividends declared per common share were $0.60 during the quarter ended March 31, 2019.

Statement of Consolidated Cash Flows (Unaudited) - USD ($)
$ in Millions

3 Months Ended

Mar. 31, 2019

Mar. 31, 2018

Cash flows from operating activities:

Net income

$ 28.0

$ 25.7

Adjustments to reconcile net income to net cash provided by operating activities:

Depreciation of property, plant and equipment

11.2

10.1

Amortization of definite-lived intangible assets

0.7

0.4

Amortization of debt discount and debt issuance costs

0.3

Deferred income taxes

10.4

7.9

Non-cash equity compensation

2.4

2.8

Gain on disposition of available for sale securities

(0.3)

(1.1)

Non-cash asset impairment charge

0.0

0.1

Other non-cash changes in assets and liabilities

3.6

8.1

Changes in operating assets and liabilities:

Trade and other receivables

(12.8)

(23.0)

Contract assets

(3.5)

(1.9)

Inventories

(18.8)

(9.6)

Prepaid expenses and other current assets

(3.4)

(2.2)

Accounts payable

7.4

32.0

Accrued liabilities

(0.4)

(7.3)

Annual variable cash contributions to VEBAs

(2.1)

(15.7)

Long-term assets and liabilities, net

0.1

(0.5)

Net cash provided by (used in) operating activities

22.8

26.1

Cash flows from investing activities

Capital expenditures

(13.6)

(19.7)

Purchase of available for sale securities

(18.1)

0.0

Proceeds from disposition of property, plant and equipment

32.7

100.3

Net cash provided by investing activities

^[1]

1.0

80.6

Cash flows from financing activities

Repayment of finance lease

(0.3)

(0.2)

Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares

(5.0)

(6.9)

Repurchase of common stock

(18.5)

(5.7)

Cash dividends and dividend equivalents paid

(10.2)

(10.0)

Net cash used in financing activities

^[1]

(34.0)

(22.8)

Net increase in cash, cash equivalents and restricted cash during the period

(10.2)

83.9

Cash, cash equivalents and restricted cash at beginning of period

139.6

64.3

Cash, cash equivalents and restricted cash at end of period

$ 129.4

$ 148.2

[1]	See Note 12 for supplemental cash flow information.

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies This Quarterly Report on Form 10-Q (this "Report") should be read in conjunction with the Company's Annual Report on Form 10-K for the year ended December 31, 2018. 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. Organization and Nature of Operations. Kaiser Aluminum Corporation specializes in the production of semi-fabricated specialty aluminum mill products, such as aluminum plate and sheet and extruded and drawn products, for the following end market applications: aerospace and high strength ("Aero/HS products"), automotive ("Automotive Extrusions"), general engineering ("GE products") and other industrial ("Other products"). Our business is organized into one operating segment. See Note 13 for additional information regarding our business, product and geographical area information and concentration of risk. 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 2019 fiscal year. The financial information as of December 31, 2018 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, 2018. 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. Fair Value Measurements. We apply the fair value hierarchy established by GAAP for the recognition and measurement of certain financial assets and liabilities. An asset or liability's fair value classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. In determining fair value, we utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible and consider counterparty risk in our assessment of fair value. We also review the underlying inputs that are significant to the fair value measurement of financial instruments to determine if a transfer among hierarchy levels is appropriate. We historically have not had significant transfers into or out of each hierarchy level. Financial assets and liabilities that we measure at fair value each period include our derivative instruments, equity investments related to our deferred compensation plan and debt investment securities classified as available for sale securities (see Note 4). Additionally, we measure at fair value once each year at December 31 our Canadian defined benefit pension plan and the plan assets of the Salaried VEBA (defined in Note 4). We record our remaining financial assets and liabilities at carrying value. For a majority of our non-financial assets and liabilities, which include goodwill, intangible assets, inventories and property, plant and equipment, we are not required to measure their fair value on a recurring basis. However, if certain triggering events occur (or at least annually for goodwill), an evaluation of the affected non-financial asset or liability will be required, which could result in a reduction to the carrying amount of such asset or liability. None of our non-financial assets and liabilities subject to fair value assessments on a non-recurring basis required a material adjustment to the carrying amount of such assets and liabilities for the quarter ended March 31, 2019. Inventories. Inventories are stated at the lower of cost or market value. Finished products, work-in-process and raw material inventories are stated on the last-in, first-out ("LIFO") basis. At March 31, 2019 and December 31, 2018, the current cost of our inventory exceeded its stated LIFO value by $17.2 million and $31.7 million, respectively. Other inventories are stated on the first-in, first-out basis and consist of operating supplies, which are materials and supplies to be consumed during the production process. Inventory costs consist of material, labor and manufacturing overhead, including depreciation. Abnormal costs, such as idle facility expenses, freight, handling costs and spoilage, are accounted for as current period charges (see Note 2 for the components of inventories). Replacement Parts. Replacement parts consist of preventative maintenance and capital spare parts, which are stated on the first-in, first-out basis. Replacement parts are recorded within Prepaid expenses and other current assets or Other assets depending on whether or not the expected utilization of the replacement parts is to occur within the current operating cycle. Property, Plant and Equipment, Net. Property, plant and equipment, net is recorded at cost and includes construction in progress (see Note 2). Interest related to the construction of qualifying assets is capitalized as part of the construction costs. The amount of interest expense capitalized as construction in progress was $0.5 million during each of the quarters ended March 31, 2019 and March 31, 2018, respectively. Depreciation is computed using the straight-line method at rates based on the estimated useful lives of the various classes of assets. Finance lease assets and leasehold improvements are depreciated on a straight-line basis over the shorter of the estimated useful lives of the assets or the lease term. We classify assets as held for sale only when an asset is being actively marketed and expected to sell within 12 months. Assets held for sale are initially measured at the lesser of the assets' carrying amount and the fair value less costs to sell. Derivative Financial Instruments. Consistent with guidelines established by management and approved by our Board of Directors, we use derivative financial instruments to mitigate our exposure to changes in the market price of aluminum, alloying metals, energy, and, to a lesser extent, foreign currency exchange rates. We do not use derivative financial instruments for trading or other speculative purposes. Hedging transactions are executed centrally on behalf of all of our operations to minimize transaction costs, monitor consolidated net exposures and allow for increased responsiveness to changes in market factors. We reflect the fair value of all of our derivative instruments on our Consolidated Balance Sheets (see Note 5). The fair value of hedges settling within one year is included in Prepaid expenses and other current assets or Other accrued liabilities. The fair value of hedges settling beyond one year is included in Other assets or Long-term liabilities. Our aluminum and energy derivatives qualify for hedge (deferral) accounting and, as such, we designate such hedges as cash flow hedges. Forward swap contracts for zinc and copper ("Alloying Metals") used in our fabrication operations are also designated as cash flow hedges. Unrealized gains and losses associated with our cash flow hedges are deferred in Other comprehensive income, net of tax, and reclassified to Cost of products sold, excluding depreciation and amortization and other items ("COGS") when such hedges settle (see Note 5). Self Insurance of Workers' Compensation and Employee Healthcare Liabilities. We self-insure the majority of the costs of workers' compensation benefits and employee healthcare benefits and rely on insurance coverage to protect us from large losses on individual claims. Workers' compensation liabilities are based on a combination of estimates for: (i) incurred-but-not-reported claims and (ii) the ultimate expense of incurred claims. Such estimates are based on judgment, using our historical claims data and information and analysis provided by actuarial and claims advisors, our insurance carriers and other professionals. Our undiscounted workers' compensation liabilities were estimated at $28.1 million and $27.6 million as of March 31, 2019 and December 31, 2018, respectively. However, we accounted for our workers' compensation accrued liabilities on a discounted basis (see Note 2), using a discount rate of 2.50% and 3.00% at March 31, 2019 and December 31, 2018, respectively. Accrued liabilities for employee healthcare benefits, which are estimates of unpaid incurred medical and prescription drug costs as provided by our healthcare administrators, were $3.4 million and $3.6 million as of March 31, 2019 and December 31, 2018, respectively. 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, 2019, we had a liability of $3.9 million recorded within Accrued salaries, wages and related expenses for estimated probable future payments relating to the three month performance period of our 2019 STI Plan. Long-Term Incentive Programs. Executive officers and other key employees of the Company, as well as non-employee directors of the Company, are eligible to participate in the Kaiser Aluminum Corporation 2016 Equity and Incentive Compensation Plan approved by stockholders on May 26, 2016 ("2016 Plan"). At March 31, 2019, 503,379 shares were available for awards under the 2016 Plan. We issue new shares of our common stock upon vesting under the 2016 Plan. Adoption of New Accounting Pronouncements ASU No. 2016-02, Leases (Topic 842): Amendments to the Financial Accounting Standards Board Accounting Standards Codification ("ASU 2016-02"), was issued in February 2016 (with amendments issued in 2018) and requires lessees to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). For income statement purposes, a dual model was retained, requiring leases to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to operating leases under the previous guidance) while finance leases will result in a front-loaded expense pattern (similar to capital leases under the previous guidance). We adopted ASU 2016-02 and its subsequent amendments (together "ASC 842") during the quarter ended March 31, 2019 using the transition approach provided for under ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, which allowed us to apply the new lease standard as of January 1, 2019, rather than the beginning of the earliest period presented. We elected the package of practical expedients, which permitted us to: (i) not reassess whether any of our contracts contained leases; (ii) carry forward the historical lease classification of our existing leases; and (iii) not reassess initial direct costs for our existing leases. We did not elect to apply the hindsight practical expedient when determining lease term and assessing impairment of right-of-use assets. Due to our adoption of ASC 842, we recorded an operating lease right-of-use asset of $29.0 million, a current operating lease liability of $4.1 million and a long-term operating lease liability of $27.4 million on our Consolidated Balance Sheets as of January 1, 2019. There was no cumulative-effect adjustment to Retained earnings required. The standard did not materially impact our consolidated net earnings and had no impact on cash flows. Comparative information in this Report has not been adjusted and continues to be reported under the previous lease accounting rules. See Note 3 for details of the significant changes and quantitative impacts of the changes, as well as other required disclosures related to our adoption of ASC 842. There were no material impacts on our consolidated financial statements resulting from our adoption in the quarter ended March 31, 2019 of: (i) ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting and (ii) ASU No. 2018-08, Not-for-Profit Entities (Topic 958): Clarifying the Scope and the Accounting Guidance for Contributions Received and Contributions Made. Accounting Pronouncements Issued But Not Yet Adopted 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 will be replaced with a new forward-looking "expected loss" model that generally will result in the earlier recognition of allowances for losses. We are currently in the process of evaluating the impact of adopting ASU 2016-13 in 2020, but do not expect it to have a material impact on our consolidated financial statements. 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. We are currently in the process of evaluating the impact of adopting ASU 2018-15 in 2020, but do not expect it to have a material impact on our consolidated financial statements.

Supplemental Balance Sheet Information

3 Months Ended

Mar. 31, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Supplemental Balance Sheet Information



	March 31, 2019			December 31, 2018
	(In millions of dollars)
Cash and Cash Equivalents
Cash and money market funds	$	29.3		$	22.9
Commercial paper	86.0			102.7
Total	$	115.3		$	125.6

Trade Receivables, Net
Billed trade receivables	$	196.6		$	179.5
Unbilled trade receivables	—			1.1
Trade receivables, gross	196.6			180.6
Allowance for doubtful receivables	(0.8		)	(0.8		)
Trade receivables, net	$	195.8		$	179.8

Inventories
Finished products	$	47.1		$	48.0
Work-in-process	104.9			85.6
Raw materials	74.8			75.0
Operating supplies	7.1			6.5
Total	$	233.9		$	215.1

Property, Plant and Equipment, Net
Land and improvements	$	21.4		$	21.4
Buildings and leasehold improvements	97.8			97.0
Machinery and equipment	766.9			755.6
Construction in progress	41.8			43.6
Property, plant and equipment, gross	927.9			917.6
Accumulated depreciation	(318.6		)	(307.4		)
Assets held for sale	1.6			1.6
Property, plant and equipment, net	$	610.9		$	611.8

Other Accrued Liabilities
Uncleared cash disbursements	$	6.6		$	4.8
Accrued income taxes and taxes payable	9.9			6.5
Accrued annual contribution to Salaried VEBA	—			2.1
Accrued interest	8.4			2.9
Other – Note 5	26.7			27.7
Total	$	51.6		$	44.0



	March 31, 2019		December 31, 2018
	(In millions of dollars)
Long-Term Liabilities
Workers' compensation accruals	$	25.5	$	24.6
Long-term environmental accrual – Note 7	13.1		14.3
Other long-term liabilities	23.2		27.5
Total	$	61.8	$	66.4

Leases

3 Months Ended

Mar. 31, 2019

Leases [Abstract]

Leases

We determine if 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 one year to 15 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 in 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 applied the practical expedient within ASU 2016-02 to not separate lease and non-lease components to only 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, 2019:

The following table summarizes the classification of lease assets and lease liabilities in our Consolidated Balance Sheet at March 31, 2019 (in millions of dollars):



Leases	Classification	March 31, 2019
Assets
Operating lease assets	Operating lease assets	$	27.4
Finance lease assets	Property, plant and equipment, net	6.7
Total lease assets		$	34.1

Liabilities
Current:
Operating lease liabilities	Other accrued liabilities	$	3.5
Finance lease liabilities	Other accrued liabilities	1.3
Non-current:
Operating lease liabilities	Long-term portion of operating lease liabilities	26.6
Finance lease liabilities	Long-term liabilities	5.4
Total lease liabilities		$	36.8

The following table summarizes the components of lease cost in our Statements of Consolidated Income during the quarter ended March 31, 2019 (in millions of dollars):



Lease Cost	Quarter Ended March 31, 2019
Operating lease cost	$	2.0
Short-term lease cost	0.3
Finance lease cost:
Amortization of leased assets	0.4
Interest on lease liabilities	0.1
Total lease cost	$	2.8

The following table presents the maturity of our lease liabilities as of March 31, 2019 (in millions of dollars):



Maturity of Lease Liabilities	Finance Leases			Operating Leases
Remainder of 2019	$	1.2		$	3.7
2020	1.4			4.7
2021	1.2			4.1
2022	1.1			3.6
2023	1.0			3.4
2024	0.6			3.3
2025 and thereafter	1.2			18.7
Total minimum lease payments	$	7.7		$	41.5

Less: interest	(1.0		)	(11.4		)
Present value	$	6.7		$	30.1

The following table presents minimum rental commitments at December 31, 2018 (in millions of dollars):



Year Ended December 31,	Finance Leases			Operating Leases
2019	$	1.7		$	6.1
2020	1.4			3.7
2021	1.2			2.8
2022	1.1			2.4
2023	1.0			2.2
2024 and thereafter	1.8			20.8
Total minimum lease payments	$	8.2		$	38.0

Less: interest	(1.2		)
Present value¹	$	7.0

_________________________

^1.

Of the $7.0 million in finance lease obligations as of December 31, 2018, $1.4 million was included in Other accrued liabilities and $5.6 million was included in Long-term liabilities. Assets recorded under finance leases and the accumulated amortization thereon were $8.3 million and $1.3 million, respectively, as of December 31, 2018.

Leases

The following table presents lease terms and discount rates as of March 31, 2019:

The following table summarizes the classification of lease assets and lease liabilities in our Consolidated Balance Sheet at March 31, 2019 (in millions of dollars):



Leases	Classification	March 31, 2019
Assets
Operating lease assets	Operating lease assets	$	27.4
Finance lease assets	Property, plant and equipment, net	6.7
Total lease assets		$	34.1

Liabilities
Current:
Operating lease liabilities	Other accrued liabilities	$	3.5
Finance lease liabilities	Other accrued liabilities	1.3
Non-current:
Operating lease liabilities	Long-term portion of operating lease liabilities	26.6
Finance lease liabilities	Long-term liabilities	5.4
Total lease liabilities		$	36.8

The following table summarizes the components of lease cost in our Statements of Consolidated Income during the quarter ended March 31, 2019 (in millions of dollars):



Lease Cost	Quarter Ended March 31, 2019
Operating lease cost	$	2.0
Short-term lease cost	0.3
Finance lease cost:
Amortization of leased assets	0.4
Interest on lease liabilities	0.1
Total lease cost	$	2.8

The following table presents the maturity of our lease liabilities as of March 31, 2019 (in millions of dollars):



Maturity of Lease Liabilities	Finance Leases			Operating Leases
Remainder of 2019	$	1.2		$	3.7
2020	1.4			4.7
2021	1.2			4.1
2022	1.1			3.6
2023	1.0			3.4
2024	0.6			3.3
2025 and thereafter	1.2			18.7
Total minimum lease payments	$	7.7		$	41.5

Less: interest	(1.0		)	(11.4		)
Present value	$	6.7		$	30.1

The following table presents minimum rental commitments at December 31, 2018 (in millions of dollars):



Year Ended December 31,	Finance Leases			Operating Leases
2019	$	1.7		$	6.1
2020	1.4			3.7
2021	1.2			2.8
2022	1.1			2.4
2023	1.0			2.2
2024 and thereafter	1.8			20.8
Total minimum lease payments	$	8.2		$	38.0

Less: interest	(1.2		)
Present value¹	$	7.0

_________________________

^1.

Employee Benefits

3 Months Ended

Mar. 31, 2019

Retirement Benefits [Abstract]

Employee Benefits

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 income, net. During the quarter ended March 31, 2019, we recognized a $0.5 million gain on equity securities still held at March 31, 2019 related to our deferred compensation plan. For the quarter ended March 31, 2018, the corresponding amount was immaterial. Assets of our deferred compensation plan are 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, 2019 and December 31, 2018 was $11.0 million and $9.8 million, respectively, and are included in Other assets. 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 $2.1 million with respect to 2018 during the quarter ended March 31, 2019. We account for the Salaried VEBA as a defined benefit plan in our financial statements.

Union VEBA Postretirement Obligation. Certain other eligible retirees represented by certain unions, along with their surviving spouses and eligible dependents, participate in a separate VEBA ("Union VEBA"). During the first quarter of 2018,

we made a $12.8 million cash contribution to the Union VEBA with respect to the nine months ended September 30, 2017. This was our final contribution. We have no ongoing obligation to make further contributions to the Union VEBA.

Fair Value of Plan Assets. The plan assets of our Canadian pension plan and the Salaried VEBA are measured annually on December 31 and reflected in our Consolidated Balance Sheets at fair value. In determining the fair value of the plan assets at an annual period end, we utilize primarily the results of valuations supplied by the investment advisors responsible for managing the assets of each plan, which we independently review for reasonableness.

The following tables present the total expense related to all benefit plans for the periods presented (in millions of dollars):



	Quarter Ended
	March 31,
	2019		2018
Defined contribution plans¹	$	3.9	$	4.3
Deferred compensation plan¹	0.7		0.1
Multiemployer pension plans¹	1.2		1.2
Net periodic postretirement benefit cost relating to Salaried VEBA²	1.7		1.5
Total	$	7.5	$	7.1

____________________


¹	Substantially all of the expense related to employee benefits are in 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 income, net in 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 return on plan assets; and (iv) amortization of prior service costs associated with plan amendments, net gains or losses on assets and actuarial differences. Net periodic benefit cost related to our Canadian pension plan was not material for the quarters ended March 31, 2019 and March 31, 2018.

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,
	2019			2018
Salaried VEBA¹:
Interest cost	$	0.8		$	0.7
Expected return on plan assets	(0.6		)	(0.7		)
Amortization of prior service cost²	1.4			1.3
Amortization of net actuarial loss	0.1			0.2
Total net periodic postretirement benefit cost relating to Salaried VEBA	$	1.7		$	1.5

____________________


¹	The service cost was insignificant for all periods presented.

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 and Other Financial Instruments

3 Months Ended

Mar. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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 and (ii) energy price risk relating to fluctuating prices of natural gas and electricity used in our production processes.

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 $6.0 million and $12.6 million at March 31, 2019 and December 31, 2018, 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. We had $0.2 million cash collateral posted from our customers as of December 31, 2018. Cash collateral posted from our customers as of March 31, 2019 was immaterial. For more information about concentration risks concerning customers and suppliers, see Note 13.

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.

Notional Amount of Derivative Contracts

The following table summarizes our derivative positions at March 31, 2019:



Aluminum	Maturity Period (month/year)	Notional Amount of Contracts (mmlbs)
Fixed price purchase contracts	4/19 through 12/21	117.1
Fixed price sales contracts	4/19 through 11/19	0.5
Midwest premium swap contracts¹	4/19 through 12/21	89.4



Alloying Metals	Maturity Period (month/year)	Notional Amount of Contracts (mmlbs)
Fixed price purchase contracts	4/19 through 12/20	10.5



Natural Gas²	Maturity Period (month/year)	Notional Amount of Contracts (mmbtu)
Fixed price purchase contracts	4/19 through 12/24	8,530,000



Electricity³	Maturity Period (month/year)	Notional Amount of Contracts (Mwh)
Fixed price purchase contracts	1/20 through 12/21	307,080

____________________


¹	Regional premiums represent the premium over the London Metal Exchange price for primary aluminum which is incurred on our purchases of primary aluminum.

As of March 31, 2019, we had derivative and/or physical delivery commitments with energy companies in place to cover exposure to fluctuations in prices for approximately 69% of the expected natural gas purchases for the remainder of 2019, 66% of the expected natural gas purchases for both 2020 and 2021, 37% of the expected natural gas purchases for both 2022 and 2023 and 31% of the expected natural gas purchases for 2024.


³	As of March 31, 2019, we had derivative and/or physical delivery commitments with energy companies in place to cover exposure to fluctuations in prices for approximately 54% of our expected electricity purchases for both the remainder of 2019 and 2020 and 27% of our expected electricity purchases for 2021.

Loss (Gain)

See Note 8 for the total amount of loss (gain) on derivative instruments designated and qualifying as cash flow hedging instruments that was reported in Accumulated other comprehensive income ("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 when the associated hedged commodity purchases impact earnings.

The amount of loss (gain) included on our Statements of Consolidated Income (all within COGS) associated with all derivative contracts consisted of the following for each period presented (in millions of dollars):



	Quarter Ended March 31,
	2019			2018
Total amounts of income and expense line items presented in our Statements of Consolidated Income in which the effects of hedges are recorded	$	315.1		$	316.7

Loss (gain) recognized in income related to cash flow hedges:
Aluminum	$	4.2		$	0.3
Alloying metals	0.1			(0.4		)
Natural gas	(0.1		)	—
Total loss (gain) recognized in income	$	4.2		$	(0.1	)

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, 2019								December 31, 2018
	Derivative Assets		Derivative Liabilities			Net Amount			Derivative Assets		Derivative Liabilities			Net Amount
Cash Flow Hedges:
Aluminum –
Fixed price purchase contracts	$	0.6	$	(7.9	)	$	(7.3	)	$	0.1	$	(13.2	)	$	(13.1	)
Fixed price sales contracts	—		—			—			0.1		—			0.1
Midwest premium swap contracts	2.8		(0.2		)	2.6			3.2		(0.5		)	2.7
Alloying Metals – Fixed price purchase contracts	0.9		(0.3		)	0.6			—		(1.7		)	(1.7		)
Natural gas – Fixed price purchase contracts	0.4		(0.8		)	(0.4		)	0.2		(0.5		)	(0.3		)
Electricity – Fixed price purchase contracts	2.0		—			2.0			0.7		—			0.7

Total	$	6.7	$	(9.2	)	$	(2.5	)	$	4.3	$	(15.9	)	$	(11.6	)

The following table presents the balance sheet location of derivative assets and liabilities as of the periods presented (in millions of dollars):



	March 31, 2019			December 31, 2018
Assets:
Prepaid expenses and other current assets	$	4.1		$	3.4
Other assets	2.6			0.9
Total assets	$	6.7		$	4.3

Liabilities:
Other accrued liabilities	$	(8.1	)	$	(13.2	)
Long-term liabilities	(1.1		)	(2.7		)
Total liabilities	$	(9.2	)	$	(15.9	)

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. At March 31, 2019, all of our short-term investments had maturity dates within 12 months. We review our debt investment portfolio for other-than-temporary impairment at least quarterly or when there are changes in credit risk or other potential valuation concerns. At March 31, 2019 and December 31, 2018, the total unrealized loss, net of tax, included in AOCI was immaterial and was not other-than-temporarily impaired. We believe that it is probable that the principal and interest will be collected in accordance with the contractual terms, and that the unrealized loss on these securities was due to normal market fluctuations, and not due to increased credit risk or other valuation concerns. The fair value input of our available for sale securities, which are classified within Level 2 of the fair value hierarchy, is calculated based on broker quotes. The amortized cost for available for sale securities approximates their fair value.

The following table presents our other financial assets, classified under the appropriate level of the fair value hierarchy, as of March 31, 2019 (in millions of dollars):



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	29.3	$	86.0	$	—	$	115.3
Short-term investments	—		22.3		—		22.3
Total	$	29.3	$	108.3	$	—	$	137.6

The following table presents our other financial assets, classified under the appropriate level of the fair value hierarchy, as of December 31, 2018 (in millions of dollars):



	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	22.9	$	102.7	$	—	$	125.6
Short-term investments	—		36.7		—		36.7
Total	$	22.9	$	139.4	$	—	$	162.3

All Other Financial Assets and Liabilities. We believe that the fair values of our accounts receivable, contract assets, accounts payable and accrued liabilities approximate their respective carrying values due to their short maturities and nominal credit risk.

Debt and Credit Facility	3 Months Ended
Debt and Credit Facility	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt and Credit Facility	Debt and Credit Facility Senior Notes In May 2016, we issued $375.0 million principal amount of 5.875% unsecured senior notes due May 15, 2024 ("Senior Notes") at 100% of the principal amount. The unamortized amount of debt issuance costs as of March 31, 2019 was $4.4 million. Interest expense, including amortization of debt issuance costs, relating to the Senior Notes was $5.7 million for each of the quarters ended March 31, 2019 and March 31, 2018. A portion of the interest relating to the Senior Notes was capitalized as construction in progress. The effective interest rate of the Senior Notes is approximately 6.1% per annum, taking into account the amortization of debt issuance costs. The fair value of the outstanding Senior Notes, which are Level 1 liabilities, was approximately $387.1 million and $369.9 million at March 31, 2019 and December 31, 2018, respectively. Revolving Credit Facility Our credit agreement with JPMorgan Chase Bank, N.A., as administrative agent, and the other financial institutions party thereto ("Revolving Credit Facility") provides us with a $300.0 million funding commitment through December 2020. We had $300.0 million of borrowing availability under the Revolving Credit Facility at March 31, 2019, based on the borrowing base determination then in effect. At March 31, 2019, there were no borrowings under the Revolving Credit Facility and $8.0 million was being used to support outstanding letters of credit, leaving $292.0 million of net borrowing availability. The interest rate applicable to any overnight borrowings under the Revolving Credit Facility would have been 5.75% at March 31, 2019.

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2019
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 9 months. At March 31, 2019, our environmental accrual of $17.1 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 Loss

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Accumulated Other Comprehensive Loss

The following table presents the changes in the accumulated balances for each component of AOCI for each period presented (in millions of dollars):



	Quarter Ended
	March 31,
	2019			2018
Defined Benefit Pension Plan and Salaried VEBA:
Beginning balance	$	(35.6	)	$	(38.5	)
Amortization of net actuarial loss¹	0.1			0.2
Amortization of prior service cost¹	1.4			1.3
Less: income tax expense²	(0.4		)	(0.3		)
Net amortization reclassified from AOCI to Net income	1.1			1.2
Other comprehensive income, net of tax	1.1			1.2
Ending balance	$	(34.5	)	$	(37.3	)

Available for Sale Securities:
Beginning balance	$	0.3		$	0.9
Unrealized gain on available for sale securities	1.0			1.0
Less: income tax expense	(0.3		)	(0.2		)
Net unrealized gain on available for sale securities	0.7			0.8
Reclassification of unrealized gain upon sale of available for sale securities³	(1.2		)	(1.5		)
Less: income tax benefit²	0.3			0.5
Net gain reclassified from AOCI to Net income	(0.9		)	(1.0		)
Other comprehensive loss, net of tax	(0.2		)	(0.2		)
Ending balance	$	0.1		$	0.7

Cash Flow Hedges:
Beginning balance	$	(13.4	)	$	0.5
Unrealized gain (loss) on cash flow hedges	7.4			(12.2		)
Less: income tax (expense) benefit	(1.8		)	3.0
Net unrealized gain (loss) on cash flow hedges	5.6			(9.2		)
Reclassification of unrealized loss (gain) upon settlement of cash flow hedges⁴	4.2			(0.1		)
Less: income tax expense²	(1.0		)	—
Net loss (gain) reclassified from AOCI to Net income	3.2			(0.1		)
Other comprehensive income (loss), net of tax	8.8			(9.3		)
Ending balance	$	(4.6	)	$	(8.8	)

Foreign Currency Translation:
Beginning balance	$	(0.1	)	$	—
Other comprehensive income, net of tax	—			—
Ending balance	$	(0.1	)	$	—

Total AOCI ending balance	$	(39.1	)	$	(45.4	)

____________________


¹	Amounts amortized out of AOCI relating to Salaried VEBA adjustments were included within Other 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 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, 2019, we estimate a net mark-to-market loss before tax of $7.4 million in AOCI will be reclassified into Net income within the next 12 months.

Other Income, Net

3 Months Ended

Mar. 31, 2019

Other Income and Expenses [Abstract]

Other Income, Net

Other income, net, consisted of the following for each period presented (in millions of dollars):



	Quarter Ended
	March 31,
	2019			2018
Interest income	$	0.2		$	0.1
Net periodic postretirement benefit cost relating to Salaried VEBA	(1.6		)	(1.5		)
Realized gain on investments	1.2			1.6
All other income (expense), net	0.7			(0.1		)
Other income, net	$	0.5		$	0.1

Finance Leases

Operating Leases

Weighted-average lease term (in years):

Weighted-average discount rate: