Ak Steel Holding (AKS) 10-K 19 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 17, 2016	Jun. 30, 2015
Entity Information [Line Items]
Entity Registrant Name	AK STEEL HOLDING CORP
Entity Central Index Key	918,160
Trading Symbol	AKS
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		178,344,667
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 680,365,760

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net sales	$ 1,542.7	$ 1,709.9	$ 1,689.4	$ 1,750.9	$ 1,997.6	$ 1,593.8	$ 1,530.8	$ 1,383.5	$ 6,692.9	$ 6,505.7	$ 5,570.4
Cost of products sold (exclusive of items shown separately below)									6,032	6,007.7	5,107.8
Selling and administrative expenses (exclusive of items shown separately below)									261.9	247.2	205.3
Depreciation									216	201.9	190.1
Pension and OPEB expense (income) (exclusive of corridor charges shown below)									(63)	(92.5)	(68.6)
Pension and OPEB net corridor charge									131.2	2	0
Charge for facility idling									28.1	0	0
Total operating costs									6,606.2	6,366.3	5,434.6
Operating profit	(34.4)	80.2	7.1	33.8	74.5	63.7	36.5	(35.3)	86.7	139.4	135.8
Interest expense									173	144.7	127.4
Impairment of Magnetation investment				(256.3)					(256.3)	0	0
Impairment of AFSG investment									(41.6)	0	0
Other income (expense)									1.4	(21.1)	(1.4)
Income (loss) before income taxes									(382.8)	(26.4)	7
Income tax expense (benefit)									63.4	7.7	(10.4)
Net income (loss)									(446.2)	(34.1)	17.4
Less: Net income attributable to noncontrolling interests									62.8	62.8	64.2
Net income (loss) attributable to AK Steel Holding Corporation	$ (145.4)	$ 6.7	$ (64)	$ (306.3)	$ 13.5	$ (7.2)	$ (17.1)	$ (86.1)	$ (509)	$ (96.9)	$ (46.8)
Basic and diluted earnings per share:
Net income (loss) attributable to AK Steel Holding Corporation common stockholders (in dollars per share)	$ (0.82)	$ 0.04	$ (0.36)	$ (1.72)					$ (2.86)	$ (0.65)	$ (0.34)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net income (loss)	$ (446.2)	$ (34.1)	$ 17.4
Other comprehensive income (loss), before tax:
Foreign currency translation gain (loss)	(3.1)	(3.7)	1.2
Cash flow hedges:
Gains (losses) arising in period	(64.2)	(51.6)	3.5
Reclassification of losses (gains) to net income (loss)	61.4	1.1	(25.2)
Unrealized holding gains on securities:
Unrealized holding gains (losses) arising in period	0	0	0.2
Pension and OPEB plans:
Prior service credit (cost) arising in period	(7.7)	10.9	(6.1)
Gains (losses) arising in period	(60.8)	(422.5)	422.3
Reclassification of prior service cost (credits) included in net income (loss)	(60.2)	(68.9)	(76.2)
Reclassification of losses (gains) included in net income (loss)	165	6.9	25.3
Other comprehensive income (loss), before tax	30.4	(527.8)	345
Income tax expense in other comprehensive income (loss)	13.2	0	22.7
Other comprehensive income (loss)	17.2	(527.8)	322.3
Comprehensive income (loss)	(429)	(561.9)	339.7
Less: Comprehensive income attributable to noncontrolling interests	62.8	62.8	64.2
Comprehensive income (loss) attributable to AK Steel Holding Corporation	$ (491.8)	$ (624.7)	$ 275.5

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 56.6	$ 70.2
Accounts receivable, net	444.9	644.3
Inventory, net	1,226.3	1,172.1
Other current assets	78.4	71.4
Total current assets	1,806.2	1,958
Property, plant and equipment	6,466	6,388.4
Accumulated depreciation	(4,379.5)	(4,175.2)
Property, plant and equipment, net	2,086.5	2,213.2
Other non-current assets:
Investments in affiliates	70.7	388.7
Other non-current assets	121	268.1
TOTAL ASSETS	4,084.4	4,828
Current liabilities:
Accounts payable	703.4	803.1
Accrued liabilities	261.5	266.5
Current portion of pension and other postretirement benefit obligations	77.7	55.6
Total current liabilities	1,042.6	1,125.2
Non-current liabilities:
Long-term debt	2,354.1	2,422
Pension and other postretirement benefit obligations	1,146.9	1,225.3
Other non-current liabilities	136.4	132.5
TOTAL LIABILITIES	4,680	4,905
Equity (deficit):
Common stock, authorized 300,000,000 shares of $.01 par value each; issued 178,284,137 and 177,362,600 shares in 2015 and 2014; outstanding 177,893,562 and 177,215,816 shares in 2015 and 2014	1.8	1.8
Additional paid-in capital	2,266.8	2,259.1
Treasury stock, common shares at cost, 390,575 and 146,784 shares in 2015 and 2014	(2)	(1)
Accumulated deficit	(3,057)	(2,548)
Accumulated other comprehensive loss	(187.2)	(204.4)
Total stockholders' equity (deficit)	(977.6)	(492.5)
Noncontrolling interests	382	415.5
TOTAL EQUITY (DEFICIT)	(595.6)	(77)
TOTAL LIABILITIES AND EQUITY (DEFICIT)	4,084.4	4,828
Variable Interest Entity, Primary Beneficiary [Member] | SunCoke Middletown [Member]
Current assets:
Cash and cash equivalents	7.6	18.2
Inventory, net	19.8	29.6
Property, plant and equipment	421.5	420.1
Accumulated depreciation	(57.6)	(43.3)
Other assets (liabilities), net	(0.5)	(0.3)
Current liabilities:
Accounts payable	10.8	10.6
Equity (deficit):
Noncontrolling interests	380	413.7
Variable Interest Entity, Primary Beneficiary [Member] | Other Variable Interest Entities [Member]
Current assets:
Cash and cash equivalents	1.1	1
Property, plant and equipment	11.5	11.4
Accumulated depreciation	(9.4)	(9.3)
Other assets (liabilities), net	0.9	0.6
Equity (deficit):
Noncontrolling interests	$ 2	$ 1.8

CONSOLIDATED BALANCE SHEETS Par

CONSOLIDATED BALANCE SHEETS Parentheticals - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Common stock, shares authorized	300,000,000	300,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares issued	178,284,137	177,362,600
Common stock, shares outstanding	177,893,562	177,215,816
Treasury stock, shares	390,575	146,784

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ (446.2)	$ (34.1)	$ 17.4
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	216	201.9	190.1
Amortization	21.2	20.4	19.1
Impairment of Magnetation and AFSG investments	297.9	0	0
Deferred income taxes	62.1	8.2	(7.3)
Contributions to pension trust	(24.1)	(196.5)	(181.1)
Pension and OPEB expense (income)	(63)	(92.5)	(68.6)
Pension and OPEB net corridor charge	131.2	2	0
Affiliate (earnings) losses and distributions,net	19.7	9.8	11.3
Other operating items, net	(4.4)	6	(1.9)
Change in assets and liabilities, net of effect of acquired business:
Accounts receivable	228.1	33.8	(50.1)
Inventories	(53.8)	(223.4)	22.6
Accounts payable and other current liabilities	(139.7)	25.2	46.7
Charge for facility idling	28.1	0	0
Other assets	(7.6)	(8.2)	(4.7)
Pension obligations	(12.7)	(18.2)	(10)
Postretirement benefit obligations	(48.3)	(63.9)	(63.4)
Other liabilities	(1.1)	9.8	0.5
Net cash flows from operating activities	200.3	(322.8)	(110.2)
Cash flows from investing activities:
Capital investments	(99)	(81.1)	(63.6)
Investments in Magnetation LLC	0	(100)	(50)
Investments in acquired business, net of cash acquired	0	(690.3)	0
Proceeds from sale of equity investee	25	0	0
Proceeds from AFSG Holdings, Inc. distribution	14	0	0
Other investing items, net	12.5	13.6	15.1
Net cash flows from investing activities	(47.5)	(857.8)	(98.5)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility	(55)	515	90
Proceeds from issuance of long-term debt	0	427.1	31.9
Redemption of long-term debt	(14.1)	(0.8)	(27.4)
Proceeds from issuance of common stock	0	345.3	0
Debt issuance costs	0	(15.5)	(3.4)
SunCoke Middletown distributions to noncontrolling interest owners	(96.3)	(61)	(64.8)
Other financing items, net	(1)	(4.6)	0.7
Net cash flows from financing activities	(166.4)	1,205.5	27
Net increase (decrease) in cash and cash equivalents	(13.6)	24.9	(181.7)
Cash and cash equivalents, beginning of year	70.2	45.3	227
Cash and cash equivalents, end of year	56.6	70.2	45.3
Butler and Zanesville Works Retiree Healthcare Benefits Litigation [Member]
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Contributions to retirees VEBAs	(3.1)	(3.1)	(30.8)
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	201.7	187.6	176.1
SunCoke Middletown [Member]
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	14.3	14.3	14
Cash flows from financing activities:
SunCoke Middletown distributions to noncontrolling interest owners	$ (96.3)	$ (61)	$ (64.8)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2012	$ (91)	$ 1.5	$ 2,069.7	$ (173.3)	$ (2,404.3)	$ 1.1	$ 414.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	17.4				(46.8)		64.2
Share-based compensation	9.5		9.5
Purchase of treasury stock	(0.7)			(0.7)
Change in accumulated other comprehensive income (loss)	322.3					322.3
Net distributions to noncontrolling interests	(64.8)						(64.8)
Balance at Dec. 31, 2013	192.7	1.5	2,079.2	(174)	(2,451.1)	323.4	413.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(34.1)				(96.9)		62.8
Issuance of common stock	345.3	0.4	344.9
Retirement of treasury stock	0	(0.1)	(173.9)	174
Share-based compensation	8.9		8.9
Purchase of treasury stock	(1)			(1)
Change in accumulated other comprehensive income (loss)	(527.8)					(527.8)
Net distributions to noncontrolling interests	(61)						(61)
Balance at Dec. 31, 2014	(77)	1.8	2,259.1	(1)	(2,548)	(204.4)	415.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(446.2)				(509)		62.8
Share-based compensation	7.7		7.7
Purchase of treasury stock	(1)			(1)
Change in accumulated other comprehensive income (loss)	17.2					17.2
Net distributions to noncontrolling interests	(96.3)						(96.3)
Balance at Dec. 31, 2015	$ (595.6)	$ 1.8	$ 2,266.8	$ (2)	$ (3,057)	$ (187.2)	$ 382

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation: These financial statements consolidate the operations and accounts of AK Steel Holding Corporation (“AK Holding”), its wholly-owned subsidiary AK Steel Corporation (“AK Steel”), all subsidiaries in which AK Holding has a controlling interest, and two variable interest entities for which AK Steel is the primary beneficiary. Unless the context indicates otherwise, references to “we,” “us” and “our” refer to AK Holding and its subsidiaries. We also operate Mexican and European trading companies that buy and sell steel and steel products and other materials. We manage operations on a consolidated, integrated basis so that we can use the most appropriate equipment and facilities for the production of a product, regardless of product line. Therefore, we conclude that we operate in a single business segment. All intercompany transactions and balances have been eliminated. Use of Estimates: The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires the use of estimates and assumptions that affect the amounts reported. We base these estimates on historical experience and information available to us about current events and actions we may take in the future. Estimates and assumptions affect significant items that include the carrying value of long-lived assets, including investments and goodwill; valuation allowances for receivables, inventories and deferred income tax assets; legal and environmental liabilities; workers compensation and asbestos liabilities; share-based compensation; excess cost of operations; and assets and obligations of employee benefit plans. There can be no assurance that actual results will not differ from these estimates. Revenue Recognition: Revenue from sales of products is recognized at the time that title and the risks and rewards of ownership pass, which can be on the date of shipment or the date of receipt by the customer depending on when the terms of customers’ arrangements are met, the sales price is fixed or determinable, and collection is reasonably assured. Sales taxes collected from customers are recorded on a net basis with no revenue recognized. Cost of Products Sold: Cost of products sold consists primarily of raw materials, energy costs, supplies consumed in the manufacturing process, manufacturing labor, contract labor and direct overhead expense necessary to manufacture the finished steel product, as well as distribution and warehousing costs. Our share of the income (loss) of investments in associated companies accounted for under the equity method is included in costs of products sold since these operations are integrated with our overall steelmaking operations, except for our share of the income (loss) of Magnetation LLC, which is included in other income (expense). Share-Based Compensation: Compensation costs for stock awards granted under our Stock Incentive Plan are recognized over their vesting period using the straight-line method. Legal Fees: Legal fees associated with litigation and similar proceedings that are not expected to provide a benefit in future periods are generally expensed as incurred. Legal fees associated with activities that are expected to provide a benefit in future periods, such as costs associated with the issuance of debt, are generally capitalized as incurred. Income Taxes: Interest and penalties from uncertain tax positions are included in income tax expense. Deferred tax assets do not include certain amounts that arise from tax deductions from share-based compensation in excess of compensation recognized for financial reporting when net operating loss carryforwards are created. We use tax law ordering to determine when excess tax benefits have been realized. Earnings per Share: Earnings per share is calculated using the “two-class” method. Under the “two-class” method, undistributed earnings are allocated to both common shares and participating securities. We divide the sum of distributed earnings to common stockholders and undistributed earnings allocated to common stockholders by the weighted-average number of common shares outstanding during the period. The restricted stock granted by AK Holding is entitled to dividends before vesting and meets the criteria of a participating security. Cash Equivalents: Cash equivalents include short-term, highly-liquid investments that are readily convertible to known amounts of cash and have an original maturity of three months or less. Inventories: Inventories are valued at the lower of cost or market. We measure the cost of the majority of inventories on the last-in, first-out (LIFO) method. Other inventories are measured principally at average cost and consist mostly of foreign inventories and certain raw materials. Property, Plant and Equipment: Plant and equipment are depreciated under the straight-line method over their estimated lives. Estimated lives are as follows: land improvements over 20 years, leaseholds over the life of the lease, buildings over 40 years and machinery and equipment over two to 20 years. The estimated weighted-average life of our machinery and equipment is 12 years at the end of the current year. Costs incurred to develop coal mines are capitalized when incurred. We use the units-of-production method utilizing only proven and probable reserves in the depletion base to compute the depletion of coal reserves and mine development costs. We expense costs associated with major maintenance activities at our operating facilities in the period in which they occur. We review the carrying value of long-lived assets to be held and used and long-lived assets to be disposed of when events and circumstances warrant such a review. If the carrying value of a long-lived asset exceeds its fair value, an impairment has occurred and a loss is recognized based on the amount by which the carrying value exceeds the fair value, less cost to dispose, for assets to be sold or abandoned. We determine fair value by using quoted market prices, estimates based on prices of similar assets or anticipated cash flows discounted at a rate commensurate with risk. Investments: Investments in associated companies are accounted for under the equity method. We review investments for impairment when circumstances indicate that a loss in value below its carrying amount is other than temporary. Goodwill: Goodwill relates to our tubular business. We review goodwill for potential impairment at least annually on October 1 each year and whenever events or circumstances make it more likely than not that impairment may have occurred. Considering operating results and the estimated fair value of the business, the most recent annual goodwill impairment test indicated that the fair value of our tubular business reporting unit was in excess of its carrying value. No goodwill impairment was recorded as a result of the 2015 , 2014 and 2013 annual impairment tests. Debt Issuance Costs: Debt issuance costs for the revolving credit facility are included in other non-current assets and all other debt issuance costs reduce the carrying amount of long-term debt. Pension and Other Postretirement Benefits: We recognize, as of the measurement date, any unrecognized actuarial net gains or losses that exceed 10% of the larger of the projected benefit obligations or the plan assets, defined as the “corridor”. Amounts inside the corridor are amortized over the plan participants’ life expectancy. We determine the expected return on assets using the fair value of plan assets. Concentrations of Credit Risk: We are primarily a producer of carbon, stainless and electrical steels and steel products, which are sold to a number of markets, including automotive, industrial machinery and equipment, construction, power distribution and appliances. Net sales by product line are presented below: 2015 2014 2013 Carbon $ 4,746.8 $ 4,423.3 $ 3,643.4 Stainless and electrical 1,733.0 1,836.5 1,705.3 Tubular 201.3 231.4 220.7 Other 11.8 14.5 1.0 Total $ 6,692.9 $ 6,505.7 $ 5,570.4 Percentages of our net sales attributable to various markets are presented below: 2015 2014 2013 Automotive 60 % 53 % 51 % Infrastructure and Manufacturing 16 % 18 % 20 % Distributors and Converters 24 % 29 % 29 % We sell domestically to customers located primarily in the Midwestern and Eastern United States and to foreign customers, primarily in Canada, Mexico and Western Europe. Net sales to customers located outside the United States totaled $855.7 , $755.4 and $708.0 for 2015 , 2014 and 2013 . We had two customers that accounted for 12% and 11% of net sales in 2015 . No customer accounted for more than 10% of our net sales during 2014 and 2013 . Approximately 65% and 43% of accounts receivable outstanding at December 31, 2015 and 2014 , are due from businesses associated with the U.S. automotive industry, including 20% and 14% of receivables due from one automotive customer as of December 31, 2015 and 2014 . Except in a few situations where the risk warrants it, collateral is not required on accounts receivable. While we believe our recorded accounts receivable will be collected, in the event of default we would follow normal collection procedures. We maintain an allowance for doubtful accounts for the loss that would be incurred if a customer is unable to pay amounts due. We determine this allowance based on various factors, including the customer’s financial condition and changes in customer payment patterns. We write off accounts receivable against the allowance for doubtful accounts when it is remote that collection will occur. Union Contracts: At December 31, 2015 , we employed approximately 8,500 people, of which approximately 6,300 are represented by labor unions under various contracts that expire between 2016 and 2019 . On February 5, 2015, members of the United Steelworkers, Local 1190 , ratified a labor agreement covering approximately 215 production and maintenance employees at Mountain State Carbon, LLC. The new agreement took effect on March 1, 2015 and will expire on March 1, 2019 . This is the initial labor agreement with the union at Mountain State Carbon. On May 8, 2015, members of the United Auto Workers, Local 4104 , ratified a labor agreement covering approximately 140 production and maintenance employees at Zanesville Works. The new agreement took effect on May 20, 2015 and will expire on May 31, 2019 . An agreement with the United Auto Workers, Local 3462 , which represents approximately 330 employees at our Coshocton Works, is scheduled to expire on March 31, 2016 . An agreement with the United Auto Workers, Local 3303 , which represents approximately 1,240 employees at our Butler Works, is scheduled to expire on October 1, 2016 . Financial Instruments: We classify investments in equity securities as available-for-sale and carry them at fair value with unrealized gains and losses, net of tax, reported in other comprehensive income. Realized gains and losses on sales of available-for-sale securities are computed based upon initial cost adjusted for any other-than-temporary declines in fair value. We have no investments that are considered to be trading securities. We are a party to derivative instruments that are designated and qualify as hedges for accounting purposes. We may also use derivative instruments to which we do not apply hedge accounting treatment. Our objective in using these instruments is to protect earnings and cash flows from fluctuations in the fair value of selected commodities and currencies. Fluctuations in the price of certain commodities we use in production processes and in the selling price of certain commodity steel (hot roll carbon steel coils) may affect our income and cash flows. We have implemented raw material and energy surcharges for spot market customers and some contract customers. For certain commodities where such exposure exists, we may use cash-settled commodity price swaps, collars and purchase options, with a duration of up to three years, to hedge the price of a portion of our natural gas, iron ore, electricity, aluminum, zinc and nickel requirements or the selling price of hot roll carbon steel coils. We may designate some of these instruments as cash flow hedges and the effective portion of the changes in their fair value and settlements are recorded in accumulated other comprehensive income. Gains and losses are subsequently reclassified from accumulated other comprehensive income and recorded in cost of products sold or net sales in the same period as the earnings recognition of the associated underlying transaction. Other instruments are marked to market and recorded in cost of products sold or net sales with the offset recorded as current assets or accrued liabilities. In addition, exchange rate fluctuations on monies we receive from European subsidiaries and other customers invoiced in European currencies create cash flow and income statement risks. To reduce these risks, we have entered a series of agreements to sell euros in the future at fixed dollar rates. These forward contracts are entered with durations up to twenty-four months . A typical contract is used as a cash flow hedge for the period that begins when an order is taken and ends when a sale is recognized, at which time it converts into a fair value hedge of a receivable we collect in euros. We do not designate these derivatives as hedges for accounting purposes and we recognize the change in fair value as expense or income in other income (expense). We formally document all relationships between hedging instruments and hedged items, as well as risk management objectives and strategies for undertaking various hedge transactions. In this documentation, we specifically identify the asset, liability, firm commitment or forecasted transaction that has been designated as a hedged item, and state how the hedging instrument is expected to hedge the risks from that item. We formally measure effectiveness of hedging relationships both at the hedge inception and on an ongoing basis. We discontinue hedge accounting prospectively when we determine that the derivative is no longer effective in offsetting changes in the fair value or cash flows of a hedged item; when the derivative expires or is sold, terminated or exercised; when it is probable that the forecasted transaction will not occur; when a hedged firm commitment no longer meets the definition of a firm commitment; or when we determine that designation of the derivative as a hedge instrument is no longer appropriate. Our derivative contracts contain collateral funding requirements. We have master netting arrangements with counterparties, giving us the right to offset amounts owed under the derivative instruments and the collateral. We do not offset derivative assets and liabilities or collateral on our consolidated balance sheets. Asbestos and Environmental Accruals: For a number of years, we have been remediating sites where hazardous materials may have been released, including sites no longer owned by us. In addition, a number of lawsuits alleging asbestos exposure have been filed and continue to be filed against us. We have established accruals for estimated probable costs from asbestos claim settlements and environmental investigation, monitoring and remediation. If the accruals are not adequate to meet future claims, operating results and cash flows may be negatively affected. Our accruals do not consider the potential for insurance recoveries, for which we have partial insurance coverage for some future asbestos claims. In addition, some existing insurance policies covering asbestos and environmental contingencies may serve to partially reduce future covered expenditures. New Accounting Pronouncements: The Financial Accounting Standards Board issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) , during the second quarter of 2014. Topic 606, as further amended by subsequent Accounting Standard Updates, affects virtually all aspects of an entity’s revenue recognition, including determining the measurement of revenue and the timing of when it is recognized for the transfer of goods or services to customers. Topic 606 is effective for annual reporting periods beginning after December 15, 2017. We are currently evaluating the effect of the adoption of Topic 606 on our financial position and results of operations. The Financial Accounting Standards Board issued Accounting Standards Update No. 2015-02, Amendments to the Consolidation Analysis (“ASU 2015-02”), during the first quarter of 2015. ASU 2015-02 changes the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. ASU 2015-02 is effective for annual reporting periods beginning after December 15, 2015, unless early adoption is elected. We are currently evaluating the effect of the adoption of ASU 2015-02 on our financial position and results of operations, but we do not expect the adoption to have a material effect on our consolidated financial statements. In April 2015 and August 2015, the Financial Accounting Standards Board issued accounting guidance to simplify the presentation of debt issuance costs by requiring that debt issuance costs from a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. We elected to early adopt this guidance during 2015 on a retrospective basis. As a result, $24.8 of debt issuance costs was presented as a reduction of long-term debt as of December 31, 2015 and we reclassified $30.5 from other non-current assets to long-term debt as of December 31, 2014. In November 2015, the Financial Accounting Standards Board issued accounting guidance to simplify the presentation of deferred tax assets and liabilities by requiring that all amounts be presented in the balance sheet as noncurrent assets or liabilities. We elected to early adopt this guidance during 2015 on a retrospective basis. As a result, we reclassified $67.7 from other current assets to other non-current assets as of December 31, 2014. Reclassifications: We reclassified certain prior-year amounts to conform to the current-year presentation.

Supplementary Financial Stateme

Supplementary Financial Statement Information (Notes)	12 Months Ended
	Dec. 31, 2015
Supplementary Financial Statement Information [Abstract]
Supplementary Financial Statement Information	Supplementary Financial Statement Information Research and Development Costs We conduct a broad range of research and development activities aimed at improving existing products and manufacturing processes and developing new products and processes. Research and development costs, which are recorded as cost of products sold when incurred, totaled $27.6 , $17.5 and $13.2 in 2015 , 2014 and 2013 . Allowance for Doubtful Accounts Changes in the allowance for doubtful accounts for the years ended December 31, 2015 , 2014 and 2013 , are presented below: 2015 2014 2013 Balance at beginning of year $ 9.0 $ 8.1 $ 9.1 Increase (decrease) in allowance (3.0 ) 0.9 (0.4 ) Receivables written off — — (0.6 ) Balance at end of year $ 6.0 $ 9.0 $ 8.1 Inventory, net Inventories as of December 31, 2015 and 2014 , consist of: 2015 2014 Finished and semi-finished $ 996.5 $ 1,053.4 Raw materials 410.0 494.2 Total cost 1,406.5 1,547.6 Adjustment to state inventories at LIFO value (180.2 ) (375.5 ) Inventory, net $ 1,226.3 $ 1,172.1 There was no liquidation of LIFO layers in 2015 or 2014 . During 2013 , liquidation of LIFO layers generated income of $11.9 . Changes in the LIFO reserve for the years ended December 31, 2015 , 2014 and 2013 , are presented below: 2015 2014 2013 Balance at beginning of year $ 375.5 $ 396.5 $ 435.0 Change in reserve (195.3 ) (21.0 ) (38.5 ) Balance at end of year $ 180.2 $ 375.5 $ 396.5 Property, Plant and Equipment Property, plant and equipment as of December 31, 2015 and 2014 , consist of: 2015 2014 Land, land improvements and leaseholds $ 263.0 $ 260.7 Buildings 465.9 466.7 Machinery and equipment 5,628.2 5,571.0 Construction in progress 108.9 90.0 Total 6,466.0 6,388.4 Less accumulated depreciation (4,379.5 ) (4,175.2 ) Property, plant and equipment, net $ 2,086.5 $ 2,213.2 Interest on capital projects capitalized in 2015 , 2014 and 2013 was $2.1 , $2.7 and $2.7 . Asset retirement obligations were $6.6 and $6.0 at December 31, 2015 and 2014 . Other Non-current Assets Other non-current assets as of December 31, 2015 and 2014 , consist of: 2015 2014 Investment in AFSG Holdings, Inc. $ — $ 55.6 Goodwill 32.8 32.8 Deferred tax assets, non-current 62.7 138.0 Other 25.5 41.7 Other non-current assets $ 121.0 $ 268.1 Our investment in AFSG Holdings, Inc. (“AFSG”) represented the carrying value of our former insurance and finance leasing businesses, which have been largely liquidated. The activities of the remaining operating companies are being “run off”. We have no obligation to support the operations or liabilities of these companies. As part of our ongoing strategic review of our business and operations, we re-evaluated our investment in AFSG. During the fourth quarter of 2015, we received a distribution of $14.0 from AFSG. Since the distribution reduced our ability to recover our remaining investment in AFSG after the distribution, we determined our remaining investment in AFSG was impaired and recognized a non-cash charge of $41.6 , or $0.23 per diluted share. In the first quarter of 2016, an AFSG subsidiary entered into a stock purchase agreement to sell the remaining non-captive insurance operations, subject to certain customary closing conditions, including regulatory approval. Facility Idling In the fourth quarter of 2015, we temporarily idled the Ashland Works blast furnace and steelmaking operations. We incurred a $28.1 charge during the quarter, which included $22.2 for supplemental unemployment and other employee benefit costs and $5.9 for equipment idling and other costs. The supplemental unemployment and other employee benefit costs are expected to be paid in 2016 and are recorded as accrued liabilities at December 31, 2015 in the consolidated balance sheet. Beginning in the first quarter of 2016, we estimate we will incur on-going costs of approximately $2.0 to $3.0 per month for employees needed to maintain the equipment, utilities and supplier obligations related to the idled Ashland Works operations.

Acquisition of Dearborn (Notes)

Acquisition of Dearborn (Notes)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Acquisition of Dearborn	Acquisition of Dearborn On September 16, 2014 , we acquired Severstal Dearborn, LLC (“Dearborn”) from Severstal Columbus Holdings, LLC (“Severstal”). The assets acquired from Severstal included the integrated steelmaking assets located in Dearborn, Michigan (“Dearborn Works”), the Mountain State Carbon, LLC (“Mountain State Carbon”) cokemaking facility located in Follansbee, West Virginia, and interests in joint ventures that process flat-rolled steel products. The acquisition of Dearborn enhances and complements our business and operational strategies by positioning our carbon steelmaking operations close to our major northern automotive and other customers, expanding our platform to meet the increasing light-weighting demands of our automotive customers, and enhancing our operational flexibility. In addition, we acquired highly modernized and upgraded steelmaking equipment and facilities and the opportunity to achieve significant cost-based synergies. Immediately after the acquisition, Dearborn was merged with and into AK Steel. The final cash purchase price was $690.3 , net of cash acquired. We issued $430.0 of 7.625% Senior Notes due October 2021 at a price of 99.325% of par to pay part of the purchase price. We issued 40.25 million shares of AK Holding common stock at a price of $9.00 per share to pay the balance of the purchase price, to repay a portion of outstanding borrowings under our asset-backed revolving credit facility (“Credit Facility”) and for general corporate purposes. For the year ended December 31, 2014 , we incurred acquisition costs of $8.1 in selling and administrative expenses, primarily for transaction fees and direct costs, including legal, finance, consulting and other professional fees, and we incurred $12.6 of costs in other income (expense) for committed bridge financing that we arranged but did not use for the Dearborn acquisition. For the year ended December 31, 2014 , we incurred severance costs of $2.6 after the acquisition for certain employees of Dearborn in selling and administrative expenses and an income tax charge of $8.4 for changes in the value of deferred tax assets resulting from the acquisition. During the second quarter of 2015, we sold our 50.0% equity interest in Double Eagle Steel Coating Company (“Double Eagle”), which we acquired as part of the acquisition of Dearborn, for $25.0 in cash. The sale resolved a dispute with the other equity interest holder over the fair market value of our interest in Double Eagle. In July 2015, we received $25.0 from DTE Electric Company (“DTE”) to resolve a favorable administrative decision that concluded Dearborn Works had been overcharged for electricity for several years prior to our acquisition of that facility. Both of these matters resolved disputes that existed at the time of our acquisition of Dearborn. The purchase price allocation shown below reflects the updated estimates in value of these matters. Neither the proceeds from our sale of our equity interest in Double Eagle nor the proceeds from DTE had a material impact, individually or in the aggregate, on our results of operations for 2015 or the consolidated balance sheet at December 31, 2015. A summary of the final purchase price allocation for the fair value of the assets acquired and the obligations assumed at the date of the acquisition is presented below. Accounts receivable $ 180.6 Inventory 362.6 Other current assets 3.6 Property, plant and equipment 445.5 Investment in affiliates 72.5 Total assets acquired 1,064.8 Accounts payable (201.4 ) Accrued liabilities (32.8 ) Other postretirement benefit obligations (128.2 ) Other non-current liabilities (12.1 ) Total liabilities assumed (374.5 ) Purchase price, net of cash acquired $ 690.3 The consolidated financial statements reflect the effects of the acquisition and Dearborn’s financial results beginning September 16, 2014 . The net sales and operating profit (loss) attributable to Dearborn since the acquisition date and through December 31, 2014 were $567.0 and $12.2 , respectively. Assuming the acquisition had been completed at the beginning of 2014, unaudited pro forma net sales and operating profit (loss) for the full year ended December 31, 2014 were $7,942.7 and $ (816.2) , respectively, including charges for asset impairments of $1,005.1 recorded by Severstal before the acquisition. We included this selected unaudited pro forma consolidated financial data only for the purpose of illustration. Therefore, it does not necessarily indicate what the operating results would have been if the acquisition had been completed at the beginning of 2014. Moreover, this information does not indicate what our future operating results will be. This information includes net sales and operating profit (loss) attributable to Dearborn following the acquisition.

Investments in Affiliates (Note

Investments in Affiliates (Notes)	12 Months Ended
	Dec. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Investments in Affiliates	Investments in Affiliates We have investments in several businesses accounted for using the equity method of accounting. Investees and equity ownership percentages are presented below: Equity Ownership % Combined Metals of Chicago, LLC 40.0% Delaco Processing, LLC 49.0% Magnetation LLC 49.9% Rockport Roll Shop LLC 50.0% Spartan Steel Coating, LLC 48.0% Cost of products sold includes $6.7 , $11.7 and $8.1 in 2015 , 2014 and 2013 for our share of income of equity investees other than Magnetation LLC (“Magnetation”). Our share of loss from Magnetation through the first quarter of 2015 is included in other income (expense) and totaled $16.3 , $15.2 and $4.9 for 2015 , 2014 and 2013 . No amounts for Magnetation are included in our results after March 31, 2015, since the investment has been written off. As of December 31, 2015 , our carrying cost of our investment in Spartan Steel exceeded our share of the underlying equity in net assets by $13.9 . This difference is being amortized and is included in cost of products sold. Summarized financial statement data for all investees is presented below. The financial results for the acquired joint ventures are only included for the period since the acquisition and the financial results for Magnetation are only included through March 31, 2015, since it is unlikely that we will retain our equity interest as a result of Magnetation’s bankruptcy. 2015 2014 2013 Revenue $ 356.4 $ 386.1 $ 293.9 Gross profit 68.3 93.2 103.7 Net income (loss) (9.8 ) 10.8 20.1 2015 2014 Current assets $ 89.3 $ 211.8 Noncurrent assets 66.9 879.1 Current liabilities 14.5 157.1 Noncurrent liabilities 33.8 516.6 We regularly transact business with these equity investees. Transactions with all equity investees for the years indicated are presented below: 2015 2014 2013 Sales to equity investees $ 61.4 $ 93.4 $ 71.6 Purchases from equity investees 251.0 67.7 12.5 Outstanding receivables and payables with all equity investees as of the end of the year indicated are presented below: 2015 2014 Accounts receivable from equity investees $ 0.4 $ 2.5 Accounts payable to equity investees 33.1 10.9 Magnetation As of March 31, 2015, we concluded that our 49.9% equity interest in Magnetation was fully impaired and recorded a non-cash impairment charge of $256.3 for the quarter ended March 31, 2015. Key factors that affected our conclusion that an other-than-temporary impairment had occurred as of March 31, 2015, included (i) the significant market decline in global iron ore pellet pricing during the first quarter of 2015 and resulting negative cash flow effects on Magnetation’s results; (ii) a less favorable longer-term forecast of iron ore prices and resulting cash flow outlook for Magnetation; (iii) the likely loss of our equity interest in Magnetation if it filed for bankruptcy; and (iv) Magnetation’s existing capital structure and its inability to raise additional capital from third parties or the equity holders. Before March 31, 2015, we believed that the fair value of our interest in Magnetation exceeded its carrying amount and that despite near-term temporary pressures on liquidity, long-term cash flow projections of Magnetation were sufficient to allow us to recover our investment in Magnetation. During the quarter ended March 31, 2015, the near-term liquidity issues faced by Magnetation intensified due to a combination of an approximately 20.0% decline in the daily IODEX index and substantially lower IODEX futures pricing toward the end of the quarter, a slower-than-expected ramp-up of its pellet plant operations and resulting lower sales levels, payments due for construction overruns on the pellet and third concentrate plants, and higher-than-expected start-up and operating costs. Although Magnetation accomplished several actions in late 2014 and early 2015 to increase its liquidity, such liquidity enhancements and other cost reduction initiatives did not increase liquidity enough for it to withstand the significant market decline in iron ore pricing during the first quarter of 2015. Based on the outlook for iron ore prices at March 31, 2015, we concluded that prices could remain suppressed for the near future and it raised questions about the ability of Magnetation to operate profitably. In March 2015, Magnetation began discussions with certain debtholders to seek a solution to its liquidity issues. We also participated in those discussions but no acceptable restructuring was agreed upon. On May 5, 2015 , Magnetation and its subsidiaries filed voluntary petitions for relief under Chapter 11 of the Bankruptcy Code with the United States Bankruptcy Court for the District of Minnesota. Magnetation’s outstanding indebtedness is non-recourse to us. We are not required to make any additional capital contributions or other future investments in Magnetation and have not guaranteed any obligations of Magnetation. Because we consider it unlikely that we will retain an equity interest in Magnetation following Magnetation’s bankruptcy, we do not expect to record any further impact in our financial statements from our equity investment in Magnetation.

Income Taxes (Notes)

Income Taxes (Notes)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We and our subsidiaries file a consolidated federal income tax return that includes all domestic companies owned 80% or more by us and the proportionate share of our interest in equity method investments. State tax returns are filed on a consolidated, combined or separate basis depending on the applicable laws relating to us and our domestic subsidiaries. Components of income (loss) before income taxes are presented below: 2015 2014 2013 United States $ (452.1 ) $ (94.3 ) $ (61.1 ) Foreign 6.5 5.1 3.9 Noncontrolling interests 62.8 62.8 64.2 Income (loss) before income taxes $ (382.8 ) $ (26.4 ) $ 7.0 Significant components of deferred tax assets and liabilities at December 31, 2015 and 2014 are presented below: 2015 2014 Deferred tax assets: Net operating and capital loss and tax credit carryforwards $ 847.3 $ 778.1 Postretirement benefits 158.9 201.2 Pension benefits 278.6 258.6 Inventories 139.2 152.6 Other assets 132.8 114.2 Valuation allowance (1,215.5 ) (1,000.4 ) Total deferred tax assets 341.3 504.3 Deferred tax liabilities: Depreciable assets (248.0 ) (322.7 ) Other liabilities (30.6 ) (43.6 ) Total deferred tax liabilities (278.6 ) (366.3 ) Net deferred tax assets $ 62.7 $ 138.0 We regularly evaluate the need for a valuation allowance for deferred tax assets by assessing whether it is more likely than not that we will realize future deferred tax assets. We assess the valuation allowance each reporting period and reflect any additions or adjustments in earnings in the same period. When we assess the need for a valuation allowance, we consider both positive and negative evidence of the likelihood that we will realize deferred tax assets in each jurisdiction. In general, cumulative losses in recent periods provides significant objective negative evidence on our ability to generate future taxable income. As of December 31, 2015 and 2014 , we concluded that the negative evidence outweighed the positive evidence and we recorded a valuation allowance for a significant portion of our deferred tax assets. To determine the appropriate valuation allowance, we considered the timing of future reversal of our taxable temporary differences and available tax strategies that, if implemented, would result in realizing deferred tax assets. We identified the potential change from the LIFO inventory accounting method as such a tax-planning strategy. We believe that this strategy is prudent and feasible to use certain federal and state tax loss carryforwards before their expirations. In addition, we believe that the future reversal of our deferred tax liabilities serves as a source of taxable income that supports realizing a portion of our federal and state deferred tax assets. This accounting treatment has no effect on our ability to use the loss carryforwards and tax credits to reduce future cash tax payments. Federal net operating loss carryforwards do not begin to expire until 2023 and substantial amounts of those loss carryforwards have most of their 20-year life remaining before expiration. Changes in the valuation allowance for the years ended December 31, 2015 , 2014 and 2013 , are presented below: 2015 2014 2013 Balance at beginning of year $ 1,000.4 $ 764.1 $ 873.1 Change in valuation allowance: Included in income tax expense (benefit) 228.6 36.7 21.9 Change in deferred assets in other comprehensive income (13.5 ) 199.6 (130.9 ) Balance at end of year $ 1,215.5 $ 1,000.4 $ 764.1 At December 31, 2015 , we had $2,372.3 in federal regular net operating loss carryforwards and $2,672.8 in federal alternative minimum tax (“AMT”) net operating loss carryforwards, which will expire between 2023 and 2035 . At December 31, 2015 , we had unused AMT credit carryforwards of $17.7 and research and development (“R&D”) credit carryforwards of $1.2 . We may use the loss and credit carryforwards to offset future regular and AMT income tax liabilities. We may carry unused AMT credits forward indefinitely and the R&D credits don’t begin to expire until 2027 . At December 31, 2015 , we had $77.4 in deferred tax assets before considering valuation allowances for state net operating loss carryforwards and tax credit carryforwards, which will expire between 2016 and 2035 . As of December 31, 2015 , there were $21.3 of unrecognized deferred tax assets from tax deductions for share-based compensation in excess of compensation recognized for financial reporting when net operating loss carryforwards were created. When we realize the deferred tax assets, we will increase additional paid-in capital. We had undistributed earnings of foreign subsidiaries of approximately $38.2 at December 31, 2015 . Since we consider these earnings to be permanently invested in our foreign subsidiaries, we did not record deferred taxes for them. If we repatriated the earnings, we estimate that the additional tax expense would be approximately $13.4 before considering the effects on the valuation allowance. Significant components of income tax expense (benefit) are presented below: 2015 2014 2013 Current: Federal $ — $ — $ (3.4 ) State 0.2 (1.1 ) 0.2 Foreign 1.8 2.1 1.9 Deferred: Federal 68.8 7.7 14.0 State 6.5 0.2 1.2 Amount allocated to other comprehensive income (13.2 ) — (22.7 ) Change in valuation allowance on beginning-of-the-year deferred tax assets (0.7 ) (1.2 ) (1.6 ) Income tax expense (benefit) $ 63.4 $ 7.7 $ (10.4 ) The reconciliation of income tax on income (loss) before income taxes computed at the U.S. federal statutory tax rates to actual income tax expense (benefit) is presented below: 2015 2014 2013 Income tax expense (benefit) at U.S. federal statutory rate $ (134.0 ) $ (9.2 ) $ 2.4 Income tax expense calculated on noncontrolling interests (22.0 ) (22.0 ) (22.5 ) State and foreign tax expense, net of federal tax (0.9 ) (3.1 ) 1.7 Increase in deferred tax asset valuation allowance 228.6 36.7 21.9 Amount allocated to other comprehensive income (13.2 ) — (22.7 ) Change in accrual for uncertain tax positions 0.3 (0.9 ) (1.7 ) Stock compensation in excess of tax deduction — 2.0 3.1 Expiration of charitable contribution carryforwards — — 2.5 Other permanent differences 4.6 4.2 4.9 Income tax expense (benefit) $ 63.4 $ 7.7 $ (10.4 ) Our federal, state and local tax returns are subject to examination by various taxing authorities. Federal returns for periods beginning in 2012 are open for examination, while certain state and local returns are open for examination for periods beginning in 2007 . However, taxing authorities have the ability to adjust net operating loss carryforwards generated in years before these periods. We have not recognized certain tax benefits because of the uncertainty of realizing the entire value of the tax position taken on income tax returns until taxing authorities review them. We have established appropriate income tax accruals, and believe that the outcomes of future federal examinations as well as ongoing and future state and local examinations will not have a material adverse impact on our financial position, results of operations or cash flows. When statutes of limitations expire or taxing authorities resolve uncertain tax positions, we will adjust income tax expense for the unrecognized tax benefits. We have no tax positions for which it is reasonably possible that the total amounts of unrecognized tax benefits will significantly change within twelve months of December 31, 2015 . A reconciliation of the change in unrecognized tax benefits for 2015 , 2014 and 2013 is presented below: 2015 2014 2013 Balance at beginning of year $ 59.9 $ 53.8 $ 54.0 Increases (decreases) for prior year tax positions (0.3 ) (0.2 ) (0.8 ) Increases (decreases) for current year tax positions 70.7 7.7 0.9 (Decreases) from statute lapses — (1.4 ) (0.3 ) Balance at end of year $ 130.3 $ 59.9 $ 53.8 Included in the balance of unrecognized tax benefits at December 31, 2015 and 2014 , are $111.6 and $41.6 of tax benefits that, if recognized, would affect the effective tax rate. Also included in the balance of unrecognized tax benefits at December 31, 2015 and 2014 , are $18.7 and $18.4 of tax benefits that, if recognized, would result in adjustments to other tax accounts, primarily deferred taxes.

Long-term Debt and Other Financ

Long-term Debt and Other Financing (Notes)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Long-term Debt and Other Financing	Long-term Debt and Other Financing Debt balances, including current portions, at December 31, 2015 and 2014 , are presented below: 2015 2014 Credit Facility $ 550.0 $ 605.0 8.75% Senior Secured Notes due December 2018 380.0 380.0 5.00% Exchangeable Senior Notes due November 2019 (effective rate of 10.8%) 150.0 150.0 7.625% Senior Notes due May 2020 529.8 529.8 7.625% Senior Notes due October 2021 406.2 430.0 8.375% Senior Notes due April 2022 290.2 290.2 Industrial Revenue Bonds due 2020 through 2028 99.3 99.3 Unamortized debt discount/premium and debt issuance costs (51.4 ) (62.3 ) Total long-term debt $ 2,354.1 $ 2,422.0 During the period, we were in compliance with all the terms and conditions of our debt agreements. Maturities of long-term debt, including the amount outstanding on the Credit Facility, for the next five years, at December 31, 2015 , are presented below: Year Debt Maturities 2016 $ — 2017 — 2018 380.0 2019 (including $550.0 of Credit Facility borrowings) 700.0 2020 537.1 Credit Facility We have a $1,500.0 Credit Facility, which expires in March 2019 and is guaranteed by AK Steel’s parent company, AK Holding, and by AK Tube LLC (“AK Tube”) and AK Steel Properties, Inc. (“AK Properties”), two 100%-owned subsidiaries of AK Steel. The Credit Facility contains common restrictions, including limitations on, among other things, distributions and dividends, acquisitions and investments, indebtedness, liens and affiliate transactions. The Credit Facility requires that we maintain a minimum fixed charge coverage ratio of one to one if availability under the Credit Facility is less than $150.0 . The Credit Facility’s current availability significantly exceeds $150.0 . Availability is calculated as the lesser of the Credit Facility commitment or our eligible collateral after advance rates, less in either case outstanding borrowings and letters of credit. We secure our Credit Facility obligations with our inventory and accounts receivable, and the Credit Facility’s availability fluctuates monthly based on the varying levels of eligible collateral. We do not expect any of these restrictions to affect or limit our ability to conduct business in the ordinary course. The Credit Facility includes a separate “first-in, last-out”, or “FILO” tranche, which allows us to use a portion of our eligible collateral at higher advance rates. At December 31, 2015 , our eligible collateral, after application of applicable advance rates, was $1,275.2 . As of December 31, 2015 , there were outstanding borrowings of $550.0 . Availability as of December 31, 2015 was further reduced by $72.9 attributable to outstanding letters of credit, resulting in remaining availability of $652.3 . The weighted-average interest rate on the outstanding borrowings at December 31, 2015 and 2014 was 2.1% and 2.2% . Senior Secured Notes AK Steel has outstanding $380.0 aggregate principal amount of 8.75% Senior Secured Notes due December 2018 (the “Secured Notes”). Substantially all property, plant and equipment of AK Steel are pledged as collateral for the Secured Notes. AK Holding, AK Tube and AK Properties each fully and unconditionally, jointly and severally, guarantees the payment of interest, principal and premium, if any, on the Secured Notes. The book value of the collateral as of December 31, 2015 was approximately $1.6 billion . The indenture governing the Secured Notes includes covenants with customary restrictions on (a) the incurrence of additional debt by certain subsidiaries, (b) the incurrence of certain liens, (c) the amount of sale/leaseback transactions, (d) the use of proceeds from the sale of collateral, and (e) our ability to merge or consolidate with other entities or to sell, lease or transfer all or substantially all of our assets to another entity. The Secured Notes also contain customary events of default. We may redeem the Secured Notes at a price equal to 104.375% of par until December 1, 2016, then at a price of 102.188% until December 1, 2017, and 100.0% thereafter, together with all accrued and unpaid interest to the date of redemption. Exchangeable Notes AK Steel has $150.0 of outstanding 5.0% Exchangeable Senior Notes due November 2019 (the “Exchangeable Notes”). We may not redeem the Exchangeable Notes before their maturity date. The indenture governing the Exchangeable Notes (the “Exchangeable Notes Indenture”) provides noteholders with an exchange right at their option before August 15, 2019, if the closing price of our common stock is greater than or equal to $7.02 per share ( 130% of the exchange price of the Exchangeable Notes) for at least 20 trading days during the last 30 consecutive trading days of a calendar quarter. On or after August 15, 2019, holders may exchange their Exchangeable Notes at any time. Upon exchange, we will be obligated to (i) pay an amount in cash equal to the aggregate principal amount of the Exchangeable Notes to be exchanged and (ii) at our election, pay cash, deliver shares of AK Holding common stock or a combination for any remaining exchange obligation in excess of the aggregate principal amount of the Exchangeable Notes being exchanged. Holders may exchange their Exchangeable Notes into shares of AK Holding common stock at their option at an initial exchange rate of 185.1852 shares of AK Holding common stock per $1,000 principal amount of Exchangeable Notes. The initial exchange rate is equivalent to a conversion price of approximately $5.40 per share of common stock, which equates to 27.8 million shares to be used to determine the aggregate equity consideration to be delivered upon exchange, which could be adjusted for certain dilutive effects from potential future events. Holders may exchange their Exchangeable Notes before August 15, 2019 only under certain circumstances. The Exchangeable Notes Indenture does not contain any financial or operating covenants or restrict us or our subsidiaries from paying dividends, incurring debt or issuing or repurchasing securities. If we undergo a fundamental change, as defined in Exchangeable Notes Indenture (which, for example, would include various transactions in which we would undergo a change of control), holders may require us to repurchase the Exchangeable Notes in whole or in part for cash at a price equal to par plus any accrued and unpaid interest. In addition, if we undergo a “make-whole fundamental change,” as defined in the Exchangeable Notes Indenture, before the maturity date, in addition to requiring us to repurchase the Exchangeable Notes in whole or in part for cash at a price equal to par plus any accrued and unpaid interest, the exchange rate will be increased in certain circumstances for a holder who elects to exchange its notes in connection with the event. Based on the initial exchange rate, the Exchangeable Notes are exchangeable into a maximum of 37.5 million shares of AK Holding common stock. However, we would only deliver the maximum amount of shares if, following a “make-whole fundamental change” described above, we elect to deliver the shares to satisfy the higher exchange rate. Although the Exchangeable Notes were issued at par, for accounting purposes the proceeds received from the issuance of the notes are allocated between debt and equity to reflect the fair value of the exchange option embedded in the notes and the fair value of similar debt without the exchange option. Therefore, we recorded $38.7 of the gross proceeds of the Exchangeable Notes as an increase in additional paid-in capital with the offsetting amount recorded as a debt discount. We are amortizing the debt discount over the term of the Exchangeable Notes using the effective interest method. As of December 31, 2015 and 2014 , the remaining unamortized debt discount was $24.9 and $29.9 and the net carrying amount of the Exchangeable Notes was $125.1 and $120.1 . Senior Unsecured Notes AK Steel has outstanding 7.625% Senior Notes due May 2020 (the “2020 Notes”). We may redeem the 2020 Notes at a price equal to 103.813% of par until May 15, 2016, 102.542% thereafter until May 15, 2017, 101.271% thereafter until May 15, 2018, and 100.0% thereafter, together with all accrued and unpaid interest to the date of redemption. AK Steel has outstanding 7.625% Senior Notes due October 2021 (the “2021 Notes”). The 2021 Notes were issued under a supplemental indenture, which includes covenants and restrictions substantially similar to the existing indentures governing the 7.625% Senior Notes due 2020 and the 8.375% Senior Notes due 2022 and are equal in right of payment to those notes. Before October 1, 2017, we may redeem the 2021 Notes at a price equal to par plus a make-whole premium and all accrued and unpaid interest to the date of redemption. After that date, they are redeemable at 103.813% until October 1, 2018, 101.906% thereafter until October 1, 2019, and 100.0% thereafter, together with all accrued and unpaid interest to the date of redemption. AK Steel’s outstanding 8.375% Senior Notes are due April 2022 (the “2022 Notes”). Before April 1, 2017, we may redeem the 2022 Notes at a price equal to par plus a make-whole premium and all accrued and unpaid interest to the date of redemption. After that date, they are redeemable at 104.188% until April 1, 2018, 102.792% thereafter until April 1, 2019, 101.396% thereafter until April 1, 2020, and 100.0% thereafter, together with all accrued and unpaid interest to the date of redemption. The Exchangeable Notes, the 2020 Notes, the 2021 Notes, the 2022 Notes and the unsecured IRBs discussed below (collectively, the “Senior Unsecured Notes”) are equal in right of payment. AK Holding, AK Tube and AK Properties each fully and unconditionally, jointly and severally, guarantees the payment of interest, principal and premium, if any, on the Senior Unsecured Notes. The indentures governing the 2020 Notes, the 2021 Notes, the 2022 Notes and the unsecured IRBs include covenants with customary restrictions on (a) the incurrence of additional debt by certain subsidiaries, (b) the incurrence of certain liens, (c) the amount of sale/leaseback transactions, and (d) our ability to merge or consolidate with other entities or to sell, lease or transfer all or substantially all of our assets to another entity. The indentures governing the Senior Unsecured Notes also contain customary events of default. The Senior Unsecured Notes rank junior in priority to the Secured Notes to the extent of the value of the assets securing the Secured Notes. During 2015, we repurchased an aggregate principal amount of $23.8 of the 2021 Notes in private, open market transactions. These repurchases were unsolicited and completed at a discount to the notes’ par values. We recognized gains on the repurchases of $9.4 for the year ended December 31, 2015, which is included in other income (expense). We may, from time to time, repurchase additional outstanding notes in the open market on an unsolicited basis, by tender offer, through privately negotiated transactions or otherwise. During 2013, we repurchased an aggregate principal amount of $20.2 and $9.8 of the 2020 Notes and the 2022 Notes, respectively, in private, open market transactions. These repurchases were unsolicited and completed at a discount to the notes’ par values. We recognized a gain on the repurchases of $2.9 for the year ended December 31, 2013, which is included in other income (expense). Other Financings AK Steel has outstanding $73.3 aggregate principal amount of fixed-rate tax-exempt industrial revenue bonds (the “unsecured IRBs”) at December 31, 2015 . The weighted-average fixed interest rate of the unsecured IRBs is 6.8% . The unsecured IRBs are unsecured senior debt obligations of AK Steel that are equal in ranking with the other Senior Unsecured Notes. In addition, AK Steel has outstanding $26.0 aggregate principal amount of variable-rate taxable industrial revenue bonds at December 31, 2015 , that are backed by letters of credit. In 1997, the Spencer County (IN) Redevelopment District (the “District”) issued $23.0 in taxable tax increment revenue bonds with our construction of Rockport Works. We used the bond issue’s proceeds to acquire land and improve the facility. The source of the District’s scheduled principal and interest payments through maturity in 2017 is a designated portion of our real and personal property tax payments. We are obligated to pay any deficiency if our annual tax payments are insufficient to enable the District to make principal and interest payments when due. In 2015 , we made deficiency payments totaling $1.3 . At December 31, 2015 , the remaining payments of principal and interest due through the year 2017 total $10.4 . We include potential payments due in the coming year under this agreement in our annual property tax accrual.

Pension and Other Postretiremen

Pension and Other Postretirement Benefits (Notes)	12 Months Ended
	Dec. 31, 2015
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Pension and Other Postretirement Benefits	Pension and Other Postretirement Benefits Summary We provide noncontributory pension and various healthcare and life insurance benefits to a significant portion of our employees and retirees. Benefits are provided through defined benefit and defined contribution plans that we administer, as well as multiemployer plans for certain union members. The pension plan is not fully funded. We contributed $24.1 to the pension plan in 2015 and have no required contribution for 2016 . Based on current actuarial assumptions, we estimate that our required pension contributions will be approximately $50.0 and $75.0 in 2017 and 2018 , though the amounts we will be required to pay are more dependent on plan asset returns than in the past. In July 2015, we paid the final payment of $3.1 to a Voluntary Employees Beneficiary Association (“VEBA”) trust for a settlement of other postretirement benefit (“OPEB”) obligations with certain retirees from our Zanesville Works. We expect to make OPEB payments, after receipt of Medicare subsidy reimbursements, of approximately $46.5 in 2016 . Plan Obligations Amounts presented below are calculated based on benefit obligation and asset valuation measurement dates of December 31, 2015 and 2014 . Pension Benefits Other Benefits 2015 2014 2015 2014 Change in benefit obligations: Benefit obligations at beginning of year $ 3,545.2 $ 3,380.6 $ 599.3 $ 479.2 Service cost 2.2 1.7 7.1 4.9 Interest cost 130.0 146.0 22.5 21.7 Plan participants’ contributions — — 24.9 25.4 Actuarial loss (gain) (147.8 ) 432.1 (83.3 ) 45.1 Amendments 13.3 2.0 (5.6 ) (12.8 ) Dearborn acquisition — — — 128.2 Contributions to Zanesville retirees’ VEBA trust — — (3.1 ) (3.1 ) Benefits paid (295.1 ) (416.6 ) (76.5 ) (96.6 ) Medicare subsidy reimbursement received — — 3.3 7.3 Foreign currency exchange rate changes (0.4 ) (0.6 ) — — Benefit obligations at end of year $ 3,247.4 $ 3,545.2 $ 488.6 $ 599.3 Change in plan assets: Fair value of plan assets at beginning of year $ 2,863.6 $ 2,808.5 $ — $ — Actual gain (loss) on plan assets (93.6 ) 257.8 — — Employer contributions 36.5 213.9 48.3 63.9 Plan participants’ contributions — — 24.9 25.4 Benefits paid (295.1 ) (416.6 ) (76.5 ) (96.6 ) Medicare subsidy reimbursement received — — 3.3 7.3 Fair value of plan assets at end of year $ 2,511.4 $ 2,863.6 $ — $ — Funded status $ (736.0 ) $ (681.6 ) $ (488.6 ) $ (599.3 ) Amounts recognized in the consolidated balance sheets: Current liabilities $ (31.2 ) $ (2.1 ) $ (46.5 ) $ (53.5 ) Noncurrent liabilities (704.8 ) (679.5 ) (442.1 ) (545.8 ) Total $ (736.0 ) $ (681.6 ) $ (488.6 ) $ (599.3 ) Amounts recognized in accumulated other comprehensive income, before tax: Actuarial loss (gain) $ 323.5 $ 355.7 $ (48.8 ) $ 23.1 Prior service cost (credit) 25.1 16.3 (199.0 ) (258.1 ) Total $ 348.6 $ 372.0 $ (247.8 ) $ (235.0 ) The accumulated benefit obligation for all defined benefit pension plans was $3,222.0 and $3,513.7 at December 31, 2015 and 2014 . All our pension plans have an accumulated benefit obligation in excess of plan assets. The amounts included in current liabilities represent only the amounts of our unfunded pension and OPEB benefit plans that we expect to pay in the next year. During 2015, we updated the major demographic assumptions we use to determine our pension and OPEB obligations after examining the recent experience among the plans’ participants. Included in the 2015 actuarial loss (gain) in the table above were actuarial gains of approximately $7.0 and $58.0 for the changes in demographic assumptions on pension benefits and other postretirement benefits, respectively. During 2014, we offered a voluntary lump-sum settlement to terminated vested participants in the pension plan, which reduced a portion of the pension obligation. The pension plan paid approximately $105.0 in December 2014 out of the pension trust assets to participants and recognized an actuarial gain of $20.0 . As a result of new mortality tables issued in October 2014 by the Society of Actuaries, we revised our mortality assumptions in 2014, which significantly increased our pension and OPEB obligations. The new mortality assumptions increased the assumed life expectancy of participants in our benefit plans, increasing the total expected benefit payments over a longer time horizon. Included in the 2014 actuarial loss (gain) in the table above were $233.5 and $12.0 for the change in the mortality tables on pension benefits and other postretirement benefits, respectively. The actuarial loss (gain) for pension benefits also included a $25.8 out-of-period adjustment to reduce the benefit obligation for a correction of census data used in the 2013 financial results. The effects of this adjustment were not material to the financial position or results of operations in any of the periods presented. Assumptions used to value benefit obligations and determine pension and OPEB expense (income) are presented below: Pension Benefits Other Benefits 2015 2014 2013 2015 2014 2013 Assumptions used to determine benefit obligations at December 31: Discount rate 4.15 % 3.82 % 4.53 % 4.22 % 3.90 % 4.48 % Rate of compensation increase 4.00 % 4.00 % 4.00 % 4.00 % 4.00 % 4.00 % Subsequent year healthcare cost trend rate 7.00 % 7.00 % 7.00 % Ultimate healthcare cost trend rate 4.50 % 4.50 % 4.50 % Year ultimate healthcare cost trend rate begins 2024 2020 2019 Assumptions used to determine pension and OPEB expense (income) for the year ended December 31: Discount rate 3.82 % 4.53 % 3.85 % 3.90 % 4.48 % 3.77 % Expected return on plan assets 7.25 % 7.25 % 7.25 % Rate of compensation increase 4.00 % 4.00 % 4.00 % 4.00 % 4.00 % 4.00 % We determined the discount rate by finding a hypothetical portfolio of individual high-quality corporate bonds available at the measurement date with coupon and principal payments that could satisfy the plans’ expected future benefit payments that we use to calculate the projected benefit obligation. The discount rate is the single rate that is equivalent to the average yield on that hypothetical portfolio of bonds. Assumed healthcare cost trend rates generally have a significant effect on the amounts reported for healthcare plans. However, caps on the share of OPEB obligations that we pay limit the effect of changes in OPEB assumptions. As of December 31, 2015 , a one-percentage-point change in the assumed healthcare cost trend rates would have the following effects: One Percentage Point Increase Decrease Effect on total service cost and interest cost components $ 0.1 $ (0.1 ) Effect on postretirement benefit obligation 3.3 (3.1 ) Estimated future benefit payments to beneficiaries are presented below: Pension Plans Other Benefits Medicare Subsidy 2016 $ 330.4 $ 47.9 $ (1.4 ) 2017 293.0 44.8 (1.4 ) 2018 279.1 42.6 (1.5 ) 2019 272.0 40.8 (1.5 ) 2020 259.0 39.0 (1.5 ) 2021 through 2025 1,159.6 171.7 (9.1 ) Plan Assets Our investments in the master pension trust primarily include indexed and actively-managed funds. A fiduciary committee sets the target asset mix and monitors asset performance. We determine the master pension trust’s projected long-term rate of return based on the asset allocation, the trust’s investment policy statement and our long-term capital market return assumptions for the master trust. We have developed an investment policy which considers liquidity requirements, expected investment return and expected asset risk, as well as standard industry practices. The target asset allocation for the plan assets is 60% equity, 38% fixed income, and 2% cash. Equity investments consist of individual securities and common/collective trusts with equity investment strategies diversified across multiple industry sectors and company market capitalization within specific geographical investment strategies. Fixed income investments consist of individual securities and common/collective trusts, which invest primarily in investment-grade and high-yield corporate bonds and U.S. treasury securities. The common/collective trusts have no unfunded commitments or redemption restrictions. The fixed income investments are diversified by ratings, maturities, industries and other factors. Plan assets contain no significant concentrations of risk from individual securities or industry sectors. The plan has no direct investments in our common stock or fixed income securities. Plan investments measured at fair value on a recurring basis at December 31, 2015 and 2014 , are presented below by level within the fair value hierarchy. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Activity for Level 3 assets was insignificant for 2015 and 2014 . See Note 16 for more information on the determination of fair value. Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs (Level 1) (Level 2) (Level 3) Total 2015 2014 2015 2014 2015 2014 2015 2014 Equity Investments: U.S. securities $ 138.4 $ 199.4 $ — $ — $ — $ — $ 138.4 $ 199.4 U.S. common/collective trusts — — 814.5 862.4 — — 814.5 862.4 EAFE common/collective trusts — — 261.5 272.9 — — 261.5 272.9 Emerging market common/collective trusts — — 103.9 125.7 — — 103.9 125.7 Global investments — — 179.6 210.7 — — 179.6 210.7 Fixed Income Investments: U.S. investment-grade corporate common/collective trusts — — 391.0 421.8 — — 391.0 421.8 U.S. treasuries common/collective trusts — — 85.3 98.4 — — 85.3 98.4 Mortgage-backed common/collective trusts — — — 18.0 — — — 18.0 Global investments — — 389.7 435.4 — — 389.7 435.4 U.S. high-yield corporate securities — — 109.7 178.4 — — 109.7 178.4 Other Investments: Private equity funds (a) — — — — 0.5 0.9 0.5 0.9 Cash and cash equivalents 37.3 39.6 — — — — 37.3 39.6 Total $ 175.7 $ 239.0 $ 2,335.2 $ 2,623.7 $ 0.5 $ 0.9 $ 2,511.4 $ 2,863.6 (a) Consists of private equity funds that have no remaining capital commitments. Periodic Benefit Costs Components of pension and OPEB expense (income) for the years 2015 , 2014 and 2013 are presented below: Pension Benefits Other Benefits 2015 2014 2013 2015 2014 2013 Components of pension and OPEB expense (income): Service cost $ 2.2 $ 1.7 $ 2.4 $ 7.1 $ 4.9 $ 4.7 Interest cost 130.0 146.0 138.8 22.5 21.7 21.0 Expected return on plan assets (198.4 ) (202.8 ) (184.5 ) — — — Amortization of prior service cost (credit) 4.4 4.3 3.8 (64.6 ) (73.2 ) (80.0 ) Recognized net actuarial loss (gain): Annual amortization 31.2 2.5 23.6 1.6 (1.3 ) 2.4 Corridor charge (credit) 144.3 2.0 — (13.1 ) — — Settlement (gain) loss 1.0 0.2 (0.8 ) — 3.5 — Pension and OPEB expense (income) $ 114.7 $ (46.1 ) $ (16.7 ) $ (46.5 ) $ (44.4 ) $ (51.9 ) In January 2011, we reached a final settlement agreement (the “Butler Retiree Settlement”) of a class action filed on behalf of certain retirees from our Butler Works for our OPEB obligations to such retirees. We agreed to continue to provide company-paid health and life insurance to class members through December 31, 2014, and made combined lump sum payments totaling $91.0 to a VEBA trust and to plaintiffs’ counsel, with the final payment made in 2013. Effective January 1, 2015, we transferred to the VEBA trust all OPEB obligations owed to the class members under our applicable health and welfare plans and have no further liability for OPEB benefits after December 31, 2014. For accounting purposes, a settlement of our OPEB obligations occurred when we made the final benefit payments in 2014 and a settlement loss of $3.5 was recorded in 2014. In December 2012, we reached a final settlement agreement (the “Zanesville Retiree Settlement”) of a class action filed on behalf of certain retirees from our Zanesville Works for our OPEB obligations to such retirees. We agreed to continue to provide company-paid health and life insurance to class members through December 31, 2015, and to make combined lump sum payments totaling $10.6 to a VEBA trust and to plaintiffs’ counsel over three years. We made the final payment to the Zanesville VEBA trust of $3.1 in 2015. Effective January 1, 2016, we transferred to the VEBA trust all OPEB obligations owed to the class members under our applicable health and welfare plans and have no further liability for OPEB benefits after December 31, 2015. During 2015, 2014 and 2013, we performed remeasurements of an unfunded supplemental retirement plan and recognized settlement (gains) losses as a result of lump sum benefit payments made to retired participants. Pension and OPEB expense (income) for the defined benefit pension plans over the next year will include amortization of $27.9 of the unrealized net loss and $5.2 from the prior service cost in accumulated other comprehensive income. Pension and OPEB expense (income) for the other postretirement benefit plans over the next fiscal year will include amortization of $(4.3) of the unrealized net gain and $(60.3) from the prior service credit in accumulated other comprehensive income. Defined Contribution Plans All employees are eligible to participate in various defined contribution plans. Certain of these plans have features with matching contributions or other company contributions based on our financial results. Total expense from these plans was $14.5 , $12.1 and $11.5 in 2015 , 2014 and 2013 . Multiemployer Plans We contribute to multiemployer pension plans according to collective bargaining agreements that cover certain union-represented employees. The following risks of participating in these multiemployer plans differ from single employer plans: • Employer contributions to a multiemployer plan may be used to provide benefits to employees of other participating employers. • If a participating employer stops contributing to a multiemployer plan, the remaining participating employers may need to assume the unfunded obligations of the plan. • If the plan becomes significantly underfunded or is unable to pay its benefits, we may be required to contribute additional amounts in excess of the rate required by the collective bargaining agreements. • If we choose to stop participating in a multiemployer plan, we may be required to pay that plan an amount based on the underfunded status of the plan, referred to as a withdrawal liability. Our participation in these plans for the years ended December 31, 2015 , 2014 and 2013 , is presented below. We do not provide more than five percent of the total contributions to any multiemployer plan. Forms 5500 are not yet available for plan years ending in 2015 . Pension Fund EIN/Pension Plan Number Pension Protection Act Zone Status (a) FIP/RP Status Pending/Implemented (b) Contributions Surcharge Imposed (c) Expiration Date of Collective Bargaining Agreement 2015 2014 2015 2014 2013 Steelworkers Pension Trust 23-6648508/499 Green Green No $ 7.3 $ 8.1 $ 7.3 No 3/31/2017 to 9/1/2018 (d) IAM National Pension Fund’s National Pension Plan 51-6031295/002 Green Green No 16.0 16.5 14.8 No 10/1/2016 to 5/31/2019 (e) $ 23.3 $ 24.6 $ 22.1 (a) The most recent Pension Protection Act zone status available in 2015 and 2014 is for each plan’s year-end at December 31, 2014 and 2013 . The plan’s actuary certifies the zone status. Generally, plans in the red zone are less than 65% funded, plans in the yellow zone are between 65% and 80% funded, and plans in the green zone are at least 80% funded. The Steelworkers Pension Trust and IAM National Pension Fund’s National Pension Plan elected funding relief under section 431(b)(8) of the Internal Revenue Code and section 304(b)(8) of the Employment Retirement Income Security Act of 1974 (ERISA). This election allows those plans’ investment losses for the plan year ended December 31, 2008, to be amortized over 29 years for funding purposes. (b) The “FIP/RP Status Pending/Implemented” column indicates plans for which a financial improvement plan (FIP) or a rehabilitation plan (RP) is either pending or has been implemented, as defined by ERISA. (c) The surcharge represents an additional required contribution due as a result of the critical funding status of the plan. (d) We are a party to three collective bargaining agreements (at our Ashland Works, Mansfield Works and at the AK Tube Walbridge plant) that require contributions to the Steelworkers Pension Trust. The labor contract for approximately 300 hourly employees at Mansfield Works expires on March 31, 2017 . The labor contract for approximately 85 hourly employees at the AK Tube Walbridge plant expires January 22, 2018 . The labor contract for approximately 820 hourly employees at the Ashland Works expires on September 1, 2018 . (e) We are a party to three collective bargaining agreements (at our Butler Works, Middletown Works and Zanesville Works) that require contributions to the IAM National Pension Fund’s National Pension Plan. The labor contract for approximately 1,240 hourly employees at Butler Works expires on October 1, 2016 . The labor contract for approximately 1,725 hourly employees at Middletown Works expires on March 15, 2018 . The labor contract for approximately 140 hourly employees at Zanesville Works expires on May 31, 2019 .

Operating Leases

Operating Leases	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
Operating Leases	Operating Leases Rental expense was $44.0 , $35.7 and $27.0 for 2015 , 2014 and 2013 . Obligations to make future minimum lease payments at December 31, 2015 , are presented below: 2016 $ 20.7 2017 17.9 2018 16.9 2019 13.0 2020 10.0 2021 and thereafter 56.5 Total minimum lease payments $ 135.0

Commitments

Commitments	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments	Commitments The principal raw materials required for our steel manufacturing operations are iron ore, coal, coke, chrome, nickel, silicon, manganese, zinc, limestone, and carbon and stainless steel scrap. We also use large volumes of natural gas, electricity and industrial gases in our steel manufacturing operations. In addition, we may purchase carbon steel slabs from other steel producers to supplement the production from our own steelmaking facilities. We negotiate most of our purchases of iron ore, coal, coke and industrial gases at prices under annual and multi-year agreements. The iron ore agreements typically have a variable-price mechanism by which the price of iron ore is adjusted quarterly, based on reference to a historical iron ore index. We typically make purchases of carbon steel slabs, carbon and stainless steel scrap, natural gas, a majority of our electricity, and other raw materials at prevailing market prices, which fluctuate with supply and demand. We enter into derivative instruments for some purchases of energy and certain raw materials to hedge some of their price volatility. Commitments for future capital investments at December 31, 2015 , totaled approximately $45.7 , all of which we expect to incur in 2016 . We are building a research and innovation center in Middletown, Ohio. The construction of the 135,000 square foot facility is in progress on a 16-acre site located in the Cincinnati-Dayton growth corridor and will replace our existing research facility. We are financing the estimated $36.0 project principally through government incentives and a long-term capital lease with payments beginning when we substantially complete the project, which we believe will be in the fourth quarter of 2016.

Environmental and Legal Conting

Environmental and Legal Contingencies (Notes)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Environmental and Legal Contingencies	Environmental and Legal Contingencies Environmental Contingencies Domestic steel producers, including us, must follow stringent federal, state and local laws and regulations designed to protect human health and the environment. We have spent the following amounts over the past three years for environmental-related capital investments and environmental compliance: 2015 2014 2013 Environmental-related capital investments $ 7.1 $ 7.2 $ 1.6 Environmental compliance costs 133.2 112.4 101.1 We and our predecessors have been manufacturing steel and related operations since 1900. Although we believe our operating practices have been consistent with prevailing industry standards, hazardous materials may have been released at one or more operating sites or third-party sites in the past, including operating sites that we no longer own. If we reasonably can, we have estimated potential remediation expenditures for those sites where future remediation efforts are probable based on identified conditions, regulatory requirements or contractual obligations arising from the sale of a business or facility. For sites involving government-required investigations, we typically make an estimate of potential remediation expenditures only after the investigation is complete and when we better understand the nature and scope of the remediation. In general, the material factors in these estimates include the costs associated with investigations, delineations, risk assessments, remedial work, governmental response and oversight, site monitoring, and preparation of reports to the appropriate environmental agencies. We recorded the following liabilities for environmental matters on our condensed consolidated balance sheets: 2015 2014 Accrued liabilities $ 5.6 $ 17.6 Other non-current liabilities 41.1 32.7 We cannot predict the ultimate costs for each site with certainty because of the evolving nature of the investigation and remediation process. Rather, to estimate the probable costs, we must make certain assumptions. The most significant of these assumptions is for the nature and scope of the work that will be necessary to investigate and remediate a particular site and the cost of that work. Other significant assumptions include the cleanup technology that will be used, whether and to what extent any other parties will participate in paying the investigation and remediation costs, reimbursement of past response and future oversight costs by governmental agencies, and the reaction of the governing environmental agencies to the proposed work plans. Costs for future investigation and remediation are not discounted to their present value. If we have been able to reasonably estimate future liabilities, we do not believe that there is a reasonable possibility that we will incur a loss or losses that exceed the amounts we accrued for the environmental matters discussed below that would, either individually or in the aggregate, have a material adverse effect on our consolidated financial condition, results of operations or cash flows. However, since we recognize amounts in the consolidated financial statements in accordance with accounting principles generally accepted in the United States that exclude potential losses that are not probable or that may not be currently estimable, the ultimate costs of these environmental proceedings may be higher than the liabilities we currently have recorded in our consolidated financial statements. Except as we expressly note below, we do not currently anticipate any material effect on our consolidated financial position, results of operations or cash flows as a result of compliance with current environmental regulations. Moreover, because all domestic steel producers operate under the same federal environmental regulations, we do not believe that we are more disadvantaged than our domestic competitors by our need to comply with these regulations. Some foreign competitors may benefit from less stringent environmental requirements in the countries where they produce, resulting in lower compliance costs for them and providing those foreign competitors with a cost advantage on their products. According to the Resource Conservation and Recovery Act (“RCRA”), which governs the treatment, handling and disposal of hazardous waste, the United States Environmental Protection Agency (“EPA”) and authorized state environmental agencies may conduct inspections of RCRA-regulated facilities to identify areas where there have been releases of hazardous waste or hazardous constituents into the environment and may order the facilities to take corrective action to remediate such releases. Environmental regulators may inspect our major steelmaking facilities. While we cannot predict the future actions of these regulators, it is possible that they may identify conditions in future inspections of these facilities which they believe require corrective action. Under authority from the Comprehensive Environmental Response, Compensation and Liability Act (“CERCLA”), the EPA and state environmental authorities have conducted site investigations at certain of our facilities and other third-party facilities, portions of which previously may have been used for disposal of materials that are currently regulated. The results of these investigations are still pending, and we could be directed to spend funds for remedial activities at the former disposal areas. Because of the uncertain status of these investigations, however, we cannot reliably predict whether or when such spending might be required or their magnitude. As previously reported, on July 27, 2001, we received a Special Notice Letter from the EPA requesting that we agree to conduct a Remedial Investigation/Feasibility Study (“RI/FS”) and enter an administrative order on consent pursuant to Section 122 of CERCLA regarding our former Hamilton Plant located in New Miami, Ohio. The Hamilton Plant ceased operations in 1990, and all of its former structures have been demolished and removed. Although we did not believe that a site-wide RI/FS was necessary or appropriate, in April 2002 we entered a mutually agreed-upon administrative order on consent to perform a RI/FS of the Hamilton Plant site. We submitted the investigation portion of the RI/FS, and we completed a supplemental study in 2014. We currently have accrued $0.7 for the remaining cost of the RI/FS. Until the RI/FS is complete, we cannot reliably estimate the additional costs, if any, we may incur for potentially required remediation of the site or when we may incur them. As previously reported, on September 30, 1998, our predecessor, Armco Inc., received an order from the EPA under Section 3013 of RCRA requiring it to develop a plan for investigation of eight areas of our Mansfield Works that allegedly could be sources of contamination. A site investigation began in November 2000 and is continuing. We cannot reliably estimate at this time how long it will take to complete this site investigation. We currently have accrued approximately $1.1 for the projected cost of the study. Until the site investigation is complete, we cannot reliably estimate the additional costs, if any, we may incur for potentially required remediation of the site or when we may incur them. As previously noted, on September 26, 2012, the EPA issued an order under Section 3013 of RCRA requiring us to develop a plan for investigation of four areas at our Ashland Works coke plant. We submitted a Sampling and Analysis Plan (“SAP”) to the EPA on October 25, 2012, and revised it most recently on May 29, 2014. The EPA approved it on June 27, 2014. We completed Phase I of the SAP and submitted a report to the EPA on December 23, 2014. We cannot reliably estimate at this time how long it will take to complete the site investigation. We currently have accrued approximately $0.5 for the projected cost of the investigation. Until the site investigation is complete, we cannot reliably estimate the additional costs, if any, we may incur for potentially required remediation of the site or when we may incur them. As previously reported, on August 3, 2011, September 29, 2011, and June 28, 2012, the EPA issued a Notice of Violations (“NOV”) for our Middletown Works coke plant, alleging violations of pushing and combustion stack limits. We are investigating these claims and working with the EPA to attempt to resolve them. We believe we will reach a settlement in this matter, but cannot be certain that a settlement will be reached and cannot reliably estimate at this time how long it will take to reach a settlement or what all of its terms might be. We will vigorously contest any claims which cannot be resolved through a settlement. Until we have reached a settlement with the EPA or the NOV claims are resolved, we cannot reliably estimate the costs, if any, we may incur for potentially required operational changes at the battery or when we may incur them. As previously reported, on July 15, 2009, we and the Pennsylvania Department of Environmental Protection (“PADEP”) entered a Consent Order and Agreement (the “Consent Order”) to resolve an alleged unpermitted discharge of wastewater from the closed Hillside Landfill at our former Ambridge Works. Under the terms of the Consent Order, we paid a penalty and also agreed to implement various corrective actions, including an investigation of the area where landfill activities occurred, submission of a plan to collect and treat surface waters and seep discharges, and upon approval from PADEP, implementation of that plan. We have accrued approximately $5.5 for the remedial work required under the approved plan and Consent Order. We submitted a National Pollution Discharge Elimination System (“NPDES”) permit application to move to the next phase of the work. We currently estimate that the remaining work will be completed in 2018, though it may be delayed. As previously reported, on June 29, 2000, the United States filed a complaint on behalf of the EPA against us in the U.S. District Court for the Southern District of Ohio, Case No. C-1-00530, alleging violations of the Clean Air Act, the Clean Water Act and RCRA at our Middletown Works. Subsequently, the State of Ohio, the Sierra Club and the National Resources Defense Council intervened. On May 15, 2006, the court entered a Consent Decree in Partial Resolution of Pending Claims (the “Consent Decree”). Under the Consent Decree, we paid a civil penalty and performed a supplemental environmental project to remove ozone-depleting refrigerants from certain equipment. We further agreed to undertake a comprehensive RCRA facility investigation at Middletown Works and, as appropriate, complete a corrective measures study. The Consent Decree required us to implement certain RCRA corrective action interim measures to address polychlorinated biphenyls (“PCBs”) in sediments and soils at Dicks Creek and certain other specified surface waters, adjacent floodplain areas and other previously identified geographic areas. We have completed the remedial activity at Dicks Creek, but continue to work on the RCRA facility investigation and certain interim measures. We have accrued approximately $16.2 for the cost of known work required under the Consent Decree for the RCRA facility investigation and remaining interim measures. As previously reported, on October 17, 2012, the EPA issued an NOV and Notice of Intent to File a Civil Administrative Complaint to our Mansfield Works alleging violations of RCRA primarily for our management of electric arc furnace dust at the facility. We are investigating these claims and working with the EPA to attempt to resolve them. The NOV proposed a civil penalty of approximately $0.3 . However, on March 23, 2015, the EPA reduced its penalty demand to $0.1 . We believe we will reach a settlement in this matter, but cannot be certain that a settlement will be reached and cannot reliably estimate at this time how long it will take to reach a settlement or what all of its terms might be. We will vigorously contest any claims that a settlement cannot resolve. As previously reported, on May 12, 2014, the Michigan Department of Environmental Quality (“MDEQ”) issued to our Dearborn Works (then a part of Dearborn) an Air Permit to Install No. 182-05C (the “PTI”) to increase the emission limits for the blast furnace and other emission sources. The PTI was issued as a correction to a prior permit to install that did not include certain information during the prior permitting process. On July 10, 2014, the South Dearborn Environmental Improvement Association (“SDEIA”), Detroiters Working for Environmental Justice, Original United Citizens of Southwest Detroit and the Sierra Club filed a Claim of Appeal of the PTI in the State of Michigan, Wayne County Circuit, Case No. 14-008887-AA. Appellants and the MDEQ required the intervention of Dearborn (now owned by us) in this action as an additional appellee. The appellants allege multiple deficiencies with the PTI and the permitting process. On October 9, 2014, the appellants filed a Motion for Peremptory Reversal of the MDEQ’s decision to issue the PTI. We believe that the MDEQ issued the PTI properly in compliance with applicable law and will vigorously contest this appeal. On October 17, 2014, we filed a motion to dismiss the appeal. Additionally, on December 15, 2014, we filed a motion to dismiss the appeal for lack of jurisdiction. At the conclusion of a hearing on all three motions on February 12, 2015, all three motions were denied. On March 18, 2015, we filed an application for leave to appeal to the Michigan Court of Appeals seeking to overturn the decision of the Circuit Court denying our motion to dismiss for lack of jurisdiction. On August 27, 2015, the Michigan Court of Appeals granted our application for leave to appeal. Until the appeal is resolved, we cannot determine what the ultimate permit limits will be. Until the permit limits are determined and final, we cannot reliably estimate the costs, if any, that we may incur if the appeal causes the permit limits to change, nor can we determine if the costs will be material or when we would incur them. As previously reported, on August 21, 2014, the SDEIA filed a Complaint under the Michigan Environmental Protection Act (“MEPA”) in the State of Michigan, Wayne County Circuit Case No. 14-010875-CE. The plaintiffs allege that the air emissions from our Dearborn Works are impacting the air, water and other natural resources, as well as the public trust in such resources. The plaintiffs are requesting, among other requested relief, that the court assess and determine the sufficiency of the PTI’s limitations. On October 15, 2014, the court ordered a stay of the proceedings until a final order is issued in Wayne County Circuit Court Case No. 14-008887-AA (discussed above). When the proceedings resume, we will vigorously contest these claims. Until the claims in this Complaint are resolved, we cannot reliably estimate the costs we may incur, if any, or when we would incur them. As previously reported, on April 27, 2000, MDEQ issued a RCRA Corrective Action Order No. 111-04-00-07E to Rouge Steel Company and Ford Motor Company for the property that includes our Dearborn Works. The Corrective Action Order has been amended five times. We are a party to the Corrective Action Order as the successor-in-interest to Dearborn, which was the successor-in-interest to Rouge Steel Company. The Corrective Action Order requires the site-wide investigation, and where appropriate, remediation of the facility. The site investigation and remediation is ongoing. We cannot reliably estimate at this time how long it will take to complete this site investigation and remediation. To date, Ford Motor Company has incurred most of the costs of the investigation and remediation due to its prior ownership of the steelmaking operations at Dearborn Works. Until the site investigation is complete, we cannot reliably estimate the additional costs we may incur, if any, for any potentially required remediation of the site or when we may incur them. As previously reported, on August 29, 2013, the West Virginia Department of Environmental Protection (“WVDEP”) issued to Mountain State Carbon a renewal NPDES permit for wastewater discharge from the facility to the Ohio River. The new NPDES permit included numerous new, and more stringent, effluent limitations. On October 7, 2013, Mountain State Carbon appealed the permit to the Environmental Quality Board, Appeal No. 13-25-EQB. On February 10, 2016, we reached a partial settlement with WVDEP and we will vigorously contest the claims that were not resolved. Until the permit limits are determined and final, we cannot reliably estimate the costs that we will incur, if any, if the appeal causes the permit limits to change, or when we may incur the costs. In addition to the foregoing matters, we are or may be involved in proceedings with various regulatory authorities that may require us to pay fines, comply with more rigorous standards or other requirements or incur capital and operating expenses for environmental compliance. We believe that the ultimate disposition of the proceedings will not have, individually or in the aggregate, a material adverse effect on our consolidated financial condition, results of operations or cash flows. Legal Contingencies As previously reported, since 1990 we have been named as a defendant in numerous lawsuits alleging personal injury as a result of exposure to asbestos. The great majority of these lawsuits have been filed on behalf of people who claim to have been exposed to asbestos while visiting the premises of one of our current or former facilities. The majority of asbestos cases pending in which we are a defendant do not include a specific dollar claim for damages. In the cases that do include specific dollar claims for damages, the complaint typically includes a monetary claim for compensatory damages and a separate monetary claim in an equal amount for punitive damages, and does not attempt to allocate the total monetary claim among the various defendants. The number of asbestos cases pending at December 31, 2015 , is presented below: Asbestos Cases Pending at December 31, 2015 Cases with specific dollar claims for damages: Claims up to $0.2 122 Claims above $0.2 to $5.0 5 Claims above $5.0 to $15.0 2 Claims above $15.0 to $20.0 2 Total claims with specific dollar claims for damages (a) 131 Cases without a specific dollar claim for damages 252 Total asbestos cases pending 383 (a) Involve a total of 2,331 plaintiffs and 17,116 defendants In each case, the amount described is per plaintiff against all of the defendants, collectively. Thus, it usually is not possible at the outset of a case to determine the specific dollar amount of a claim against us. In fact, it usually is not even possible at the outset to determine which of the plaintiffs actually will pursue a claim against us. Typically, that can only be determined through written interrogatories or other discovery after a case has been filed. Therefore, in a case involving multiple plaintiffs and multiple defendants, we initially only account for the lawsuit as one claim. After we have determined through discovery whether a particular plaintiff will pursue a claim, we make an appropriate adjustment to statistically account for that specific claim. It has been our experience that only a small percentage of asbestos plaintiffs ultimately identify us as a target defendant from whom they actually seek damages and most of these claims ultimately are either dismissed or settled for a small fraction of the damages initially claimed. Asbestos-related claims information in 2015 , 2014 and 2013 , is presented below: 2015 2014 2013 New Claims Filed 52 50 42 Pending Claims Disposed Of 68 90 39 Total Amount Paid in Settlements $ 1.9 $ 0.7 $ 1.0 Since the onset of asbestos claims against us in 1990, five asbestos claims against us have proceeded to trial in four separate cases. All five concluded with a verdict in our favor. We continue to vigorously defend the asbestos claims. Based upon present knowledge, and the factors above, we believe it is unlikely that the resolution in the aggregate of the asbestos claims against us will have a materially adverse effect on our consolidated results of operations, cash flows or financial condition. However, predictions about the outcome of pending litigation, particularly claims alleging asbestos exposure, are subject to substantial uncertainties. These uncertainties include (1) the significantly variable rate at which new claims may be filed, (2) the effect of bankruptcies of other companies currently or historically defending asbestos claims, (3) the litigation process from jurisdiction to jurisdiction and from case to case, (4) the type and severity of the disease each claimant alleged to suffer, and (5) the potential for enactment of legislation affecting asbestos litigation. As previously reported, in September and October 2008 and again in July 2010, several companies filed purported class actions in the United States District Court for the Northern District of Illinois against nine steel manufacturers, including us. The case numbers for these actions are 08CV5214, 08CV5371, 08CV5468, 08CV5633, 08CV5700, 08CV5942, 08CV6197 and 10CV04236. On December 28, 2010, another action, case number 32,321, was filed in state court in the Circuit Court for Cocke County, Tennessee. The defendants removed the Tennessee case to federal court and in March 2012 it was transferred to the Northern District of Illinois. The plaintiffs in the various pending actions are companies which purport to have purchased steel products, directly or indirectly, from one or more of the defendants and they claim to file the actions on behalf of all persons and entities who purchased steel products for delivery or pickup in the United States from any of the named defendants at any time from at least as early as January 2005. The complaints allege that the defendant steel producers have conspired in violation of antitrust laws to restrict output and to fix, raise, stabilize and maintain artificially high prices for steel products in the United States. In March 2014, we reached an agreement with the direct purchaser plaintiffs to tentatively settle the claims asserted against us, subject to certain court approvals below. According to that settlement, we agreed to pay $5.8 to the plaintiff class of direct purchasers in exchange for the members of that class to completely release all claims. We continue to believe that the claims made against us lack any merit, but we elected to enter the settlement to avoid the ongoing expense of defending ourself in this protracted and expensive antitrust litigation. We provided notice of the proposed settlement to members of the settlement class. After several class members received the notice, they elected to opt out of the class settlement. Following a fairness hearing, on October 21, 2014 the Court entered an order and judgment approving the settlement and dismissing all of the direct plaintiffs’ claims against us with prejudice as to the settlement class. In the first quarter of 2014, we recorded a charge for the amount of the tentative settlement with the direct purchaser plaintiff class and paid that amount into an escrow account, which has now been disbursed in accordance with the order that approved the settlement. At this time, we do not have adequate information available to determine that a loss is probable or to reliably or accurately estimate the potential loss, if any, with respect to the remaining indirect purchaser plaintiff class members and any direct purchaser class members that have opted out of the class (hereinafter collectively referred to as the “Remaining Plaintiffs”). Because we have been unable to determine that a potential loss in this case with respect to the Remaining Plaintiffs is probable or estimable, we have not recorded an accrual for this matter for them. If our assumptions used to evaluate whether a loss is either probable or estimable with respect to the Remaining Plaintiffs prove to be incorrect or change, we may be required to record a charge for their claims. As previously reported, on January 20, 2010, ArcelorMittal France and ArcelorMittal Atlantique et Lorraine (collectively “ArcelorMittal”) filed an action in the United States District Court for the District of Delaware, Case No. 10-050-SLR against us, Dearborn, and Wheeling-Nisshin Inc., who is indemnified by Dearborn in this action. By virtue of our responsibility as a successor-in-interest to Dearborn and an indemnitor of Wheeling-Nisshin Inc, we now have complete responsibility for the defense of this action. The three named defendants are collectively referred to hereafter as “we” or “us”, though the precise claims against each separate defendant may vary. The complaint alleges that we are infringing the claims of U.S. Patent No. 6,296,805 (the “Patent”) in making pre-coated cold-rolled boron steel sheet and seeks injunctive relief and unspecified compensatory damages. We filed an answer denying ArcelorMittal’s claims and raised various affirmative defenses. We also filed counterclaims against ArcelorMittal for a declaratory judgment that we are not infringing the Patent and that the Patent is invalid. Subsequently, the trial court separated the issues of liability and damages. The case proceeded with a trial to a jury on the issue of liability during the week of January 15, 2011. The jury returned a verdict that we did not infringe the Patent and that the Patent was invalid. Judgment then was entered in our favor. ArcelorMittal filed an appeal with the United States Court of Appeals for the Federal Circuit. On November 30, 2012, the court of appeals issued a decision reversing certain findings related to claim construction and the validity of the Patent and remanded the case to the trial court for further proceedings. On January 30, 2013, ArcelorMittal filed a motion for rehearing with the court of appeals. On March 20, 2013, the court of appeals denied ArcelorMittal’s motion for rehearing. The case then was remanded to the trial court for further proceedings. On April 16, 2013, according to a petition previously filed by ArcelorMittal and ArcelorMittal USA LLC, the U.S. Patent and Trademark Office (“PTO”) reissued the Patent as U.S. Reissue Patent RE44,153 (the “Reissued Patent”). Also on April 16, 2013, ArcelorMittal filed a second action against us in the United States District Court for the District of Delaware, Case Nos. 1:13-cv-00685 and 1:13-cv-00686 (collectively the “Second Action”). The complaint filed in the Second Action alleges that we are infringing the claims of the Reissued Patent and seeks injunctive relief and unspecified compensatory damages. On April 23, 2013, we filed a motion to dismiss key elements of the complaint filed in the Second Action. In addition, the parties briefed related non-infringement and claims construction issues in the original action. On October 25, 2013, the district court granted summary judgment in our favor, confirming that our product does not infringe the original Patent or the Reissued Patent. The court further ruled that ArcelorMittal’s Reissued Patent was invalid due to ArcelorMittal’s deliberate violation of a statutory prohibition on broadening a patent through reissue more than two years after the original Patent was granted and that the original Patent had been surrendered when the Reissued Patent was issued and thus is no longer in effect. Final Judgment was entered on October 31, 2013. On November 6, 2013, ArcelorMittal filed a motion to clarify or, in the alternative, to alter or amend the October 31, 2013 judgment. We opposed the motion. On December 5, 2013, the court issued a memorandum and order denying the motion and entered final judgment in our favor, and against ArcelorMittal, specifically ruling that all claims of ArcelorMittal’s Reissued Patent are invalid as violative of 35 U.S.C. §251(d). On December 30, 2013, ArcelorMittal filed notices of appeal to the Federal Circuit Court of Appeals. The appeal has been fully briefed and the court of appeals held a hearing on November 4, 2014. On May 12, 2015, the Federal Circuit issued its decision affirming in part and reversing in part the trial court’s decision and remanding the case for further proceedings. The Federal Circuit ruled that 23 of the 25 claims of the Reissued Patent were improperly broadened and therefore invalid. However, the Federal Court found that the district court erred in invalidating the remaining two claims and remanded the case for further proceedings before the district court. Following the remand, ArcelorMittal filed a motion in the trial court for leave to amend the Second Action to assert additional patent infringement claims based on another, related patent that the PTO issued on June 10, 2014, No. RE44,940 (Second Reissue Patent). It also filed a motion to dismiss the original action on the grounds that it is now moot in light of the Court of Appeals’ last ruling. We opposed both of those motions. In addition, we filed separate motions for summary judgment in the original action on the grounds of non-infringement and invalidity. A hearing on all motions was held on October 27, 2015. On December 4, 2015, the district court issued an order granting our motion for summary judgment that both remaining claims of the Reissued Patent are not infringed and are invalid as obvious. The court therefore entered final judgment in favor of the defendants in the original case. In the court’s order, the judge also granted ArcelorMittal’s motion to file a first amended complaint in the Second Action, alleging we are infringing the claims of the Second Reissue Patent, which we deny. On December 21, 2015, ArcelorMittal filed a notice of appeal from the district court’s December 4, 2015, final judgment. On January 20, 2016, we filed a motion to dismiss the amended complaint in the Second Action, or in the alternative, a motion to stay pending a resolution of the appeal in the original case. We intend to continue to contest this matter vigorously. At this time, we have not made a determination that a loss is probable and we do not have adequate information to reliably or accurately estimate potential loss if ArcelorMittal prevails in its appeal in this dispute. Because we have been unable to determine that the potential loss in this case is probable or estimable, we have not recorded an accrual for this matter. If our assumptions used to evaluate whether a loss in this matter is either probable or estimable prove to be incorrect or change, we may be required to record a liability for an adverse outcome. As previously reported, on June 13, 2013, Cliffs Sales Company (“Cliffs”) filed an action in the United States District Court for the Northern District of Ohio, Civil Action No. 1:13 cv 1308, against us pertaining to Dearborn Works. Cliffs claims that we breached a May 21, 2008, Agreement for Sale of Reclaimed Iron Units, as amended (the “Iron Unit Agreement”). Cliffs claims that we breached the Iron Unit Agreement by failing to purchase the required amount of pellets, chips and fines as allegedly required. We filed an answer denying the material allegations of the complaint and asserting several affirmative defenses. In January of 2014, the presiding judge ordered a stay of the proceedings until we completed an arbitration of a separate dispute. That arbitration is now concluded and it is anticipated that the stay of the litigation may be lifted and discovery may re-commence in the near future. We intend to contest this matter vigorously. At this time, we have not made a determination that a loss is probable and do not have adequate information to reliably or accurately estimate our potential loss if Cliffs prevails in this lawsuit. Because we have been unable to determine that a loss is probable or estimable, we have not recorded an accrual. If our assumptions used to evaluate whether a loss in this matter is either probable or estimable prove to be incorrect or change, we may be required to record a liability for an adverse outcome. Trade Cases Grain-Oriented Electrical Steel On September 18, 2013, we, along with another domestic producer and the United Steelworkers (collectively, the “Petitioners”), filed trade cases against imports of grain-oriented electrical steel (“GOES”) from seven countries. We filed anti-dumping (“AD”) petitions against China, the Czech Republic, Germany, Japan, Poland, Russia and South Korea and a countervailing duty (“CVD”

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock: There are 25,000,000 shares of preferred stock authorized; no shares are issued or outstanding. Common Stock: Our common stockholders may receive dividends when and as declared by the Board of Directors out of funds legally available for distribution. The holders have one vote per share in respect of all matters and are not entitled to preemptive rights. On September 16, 2014 , AK Holding issued 40.25 million shares of common stock at $9.00 per share. Net proceeds were $345.3 after underwriting discounts and other fees. AK Holding used the net proceeds to pay a portion of the purchase price for the acquisition of Dearborn, to repay a portion of outstanding borrowings under the Credit Facility and for general corporate purposes. Dividends: The instruments governing our outstanding senior debt allow dividend payments. However, our Credit Facility restricts dividend payments. Dividends are permitted if (i) availability under the Credit Facility exceeds $337.5 or (ii) availability exceeds $262.5 and we meet a fixed charge coverage ratio of one to one as of the most recently ended fiscal quarter. If we cannot meet either of these thresholds, dividends would be limited to $12.0 annually. Currently, the availability under the Credit Facility significantly exceeds $337.5 . Although we have elected to suspend our dividend program, there currently are no covenants that would restrict our ability to declare and pay a dividend to our stockholders. Share Repurchase Program: In October 2008, the Board of Directors authorized us to repurchase, from time to time, up to $150.0 of our outstanding common stock. We have not made any common stock repurchases under this program in the last three years. As of December 31, 2015 , there was $125.6 remaining for repurchase under the Board of Directors’ authorization.

Share-based Compensation (Notes

Share-based Compensation (Notes)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Compensation	Share-based Compensation AK Holding’s Stock Incentive Plan (the “SIP”) permits the granting of nonqualified stock option, restricted stock, performance share and/or restricted stock unit (“RSUs”) awards to our Directors, officers and other employees. Stockholders have approved an aggregate maximum of 23 million shares issuable under the SIP through December 31, 2019, of which approximately 4 million shares are available for future grant as of December 31, 2015 . Share-based compensation expense for the years ended December 31, 2015 , 2014 and 2013 , is presented below: Share-based Compensation Expense 2015 2014 2013 Stock options $ 1.7 $ 1.7 $ 1.5 Restricted stock 3.2 3.2 2.9 Restricted stock units issued to Directors 0.9 1.1 1.0 Performance shares 1.9 2.9 4.1 Pre-tax share-based compensation expense $ 7.7 $ 8.9 $ 9.5 Stock Options Stock options have a maximum term of ten years and holders may not exercise them earlier than six months after the grant date or another term the award agreement may specify. Stock options granted to officers and key managers vest and become exercisable in three equal installments on the first, second and third anniversaries of the grant date. The exercise price of each option must equal or exceed the market price of our common stock on the grant date. We have not and do not reprice stock options to lower the exercise price. We use the Black-Scholes option valuation model to value the nonqualified stock options. We use historical data of stock option exercise behaviors to estimate the expected life that granted options will be outstanding. The risk-free interest rate is based on the Daily Treasury Yield Curve published by the U.S. Treasury on the grant date. The expected volatility is determined by using a blend of historical and implied volatility. The expected dividend yield is based on our historical dividend payments. We estimate that option holders will forfeit 5% of the options. The following weighted-average assumptions are used in the Black-Scholes option pricing model to estimate the fair value of granted options as of the grant date: 2015 2014 2013 Expected volatility 67.6% – 75.9% 58.3% – 68.2% 57.8% – 68.8% Weighted-average volatility 69.4 % 62.6 % 65.2 % Expected term (in years) 3.1 – 6.6 3.0 – 6.5 2.9 – 6.4 Risk-free interest rate 1.0% – 1.7% 0.9% – 2.3% 0.4% – 1.1% Dividend yield — % — % — % Weighted-average grant-date fair value per share of granted options $ 2.36 $ 3.50 $ 2.44 Option activity for the year ended December 31, 2015 , is presented below: Stock Options Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (in years) Aggregate Intrinsic Value Outstanding at December 31, 2014 2,696,595 $ 11.16 Granted 906,700 4.08 Exercised (2,733 ) 4.59 Forfeited and expired (296,570 ) 10.81 Outstanding at December 31, 2015 3,303,992 9.26 4.6 $ — Exercisable at December 31, 2015 1,959,959 12.33 3.3 — Unvested at December 31, 2015 1,344,033 4.77 6.5 — Unvested at December 31, 2015 expected to vest 1,276,831 4.77 6.5 — The total intrinsic value of stock option awards that holders exercised during the years ended December 31, 2015 , 2014 and 2013 , was not material in each period. Each exercised option’s intrinsic value is the quoted average of the reported high and low sales price on the exercise date. As of December 31, 2015 , total unrecognized compensation costs for non-vested stock options were $0.7 , which we expect to recognize over a weighted-average period of 1.7 years. Restricted Stock Restricted stock awards granted to officers and other employees ordinarily vest ratably on the first, second and third anniversaries of the grant. Non-vested restricted stock awards activity for the year ended December 31, 2015 , is presented below: Restricted Stock Awards Restricted Shares Weighted- Average Grant Date Fair Value Outstanding at December 31, 2014 502,413 $ 5.97 Granted 886,060 4.06 Vested/restrictions lapsed (719,955 ) 4.90 Canceled (69,203 ) 5.06 Outstanding at December 31, 2015 599,315 4.54 The weighted-average grant date fair value of restricted stock awards granted during the years ended December 31, 2015 , 2014 and 2013 , was $4.06 , $6.66 and $4.43 per share. The total intrinsic value of restricted stock awards that vested (i.e., restrictions lapsed) during the years ended December 31, 2015 , 2014 and 2013 , was $2.9 , $2.9 and $2.1 . As of December 31, 2015 , total unrecognized compensation costs for non-vested restricted stock awards granted under the SIP were $1.5 , which we expect to recognize over a weighted-average period of 1.6 years. Restricted Stock Units Restricted stock units (“RSUs”) represent equity-based compensation granted to Directors. RSU grants vest immediately, but we do not settle them (i.e., pay them) until one year after the grant date, unless a Director elects to defer the settlement. Directors have the option to defer their RSU settlement six months after their Board service is terminated and also may elect to take settlement in a single distribution or in annual installments up to fifteen years . Performance Shares Performance shares are granted to officers and key managers. They earn the awards by meeting performance measures over a three -year period. Though a target number of performance shares are awarded on the grant date, the total number of performance shares issued to the participant when they vest is based on two equally-rated metrics: (i) our share performance compared to a prescribed compounded annual growth rate and (ii) our total share return compared to Standard & Poor’s MidCap 400 index. The following weighted-average assumptions are used in a Monte Carlo simulation model to estimate the fair value of performance shares granted: 2015 2014 2013 Company expected volatility 56.4 % 59.1 % 59.2 % S&P’s MidCap 400 index expected volatility 27.0 % 32.4 % 34.7 % Risk-free interest rate 0.9 % 0.9 % 0.4 % Dividend yield — % — % — % Weighted-average grant-date fair value per performance share granted $ 3.09 $ 6.40 $ 4.68 Non-vested performance share awards activity for the year ended December 31, 2015 , is presented below: Performance Share Awards Performance Shares Weighted- Average Grant Date Fair Value Outstanding at December 31, 2014 978,952 $ 5.56 Granted 890,700 3.09 Earned — — Expired or forfeited (865,358 ) 4.36 Outstanding at December 31, 2015 1,004,294 4.40 As of December 31, 2015 , total unrecognized compensation costs for non-vested performance share awards granted under the SIP were $2.1 , which we expect to recognize over a weighted-average period of 1.6 years.

Comprehensive Income (Loss) (No

Comprehensive Income (Loss) (Notes)	12 Months Ended
	Dec. 31, 2015
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Comprehensive Income (Loss)	Comprehensive Income (Loss) Other comprehensive income (loss), net of tax, information is presented below: 2015 2014 2013 Foreign currency translation Balance at beginning of period $ 1.0 $ 4.7 $ 3.5 Other comprehensive income (loss)—foreign currency translation gain (loss) (3.1 ) (3.7 ) 1.2 Balance at end of period $ (2.1 ) $ 1.0 $ 4.7 Cash flow hedges Balance at beginning of period $ (32.2 ) $ 18.3 $ 31.7 Other comprehensive income (loss): Gains (losses) arising in period (64.2 ) (51.6 ) 3.5 Income tax expense 24.9 — 1.3 Gains (losses) arising in period, net of tax (89.1 ) (51.6 ) 2.2 Reclassification of losses (gains) to net income (loss): Hot roll carbon steel coil contracts (a) — — (0.4 ) Other commodity contracts (b) 61.4 1.1 (24.8 ) Subtotal 61.4 1.1 (25.2 ) Income tax expense (d) (25.9 ) — (9.6 ) Net amount of reclassification of losses (gains) to net income (loss) 87.3 1.1 (15.6 ) Total other comprehensive income (loss), net of tax (1.8 ) (50.5 ) (13.4 ) Balance at end of period $ (34.0 ) $ (32.2 ) $ 18.3 Unrealized holding gains on securities Balance at beginning of period $ 0.4 $ 0.4 $ 0.3 Other comprehensive income (loss): Unrealized holding gains (losses) arising in period — — 0.2 Income tax expense — — 0.1 Unrealized holding gains (losses) arising in period, net of tax — — 0.1 Reclassification of gains (losses) to net income (loss)—income tax benefit (d) 0.4 — — Total other comprehensive income (loss), net of tax (0.4 ) — 0.1 Balance at end of period $ — $ 0.4 $ 0.4 Pension and OPEB plans Balance at beginning of period $ (173.6 ) $ 300.0 $ (34.4 ) Other comprehensive income (loss): Prior service credit (cost) arising in period (7.7 ) 10.9 (6.1 ) Gains (losses) arising in period (60.8 ) (422.5 ) 422.3 Subtotal (68.5 ) (411.6 ) 416.2 Income tax expense (benefit) (d) (26.0 ) — 50.3 Gains (losses) arising in period, net of tax (42.5 ) (411.6 ) 365.9 Reclassification to net income (loss): Prior service costs (credits) (c) (60.2 ) (68.9 ) (76.2 ) Actuarial (gains) losses (c) 165.0 6.9 25.3 Subtotal 104.8 (62.0 ) (50.9 ) Income tax (expense) benefit (d) 39.8 — (19.4 ) Amount of reclassification to net income (loss), net of tax 65.0 (62.0 ) (31.5 ) Total other comprehensive income (loss), net of tax 22.5 (473.6 ) 334.4 Balance at end of period $ (151.1 ) $ (173.6 ) $ 300.0 (a) Included in net sales (b) Included in cost of products sold (c) Included in pension and OPEB expense (income) (d) Included in income tax expense (benefit)

Earnings Per Share (Notes)

Earnings Per Share (Notes)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share	Earnings per Share Reconciliation of the numerators and denominators for basic and diluted EPS computations is presented below: 2015 2014 2013 Net income (loss) attributable to AK Steel Holding Corporation $ (509.0 ) $ (96.9 ) $ (46.8 ) Less: distributed earnings to common stockholders and holders of certain stock compensation awards — — — Undistributed earnings (loss) $ (509.0 ) $ (96.9 ) $ (46.8 ) Common stockholders earnings—basic and diluted: Distributed earnings to common stockholders $ — $ — $ — Undistributed earnings (loss) to common stockholders (507.3 ) (96.6 ) (46.6 ) Common stockholders earnings (loss)—basic and diluted $ (507.3 ) $ (96.6 ) $ (46.6 ) Common shares outstanding (weighted-average shares in millions): Common shares outstanding for basic earnings per share 177.2 148.1 135.8 Effect of exchangeable debt — — — Effect of dilutive stock-based compensation — — — Common shares outstanding for diluted earnings per share 177.2 148.1 135.8 Basic and diluted earnings per share: Distributed earnings $ — $ — $ — Undistributed earnings (loss) (2.86 ) (0.65 ) (0.34 ) Basic and diluted earnings (loss) per share $ (2.86 ) $ (0.65 ) $ (0.34 ) Potentially issuable common shares (in millions) excluded from earnings per share calculation due to anti-dilutive effect 3.6 9.7 2.6

Variable Interest Entities (Not

Variable Interest Entities (Notes)	12 Months Ended
	Dec. 31, 2015
Variable Interest Entity, Primary Beneficiary, Does Not Hold Majority Voting Interest, Disclosures [Abstract]
Variable Interest Entities Disclosure [Text Block]	Variable Interest Entities SunCoke Middletown We purchase all the coke and electrical power generated from SunCoke Middletown’s plant under long-term supply agreements. SunCoke Middletown is a variable interest entity because we have committed to purchase all the expected production from the facility through at least 2031 and we are the primary beneficiary. Therefore, we consolidate SunCoke Middletown’s financial results with our financial results, even though we have no ownership interest in SunCoke Middletown. SunCoke Middletown had income before income taxes of $62.6 , $63.0 and $64.3 for the years ended December 31, 2015 , 2014 and 2013 that was included in our consolidated income (loss) before income taxes. Vicksmetal/Armco Associates We indirectly own a 50% interest in Vicksmetal/Armco Associates (“VAA”), a joint venture with Vicksmetal Company, which is owned by Sumitomo Corporation. VAA slits electrical steel primarily for AK Steel, though also for third parties. VAA is a variable interest entity and we are the primary beneficiary. Therefore, we consolidate VAA’s financial results with our financial results.

Fair Value Measurements (Notes)

Fair Value Measurements (Notes)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We measure certain assets and liabilities at fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (i.e., the “exit price”) in an orderly transaction between market participants at the measurement date. In determining fair value, we use various valuation approaches. The hierarchy of those valuation approaches is broken down into three levels based on the reliability of inputs as follows: • Level 1 inputs are quoted prices in active markets for identical assets or liabilities that we have the ability to access at the measurement date. • Level 2 inputs are inputs, other than quoted prices, that are directly or indirectly observable for the asset or liability. Level 2 inputs include model-generated values that rely on inputs either directly observed or readily-derived from available market data sources, such as Bloomberg or other news and data vendors. They include quoted prices for similar assets or liabilities in active markets, inputs other than quoted prices that are observable for the asset or liability (e.g., interest rates and yield curves observable at commonly quoted intervals or current market) and contractual prices for the underlying financial instrument, as well as other relevant economic factors. As a practical expedient, we estimate the value of common/collective trusts by using the net asset value per share multiplied by the number of shares of the trust investment held as of the measurement date. If we have the ability to redeem our investment in the respective alternative investment at the net asset value with no significant restrictions on the redemption at the consolidated balance sheet date, we categorized the alternative investment as a Level 2 measurement in the fair value hierarchy. We generate fair values for our commodity derivative contracts and foreign currency forward contracts from observable futures prices for the respective commodity or currency, from sources such as the New York Mercantile Exchange (NYMEX) or the London Metal Exchange (LME). In cases where the derivative is an option contract (including caps, floors and collars), we adjust our valuations to reflect the counterparty’s valuation assumptions. After validating that the counterparty’s assumptions for implied volatilities reflect independent source’s assumptions, we discount these model-generated future values with discount factors that reflect the counterparty’s credit quality. We apply different discount rates to different contracts since the maturities and counterparties differ. As of December 31, 2015 , a spread over benchmark rates of less than 1.5% was used for derivatives valued as assets and less than 3.6% for derivatives valued as liabilities. We have estimated the fair value of long-term debt based upon quoted market prices for the same or similar issues or on the current interest rates available to us for debt on similar terms and with similar maturities. • Level 3 inputs are unobservable inputs for the asset or liability. Unobservable inputs are used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. This level of categorization is not applicable to our valuations on a normal recurring basis other than for a portion of our pension assets. Assets and liabilities measured at fair value on a recurring basis are presented below: 2015 2014 Level 1 Level 2 Total Level 1 Level 2 Total Assets measured at fair value Cash and cash equivalents $ 56.6 $ — $ 56.6 $ 70.2 $ — $ 70.2 Other current assets: Foreign exchange contracts — 1.1 1.1 — 1.2 1.2 Commodity hedge contracts — 0.5 0.5 — 3.6 3.6 Other non-current assets: Available for sale investments—cash and cash equivalents — — — 3.3 — 3.3 Commodity hedge contracts — 0.3 0.3 — 1.8 1.8 Assets measured at fair value $ 56.6 $ 1.9 $ 58.5 $ 73.5 $ 6.6 $ 80.1 Liabilities measured at fair value Accrued liabilities: Commodity hedge contracts $ — $ (41.2 ) $ (41.2 ) $ — $ (36.2 ) $ (36.2 ) Other non-current liabilities—commodity hedge contracts — (9.5 ) (9.5 ) — (5.7 ) (5.7 ) Liabilities measured at fair value $ — $ (50.7 ) $ (50.7 ) $ — $ (41.9 ) $ (41.9 ) Liabilities measured at other than fair value Long-term debt, including current portions: Fair value $ — $ (1,573.3 ) $ (1,573.3 ) $ — $ (2,478.3 ) $ (2,478.3 ) Carrying amount — (2,354.1 ) (2,354.1 ) — (2,422.0 ) (2,422.0 ) See Note 7 for information on the fair value of pension plan assets. The carrying amounts of our other financial instruments do not differ materially from their estimated fair values at December 31, 2015 and 2014 .

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities (Notes)	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities Exchange rate fluctuations affect a portion of intercompany receivables that are denominated in foreign currencies, and we use forward currency contracts to reduce our exposure to certain of these currency price fluctuations. These contracts have not been designated as hedges for accounting purposes and gains or losses are reported in earnings on a current basis in other income (expense). We are exposed to fluctuations in market prices of raw materials and energy sources, as well as from the effect of market prices on the sale of certain commodity steel (hot roll carbon steel coils). We may use cash-settled commodity price swaps and options (including collars) to hedge the market risk associated with the purchase of certain of our raw materials and energy requirements and the sale of hot roll carbon steel coils. For input commodities, these derivatives are typically used for a portion of our natural gas, nickel, iron ore, aluminum, zinc and electricity requirements. Our hedging strategy is to reduce the effect on earnings from the price volatility of these various commodity exposures. Independent of any hedging activities, price changes in any of these commodity markets could negatively affect operating costs or selling prices. All commodity derivatives are recognized as an asset or liability at fair value. We record the effective gains and losses for commodity derivatives designated as cash flow hedges of forecasted purchases of raw materials and energy sources in accumulated other comprehensive income (loss) and reclassify them into cost of products sold in the same period we recognize earnings for the associated underlying transaction. We record the effective gains and losses for hot roll carbon steel coils derivatives designated as cash flow hedges of forecasted sales in accumulated other comprehensive income and reclassify them into net sales in the same period we recognize earnings for the associated underlying transaction. We recognize gains and losses on these designated derivatives arising from either hedge ineffectiveness or from components excluded from the assessment of effectiveness in current earnings under cost of products sold or net sales, as appropriate. We record all gains or losses from derivatives for which hedge accounting treatment has not been elected to earnings on a current basis in net sales or cost of products sold. We have provided $17.9 of collateral to counterparties under collateral funding arrangements as of December 31, 2015 . Outstanding commodity price swaps and options and forward foreign exchange contracts as of December 31, 2015 and 2014 , are presented below: Commodity 2015 2014 Nickel (in lbs) 164,800 259,300 Natural gas (in MMBTUs) 36,972,500 33,992,500 Zinc (in lbs) 54,173,800 61,800,000 Iron ore (in metric tons) 2,795,000 2,335,000 Electricity (in MWHs) 1,386,400 1,182,800 Hot roll carbon steel coils (in short tons) — 15,000 Foreign exchange contracts (in euros) € 55,500,000 € 23,675,000 The fair value of derivative instruments as of December 31, 2015 and 2014 , is presented below: Asset (liability) 2015 2014 Derivatives designated as hedging instruments: Other current assets—commodity contracts $ 0.3 $ 2.1 Other non-current assets—commodity contracts 0.3 1.8 Accrued liabilities—commodity contracts (40.9 ) (32.0 ) Other non-current liabilities—commodity contracts (9.5 ) (5.7 ) Derivatives not designated as hedging instruments: Other current assets: Foreign exchange contracts 1.1 1.2 Commodity contracts 0.2 1.5 Accrued liabilities: Commodity contracts (0.3 ) (4.2 ) Gains (losses) on derivative instruments for the years ended December 31, 2015 , 2014 and 2013 , are presented below: Gain (loss) 2015 2014 2013 Derivatives in cash flow hedging relationships— Commodity contracts: Reclassified from accumulated other comprehensive income into net sales (effective portion) $ — $ — $ 0.4 Reclassified from accumulated other comprehensive income into cost of products sold (effective portion) (61.4 ) (1.1 ) 24.8 Recorded in cost of products sold (ineffective portion and amount excluded from effectiveness testing) (23.6 ) (0.8 ) 3.3 Derivatives not designated as hedging instruments: Foreign exchange contracts—recognized in other income (expense) (0.1 ) 1.9 (0.1 ) Commodity contracts: Recognized in net sales 2.2 (5.1 ) (3.1 ) Recognized in cost of products sold (2.0 ) (35.0 ) 1.7 Gains (losses) before tax expected to be reclassified into cost of products sold within the next twelve months for our existing commodity contracts that qualify for hedge accounting, as well as the period over which we are hedging our exposure to the volatility in future cash flows, are presented below: Commodity Hedge Settlement Dates Gains (losses) Natural gas January 2016 to December 2017 $ (17.1 ) Electricity January 2016 to December 2017 (1.9 ) Iron ore January 2016 to November 2017 (7.8 ) Zinc January 2016 to December 2017 (11.2 )

Supplementary Cash Flow Informa

Supplementary Cash Flow Information (Notes)	12 Months Ended
	Dec. 31, 2015
Supplemental Cash Flow Information [Abstract]
Supplementary Cash Flow Information	Supplementary Cash Flow Information Net cash paid (received) during the period for interest, net of capitalized interest, and income taxes are presented below: 2015 2014 2013 Net cash paid (received) during the period for: Interest, net of capitalized interest $ 161.3 $ 121.9 $ 116.2 Income taxes 0.7 (0.3 ) 1.2 Included in net cash flows from operations was cash provided by SunCoke Middletown of $87.4 , $66.4 and $82.6 for the years ended December 31, 2015 , 2014 and 2013 . Consolidated cash and cash equivalents at December 31, 2015 , and 2014 , include SunCoke Middletown’s cash and cash equivalents of $7.6 and $18.2 . SunCoke Middletown’s cash and cash equivalents have no compensating balance arrangements or legal restrictions, but is not available for our use. We had capital investments during the years ended December 31, 2015 , 2014 and 2013 , that had not been paid as of the end of the respective period. These amounts are included in accounts payable and accrued liabilities and have been excluded from the consolidated statements of cash flows until paid. We also granted restricted stock to certain employees and restricted stock units to directors under the SIP. Non-cash investing and financing activities for the years ended December 31, 2015 , 2014 and 2013 , are presented below: 2015 2014 2013 Capital investments $ 37.4 $ 29.5 $ 10.2 Issuance of restricted stock and restricted stock units 4.1 4.5 3.0

Quarterly Information (Unaudite

Quarterly Information (Unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Quarterly Information (Unaudited)	Quarterly Information (Unaudited) Earnings per share for each quarter and the year are calculated individually and may not sum to the total for the year. 2015 First Quarter Second Quarter Third Quarter Fourth Quarter Year Net sales $ 1,750.9 $ 1,689.4 $ 1,709.9 $ 1,542.7 $ 6,692.9 Operating profit (loss) 33.8 7.1 80.2 (34.4 ) 86.7 Net income (loss) attributable to AK Holding (306.3 ) (64.0 ) 6.7 (145.4 ) (509.0 ) Basic and diluted earnings (loss) per share $ (1.72 ) $ (0.36 ) $ 0.04 $ (0.82 ) $ (2.86 ) 2014 First Quarter Second Quarter Third Quarter Fourth Quarter Year Net sales $ 1,383.5 $ 1,530.8 $ 1,593.8 $ 1,997.6 $ 6,505.7 Operating profit (loss) (35.3 ) 36.5 63.7 74.5 139.4 Net income (loss) attributable to AK Holding (86.1 ) (17.1 ) (7.2 ) 13.5 (96.9 ) Basic earnings (loss) per share $ (0.63 ) $ (0.13 ) $ (0.05 ) $ 0.08 $ (0.65 ) Diluted earnings (loss) per share $ (0.63 ) $ (0.13 ) $ (0.05 ) $ 0.07 $ (0.65 ) Included in net income attributable to AK Holding in the first quarter and full year of 2015 was an impairment charge of $256.3 for our investment in Magnetation. Included in the fourth quarter and full year of 2015 was an impairment charge of $41.6 for our investment in AFSG, costs of $28.1 for the temporary idling of the Ashland Works blast furnace and steelmaking operations, a pension corridor charge of $144.3 and an OPEB corridor credit of $13.1 . Dearborn’s financial results are included in the above amounts beginning September 16, 2014. Included in operating profit (loss) for the fourth quarter and full year of 2014 was a pension corridor charge of $2.0 . Included in net income attributable to AK Holding were Dearborn net-of-tax acquisition-related costs of $1.0 , $23.6 , $7.1 and $31.7 for the second, third and fourth quarters and full year of 2014.

Supplementary Guarantor Informa

Supplementary Guarantor Information (Notes)	12 Months Ended
	Dec. 31, 2015
Supplemental Guarantor Information [Abstract]
Supplemental Guarantor Information	Supplementary Guarantor Information AK Steel’s 8.75% Senior Secured Notes due December 2018, 7.625% Senior Notes due May 2020, 7.625% Senior Notes due October 2021, 8.375% Senior Notes due April 2022 (collectively, the “Senior Notes”) and 5.0% Exchangeable Senior Notes due November 2019 (the “Exchangeable Notes”) are governed by indentures entered into by AK Holding and its 100%-owned subsidiary, AK Steel. Under the terms of the indentures, AK Holding and the guarantor subsidiaries (AK Steel’s 100%-owned subsidiaries, AK Tube and AK Properties) each fully and unconditionally, jointly and severally, guarantee the payment of interest, principal and premium, if any, on each of the notes included in the Senior Notes. Under the terms of the indenture for the Exchangeable Notes, AK Holding fully and unconditionally, jointly and severally, guarantees the payment of interest, principal and premium, if any, on the notes. AK Holding remains the sole guarantor of the Exchangeable Notes. We present all investments in subsidiaries in the supplementary guarantor information using the equity method of accounting. Therefore, the net income (loss) of the subsidiaries accounted for using the equity method is in their parents’ investment accounts. The principal elimination entries eliminate investments in subsidiaries and inter-company balances and transactions. The following supplementary condensed consolidating financial statements present information about AK Holding, AK Steel, the guarantor subsidiaries of the Senior Notes and the other non-guarantor subsidiaries. Condensed Statements of Comprehensive Income (Loss) Year Ended December 31, 2015 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net sales $ — $ 6,498.2 $ 250.9 $ 538.3 $ (594.5 ) $ 6,692.9 Cost of products sold (exclusive of items shown separately below) — 5,984.9 167.5 423.3 (543.7 ) 6,032.0 Selling and administrative expenses (exclusive of items shown separately below) 4.9 270.4 10.7 25.0 (49.1 ) 261.9 Depreciation — 187.7 3.6 24.7 — 216.0 Pension and OPEB expense (income) (exclusive of corridor charges shown below) — (63.0 ) — — — (63.0 ) Pension and OPEB net corridor charge — 131.2 — — — 131.2 Charge for facility idling — 28.1 — — — 28.1 Total operating costs 4.9 6,539.3 181.8 473.0 (592.8 ) 6,606.2 Operating profit (loss) (4.9 ) (41.1 ) 69.1 65.3 (1.7 ) 86.7 Interest expense — 171.0 — 2.0 — 173.0 Impairment of Magnetation investment — — — (256.3 ) — (256.3 ) Impairment of AFSG investment — — — (41.6 ) — (41.6 ) Other income (expense) — 6.4 6.6 (11.6 ) — 1.4 Income (loss) before income taxes (4.9 ) (205.7 ) 75.7 (246.2 ) (1.7 ) (382.8 ) Income tax expense (benefit) — 39.6 28.7 (4.2 ) (0.7 ) 63.4 Equity in net income (loss) of subsidiaries (504.1 ) (258.8 ) — — 762.9 — Net income (loss) (509.0 ) (504.1 ) 47.0 (242.0 ) 761.9 (446.2 ) Less: Net income attributable to noncontrolling interests — — — 62.8 — 62.8 Net income (loss) attributable to AK Steel Holding Corporation (509.0 ) (504.1 ) 47.0 (304.8 ) 761.9 (509.0 ) Other comprehensive income (loss) 17.2 17.2 — (3.1 ) (14.1 ) 17.2 Comprehensive income (loss) attributable to AK Steel Holding Corporation $ (491.8 ) $ (486.9 ) $ 47.0 $ (307.9 ) $ 747.8 $ (491.8 ) Condensed Statements of Comprehensive Income (Loss) Year Ended December 31, 2014 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net sales $ — $ 6,284.2 $ 280.7 $ 599.6 $ (658.8 ) $ 6,505.7 Cost of products sold (exclusive of items shown separately below) — 5,937.6 199.3 484.7 (613.9 ) 6,007.7 Selling and administrative expenses (exclusive of items shown separately below) 4.6 251.0 11.3 28.3 (48.0 ) 247.2 Depreciation — 176.1 3.9 21.9 — 201.9 Pension and OPEB expense (income) — (92.5 ) — — — (92.5 ) Pension corridor charge — 2.0 — — — 2.0 Total operating costs 4.6 6,274.2 214.5 534.9 (661.9 ) 6,366.3 Operating profit (loss) (4.6 ) 10.0 66.2 64.7 3.1 139.4 Interest expense — 142.1 — 2.6 — 144.7 Other income (expense) — (17.7 ) 6.5 (9.9 ) — (21.1 ) Income (loss) before income taxes (4.6 ) (149.8 ) 72.7 52.2 3.1 (26.4 ) Income tax expense (benefit) — (19.2 ) 29.1 (3.4 ) 1.2 7.7 Equity in net income (loss) of subsidiaries (92.3 ) 38.3 — — 54.0 — Net income (loss) (96.9 ) (92.3 ) 43.6 55.6 55.9 (34.1 ) Less: Net income attributable to noncontrolling interests — — — 62.8 — 62.8 Net income (loss) attributable to AK Steel Holding Corporation (96.9 ) (92.3 ) 43.6 (7.2 ) 55.9 (96.9 ) Other comprehensive income (loss) (527.8 ) (527.8 ) — (3.7 ) 531.5 (527.8 ) Comprehensive income (loss) attributable to AK Steel Holding Corporation $ (624.7 ) $ (620.1 ) $ 43.6 $ (10.9 ) $ 587.4 $ (624.7 ) Condensed Statements of Comprehensive Income (Loss) Year Ended December 31, 2013 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net sales $ — $ 5,339.3 $ 261.5 $ 568.8 $ (599.2 ) $ 5,570.4 Cost of products sold (exclusive of items shown separately below) — 5,012.1 189.0 463.3 (556.6 ) 5,107.8 Selling and administrative expenses (exclusive of items shown separately below) 4.4 205.0 10.5 26.2 (40.8 ) 205.3 Depreciation — 169.4 4.3 16.4 — 190.1 Pension and OPEB expense (income) — (68.6 ) — — — (68.6 ) Total operating costs 4.4 5,317.9 203.8 505.9 (597.4 ) 5,434.6 Operating profit (loss) (4.4 ) 21.4 57.7 62.9 (1.8 ) 135.8 Interest expense — 125.9 — 1.5 — 127.4 Other income (expense) — (5.9 ) 6.1 (1.6 ) — (1.4 ) Income (loss) before income taxes (4.4 ) (110.4 ) 63.8 59.8 (1.8 ) 7.0 Income tax expense (benefit) — (27.8 ) 20.1 (2.0 ) (0.7 ) (10.4 ) Equity in net income (loss) of subsidiaries (42.4 ) 40.2 — — 2.2 — Net income (loss) (46.8 ) (42.4 ) 43.7 61.8 1.1 17.4 Less: Net income attributable to noncontrolling interests — — — 64.2 — 64.2 Net income (loss) attributable to AK Steel Holding Corporation (46.8 ) (42.4 ) 43.7 (2.4 ) 1.1 (46.8 ) Other comprehensive income (loss) 322.3 322.3 — 1.2 (323.5 ) 322.3 Comprehensive income (loss) attributable to AK Steel Holding Corporation $ 275.5 $ 279.9 $ 43.7 $ (1.2 ) $ (322.4 ) $ 275.5 Condensed Balance Sheets December 31, 2015 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company ASSETS Current assets: Cash and cash equivalents $ — $ 27.0 $ — $ 29.6 $ — $ 56.6 Accounts receivable, net — 411.9 23.5 32.0 (22.5 ) 444.9 Inventory, net — 1,149.6 26.1 60.6 (10.0 ) 1,226.3 Other current assets — 75.6 0.3 2.5 — 78.4 Total current assets — 1,664.1 49.9 124.7 (32.5 ) 1,806.2 Property, plant and equipment — 5,763.8 103.1 599.1 — 6,466.0 Accumulated depreciation — (4,218.0 ) (75.4 ) (86.1 ) — (4,379.5 ) Property, plant and equipment, net — 1,545.8 27.7 513.0 — 2,086.5 Other non-current assets: Investment in affiliates — 42.6 — 28.1 — 70.7 Investment in subsidiaries (3,541.0 ) 1,346.0 — — 2,195.0 — Inter-company accounts 2,563.4 (3,600.9 ) 1,403.0 (390.8 ) 25.3 — Other non-current assets — 83.0 33.0 5.0 — 121.0 TOTAL ASSETS $ (977.6 ) $ 1,080.6 $ 1,513.6 $ 280.0 $ 2,187.8 $ 4,084.4 LIABILITIES AND EQUITY (DEFICIT) Current liabilities: Accounts payable $ — $ 669.0 $ 6.3 $ 29.1 $ (1.0 ) $ 703.4 Accrued liabilities — 242.3 2.8 16.4 — 261.5 Current portion of pension and other postretirement benefit obligations — 77.3 — 0.4 — 77.7 Total current liabilities — 988.6 9.1 45.9 (1.0 ) 1,042.6 Non-current liabilities: Long-term debt — 2,354.1 — — — 2,354.1 Pension and other postretirement benefit obligations — 1,143.6 — 3.3 — 1,146.9 Other non-current liabilities — 135.3 — 1.1 — 136.4 TOTAL LIABILITIES — 4,621.6 9.1 50.3 (1.0 ) 4,680.0 Equity (deficit): Total stockholders’ equity (deficit) (977.6 ) (3,541.0 ) 1,504.5 (152.3 ) 2,188.8 (977.6 ) Noncontrolling interests — — — 382.0 — 382.0 TOTAL EQUITY (DEFICIT) (977.6 ) (3,541.0 ) 1,504.5 229.7 2,188.8 (595.6 ) TOTAL LIABILITIES AND EQUITY (DEFICIT) $ (977.6 ) $ 1,080.6 $ 1,513.6 $ 280.0 $ 2,187.8 $ 4,084.4 Condensed Balance Sheets December 31, 2014 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company ASSETS Current assets: Cash and cash equivalents $ — $ 28.5 $ 0.5 $ 41.2 $ — $ 70.2 Accounts receivable, net — 606.2 27.6 37.3 (26.8 ) 644.3 Inventory, net — 1,080.5 26.2 73.5 (8.1 ) 1,172.1 Other current assets 0.3 67.9 0.2 3.0 — 71.4 Total current assets 0.3 1,783.1 54.5 155.0 (34.9 ) 1,958.0 Property, plant and equipment — 5,695.8 97.3 595.3 — 6,388.4 Accumulated depreciation — (4,040.8 ) (71.8 ) (62.6 ) — (4,175.2 ) Property, plant and equipment, net — 1,655.0 25.5 532.7 — 2,213.2 Other non-current assets: Investment in affiliates — 84.5 — 304.2 — 388.7 Investment in subsidiaries (2,970.9 ) 1,582.4 — — 1,388.5 — Inter-company accounts 2,478.1 (3,420.4 ) 1,325.5 (412.4 ) 29.2 — Other non-current assets — 174.4 33.0 60.7 — 268.1 TOTAL ASSETS $ (492.5 ) $ 1,859.0 $ 1,438.5 $ 640.2 $ 1,382.8 $ 4,828.0 LIABILITIES AND EQUITY (DEFICIT) Current liabilities: Accounts payable $ — $ 754.9 $ 6.9 $ 42.0 $ (0.7 ) $ 803.1 Accrued liabilities — 244.6 3.0 18.9 — 266.5 Current portion of pension and other postretirement benefit obligations — 55.3 — 0.3 — 55.6 Total current liabilities — 1,054.8 9.9 61.2 (0.7 ) 1,125.2 Non-current liabilities: Long-term debt — 2,422.0 — — — 2,422.0 Pension and other postretirement benefit obligations — 1,221.3 — 4.0 — 1,225.3 Other non-current liabilities — 131.8 — 0.7 — 132.5 TOTAL LIABILITIES — 4,829.9 9.9 65.9 (0.7 ) 4,905.0 Equity (deficit): Total stockholders’ equity (deficit) (492.5 ) (2,970.9 ) 1,428.6 158.8 1,383.5 (492.5 ) Noncontrolling interests — — — 415.5 — 415.5 TOTAL EQUITY (DEFICIT) (492.5 ) (2,970.9 ) 1,428.6 574.3 1,383.5 (77.0 ) TOTAL LIABILITIES AND EQUITY (DEFICIT) $ (492.5 ) $ 1,859.0 $ 1,438.5 $ 640.2 $ 1,382.8 $ 4,828.0 Condensed Statements of Cash Flows Year Ended December 31, 2015 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net cash flows from operating activities $ (3.7 ) $ 49.0 $ 53.9 $ 104.8 $ (3.7 ) $ 200.3 Cash flows from investing activities: Capital investments — (85.0 ) (5.8 ) (8.2 ) — (99.0 ) Proceeds from sale of equity investee — 25.0 — — — 25.0 Proceeds from AFSG Holdings, Inc. distribution — — — 14.0 — 14.0 Other investing items, net — 12.5 — — — 12.5 Net cash flows from investing activities — (47.5 ) (5.8 ) 5.8 — (47.5 ) Cash flows from financing activities: Net borrowings (repayments) under credit facility — (55.0 ) — — — (55.0 ) Redemption of long-term debt — (14.1 ) — — — (14.1 ) Inter-company activity 4.7 66.1 (48.6 ) (25.9 ) 3.7 — SunCoke Middletown distributions to noncontrolling interest owners — — — (96.3 ) — (96.3 ) Other financing items, net (1.0 ) — — — — (1.0 ) Net cash flows from financing activities 3.7 (3.0 ) (48.6 ) (122.2 ) 3.7 (166.4 ) Net increase (decrease) in cash and cash equivalents — (1.5 ) (0.5 ) (11.6 ) — (13.6 ) Cash and equivalents, beginning of year — 28.5 0.5 41.2 — 70.2 Cash and equivalents, end of year $ — $ 27.0 $ — $ 29.6 $ — $ 56.6 Condensed Statements of Cash Flows Year Ended December 31, 2014 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net cash flows from operating activities $ (3.4 ) $ (447.2 ) $ 39.2 $ 91.3 $ (2.7 ) $ (322.8 ) Cash flows from investing activities: Capital investments — (63.1 ) (2.8 ) (15.2 ) — (81.1 ) Investments in Magnetation joint venture — — — (100.0 ) — (100.0 ) Investments in acquired business, net of cash acquired — (690.3 ) — — — (690.3 ) Other investing items, net — 13.6 — — — 13.6 Net cash flows from investing activities — (739.8 ) (2.8 ) (115.2 ) — (857.8 ) Cash flows from financing activities: Net borrowings (repayments) under credit facility — 515.0 — — — 515.0 Proceeds from issuance of long-term debt — 427.1 — — — 427.1 Redemption of long-term debt — (0.8 ) — — — (0.8 ) Proceeds from issuance of common stock 345.3 — — — — 345.3 Debt issuance costs — (15.5 ) — — — (15.5 ) Inter-company activity (341.0 ) 272.9 (35.9 ) 101.3 2.7 — SunCoke Middletown distributions to noncontrolling interest owners — — — (61.0 ) — (61.0 ) Other financing items, net (0.9 ) — — (3.7 ) — (4.6 ) Net cash flows from financing activities 3.4 1,198.7 (35.9 ) 36.6 2.7 1,205.5 Net increase (decrease) in cash and cash equivalents — 11.7 0.5 12.7 — 24.9 Cash and equivalents, beginning of year — 16.8 — 28.5 — 45.3 Cash and equivalents, end of year $ — $ 28.5 $ 0.5 $ 41.2 $ — $ 70.2 Condensed Statements of Cash Flows Year Ended December 31, 2013 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net cash flows from operating activities $ (3.5 ) $ (251.1 ) $ 50.4 $ 129.6 $ (35.6 ) $ (110.2 ) Cash flows from investing activities: Capital investments — (39.2 ) (1.7 ) (22.7 ) — (63.6 ) Investments in acquired businesses — — — (50.0 ) — (50.0 ) Other investing items, net — 8.5 0.3 6.3 — 15.1 Net cash flows from investing activities — (30.7 ) (1.4 ) (66.4 ) — (98.5 ) Cash flows from financing activities: Net borrowings (repayments) under credit facility — 90.0 — — — 90.0 Proceeds from issuance of long-term debt — 31.9 — — — 31.9 Redemption of long-term debt — (27.4 ) — — — (27.4 ) Debt issuance costs — (3.4 ) — — — (3.4 ) Inter-company activity 4.1 3.9 (49.0 ) 5.4 35.6 — SunCoke Middletown distributions to noncontrolling interest owners — — — (64.8 ) — (64.8 ) Other financing items, net (0.6 ) — — 1.3 — 0.7 Net cash flows from financing activities 3.5 95.0 (49.0 ) (58.1 ) 35.6 27.0 Net increase (decrease) in cash and cash equivalents — (186.8 ) — 5.1 — (181.7 ) Cash and equivalents, beginning of year — 203.6 — 23.4 — 227.0 Cash and equivalents, end of year $ — $ 16.8 $ — $ 28.5 $ — $ 45.3

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: These financial statements consolidate the operations and accounts of AK Steel Holding Corporation (“AK Holding”), its wholly-owned subsidiary AK Steel Corporation (“AK Steel”), all subsidiaries in which AK Holding has a controlling interest, and two variable interest entities for which AK Steel is the primary beneficiary. Unless the context indicates otherwise, references to “we,” “us” and “our” refer to AK Holding and its subsidiaries. We also operate Mexican and European trading companies that buy and sell steel and steel products and other materials. We manage operations on a consolidated, integrated basis so that we can use the most appropriate equipment and facilities for the production of a product, regardless of product line. Therefore, we conclude that we operate in a single business segment. All intercompany transactions and balances have been eliminated.
Use of Estimates	Use of Estimates: The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires the use of estimates and assumptions that affect the amounts reported. We base these estimates on historical experience and information available to us about current events and actions we may take in the future. Estimates and assumptions affect significant items that include the carrying value of long-lived assets, including investments and goodwill; valuation allowances for receivables, inventories and deferred income tax assets; legal and environmental liabilities; workers compensation and asbestos liabilities; share-based compensation; excess cost of operations; and assets and obligations of employee benefit plans. There can be no assurance that actual results will not differ from these estimates.
Revenue Recognition	Revenue Recognition: Revenue from sales of products is recognized at the time that title and the risks and rewards of ownership pass, which can be on the date of shipment or the date of receipt by the customer depending on when the terms of customers’ arrangements are met, the sales price is fixed or determinable, and collection is reasonably assured.
Revenue Recognition, Excise And Sales Taxes	Sales taxes collected from customers are recorded on a net basis with no revenue recognized.
Cost of Products Sold	Cost of Products Sold: Cost of products sold consists primarily of raw materials, energy costs, supplies consumed in the manufacturing process, manufacturing labor, contract labor and direct overhead expense necessary to manufacture the finished steel product, as well as distribution and warehousing costs.
Cost of Products Sold, Equity Method Investments	Our share of the income (loss) of investments in associated companies accounted for under the equity method is included in costs of products sold since these operations are integrated with our overall steelmaking operations, except for our share of the income (loss) of Magnetation LLC, which is included in other income (expense).
Share-Based Compensation	Share-Based Compensation: Compensation costs for stock awards granted under our Stock Incentive Plan are recognized over their vesting period using the straight-line method.
Legal Fees	Legal Fees: Legal fees associated with litigation and similar proceedings that are not expected to provide a benefit in future periods are generally expensed as incurred. Legal fees associated with activities that are expected to provide a benefit in future periods, such as costs associated with the issuance of debt, are generally capitalized as incurred.
Income Taxes	Income Taxes: Interest and penalties from uncertain tax positions are included in income tax expense. Deferred tax assets do not include certain amounts that arise from tax deductions from share-based compensation in excess of compensation recognized for financial reporting when net operating loss carryforwards are created. We use tax law ordering to determine when excess tax benefits have been realized.
Earnings per Share	Earnings per Share: Earnings per share is calculated using the “two-class” method. Under the “two-class” method, undistributed earnings are allocated to both common shares and participating securities. We divide the sum of distributed earnings to common stockholders and undistributed earnings allocated to common stockholders by the weighted-average number of common shares outstanding during the period. The restricted stock granted by AK Holding is entitled to dividends before vesting and meets the criteria of a participating security.
Cash Equivalents	Cash Equivalents: Cash equivalents include short-term, highly-liquid investments that are readily convertible to known amounts of cash and have an original maturity of three months or less.
Inventories	Inventories: Inventories are valued at the lower of cost or market. We measure the cost of the majority of inventories on the last-in, first-out (LIFO) method. Other inventories are measured principally at average cost and consist mostly of foreign inventories and certain raw materials.
Property, Plant and Equipment	Property, Plant and Equipment: Plant and equipment are depreciated under the straight-line method over their estimated lives. Estimated lives are as follows: land improvements over 20 years, leaseholds over the life of the lease, buildings over 40 years and machinery and equipment over two to 20 years. The estimated weighted-average life of our machinery and equipment is 12 years at the end of the current year. Costs incurred to develop coal mines are capitalized when incurred. We use the units-of-production method utilizing only proven and probable reserves in the depletion base to compute the depletion of coal reserves and mine development costs.
Property, Plant and Equipment, Planned Major Maintenance Activities	We expense costs associated with major maintenance activities at our operating facilities in the period in which they occur.
Property, Plant and Equipment, Impairment or Disposal of Long-Lived Assets	We review the carrying value of long-lived assets to be held and used and long-lived assets to be disposed of when events and circumstances warrant such a review. If the carrying value of a long-lived asset exceeds its fair value, an impairment has occurred and a loss is recognized based on the amount by which the carrying value exceeds the fair value, less cost to dispose, for assets to be sold or abandoned. We determine fair value by using quoted market prices, estimates based on prices of similar assets or anticipated cash flows discounted at a rate commensurate with risk.
Equity and Cost Method Investments, Policy [Policy Text Block]	Investments: Investments in associated companies are accounted for under the equity method. We review investments for impairment when circumstances indicate that a loss in value below its carrying amount is other than temporary.
Goodwill	Goodwill: Goodwill relates to our tubular business. We review goodwill for potential impairment at least annually on October 1 each year and whenever events or circumstances make it more likely than not that impairment may have occurred. Considering operating results and the estimated fair value of the business, the most recent annual goodwill impairment test indicated that the fair value of our tubular business reporting unit was in excess of its carrying value. No goodwill impairment was recorded as a result of the 2015 , 2014 and 2013 annual impairment tests.
Debt Issuance Costs	Debt Issuance Costs: Debt issuance costs for the revolving credit facility are included in other non-current assets and all other debt issuance costs reduce the carrying amount of long-term debt.
Pension and Other Postretirement Benefits	Pension and Other Postretirement Benefits: We recognize, as of the measurement date, any unrecognized actuarial net gains or losses that exceed 10% of the larger of the projected benefit obligations or the plan assets, defined as the “corridor”. Amounts inside the corridor are amortized over the plan participants’ life expectancy. We determine the expected return on assets using the fair value of plan assets.
Concentrations of Credit Risk	Concentrations of Credit Risk: We are primarily a producer of carbon, stainless and electrical steels and steel products, which are sold to a number of markets, including automotive, industrial machinery and equipment, construction, power distribution and appliances. Net sales by product line are presented below: 2015 2014 2013 Carbon $ 4,746.8 $ 4,423.3 $ 3,643.4 Stainless and electrical 1,733.0 1,836.5 1,705.3 Tubular 201.3 231.4 220.7 Other 11.8 14.5 1.0 Total $ 6,692.9 $ 6,505.7 $ 5,570.4 Percentages of our net sales attributable to various markets are presented below: 2015 2014 2013 Automotive 60 % 53 % 51 % Infrastructure and Manufacturing 16 % 18 % 20 % Distributors and Converters 24 % 29 % 29 % We sell domestically to customers located primarily in the Midwestern and Eastern United States and to foreign customers, primarily in Canada, Mexico and Western Europe. Net sales to customers located outside the United States totaled $855.7 , $755.4 and $708.0 for 2015 , 2014 and 2013 . We had two customers that accounted for 12% and 11% of net sales in 2015 . No customer accounted for more than 10% of our net sales during 2014 and 2013 .
Concentrations of Credit Risk, Trade Accounts Receivable	Approximately 65% and 43% of accounts receivable outstanding at December 31, 2015 and 2014 , are due from businesses associated with the U.S. automotive industry, including 20% and 14% of receivables due from one automotive customer as of December 31, 2015 and 2014 . Except in a few situations where the risk warrants it, collateral is not required on accounts receivable. While we believe our recorded accounts receivable will be collected, in the event of default we would follow normal collection procedures. We maintain an allowance for doubtful accounts for the loss that would be incurred if a customer is unable to pay amounts due. We determine this allowance based on various factors, including the customer’s financial condition and changes in customer payment patterns. We write off accounts receivable against the allowance for doubtful accounts when it is remote that collection will occur.
Union Contracts	Union Contracts: At December 31, 2015 , we employed approximately 8,500 people, of which approximately 6,300 are represented by labor unions under various contracts that expire between 2016 and 2019 . On February 5, 2015, members of the United Steelworkers, Local 1190 , ratified a labor agreement covering approximately 215 production and maintenance employees at Mountain State Carbon, LLC. The new agreement took effect on March 1, 2015 and will expire on March 1, 2019 . This is the initial labor agreement with the union at Mountain State Carbon. On May 8, 2015, members of the United Auto Workers, Local 4104 , ratified a labor agreement covering approximately 140 production and maintenance employees at Zanesville Works. The new agreement took effect on May 20, 2015 and will expire on May 31, 2019 . An agreement with the United Auto Workers, Local 3462 , which represents approximately 330 employees at our Coshocton Works, is scheduled to expire on March 31, 2016 . An agreement with the United Auto Workers, Local 3303 , which represents approximately 1,240 employees at our Butler Works, is scheduled to expire on October 1, 2016 .
Financial Instruments, Marketable Securities	Financial Instruments: We classify investments in equity securities as available-for-sale and carry them at fair value with unrealized gains and losses, net of tax, reported in other comprehensive income. Realized gains and losses on sales of available-for-sale securities are computed based upon initial cost adjusted for any other-than-temporary declines in fair value. We have no investments that are considered to be trading securities.
Financial Instruments, Derivatives	We are a party to derivative instruments that are designated and qualify as hedges for accounting purposes. We may also use derivative instruments to which we do not apply hedge accounting treatment. Our objective in using these instruments is to protect earnings and cash flows from fluctuations in the fair value of selected commodities and currencies. Fluctuations in the price of certain commodities we use in production processes and in the selling price of certain commodity steel (hot roll carbon steel coils) may affect our income and cash flows. We have implemented raw material and energy surcharges for spot market customers and some contract customers. For certain commodities where such exposure exists, we may use cash-settled commodity price swaps, collars and purchase options, with a duration of up to three years, to hedge the price of a portion of our natural gas, iron ore, electricity, aluminum, zinc and nickel requirements or the selling price of hot roll carbon steel coils. We may designate some of these instruments as cash flow hedges and the effective portion of the changes in their fair value and settlements are recorded in accumulated other comprehensive income. Gains and losses are subsequently reclassified from accumulated other comprehensive income and recorded in cost of products sold or net sales in the same period as the earnings recognition of the associated underlying transaction. Other instruments are marked to market and recorded in cost of products sold or net sales with the offset recorded as current assets or accrued liabilities. In addition, exchange rate fluctuations on monies we receive from European subsidiaries and other customers invoiced in European currencies create cash flow and income statement risks. To reduce these risks, we have entered a series of agreements to sell euros in the future at fixed dollar rates. These forward contracts are entered with durations up to twenty-four months . A typical contract is used as a cash flow hedge for the period that begins when an order is taken and ends when a sale is recognized, at which time it converts into a fair value hedge of a receivable we collect in euros. We do not designate these derivatives as hedges for accounting purposes and we recognize the change in fair value as expense or income in other income (expense). We formally document all relationships between hedging instruments and hedged items, as well as risk management objectives and strategies for undertaking various hedge transactions. In this documentation, we specifically identify the asset, liability, firm commitment or forecasted transaction that has been designated as a hedged item, and state how the hedging instrument is expected to hedge the risks from that item. We formally measure effectiveness of hedging relationships both at the hedge inception and on an ongoing basis. We discontinue hedge accounting prospectively when we determine that the derivative is no longer effective in offsetting changes in the fair value or cash flows of a hedged item; when the derivative expires or is sold, terminated or exercised; when it is probable that the forecasted transaction will not occur; when a hedged firm commitment no longer meets the definition of a firm commitment; or when we determine that designation of the derivative as a hedge instrument is no longer appropriate. Our derivative contracts contain collateral funding requirements. We have master netting arrangements with counterparties, giving us the right to offset amounts owed under the derivative instruments and the collateral. We do not offset derivative assets and liabilities or collateral on our consolidated balance sheets.
Asbestos and Environmental Reserves	Asbestos and Environmental Accruals: For a number of years, we have been remediating sites where hazardous materials may have been released, including sites no longer owned by us. In addition, a number of lawsuits alleging asbestos exposure have been filed and continue to be filed against us. We have established accruals for estimated probable costs from asbestos claim settlements and environmental investigation, monitoring and remediation. If the accruals are not adequate to meet future claims, operating results and cash flows may be negatively affected. Our accruals do not consider the potential for insurance recoveries, for which we have partial insurance coverage for some future asbestos claims. In addition, some existing insurance policies covering asbestos and environmental contingencies may serve to partially reduce future covered expenditures.
New Accounting Pronouncements	New Accounting Pronouncements: The Financial Accounting Standards Board issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) , during the second quarter of 2014. Topic 606, as further amended by subsequent Accounting Standard Updates, affects virtually all aspects of an entity’s revenue recognition, including determining the measurement of revenue and the timing of when it is recognized for the transfer of goods or services to customers. Topic 606 is effective for annual reporting periods beginning after December 15, 2017. We are currently evaluating the effect of the adoption of Topic 606 on our financial position and results of operations. The Financial Accounting Standards Board issued Accounting Standards Update No. 2015-02, Amendments to the Consolidation Analysis (“ASU 2015-02”), during the first quarter of 2015. ASU 2015-02 changes the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. ASU 2015-02 is effective for annual reporting periods beginning after December 15, 2015, unless early adoption is elected. We are currently evaluating the effect of the adoption of ASU 2015-02 on our financial position and results of operations, but we do not expect the adoption to have a material effect on our consolidated financial statements. In April 2015 and August 2015, the Financial Accounting Standards Board issued accounting guidance to simplify the presentation of debt issuance costs by requiring that debt issuance costs from a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. We elected to early adopt this guidance during 2015 on a retrospective basis. As a result, $24.8 of debt issuance costs was presented as a reduction of long-term debt as of December 31, 2015 and we reclassified $30.5 from other non-current assets to long-term debt as of December 31, 2014. In November 2015, the Financial Accounting Standards Board issued accounting guidance to simplify the presentation of deferred tax assets and liabilities by requiring that all amounts be presented in the balance sheet as noncurrent assets or liabilities. We elected to early adopt this guidance during 2015 on a retrospective basis. As a result, we reclassified $67.7 from other current assets to other non-current assets as of December 31, 2014.
Reclassifications	Reclassifications: We reclassified certain prior-year amounts to conform to the current-year presentation.

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Revenue from External Customers by Product Line	Net sales by product line are presented below: 2015 2014 2013 Carbon $ 4,746.8 $ 4,423.3 $ 3,643.4 Stainless and electrical 1,733.0 1,836.5 1,705.3 Tubular 201.3 231.4 220.7 Other 11.8 14.5 1.0 Total $ 6,692.9 $ 6,505.7 $ 5,570.4
Schedule of Percentage of Net Sales by Market	Percentages of our net sales attributable to various markets are presented below: 2015 2014 2013 Automotive 60 % 53 % 51 % Infrastructure and Manufacturing 16 % 18 % 20 % Distributors and Converters 24 % 29 % 29 %

Supplementary Financial State30

Supplementary Financial Statement Information (Tables)	12 Months Ended
	Dec. 31, 2015
Supplementary Financial Statement Information [Abstract]
Allowance for doubtful accounts	Changes in the allowance for doubtful accounts for the years ended December 31, 2015 , 2014 and 2013 , are presented below: 2015 2014 2013 Balance at beginning of year $ 9.0 $ 8.1 $ 9.1 Increase (decrease) in allowance (3.0 ) 0.9 (0.4 ) Receivables written off — — (0.6 ) Balance at end of year $ 6.0 $ 9.0 $ 8.1
Inventory, net	Inventories as of December 31, 2015 and 2014 , consist of: 2015 2014 Finished and semi-finished $ 996.5 $ 1,053.4 Raw materials 410.0 494.2 Total cost 1,406.5 1,547.6 Adjustment to state inventories at LIFO value (180.2 ) (375.5 ) Inventory, net $ 1,226.3 $ 1,172.1
Change in LIFO reserve	Changes in the LIFO reserve for the years ended December 31, 2015 , 2014 and 2013 , are presented below: 2015 2014 2013 Balance at beginning of year $ 375.5 $ 396.5 $ 435.0 Change in reserve (195.3 ) (21.0 ) (38.5 ) Balance at end of year $ 180.2 $ 375.5 $ 396.5
Property, plant and equipment	Property, plant and equipment as of December 31, 2015 and 2014 , consist of: 2015 2014 Land, land improvements and leaseholds $ 263.0 $ 260.7 Buildings 465.9 466.7 Machinery and equipment 5,628.2 5,571.0 Construction in progress 108.9 90.0 Total 6,466.0 6,388.4 Less accumulated depreciation (4,379.5 ) (4,175.2 ) Property, plant and equipment, net $ 2,086.5 $ 2,213.2
Other non-current assets	Other non-current assets as of December 31, 2015 and 2014 , consist of: 2015 2014 Investment in AFSG Holdings, Inc. $ — $ 55.6 Goodwill 32.8 32.8 Deferred tax assets, non-current 62.7 138.0 Other 25.5 41.7 Other non-current assets $ 121.0 $ 268.1

Acquisition of Dearborn Prelimi

Acquisition of Dearborn Preliminary Purchase Price Allocation (Tables)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	A summary of the final purchase price allocation for the fair value of the assets acquired and the obligations assumed at the date of the acquisition is presented below. Accounts receivable $ 180.6 Inventory 362.6 Other current assets 3.6 Property, plant and equipment 445.5 Investment in affiliates 72.5 Total assets acquired 1,064.8 Accounts payable (201.4 ) Accrued liabilities (32.8 ) Other postretirement benefit obligations (128.2 ) Other non-current liabilities (12.1 ) Total liabilities assumed (374.5 ) Purchase price, net of cash acquired $ 690.3

Investments in Affiliates (Tabl

Investments in Affiliates (Tables)	12 Months Ended
	Dec. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments [Table Text Block]	Summarized financial statement data for all investees is presented below. The financial results for the acquired joint ventures are only included for the period since the acquisition and the financial results for Magnetation are only included through March 31, 2015, since it is unlikely that we will retain our equity interest as a result of Magnetation’s bankruptcy. 2015 2014 2013 Revenue $ 356.4 $ 386.1 $ 293.9 Gross profit 68.3 93.2 103.7 Net income (loss) (9.8 ) 10.8 20.1 2015 2014 Current assets $ 89.3 $ 211.8 Noncurrent assets 66.9 879.1 Current liabilities 14.5 157.1 Noncurrent liabilities 33.8 516.6 Investees and equity ownership percentages are presented below: Equity Ownership % Combined Metals of Chicago, LLC 40.0% Delaco Processing, LLC 49.0% Magnetation LLC 49.9% Rockport Roll Shop LLC 50.0% Spartan Steel Coating, LLC 48.0%
Schedule of Related Party Transactions [Table Text Block]	Transactions with all equity investees for the years indicated are presented below: 2015 2014 2013 Sales to equity investees $ 61.4 $ 93.4 $ 71.6 Purchases from equity investees 251.0 67.7 12.5 Outstanding receivables and payables with all equity investees as of the end of the year indicated are presented below: 2015 2014 Accounts receivable from equity investees $ 0.4 $ 2.5 Accounts payable to equity investees 33.1 10.9

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	Components of income (loss) before income taxes are presented below: 2015 2014 2013 United States $ (452.1 ) $ (94.3 ) $ (61.1 ) Foreign 6.5 5.1 3.9 Noncontrolling interests 62.8 62.8 64.2 Income (loss) before income taxes $ (382.8 ) $ (26.4 ) $ 7.0
Schedule of Deferred Tax Assets and Liabilities	Significant components of deferred tax assets and liabilities at December 31, 2015 and 2014 are presented below: 2015 2014 Deferred tax assets: Net operating and capital loss and tax credit carryforwards $ 847.3 $ 778.1 Postretirement benefits 158.9 201.2 Pension benefits 278.6 258.6 Inventories 139.2 152.6 Other assets 132.8 114.2 Valuation allowance (1,215.5 ) (1,000.4 ) Total deferred tax assets 341.3 504.3 Deferred tax liabilities: Depreciable assets (248.0 ) (322.7 ) Other liabilities (30.6 ) (43.6 ) Total deferred tax liabilities (278.6 ) (366.3 ) Net deferred tax assets $ 62.7 $ 138.0
Summary of Valuation Allowance	Changes in the valuation allowance for the years ended December 31, 2015 , 2014 and 2013 , are presented below: 2015 2014 2013 Balance at beginning of year $ 1,000.4 $ 764.1 $ 873.1 Change in valuation allowance: Included in income tax expense (benefit) 228.6 36.7 21.9 Change in deferred assets in other comprehensive income (13.5 ) 199.6 (130.9 ) Balance at end of year $ 1,215.5 $ 1,000.4 $ 764.1
Schedule of Components of Income Tax Expense (Benefit)	Significant components of income tax expense (benefit) are presented below: 2015 2014 2013 Current: Federal $ — $ — $ (3.4 ) State 0.2 (1.1 ) 0.2 Foreign 1.8 2.1 1.9 Deferred: Federal 68.8 7.7 14.0 State 6.5 0.2 1.2 Amount allocated to other comprehensive income (13.2 ) — (22.7 ) Change in valuation allowance on beginning-of-the-year deferred tax assets (0.7 ) (1.2 ) (1.6 ) Income tax expense (benefit) $ 63.4 $ 7.7 $ (10.4 )
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation of income tax on income (loss) before income taxes computed at the U.S. federal statutory tax rates to actual income tax expense (benefit) is presented below: 2015 2014 2013 Income tax expense (benefit) at U.S. federal statutory rate $ (134.0 ) $ (9.2 ) $ 2.4 Income tax expense calculated on noncontrolling interests (22.0 ) (22.0 ) (22.5 ) State and foreign tax expense, net of federal tax (0.9 ) (3.1 ) 1.7 Increase in deferred tax asset valuation allowance 228.6 36.7 21.9 Amount allocated to other comprehensive income (13.2 ) — (22.7 ) Change in accrual for uncertain tax positions 0.3 (0.9 ) (1.7 ) Stock compensation in excess of tax deduction — 2.0 3.1 Expiration of charitable contribution carryforwards — — 2.5 Other permanent differences 4.6 4.2 4.9 Income tax expense (benefit) $ 63.4 $ 7.7 $ (10.4 )
Schedule of Unrecognized Tax Benefits Roll Forward	A reconciliation of the change in unrecognized tax benefits for 2015 , 2014 and 2013 is presented below: 2015 2014 2013 Balance at beginning of year $ 59.9 $ 53.8 $ 54.0 Increases (decreases) for prior year tax positions (0.3 ) (0.2 ) (0.8 ) Increases (decreases) for current year tax positions 70.7 7.7 0.9 (Decreases) from statute lapses — (1.4 ) (0.3 ) Balance at end of year $ 130.3 $ 59.9 $ 53.8

Long-term Debt and Other Fina34

Long-term Debt and Other Financing (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Debt balances, including current portions, at December 31, 2015 and 2014 , are presented below: 2015 2014 Credit Facility $ 550.0 $ 605.0 8.75% Senior Secured Notes due December 2018 380.0 380.0 5.00% Exchangeable Senior Notes due November 2019 (effective rate of 10.8%) 150.0 150.0 7.625% Senior Notes due May 2020 529.8 529.8 7.625% Senior Notes due October 2021 406.2 430.0 8.375% Senior Notes due April 2022 290.2 290.2 Industrial Revenue Bonds due 2020 through 2028 99.3 99.3 Unamortized debt discount/premium and debt issuance costs (51.4 ) (62.3 ) Total long-term debt $ 2,354.1 $ 2,422.0
Schedule of Maturities of Long-term Debt	Maturities of long-term debt, including the amount outstanding on the Credit Facility, for the next five years, at December 31, 2015 , are presented below: Year Debt Maturities 2016 $ — 2017 — 2018 380.0 2019 (including $550.0 of Credit Facility borrowings) 700.0 2020 537.1

Pension and Other Postretirem35

Pension and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2015
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Schedule of Defined Benefit Plans Disclosures	Amounts presented below are calculated based on benefit obligation and asset valuation measurement dates of December 31, 2015 and 2014 . Pension Benefits Other Benefits 2015 2014 2015 2014 Change in benefit obligations: Benefit obligations at beginning of year $ 3,545.2 $ 3,380.6 $ 599.3 $ 479.2 Service cost 2.2 1.7 7.1 4.9 Interest cost 130.0 146.0 22.5 21.7 Plan participants’ contributions — — 24.9 25.4 Actuarial loss (gain) (147.8 ) 432.1 (83.3 ) 45.1 Amendments 13.3 2.0 (5.6 ) (12.8 ) Dearborn acquisition — — — 128.2 Contributions to Zanesville retirees’ VEBA trust — — (3.1 ) (3.1 ) Benefits paid (295.1 ) (416.6 ) (76.5 ) (96.6 ) Medicare subsidy reimbursement received — — 3.3 7.3 Foreign currency exchange rate changes (0.4 ) (0.6 ) — — Benefit obligations at end of year $ 3,247.4 $ 3,545.2 $ 488.6 $ 599.3 Change in plan assets: Fair value of plan assets at beginning of year $ 2,863.6 $ 2,808.5 $ — $ — Actual gain (loss) on plan assets (93.6 ) 257.8 — — Employer contributions 36.5 213.9 48.3 63.9 Plan participants’ contributions — — 24.9 25.4 Benefits paid (295.1 ) (416.6 ) (76.5 ) (96.6 ) Medicare subsidy reimbursement received — — 3.3 7.3 Fair value of plan assets at end of year $ 2,511.4 $ 2,863.6 $ — $ — Funded status $ (736.0 ) $ (681.6 ) $ (488.6 ) $ (599.3 ) Amounts recognized in the consolidated balance sheets: Current liabilities $ (31.2 ) $ (2.1 ) $ (46.5 ) $ (53.5 ) Noncurrent liabilities (704.8 ) (679.5 ) (442.1 ) (545.8 ) Total $ (736.0 ) $ (681.6 ) $ (488.6 ) $ (599.3 ) Amounts recognized in accumulated other comprehensive income, before tax: Actuarial loss (gain) $ 323.5 $ 355.7 $ (48.8 ) $ 23.1 Prior service cost (credit) 25.1 16.3 (199.0 ) (258.1 ) Total $ 348.6 $ 372.0 $ (247.8 ) $ (235.0 )
Schedule of Assumptions Used	Assumptions used to value benefit obligations and determine pension and OPEB expense (income) are presented below: Pension Benefits Other Benefits 2015 2014 2013 2015 2014 2013 Assumptions used to determine benefit obligations at December 31: Discount rate 4.15 % 3.82 % 4.53 % 4.22 % 3.90 % 4.48 % Rate of compensation increase 4.00 % 4.00 % 4.00 % 4.00 % 4.00 % 4.00 % Subsequent year healthcare cost trend rate 7.00 % 7.00 % 7.00 % Ultimate healthcare cost trend rate 4.50 % 4.50 % 4.50 % Year ultimate healthcare cost trend rate begins 2024 2020 2019 Assumptions used to determine pension and OPEB expense (income) for the year ended December 31: Discount rate 3.82 % 4.53 % 3.85 % 3.90 % 4.48 % 3.77 % Expected return on plan assets 7.25 % 7.25 % 7.25 % Rate of compensation increase 4.00 % 4.00 % 4.00 % 4.00 % 4.00 % 4.00 %
Schedule of Change in Assumed Health Care Cost Trend Rates	As of December 31, 2015 , a one-percentage-point change in the assumed healthcare cost trend rates would have the following effects: One Percentage Point Increase Decrease Effect on total service cost and interest cost components $ 0.1 $ (0.1 ) Effect on postretirement benefit obligation 3.3 (3.1 )
Schedule of Expected Benefit Payments	Estimated future benefit payments to beneficiaries are presented below: Pension Plans Other Benefits Medicare Subsidy 2016 $ 330.4 $ 47.9 $ (1.4 ) 2017 293.0 44.8 (1.4 ) 2018 279.1 42.6 (1.5 ) 2019 272.0 40.8 (1.5 ) 2020 259.0 39.0 (1.5 ) 2021 through 2025 1,159.6 171.7 (9.1 )
Schedule of Plan Assets	Plan investments measured at fair value on a recurring basis at December 31, 2015 and 2014 , are presented below by level within the fair value hierarchy. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Activity for Level 3 assets was insignificant for 2015 and 2014 . See Note 16 for more information on the determination of fair value. Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs (Level 1) (Level 2) (Level 3) Total 2015 2014 2015 2014 2015 2014 2015 2014 Equity Investments: U.S. securities $ 138.4 $ 199.4 $ — $ — $ — $ — $ 138.4 $ 199.4 U.S. common/collective trusts — — 814.5 862.4 — — 814.5 862.4 EAFE common/collective trusts — — 261.5 272.9 — — 261.5 272.9 Emerging market common/collective trusts — — 103.9 125.7 — — 103.9 125.7 Global investments — — 179.6 210.7 — — 179.6 210.7 Fixed Income Investments: U.S. investment-grade corporate common/collective trusts — — 391.0 421.8 — — 391.0 421.8 U.S. treasuries common/collective trusts — — 85.3 98.4 — — 85.3 98.4 Mortgage-backed common/collective trusts — — — 18.0 — — — 18.0 Global investments — — 389.7 435.4 — — 389.7 435.4 U.S. high-yield corporate securities — — 109.7 178.4 — — 109.7 178.4 Other Investments: Private equity funds (a) — — — — 0.5 0.9 0.5 0.9 Cash and cash equivalents 37.3 39.6 — — — — 37.3 39.6 Total $ 175.7 $ 239.0 $ 2,335.2 $ 2,623.7 $ 0.5 $ 0.9 $ 2,511.4 $ 2,863.6 (a) Consists of private equity funds that have no remaining capital commitments.
Schedule of Net Benefit Costs	Components of pension and OPEB expense (income) for the years 2015 , 2014 and 2013 are presented below: Pension Benefits Other Benefits 2015 2014 2013 2015 2014 2013 Components of pension and OPEB expense (income): Service cost $ 2.2 $ 1.7 $ 2.4 $ 7.1 $ 4.9 $ 4.7 Interest cost 130.0 146.0 138.8 22.5 21.7 21.0 Expected return on plan assets (198.4 ) (202.8 ) (184.5 ) — — — Amortization of prior service cost (credit) 4.4 4.3 3.8 (64.6 ) (73.2 ) (80.0 ) Recognized net actuarial loss (gain): Annual amortization 31.2 2.5 23.6 1.6 (1.3 ) 2.4 Corridor charge (credit) 144.3 2.0 — (13.1 ) — — Settlement (gain) loss 1.0 0.2 (0.8 ) — 3.5 — Pension and OPEB expense (income) $ 114.7 $ (46.1 ) $ (16.7 ) $ (46.5 ) $ (44.4 ) $ (51.9 )
Schedule of Multiemployer Plans	Our participation in these plans for the years ended December 31, 2015 , 2014 and 2013 , is presented below. We do not provide more than five percent of the total contributions to any multiemployer plan. Forms 5500 are not yet available for plan years ending in 2015 . Pension Fund EIN/Pension Plan Number Pension Protection Act Zone Status (a) FIP/RP Status Pending/Implemented (b) Contributions Surcharge Imposed (c) Expiration Date of Collective Bargaining Agreement 2015 2014 2015 2014 2013 Steelworkers Pension Trust 23-6648508/499 Green Green No $ 7.3 $ 8.1 $ 7.3 No 3/31/2017 to 9/1/2018 (d) IAM National Pension Fund’s National Pension Plan 51-6031295/002 Green Green No 16.0 16.5 14.8 No 10/1/2016 to 5/31/2019 (e) $ 23.3 $ 24.6 $ 22.1 (a) The most recent Pension Protection Act zone status available in 2015 and 2014 is for each plan’s year-end at December 31, 2014 and 2013 . The plan’s actuary certifies the zone status. Generally, plans in the red zone are less than 65% funded, plans in the yellow zone are between 65% and 80% funded, and plans in the green zone are at least 80% funded. The Steelworkers Pension Trust and IAM National Pension Fund’s National Pension Plan elected funding relief under section 431(b)(8) of the Internal Revenue Code and section 304(b)(8) of the Employment Retirement Income Security Act of 1974 (ERISA). This election allows those plans’ investment losses for the plan year ended December 31, 2008, to be amortized over 29 years for funding purposes. (b) The “FIP/RP Status Pending/Implemented” column indicates plans for which a financial improvement plan (FIP) or a rehabilitation plan (RP) is either pending or has been implemented, as defined by ERISA. (c) The surcharge represents an additional required contribution due as a result of the critical funding status of the plan. (d) We are a party to three collective bargaining agreements (at our Ashland Works, Mansfield Works and at the AK Tube Walbridge plant) that require contributions to the Steelworkers Pension Trust. The labor contract for approximately 300 hourly employees at Mansfield Works expires on March 31, 2017 . The labor contract for approximately 85 hourly employees at the AK Tube Walbridge plant expires January 22, 2018 . The labor contract for approximately 820 hourly employees at the Ashland Works expires on September 1, 2018 . (e) We are a party to three collective bargaining agreements (at our Butler Works, Middletown Works and Zanesville Works) that require contributions to the IAM National Pension Fund’s National Pension Plan. The labor contract for approximately 1,240 hourly employees at Butler Works expires on October 1, 2016 . The labor contract for approximately 1,725 hourly employees at Middletown Works expires on March 15, 2018 . The labor contract for approximately 140 hourly employees at Zanesville Works expires on May 31, 2019 .

Operating Leases (Tables)

Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
Future minimum lease payments	Obligations to make future minimum lease payments at December 31, 2015 , are presented below: 2016 $ 20.7 2017 17.9 2018 16.9 2019 13.0 2020 10.0 2021 and thereafter 56.5 Total minimum lease payments $ 135.0

Environmental and Legal Conti37

Environmental and Legal Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of environmental-related capital investments and compliance costs	We have spent the following amounts over the past three years for environmental-related capital investments and environmental compliance: 2015 2014 2013 Environmental-related capital investments $ 7.1 $ 7.2 $ 1.6 Environmental compliance costs 133.2 112.4 101.1
Schedule of accrual of liabilities related to environmental loss contingencies	We recorded the following liabilities for environmental matters on our condensed consolidated balance sheets: 2015 2014 Accrued liabilities $ 5.6 $ 17.6 Other non-current liabilities 41.1 32.7
Schedule of information on pending asbestos cases	The number of asbestos cases pending at December 31, 2015 , is presented below: Asbestos Cases Pending at December 31, 2015 Cases with specific dollar claims for damages: Claims up to $0.2 122 Claims above $0.2 to $5.0 5 Claims above $5.0 to $15.0 2 Claims above $15.0 to $20.0 2 Total claims with specific dollar claims for damages (a) 131 Cases without a specific dollar claim for damages 252 Total asbestos cases pending 383 (a) Involve a total of 2,331 plaintiffs and 17,116 defendants
Schedule of number of new asbestos claims filed, number of pending asbestos claims disposed, and amount paid in settlements	Asbestos-related claims information in 2015 , 2014 and 2013 , is presented below: 2015 2014 2013 New Claims Filed 52 50 42 Pending Claims Disposed Of 68 90 39 Total Amount Paid in Settlements $ 1.9 $ 0.7 $ 1.0
Schedule of percentages to calculate cash deposits on imports from foreign countries to US	As a result of these preliminary CVD determinations, importers are required to post cash deposits with the U.S. government on imports of cold-rolled steel from these countries as presented below: Country Cold-Rolled CVD Margins Cold-Rolled AD Margins Brazil 7.42% * China 227.29% * India 4.45% * Russia 6.33% – 0.00% * As a result of these preliminary CVD and AD determinations, importers are required to post cash deposits with the U.S. government on imports of CORE from these countries as presented below: Country Corrosion-Resistant CVD Margins Corrosion-Resistant AD Margins China 235.66% – 26.26% 255.8% India 7.71% – 2.85% 6.92% – 6.64% Italy 38.41% – 0.00% 3.11% – 0.00% South Korea 1.37% – 0.00% 3.51% – 2.99%

Share-based Compensation (Table

Share-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of information about share-based compensation expense	Share-based compensation expense for the years ended December 31, 2015 , 2014 and 2013 , is presented below: Share-based Compensation Expense 2015 2014 2013 Stock options $ 1.7 $ 1.7 $ 1.5 Restricted stock 3.2 3.2 2.9 Restricted stock units issued to Directors 0.9 1.1 1.0 Performance shares 1.9 2.9 4.1 Pre-tax share-based compensation expense $ 7.7 $ 8.9 $ 9.5
Schedule of weighted-average assumptions used in Black-Scholes option calculation	The following weighted-average assumptions are used in the Black-Scholes option pricing model to estimate the fair value of granted options as of the grant date: 2015 2014 2013 Expected volatility 67.6% – 75.9% 58.3% – 68.2% 57.8% – 68.8% Weighted-average volatility 69.4 % 62.6 % 65.2 % Expected term (in years) 3.1 – 6.6 3.0 – 6.5 2.9 – 6.4 Risk-free interest rate 1.0% – 1.7% 0.9% – 2.3% 0.4% – 1.1% Dividend yield — % — % — % Weighted-average grant-date fair value per share of granted options $ 2.36 $ 3.50 $ 2.44
Schedule of stock options activity	Option activity for the year ended December 31, 2015 , is presented below: Stock Options Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (in years) Aggregate Intrinsic Value Outstanding at December 31, 2014 2,696,595 $ 11.16 Granted 906,700 4.08 Exercised (2,733 ) 4.59 Forfeited and expired (296,570 ) 10.81 Outstanding at December 31, 2015 3,303,992 9.26 4.6 $ — Exercisable at December 31, 2015 1,959,959 12.33 3.3 — Unvested at December 31, 2015 1,344,033 4.77 6.5 — Unvested at December 31, 2015 expected to vest 1,276,831 4.77 6.5 —
Schedule of nonvested restricted stock units activity	Non-vested restricted stock awards activity for the year ended December 31, 2015 , is presented below: Restricted Stock Awards Restricted Shares Weighted- Average Grant Date Fair Value Outstanding at December 31, 2014 502,413 $ 5.97 Granted 886,060 4.06 Vested/restrictions lapsed (719,955 ) 4.90 Canceled (69,203 ) 5.06 Outstanding at December 31, 2015 599,315 4.54
Schedule of weighted-average assumptions used in Monte Carlo simulation	The following weighted-average assumptions are used in a Monte Carlo simulation model to estimate the fair value of performance shares granted: 2015 2014 2013 Company expected volatility 56.4 % 59.1 % 59.2 % S&P’s MidCap 400 index expected volatility 27.0 % 32.4 % 34.7 % Risk-free interest rate 0.9 % 0.9 % 0.4 % Dividend yield — % — % — % Weighted-average grant-date fair value per performance share granted $ 3.09 $ 6.40 $ 4.68
Schedule of nonvested performance-based units activity	Non-vested performance share awards activity for the year ended December 31, 2015 , is presented below: Performance Share Awards Performance Shares Weighted- Average Grant Date Fair Value Outstanding at December 31, 2014 978,952 $ 5.56 Granted 890,700 3.09 Earned — — Expired or forfeited (865,358 ) 4.36 Outstanding at December 31, 2015 1,004,294 4.40

Comprehensive Income (Loss) (Ta

Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2015
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax	Other comprehensive income (loss), net of tax, information is presented below: 2015 2014 2013 Foreign currency translation Balance at beginning of period $ 1.0 $ 4.7 $ 3.5 Other comprehensive income (loss)—foreign currency translation gain (loss) (3.1 ) (3.7 ) 1.2 Balance at end of period $ (2.1 ) $ 1.0 $ 4.7 Cash flow hedges Balance at beginning of period $ (32.2 ) $ 18.3 $ 31.7 Other comprehensive income (loss): Gains (losses) arising in period (64.2 ) (51.6 ) 3.5 Income tax expense 24.9 — 1.3 Gains (losses) arising in period, net of tax (89.1 ) (51.6 ) 2.2 Reclassification of losses (gains) to net income (loss): Hot roll carbon steel coil contracts (a) — — (0.4 ) Other commodity contracts (b) 61.4 1.1 (24.8 ) Subtotal 61.4 1.1 (25.2 ) Income tax expense (d) (25.9 ) — (9.6 ) Net amount of reclassification of losses (gains) to net income (loss) 87.3 1.1 (15.6 ) Total other comprehensive income (loss), net of tax (1.8 ) (50.5 ) (13.4 ) Balance at end of period $ (34.0 ) $ (32.2 ) $ 18.3 Unrealized holding gains on securities Balance at beginning of period $ 0.4 $ 0.4 $ 0.3 Other comprehensive income (loss): Unrealized holding gains (losses) arising in period — — 0.2 Income tax expense — — 0.1 Unrealized holding gains (losses) arising in period, net of tax — — 0.1 Reclassification of gains (losses) to net income (loss)—income tax benefit (d) 0.4 — — Total other comprehensive income (loss), net of tax (0.4 ) — 0.1 Balance at end of period $ — $ 0.4 $ 0.4 Pension and OPEB plans Balance at beginning of period $ (173.6 ) $ 300.0 $ (34.4 ) Other comprehensive income (loss): Prior service credit (cost) arising in period (7.7 ) 10.9 (6.1 ) Gains (losses) arising in period (60.8 ) (422.5 ) 422.3 Subtotal (68.5 ) (411.6 ) 416.2 Income tax expense (benefit) (d) (26.0 ) — 50.3 Gains (losses) arising in period, net of tax (42.5 ) (411.6 ) 365.9 Reclassification to net income (loss): Prior service costs (credits) (c) (60.2 ) (68.9 ) (76.2 ) Actuarial (gains) losses (c) 165.0 6.9 25.3 Subtotal 104.8 (62.0 ) (50.9 ) Income tax (expense) benefit (d) 39.8 — (19.4 ) Amount of reclassification to net income (loss), net of tax 65.0 (62.0 ) (31.5 ) Total other comprehensive income (loss), net of tax 22.5 (473.6 ) 334.4 Balance at end of period $ (151.1 ) $ (173.6 ) $ 300.0 (a) Included in net sales (b) Included in cost of products sold (c) Included in pension and OPEB expense (income) (d) Included in income tax expense (benefit)

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Earnings per share	Reconciliation of the numerators and denominators for basic and diluted EPS computations is presented below: 2015 2014 2013 Net income (loss) attributable to AK Steel Holding Corporation $ (509.0 ) $ (96.9 ) $ (46.8 ) Less: distributed earnings to common stockholders and holders of certain stock compensation awards — — — Undistributed earnings (loss) $ (509.0 ) $ (96.9 ) $ (46.8 ) Common stockholders earnings—basic and diluted: Distributed earnings to common stockholders $ — $ — $ — Undistributed earnings (loss) to common stockholders (507.3 ) (96.6 ) (46.6 ) Common stockholders earnings (loss)—basic and diluted $ (507.3 ) $ (96.6 ) $ (46.6 ) Common shares outstanding (weighted-average shares in millions): Common shares outstanding for basic earnings per share 177.2 148.1 135.8 Effect of exchangeable debt — — — Effect of dilutive stock-based compensation — — — Common shares outstanding for diluted earnings per share 177.2 148.1 135.8 Basic and diluted earnings per share: Distributed earnings $ — $ — $ — Undistributed earnings (loss) (2.86 ) (0.65 ) (0.34 ) Basic and diluted earnings (loss) per share $ (2.86 ) $ (0.65 ) $ (0.34 ) Potentially issuable common shares (in millions) excluded from earnings per share calculation due to anti-dilutive effect 3.6 9.7 2.6

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair value assets and liabilities measured on a recurring basis	Assets and liabilities measured at fair value on a recurring basis are presented below: 2015 2014 Level 1 Level 2 Total Level 1 Level 2 Total Assets measured at fair value Cash and cash equivalents $ 56.6 $ — $ 56.6 $ 70.2 $ — $ 70.2 Other current assets: Foreign exchange contracts — 1.1 1.1 — 1.2 1.2 Commodity hedge contracts — 0.5 0.5 — 3.6 3.6 Other non-current assets: Available for sale investments—cash and cash equivalents — — — 3.3 — 3.3 Commodity hedge contracts — 0.3 0.3 — 1.8 1.8 Assets measured at fair value $ 56.6 $ 1.9 $ 58.5 $ 73.5 $ 6.6 $ 80.1 Liabilities measured at fair value Accrued liabilities: Commodity hedge contracts $ — $ (41.2 ) $ (41.2 ) $ — $ (36.2 ) $ (36.2 ) Other non-current liabilities—commodity hedge contracts — (9.5 ) (9.5 ) — (5.7 ) (5.7 ) Liabilities measured at fair value $ — $ (50.7 ) $ (50.7 ) $ — $ (41.9 ) $ (41.9 ) Liabilities measured at other than fair value Long-term debt, including current portions: Fair value $ — $ (1,573.3 ) $ (1,573.3 ) $ — $ (2,478.3 ) $ (2,478.3 ) Carrying amount — (2,354.1 ) (2,354.1 ) — (2,422.0 ) (2,422.0 )

Derivative Instruments and He42

Derivative Instruments and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Outstanding commodity price swaps and options and forward foreign exchange contracts	Outstanding commodity price swaps and options and forward foreign exchange contracts as of December 31, 2015 and 2014 , are presented below: Commodity 2015 2014 Nickel (in lbs) 164,800 259,300 Natural gas (in MMBTUs) 36,972,500 33,992,500 Zinc (in lbs) 54,173,800 61,800,000 Iron ore (in metric tons) 2,795,000 2,335,000 Electricity (in MWHs) 1,386,400 1,182,800 Hot roll carbon steel coils (in short tons) — 15,000 Foreign exchange contracts (in euros) € 55,500,000 € 23,675,000
Fair value of derivative instruments in the condensed consolidated balance sheets	The fair value of derivative instruments as of December 31, 2015 and 2014 , is presented below: Asset (liability) 2015 2014 Derivatives designated as hedging instruments: Other current assets—commodity contracts $ 0.3 $ 2.1 Other non-current assets—commodity contracts 0.3 1.8 Accrued liabilities—commodity contracts (40.9 ) (32.0 ) Other non-current liabilities—commodity contracts (9.5 ) (5.7 ) Derivatives not designated as hedging instruments: Other current assets: Foreign exchange contracts 1.1 1.2 Commodity contracts 0.2 1.5 Accrued liabilities: Commodity contracts (0.3 ) (4.2 )
Gains (losses) on derivative instruments included in the condensed consolidated statements of operations	Gains (losses) on derivative instruments for the years ended December 31, 2015 , 2014 and 2013 , are presented below: Gain (loss) 2015 2014 2013 Derivatives in cash flow hedging relationships— Commodity contracts: Reclassified from accumulated other comprehensive income into net sales (effective portion) $ — $ — $ 0.4 Reclassified from accumulated other comprehensive income into cost of products sold (effective portion) (61.4 ) (1.1 ) 24.8 Recorded in cost of products sold (ineffective portion and amount excluded from effectiveness testing) (23.6 ) (0.8 ) 3.3 Derivatives not designated as hedging instruments: Foreign exchange contracts—recognized in other income (expense) (0.1 ) 1.9 (0.1 ) Commodity contracts: Recognized in net sales 2.2 (5.1 ) (3.1 ) Recognized in cost of products sold (2.0 ) (35.0 ) 1.7
Amount of gains (losses) expected to be reclassified into earnings within the next twelve months	Gains (losses) before tax expected to be reclassified into cost of products sold within the next twelve months for our existing commodity contracts that qualify for hedge accounting, as well as the period over which we are hedging our exposure to the volatility in future cash flows, are presented below: Commodity Hedge Settlement Dates Gains (losses) Natural gas January 2016 to December 2017 $ (17.1 ) Electricity January 2016 to December 2017 (1.9 ) Iron ore January 2016 to November 2017 (7.8 ) Zinc January 2016 to December 2017 (11.2 )

Supplementary Cash Flow Infor43

Supplementary Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2015
Supplemental Cash Flow Information [Abstract]
Schedule of cash flow, supplemental disclosures	Net cash paid (received) during the period for interest, net of capitalized interest, and income taxes are presented below: 2015 2014 2013 Net cash paid (received) during the period for: Interest, net of capitalized interest $ 161.3 $ 121.9 $ 116.2 Income taxes 0.7 (0.3 ) 1.2
Schedule of non-cash investing and financing activities	Non-cash investing and financing activities for the years ended December 31, 2015 , 2014 and 2013 , are presented below: 2015 2014 2013 Capital investments $ 37.4 $ 29.5 $ 10.2 Issuance of restricted stock and restricted stock units 4.1 4.5 3.0

Quarterly Information (Unaudi44

Quarterly Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Earnings per share for each quarter and the year are calculated individually and may not sum to the total for the year. 2015 First Quarter Second Quarter Third Quarter Fourth Quarter Year Net sales $ 1,750.9 $ 1,689.4 $ 1,709.9 $ 1,542.7 $ 6,692.9 Operating profit (loss) 33.8 7.1 80.2 (34.4 ) 86.7 Net income (loss) attributable to AK Holding (306.3 ) (64.0 ) 6.7 (145.4 ) (509.0 ) Basic and diluted earnings (loss) per share $ (1.72 ) $ (0.36 ) $ 0.04 $ (0.82 ) $ (2.86 ) 2014 First Quarter Second Quarter Third Quarter Fourth Quarter Year Net sales $ 1,383.5 $ 1,530.8 $ 1,593.8 $ 1,997.6 $ 6,505.7 Operating profit (loss) (35.3 ) 36.5 63.7 74.5 139.4 Net income (loss) attributable to AK Holding (86.1 ) (17.1 ) (7.2 ) 13.5 (96.9 ) Basic earnings (loss) per share $ (0.63 ) $ (0.13 ) $ (0.05 ) $ 0.08 $ (0.65 ) Diluted earnings (loss) per share $ (0.63 ) $ (0.13 ) $ (0.05 ) $ 0.07 $ (0.65 )

Supplementary Guarantor Infor45

Supplementary Guarantor Information (Tables)	12 Months Ended
	Dec. 31, 2015
Supplemental Guarantor Information [Abstract]
Condensed Statements of Comprehensive Income (Loss)	Condensed Statements of Comprehensive Income (Loss) Year Ended December 31, 2015 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net sales $ — $ 6,498.2 $ 250.9 $ 538.3 $ (594.5 ) $ 6,692.9 Cost of products sold (exclusive of items shown separately below) — 5,984.9 167.5 423.3 (543.7 ) 6,032.0 Selling and administrative expenses (exclusive of items shown separately below) 4.9 270.4 10.7 25.0 (49.1 ) 261.9 Depreciation — 187.7 3.6 24.7 — 216.0 Pension and OPEB expense (income) (exclusive of corridor charges shown below) — (63.0 ) — — — (63.0 ) Pension and OPEB net corridor charge — 131.2 — — — 131.2 Charge for facility idling — 28.1 — — — 28.1 Total operating costs 4.9 6,539.3 181.8 473.0 (592.8 ) 6,606.2 Operating profit (loss) (4.9 ) (41.1 ) 69.1 65.3 (1.7 ) 86.7 Interest expense — 171.0 — 2.0 — 173.0 Impairment of Magnetation investment — — — (256.3 ) — (256.3 ) Impairment of AFSG investment — — — (41.6 ) — (41.6 ) Other income (expense) — 6.4 6.6 (11.6 ) — 1.4 Income (loss) before income taxes (4.9 ) (205.7 ) 75.7 (246.2 ) (1.7 ) (382.8 ) Income tax expense (benefit) — 39.6 28.7 (4.2 ) (0.7 ) 63.4 Equity in net income (loss) of subsidiaries (504.1 ) (258.8 ) — — 762.9 — Net income (loss) (509.0 ) (504.1 ) 47.0 (242.0 ) 761.9 (446.2 ) Less: Net income attributable to noncontrolling interests — — — 62.8 — 62.8 Net income (loss) attributable to AK Steel Holding Corporation (509.0 ) (504.1 ) 47.0 (304.8 ) 761.9 (509.0 ) Other comprehensive income (loss) 17.2 17.2 — (3.1 ) (14.1 ) 17.2 Comprehensive income (loss) attributable to AK Steel Holding Corporation $ (491.8 ) $ (486.9 ) $ 47.0 $ (307.9 ) $ 747.8 $ (491.8 ) Condensed Statements of Comprehensive Income (Loss) Year Ended December 31, 2014 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net sales $ — $ 6,284.2 $ 280.7 $ 599.6 $ (658.8 ) $ 6,505.7 Cost of products sold (exclusive of items shown separately below) — 5,937.6 199.3 484.7 (613.9 ) 6,007.7 Selling and administrative expenses (exclusive of items shown separately below) 4.6 251.0 11.3 28.3 (48.0 ) 247.2 Depreciation — 176.1 3.9 21.9 — 201.9 Pension and OPEB expense (income) — (92.5 ) — — — (92.5 ) Pension corridor charge — 2.0 — — — 2.0 Total operating costs 4.6 6,274.2 214.5 534.9 (661.9 ) 6,366.3 Operating profit (loss) (4.6 ) 10.0 66.2 64.7 3.1 139.4 Interest expense — 142.1 — 2.6 — 144.7 Other income (expense) — (17.7 ) 6.5 (9.9 ) — (21.1 ) Income (loss) before income taxes (4.6 ) (149.8 ) 72.7 52.2 3.1 (26.4 ) Income tax expense (benefit) — (19.2 ) 29.1 (3.4 ) 1.2 7.7 Equity in net income (loss) of subsidiaries (92.3 ) 38.3 — — 54.0 — Net income (loss) (96.9 ) (92.3 ) 43.6 55.6 55.9 (34.1 ) Less: Net income attributable to noncontrolling interests — — — 62.8 — 62.8 Net income (loss) attributable to AK Steel Holding Corporation (96.9 ) (92.3 ) 43.6 (7.2 ) 55.9 (96.9 ) Other comprehensive income (loss) (527.8 ) (527.8 ) — (3.7 ) 531.5 (527.8 ) Comprehensive income (loss) attributable to AK Steel Holding Corporation $ (624.7 ) $ (620.1 ) $ 43.6 $ (10.9 ) $ 587.4 $ (624.7 ) Condensed Statements of Comprehensive Income (Loss) Year Ended December 31, 2013 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net sales $ — $ 5,339.3 $ 261.5 $ 568.8 $ (599.2 ) $ 5,570.4 Cost of products sold (exclusive of items shown separately below) — 5,012.1 189.0 463.3 (556.6 ) 5,107.8 Selling and administrative expenses (exclusive of items shown separately below) 4.4 205.0 10.5 26.2 (40.8 ) 205.3 Depreciation — 169.4 4.3 16.4 — 190.1 Pension and OPEB expense (income) — (68.6 ) — — — (68.6 ) Total operating costs 4.4 5,317.9 203.8 505.9 (597.4 ) 5,434.6 Operating profit (loss) (4.4 ) 21.4 57.7 62.9 (1.8 ) 135.8 Interest expense — 125.9 — 1.5 — 127.4 Other income (expense) — (5.9 ) 6.1 (1.6 ) — (1.4 ) Income (loss) before income taxes (4.4 ) (110.4 ) 63.8 59.8 (1.8 ) 7.0 Income tax expense (benefit) — (27.8 ) 20.1 (2.0 ) (0.7 ) (10.4 ) Equity in net income (loss) of subsidiaries (42.4 ) 40.2 — — 2.2 — Net income (loss) (46.8 ) (42.4 ) 43.7 61.8 1.1 17.4 Less: Net income attributable to noncontrolling interests — — — 64.2 — 64.2 Net income (loss) attributable to AK Steel Holding Corporation (46.8 ) (42.4 ) 43.7 (2.4 ) 1.1 (46.8 ) Other comprehensive income (loss) 322.3 322.3 — 1.2 (323.5 ) 322.3 Comprehensive income (loss) attributable to AK Steel Holding Corporation $ 275.5 $ 279.9 $ 43.7 $ (1.2 ) $ (322.4 ) $ 275.5
Condensed Balance Sheets	Condensed Balance Sheets December 31, 2015 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company ASSETS Current assets: Cash and cash equivalents $ — $ 27.0 $ — $ 29.6 $ — $ 56.6 Accounts receivable, net — 411.9 23.5 32.0 (22.5 ) 444.9 Inventory, net — 1,149.6 26.1 60.6 (10.0 ) 1,226.3 Other current assets — 75.6 0.3 2.5 — 78.4 Total current assets — 1,664.1 49.9 124.7 (32.5 ) 1,806.2 Property, plant and equipment — 5,763.8 103.1 599.1 — 6,466.0 Accumulated depreciation — (4,218.0 ) (75.4 ) (86.1 ) — (4,379.5 ) Property, plant and equipment, net — 1,545.8 27.7 513.0 — 2,086.5 Other non-current assets: Investment in affiliates — 42.6 — 28.1 — 70.7 Investment in subsidiaries (3,541.0 ) 1,346.0 — — 2,195.0 — Inter-company accounts 2,563.4 (3,600.9 ) 1,403.0 (390.8 ) 25.3 — Other non-current assets — 83.0 33.0 5.0 — 121.0 TOTAL ASSETS $ (977.6 ) $ 1,080.6 $ 1,513.6 $ 280.0 $ 2,187.8 $ 4,084.4 LIABILITIES AND EQUITY (DEFICIT) Current liabilities: Accounts payable $ — $ 669.0 $ 6.3 $ 29.1 $ (1.0 ) $ 703.4 Accrued liabilities — 242.3 2.8 16.4 — 261.5 Current portion of pension and other postretirement benefit obligations — 77.3 — 0.4 — 77.7 Total current liabilities — 988.6 9.1 45.9 (1.0 ) 1,042.6 Non-current liabilities: Long-term debt — 2,354.1 — — — 2,354.1 Pension and other postretirement benefit obligations — 1,143.6 — 3.3 — 1,146.9 Other non-current liabilities — 135.3 — 1.1 — 136.4 TOTAL LIABILITIES — 4,621.6 9.1 50.3 (1.0 ) 4,680.0 Equity (deficit): Total stockholders’ equity (deficit) (977.6 ) (3,541.0 ) 1,504.5 (152.3 ) 2,188.8 (977.6 ) Noncontrolling interests — — — 382.0 — 382.0 TOTAL EQUITY (DEFICIT) (977.6 ) (3,541.0 ) 1,504.5 229.7 2,188.8 (595.6 ) TOTAL LIABILITIES AND EQUITY (DEFICIT) $ (977.6 ) $ 1,080.6 $ 1,513.6 $ 280.0 $ 2,187.8 $ 4,084.4 Condensed Balance Sheets December 31, 2014 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company ASSETS Current assets: Cash and cash equivalents $ — $ 28.5 $ 0.5 $ 41.2 $ — $ 70.2 Accounts receivable, net — 606.2 27.6 37.3 (26.8 ) 644.3 Inventory, net — 1,080.5 26.2 73.5 (8.1 ) 1,172.1 Other current assets 0.3 67.9 0.2 3.0 — 71.4 Total current assets 0.3 1,783.1 54.5 155.0 (34.9 ) 1,958.0 Property, plant and equipment — 5,695.8 97.3 595.3 — 6,388.4 Accumulated depreciation — (4,040.8 ) (71.8 ) (62.6 ) — (4,175.2 ) Property, plant and equipment, net — 1,655.0 25.5 532.7 — 2,213.2 Other non-current assets: Investment in affiliates — 84.5 — 304.2 — 388.7 Investment in subsidiaries (2,970.9 ) 1,582.4 — — 1,388.5 — Inter-company accounts 2,478.1 (3,420.4 ) 1,325.5 (412.4 ) 29.2 — Other non-current assets — 174.4 33.0 60.7 — 268.1 TOTAL ASSETS $ (492.5 ) $ 1,859.0 $ 1,438.5 $ 640.2 $ 1,382.8 $ 4,828.0 LIABILITIES AND EQUITY (DEFICIT) Current liabilities: Accounts payable $ — $ 754.9 $ 6.9 $ 42.0 $ (0.7 ) $ 803.1 Accrued liabilities — 244.6 3.0 18.9 — 266.5 Current portion of pension and other postretirement benefit obligations — 55.3 — 0.3 — 55.6 Total current liabilities — 1,054.8 9.9 61.2 (0.7 ) 1,125.2 Non-current liabilities: Long-term debt — 2,422.0 — — — 2,422.0 Pension and other postretirement benefit obligations — 1,221.3 — 4.0 — 1,225.3 Other non-current liabilities — 131.8 — 0.7 — 132.5 TOTAL LIABILITIES — 4,829.9 9.9 65.9 (0.7 ) 4,905.0 Equity (deficit): Total stockholders’ equity (deficit) (492.5 ) (2,970.9 ) 1,428.6 158.8 1,383.5 (492.5 ) Noncontrolling interests — — — 415.5 — 415.5 TOTAL EQUITY (DEFICIT) (492.5 ) (2,970.9 ) 1,428.6 574.3 1,383.5 (77.0 ) TOTAL LIABILITIES AND EQUITY (DEFICIT) $ (492.5 ) $ 1,859.0 $ 1,438.5 $ 640.2 $ 1,382.8 $ 4,828.0
Condensed Statements of Cash Flows	Condensed Statements of Cash Flows Year Ended December 31, 2015 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net cash flows from operating activities $ (3.7 ) $ 49.0 $ 53.9 $ 104.8 $ (3.7 ) $ 200.3 Cash flows from investing activities: Capital investments — (85.0 ) (5.8 ) (8.2 ) — (99.0 ) Proceeds from sale of equity investee — 25.0 — — — 25.0 Proceeds from AFSG Holdings, Inc. distribution — — — 14.0 — 14.0 Other investing items, net — 12.5 — — — 12.5 Net cash flows from investing activities — (47.5 ) (5.8 ) 5.8 — (47.5 ) Cash flows from financing activities: Net borrowings (repayments) under credit facility — (55.0 ) — — — (55.0 ) Redemption of long-term debt — (14.1 ) — — — (14.1 ) Inter-company activity 4.7 66.1 (48.6 ) (25.9 ) 3.7 — SunCoke Middletown distributions to noncontrolling interest owners — — — (96.3 ) — (96.3 ) Other financing items, net (1.0 ) — — — — (1.0 ) Net cash flows from financing activities 3.7 (3.0 ) (48.6 ) (122.2 ) 3.7 (166.4 ) Net increase (decrease) in cash and cash equivalents — (1.5 ) (0.5 ) (11.6 ) — (13.6 ) Cash and equivalents, beginning of year — 28.5 0.5 41.2 — 70.2 Cash and equivalents, end of year $ — $ 27.0 $ — $ 29.6 $ — $ 56.6 Condensed Statements of Cash Flows Year Ended December 31, 2014 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net cash flows from operating activities $ (3.4 ) $ (447.2 ) $ 39.2 $ 91.3 $ (2.7 ) $ (322.8 ) Cash flows from investing activities: Capital investments — (63.1 ) (2.8 ) (15.2 ) — (81.1 ) Investments in Magnetation joint venture — — — (100.0 ) — (100.0 ) Investments in acquired business, net of cash acquired — (690.3 ) — — — (690.3 ) Other investing items, net — 13.6 — — — 13.6 Net cash flows from investing activities — (739.8 ) (2.8 ) (115.2 ) — (857.8 ) Cash flows from financing activities: Net borrowings (repayments) under credit facility — 515.0 — — — 515.0 Proceeds from issuance of long-term debt — 427.1 — — — 427.1 Redemption of long-term debt — (0.8 ) — — — (0.8 ) Proceeds from issuance of common stock 345.3 — — — — 345.3 Debt issuance costs — (15.5 ) — — — (15.5 ) Inter-company activity (341.0 ) 272.9 (35.9 ) 101.3 2.7 — SunCoke Middletown distributions to noncontrolling interest owners — — — (61.0 ) — (61.0 ) Other financing items, net (0.9 ) — — (3.7 ) — (4.6 ) Net cash flows from financing activities 3.4 1,198.7 (35.9 ) 36.6 2.7 1,205.5 Net increase (decrease) in cash and cash equivalents — 11.7 0.5 12.7 — 24.9 Cash and equivalents, beginning of year — 16.8 — 28.5 — 45.3 Cash and equivalents, end of year $ — $ 28.5 $ 0.5 $ 41.2 $ — $ 70.2 Condensed Statements of Cash Flows Year Ended December 31, 2013 AK Holding AK Steel Guarantor Subsidiaries of the Senior Notes Other Non-Guarantor Subsidiaries Eliminations Consolidated Company Net cash flows from operating activities $ (3.5 ) $ (251.1 ) $ 50.4 $ 129.6 $ (35.6 ) $ (110.2 ) Cash flows from investing activities: Capital investments — (39.2 ) (1.7 ) (22.7 ) — (63.6 ) Investments in acquired businesses — — — (50.0 ) — (50.0 ) Other investing items, net — 8.5 0.3 6.3 — 15.1 Net cash flows from investing activities — (30.7 ) (1.4 ) (66.4 ) — (98.5 ) Cash flows from financing activities: Net borrowings (repayments) under credit facility — 90.0 — — — 90.0 Proceeds from issuance of long-term debt — 31.9 — — — 31.9 Redemption of long-term debt — (27.4 ) — — — (27.4 ) Debt issuance costs — (3.4 ) — — — (3.4 ) Inter-company activity 4.1 3.9 (49.0 ) 5.4 35.6 — SunCoke Middletown distributions to noncontrolling interest owners — — — (64.8 ) — (64.8 ) Other financing items, net (0.6 ) — — 1.3 — 0.7 Net cash flows from financing activities 3.5 95.0 (49.0 ) (58.1 ) 35.6 27.0 Net increase (decrease) in cash and cash equivalents — (186.8 ) — 5.1 — (181.7 ) Cash and equivalents, beginning of year — 203.6 — 23.4 — 227.0 Cash and equivalents, end of year $ — $ 16.8 $ — $ 28.5 $ — $ 45.3

Summary of Significant Accoun46

Summary of Significant Accounting Policies (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015USD ($)employees	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)employees	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Concentration Of Risk [Line Items]
Net sales	$ 1,542.7	$ 1,709.9	$ 1,689.4	$ 1,750.9	$ 1,997.6	$ 1,593.8	$ 1,530.8	$ 1,383.5	$ 6,692.9	$ 6,505.7	$ 5,570.4
Number of Employees | employees	8,500								8,500
Workforce Subject to Collective Bargaining Arrangements [Member]
Concentration Of Risk [Line Items]
Number of Employees | employees	6,300								6,300
Workforce Subject to Collective Bargaining Arrangements [Member] | Mountain State Carbon, LLC [Member]
Concentration Of Risk [Line Items]
Number of Employees | employees	215								215
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] | Coshocton, OH Works [Member]
Concentration Of Risk [Line Items]
Number of Employees | employees	330								330
Customer Concentration Risk [Member] | Automotive Market [Member] | Sales Revenue, Goods, Net [Member]
Concentration Of Risk [Line Items]
Percentage of total (in hundredths)									60.00%	53.00%	51.00%
Customer Concentration Risk [Member] | Infrastructure and Manufacturing Market [Member] | Sales Revenue, Goods, Net [Member]
Concentration Of Risk [Line Items]
Percentage of total (in hundredths)									16.00%	18.00%	20.00%
Customer Concentration Risk [Member] | Distributors and Converters Market [Member] | Sales Revenue, Goods, Net [Member]
Concentration Of Risk [Line Items]
Percentage of total (in hundredths)									24.00%	29.00%	29.00%
Customer Concentration Risk [Member] | Foreign Customers [Member] | Sales Revenue, Goods, Net [Member]
Concentration Of Risk [Line Items]
Net sales									$ 855.7	$ 755.4	$ 708
Customer Concentration Risk [Member] | One Automotive Customer [Member] | Accounts Receivable [Member]
Concentration Of Risk [Line Items]
Percentage of total (in hundredths)									20.00%	14.00%
Customer Concentration Risk [Member] | Major Customer A [Member] | Sales Revenue, Goods, Net [Member]
Concentration Of Risk [Line Items]
Percentage of total (in hundredths)									12.00%
Customer Concentration Risk [Member] | Major Customer B [Member] | Sales Revenue, Goods, Net [Member]
Concentration Of Risk [Line Items]
Percentage of total (in hundredths)									11.00%
Credit Concentration Risk [Member] | Automotive Market [Member] | Accounts Receivable [Member]
Concentration Of Risk [Line Items]
Percentage of total (in hundredths)									65.00%	43.00%
Carbon [Member]
Concentration Of Risk [Line Items]
Net sales									$ 4,746.8	$ 4,423.3	3,643.4
Stainless And Electrical [Member]
Concentration Of Risk [Line Items]
Net sales									1,733	1,836.5	1,705.3
Tubular [Member]
Concentration Of Risk [Line Items]
Net sales									201.3	231.4	220.7
Other Product Lines [Member]
Concentration Of Risk [Line Items]
Net sales									11.8	$ 14.5	$ 1
Year Ended December 31 2014 [Member] | Reclassification From Other Noncurrent Assets To Longterm Debt [Member]
Concentration Of Risk [Line Items]
Prior Period Reclassification Adjustment									30.5
Year Ended December 31 2014 [Member] | Reclassification From Other Current Assets To Noncurrent Assets [Member]
Concentration Of Risk [Line Items]
Prior Period Reclassification Adjustment									$ 67.7
IAM National Pension Fund's National Pension Plan [Member] | Workforce Subject to Collective Bargaining Arrangements [Member] | Zanesville Works [Member]
Concentration Of Risk [Line Items]
Number of Employees | employees	140								140
IAM National Pension Fund's National Pension Plan [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] | Butler Works [Member]
Concentration Of Risk [Line Items]
Number of Employees | employees	1,240								1,240
Maximum [Member] | Commodity [Member]
Concentration Of Risk [Line Items]
Forward contracts duration (in months)									3 years
Maximum [Member] | Forward Contracts [Member]
Concentration Of Risk [Line Items]
Forward contracts duration (in months)									24 months
Long-term Debt [Member] | New Accounting Principles, Early Adoption [Member]
Concentration Of Risk [Line Items]
Unamortized Debt Issuance Expense	$ 24.8								$ 24.8

Summary of Significant Accoun47

Summary of Significant Accounting Policies - Property Plant and Equipment Useful Lives (Details 2)	12 Months Ended
	Dec. 31, 2015
Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Minimum [Member] | Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Maximum [Member] | Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Weighted Average [Member] | Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	12 years

Supplementary Financial State48

Supplementary Financial Statement Information - Research & Development (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplementary Financial Statement Information [Abstract]
Research and development costs	$ 27.6	$ 17.5	$ 13.2

Supplementary Financial State49

Supplementary Financial Statement Information - Allowance for Doubtful Accounts (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance For Doubtful Accounts
Balance at beginning of year	$ 9	$ 8.1	$ 9.1
Increase (decrease) in allowance	(3)	0.9	(0.4)
Receivables written off	0	0	(0.6)
Balance at end of year	$ 6	$ 9	$ 8.1

Supplementary Financial State50

Supplementary Financial Statement Information - Inventory (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Finished and semi-finished	$ 996.5	$ 1,053.4
Raw materials	410	494.2
Total cost	1,406.5	1,547.6
Adjustment to state inventories at LIFO value	(180.2)	(375.5)	$ (396.5)	$ (435)
Inventory, net	1,226.3	1,172.1
Effect of LIFO inventory liquidation on income	$ 0	$ 0	$ 11.9

Supplementary Financial State51

Supplementary Financial Statement Information - LIFO Reserve (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Changes in LIFO Reserve
Balance at beginning of year	$ 375.5	$ 396.5	$ 435
Change in reserve	(195.3)	(21)	(38.5)
Balance at end of year	$ 180.2	$ 375.5	$ 396.5

Supplementary Financial State52

Supplementary Financial Statement Information - Property, Plant and Equipment (Details 5) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Proceeds from AFSG Holdings, Inc. distribution		$ 14	$ 0	$ 0
Charge for facility idling		28.1	0	0
Property, plant and equipment	$ 6,466	6,466	6,388.4
Less accumulated depreciation	(4,379.5)	(4,379.5)	(4,175.2)
Property, plant and equipment, net	2,086.5	2,086.5	2,213.2
Capitalized interest on capital projects		2.1	2.7	$ 2.7
Asset retirement obligations	6.6	6.6	6
Land, land improvements and leaseholds [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	263	263	260.7
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	465.9	465.9	466.7
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	5,628.2	5,628.2	5,571
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	108.9	108.9	$ 90
Ashland Works Hot End [Member]
Property, Plant and Equipment [Line Items]
Charge for facility idling	28.1
Ashland Works Hot End [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Restructuring and Related Cost, Expected Cost	2	2
Ashland Works Hot End [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Restructuring and Related Cost, Expected Cost	3	$ 3
Supplemental Unemployment Benefits [Member] | Ashland Works Hot End [Member]
Property, Plant and Equipment [Line Items]
Charge for facility idling	22.2
Equipment Idling And Other Costs [Member] | Ashland Works Hot End [Member]
Property, Plant and Equipment [Line Items]
Charge for facility idling	$ 5.9

Supplementary Financial State53

Supplementary Financial Statement Information - Other Non-current Assets (Details 6) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Assets, Noncurrent [Abstract]
Investment in AFSG Holdings, Inc.	$ 0	$ 0	$ 55.6
Goodwill	32.8	32.8	32.8
Deferred tax assets, non-current	62.7	62.7	138
Other Assets, Miscellaneous, Noncurrent	25.5	25.5	41.7
Other non-current assets	$ 121	121	268.1
Impairment of AFSG investment		$ 41.6	$ 0	$ 0
AFSG Holdings Inc [Member]
Investment [Line Items]
Impairment Effect on Earnings Per Share, Pretax	$ 0.23
Other Assets, Noncurrent [Abstract]
Impairment of AFSG investment	$ 41.6

Acquisition of Dearborn (Detail

Acquisition of Dearborn (Details) - Severstal Dearborn [Member] - USD ($) $ in Millions	4 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Sep. 16, 2014
Business Acquisition [Line Items]
Accounts receivable			$ 180.6
Inventory			362.6
Other current assets			3.6
Property, plant and equipment			445.5
Investment in affilates			72.5
Total assets acquired			1,064.8
Accounts payable			(201.4)
Accrued liabilities			(32.8)
Other postretirement benefit obligations			(128.2)
Other non-current liabilities			(12.1)
Total liabilities assumed			(374.5)
Purchase price, net of cash acquired			$ 690.3
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	$ 567
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	$ 12.2
Business Acquisition, Pro Forma Revenue		$ 7,942.7
Business Acquisition, Pro Forma Operating Profit (Loss)		(816.2)
Business Combination, Pro Forma Asset Impairment Charge		$ 1,005.1

Acquisition of Dearborn (Deta55

Acquisition of Dearborn (Details2) - USD ($) $ / shares in Units, $ in Millions	Sep. 16, 2014	Jul. 31, 2015	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired				$ 0	$ 690.3	$ 0
Stock Issued During Period, Shares, New Issues	40,250,000
Shares Issued, Price Per Share	$ 9
Proceeds from Sale of Equity Method Investments				$ 25	0	$ 0
Severstal Dearborn [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired					690.3
Business Combination, Additional Disclosures, Income Tax Charge					8.4
Other Income (Expense) [Member] | Severstal Dearborn [Member]
Business Acquisition [Line Items]
Business Combination, Additional Disclosures, Unused Bridge Commitment Expensed					12.6
Selling, General and Administrative Expenses [Member] | Severstal Dearborn [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs					8.1
Business Combination, Additional Disclosures, Severance Costs Expensed					$ 2.6
Senior Notes Due October 2021 [Member]
Business Acquisition [Line Items]
Debt Instrument, Face Amount	$ 430
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)	7.625%			7.625%	7.625%
Debt Instrument, Maturity Date	Oct. 1, 2021			Oct. 1, 2021
Debt Instrument Offering Price	99.325%
Double Eagle Steel Coating Company [Member]
Business Acquisition [Line Items]
Equity method investment, ownership percentage (in hundredths)			50.00%
Proceeds from Sale of Equity Method Investments			$ 25
DTE Electric Company [Member]
Business Acquisition [Line Items]
Loss Contingency, Damages Awarded, Value		$ 25

Investments in Affiliates (Deta

Investments in Affiliates (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Other than Temporary Impairment	$ 256.3	$ 256.3	$ 0	$ 0
Combined Metals of Chicago, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage (in hundredths)		40.00%
Delaco Processing, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage (in hundredths)		49.00%
Magnetation LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage (in hundredths)		49.90%
Equity Method Investment, Other than Temporary Impairment	$ 256.3
Rockport Roll Shop LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage (in hundredths)		50.00%
Spartan Steel Coating, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage (in hundredths)		48.00%
Difference between carrying amount and underlying equity		$ 13.9
Other Income (Expense) [Member] | Magnetation LLC [Member]
Schedule of Equity Method Investments [Line Items]
Share of income (loss) from equity method investments		(16.3)	(15.2)	(4.9)
Cost of Products Sold [Member]
Schedule of Equity Method Investments [Line Items]
Share of income (loss) from equity method investments		$ 6.7	$ 11.7	$ 8.1
Iron Ore [Member]
Schedule of Equity Method Investments [Line Items]
Spot Commodities, Price Increase (Decrease), Percentage	(20.00%)

Investments in Affiliates Equit

Investments in Affiliates Equity Investee Summarized Financial Information (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Method Investment, Summarized Financial Information [Abstract]
Revenue	$ 356.4	$ 386.1	$ 293.9
Gross profit	68.3	93.2	103.7
Net income (loss)	(9.8)	10.8	$ 20.1
Current assets	89.3	211.8
Noncurrent assets	66.9	879.1
Current liabilities	14.5	157.1
Noncurrent liabilities	$ 33.8	$ 516.6

Investments in Affiliates Relat

Investments in Affiliates Related Party Transactions (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Transactions [Abstract]
Sales to equity investees	$ 61.4	$ 93.4	$ 71.6
Purchases from equity investees	251	67.7	$ 12.5
Accounts receivable from equity investees	0.4	2.5
Accounts payable to equity investees	$ 33.1	$ 10.9

Income Taxes - Detail of Income

Income Taxes - Detail of Income (Loss) before Taxes by Geography (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest [Abstract]
United States	$ (452.1)	$ (94.3)	$ (61.1)
Foreign	6.5	5.1	3.9
Noncontrolling interests	62.8	62.8	64.2
Income (loss) before income taxes	$ (382.8)	$ (26.4)	$ 7

Income Taxes - Detail of Deferr

Income Taxes - Detail of Deferred Tax Assets and Liabilities (Details 2) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Net operating and capital loss and tax credit carryforwards	$ 847.3	$ 778.1
Postretirement benefits	158.9	201.2
Pension benefits	278.6	258.6
Inventories	139.2	152.6
Other assets	132.8	114.2
Valuation allowance	(1,215.5)	(1,000.4)	$ (764.1)	$ (873.1)
Total deferred tax assets	341.3	504.3
Deferred tax liabilities:
Depreciable assets	(248)	(322.7)
Other liabilities	(30.6)	(43.6)
Total deferred tax liabilities	(278.6)	(366.3)
Net deferred tax assets	62.7	$ 138
Undistributed earnings of foreign subsidiaries	38.2
Unrecorded tax liability on undistributed earnings of foreign subsidiaries	$ 13.4

Income Taxes - Valuation Allowa

Income Taxes - Valuation Allowance (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 1,000.4	$ 764.1	$ 873.1
Balance at end of year	1,215.5	1,000.4	764.1
Included in income tax expense (benefit) [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Change in valuation allowance	228.6	36.7	21.9
Change in deferred assets in other comprehensive income [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Change in valuation allowance	$ (13.5)	$ 199.6	$ (130.9)

Income Taxes - Loss Carryforwar

Income Taxes - Loss Carryforwards (Details 4) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Tax Credit Carryforward [Line Items]
Unrecognized deferred tax assets	$ 21.3
Domestic Tax Authority [Member] | Operating Loss Carryforward [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards	2,372.3
Domestic Tax Authority [Member] | Alternative Minimum Tax [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards	2,672.8
Tax Credit Carryforward, Amount	17.7
Domestic Tax Authority [Member] | Research [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	1.2
State and Local Jurisdiction [Member] | Operating Loss and Tax Credit Carryforwards [Member]
Tax Credit Carryforward [Line Items]
Deferred tax assets from operating loss and tax credit carryforwards	$ 77.4
Earliest Tax Year [Member] | Domestic Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Dates	Dec. 31, 2023
Earliest Tax Year [Member] | Domestic Tax Authority [Member] | Research [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Date	Dec. 31, 2027
Earliest Tax Year [Member] | State and Local Jurisdiction [Member] | Operating Loss and Tax Credit Carryforwards [Member]
Tax Credit Carryforward [Line Items]
Operating Loss and Tax Credit Carryforwards, Expiration Date	Dec. 31, 2016
Latest Tax Year [Member] | Domestic Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Dates	Dec. 31, 2035
Latest Tax Year [Member] | State and Local Jurisdiction [Member] | Operating Loss and Tax Credit Carryforwards [Member]
Tax Credit Carryforward [Line Items]
Operating Loss and Tax Credit Carryforwards, Expiration Date	Dec. 31, 2035

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Details 5) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
Federal	$ 0	$ 0	$ (3.4)
State	0.2	(1.1)	0.2
Foreign	1.8	2.1	1.9
Deferred:
Federal	68.8	7.7	14
State	6.5	0.2	1.2
Amount allocated to other comprehensive income	(13.2)	0	(22.7)
Change in valuation allowance on beginning-of-the-year deferred tax assets	(0.7)	(1.2)	(1.6)
Income tax expense (benefit)	$ 63.4	$ 7.7	$ (10.4)

Income Taxes - Effective Tax Ra

Income Taxes - Effective Tax Rate Reconciliation (Details 6) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income tax expense (benefit) at U.S. federal statutory rate	$ (134)	$ (9.2)	$ 2.4
Income tax expense calculated on noncontrolling interests	(22)	(22)	(22.5)
State and foreign tax expense, net of federal tax	(0.9)	(3.1)	1.7
Increase in deferred tax asset valuation allowance	228.6	36.7	21.9
Amount allocated to other comprehensive income	(13.2)	0	(22.7)
Change in accrual for uncertain tax positions	0.3	(0.9)	(1.7)
Stock compensation in excess of tax deduction	0	2	3.1
Expiration of charitable contribution carryforwards	0	0	2.5
Other permanent differences	4.6	4.2	4.9
Income tax expense (benefit)	$ 63.4	$ 7.7	$ (10.4)

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details 7) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits
Balance at beginning of year	$ 59.9	$ 53.8	$ 54
Increases (decreases) for prior year tax positions	(0.3)	(0.2)	(0.8)
Increases (decreases) for current year tax positions	70.7	7.7	0.9
(Decreases) from statute lapses	0	(1.4)	(0.3)
Balance at end of year	130.3	59.9	$ 53.8
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	0
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	111.6	41.6
Unrecognized tax benefits that would result in adjustments to other tax accounts	$ 18.7	$ 18.4
Earliest Tax Year [Member] | Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Open Tax Year by Major Tax Jurisdiction	2,012
Earliest Tax Year [Member] | State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Open Tax Year by Major Tax Jurisdiction	2,007

Long-term Debt and Other Fina66

Long-term Debt and Other Financing Debt Instrument Table (Details)	Sep. 16, 2014USD ($)	Nov. 30, 2012USD ($)	Dec. 31, 2015USD ($)shares$ / shares	Dec. 31, 2013USD ($)	Dec. 31, 2014USD ($)
Debt Instrument [Line Items]
Unamortized discount/premium and debt issuance costs			$ (51,400,000)		$ (62,300,000)
Total long-term debt			2,354,100,000		2,422,000,000
Other Income (Expense) [Member]
Debt Instrument [Line Items]
Gain (Loss) on Repurchase of Debt Instrument			9,400,000	$ 2,900,000
Senior Secured Notes Due December 2018 [Member]
Debt Instrument [Line Items]
Long-term debt, gross			$ 380,000,000		$ 380,000,000
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)			8.75%		8.75%
Debt Instrument, Maturity Date			Dec. 1, 2018
Assets Pledged as Collateral, Carrying Amount			$ 1,600,000,000
Senior Secured Notes Due December 2018 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			104.375%
Debt Instrument, Redemption Period, Start Date			Dec. 1, 2015
Debt Instrument, Redemption Period, End Date			Nov. 30, 2016
Senior Secured Notes Due December 2018 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			102.188%
Debt Instrument, Redemption Period, Start Date			Dec. 1, 2016
Debt Instrument, Redemption Period, End Date			Nov. 30, 2017
Senior Secured Notes Due December 2018 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			100.00%
Debt Instrument, Redemption Period, Start Date			Dec. 1, 2017
Debt Instrument, Redemption Period, End Date			Nov. 30, 2018
Exchangeable Senior Notes Due November 2019 [Member]
Debt Instrument [Line Items]
Long-term debt, gross			$ 150,000,000		$ 150,000,000
Debt Instrument, Face Amount			$ 150,000,000
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)			5.00%		5.00%
Debt Instrument, Maturity Date			Nov. 15, 2019
Debt Instrument, Convertible, Effective Interest Rate			10.80%		10.80%
Debt Instrument, Convertible, Stock Price Trigger | $ / shares			$ 7.02
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger			130.00%
Debt Instrument, Convertible, Threshold Trading Days			20
Debt Instrument, Convertible, Threshold Consecutive Trading Days			30 days
Debt Instrument, Convertible, Conversion Ratio (in shares per $1,000 principal amount)			185.1852
Debt Instrument, Convertible, Conversion Price (in dollars per share) | $ / shares			$ 5.40
Debt Instrument, Convertible, Number of Equity Instruments Used to Determine Consideration to Be Delivered Upon Conversion (in shares) | shares			27,800,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt		$ 38,700,000
Debt Instrument, Unamortized Discount			$ 24,900,000		$ 29,900,000
Carrying Value of Long-term Debt			$ 125,100,000		120,100,000
Exchangeable Senior Notes Due November 2019 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Convertible, Number Of Equity Instruments (in shares) | shares			37,500,000
Senior Notes Due May 2020 [Member]
Debt Instrument [Line Items]
Long-term debt, gross			$ 529,800,000		$ 529,800,000
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)			7.625%		7.625%
Debt Instrument, Maturity Date			May 15, 2020
Debt Instrument, Repurchased Face Amount				20,200,000
Senior Notes Due May 2020 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			103.813%
Debt Instrument, Redemption Period, Start Date			May 15, 2015
Debt Instrument, Redemption Period, End Date			May 14, 2016
Senior Notes Due May 2020 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			102.542%
Debt Instrument, Redemption Period, Start Date			May 15, 2016
Debt Instrument, Redemption Period, End Date			May 14, 2017
Senior Notes Due May 2020 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			101.271%
Debt Instrument, Redemption Period, Start Date			May 15, 2017
Debt Instrument, Redemption Period, End Date			May 14, 2018
Senior Notes Due May 2020 [Member] | Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			100.00%
Debt Instrument, Redemption Period, Start Date			May 15, 2018
Debt Instrument, Redemption Period, End Date			May 14, 2020
Senior Notes Due October 2021 [Member]
Debt Instrument [Line Items]
Long-term debt, gross			$ 406,200,000		$ 430,000,000
Debt Instrument, Face Amount	$ 430,000,000
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)	7.625%		7.625%		7.625%
Debt Instrument, Maturity Date	Oct. 1, 2021		Oct. 1, 2021
Debt Instrument, Repurchased Face Amount			$ 23,800,000
Senior Notes Due October 2021 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption, Description			Before October 1, 2017, we may redeem the 2021 Notes at a price equal to par plus a make-whole premium and all accrued and unpaid interest to the date of redemption.
Debt Instrument, Redemption Period, End Date			Sep. 30, 2017
Senior Notes Due October 2021 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			103.813%
Debt Instrument, Redemption Period, Start Date			Oct. 1, 2017
Debt Instrument, Redemption Period, End Date			Sep. 30, 2018
Senior Notes Due October 2021 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			101.906%
Debt Instrument, Redemption Period, Start Date			Oct. 1, 2018
Debt Instrument, Redemption Period, End Date			Sep. 30, 2019
Senior Notes Due October 2021 [Member] | Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			100.00%
Debt Instrument, Redemption Period, Start Date			Oct. 1, 2019
Debt Instrument, Redemption Period, End Date			Sep. 30, 2021
Senior Notes Due April 2022 [Member]
Debt Instrument [Line Items]
Long-term debt, gross			$ 290,200,000		$ 290,200,000
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)			8.375%		8.375%
Debt Instrument, Maturity Date			Apr. 1, 2022
Debt Instrument, Repurchased Face Amount				$ 9,800,000
Senior Notes Due April 2022 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption, Description			Before April 1, 2017, we may redeem the 2022 Notes at a price equal to par plus a make-whole premium and all accrued and unpaid interest to the date of redemption.
Debt Instrument, Redemption Period, End Date			Mar. 31, 2017
Senior Notes Due April 2022 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			104.188%
Debt Instrument, Redemption Period, Start Date			Apr. 1, 2017
Debt Instrument, Redemption Period, End Date			Mar. 31, 2018
Senior Notes Due April 2022 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			102.792%
Debt Instrument, Redemption Period, Start Date			Apr. 1, 2018
Debt Instrument, Redemption Period, End Date			Mar. 31, 2019
Senior Notes Due April 2022 [Member] | Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			101.396%
Debt Instrument, Redemption Period, Start Date			Apr. 1, 2019
Debt Instrument, Redemption Period, End Date			Mar. 31, 2020
Senior Notes Due April 2022 [Member] | Debt Instrument, Redemption, Period Five [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage			100.00%
Debt Instrument, Redemption Period, Start Date			Apr. 1, 2020
Debt Instrument, Redemption Period, End Date			Mar. 31, 2022
Unsecured Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Long-term debt, gross			$ 73,300,000
Long-term Debt, Weighted Average Interest Rate			6.80%
Secured Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Long-term debt, gross			$ 26,000,000
Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Long-term debt, gross			$ 99,300,000		$ 99,300,000
Debt Instrument, Maturity Date Range, Start			Jun. 1, 2020
Debt Instrument, Maturity Date Range, End			Jun. 1, 2028
Taxable Tax Increment Revenue Bonds Issued [Member] | Spencer County Bonds [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 23,000,000
Deficiency Payments			1,300,000
Long-term Debt Maturities, Repayments of Principal and Interest			10,400,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit Facility			$ 550,000,000		$ 605,000,000

Long-term Debt and Other Fina67

Long-term Debt and Other Financing Debt Maturities (Details 2) $ in Millions	Dec. 31, 2015USD ($)
Line of Credit Facility [Line Items]
2016 debt maturities	$ 0
2017 debt maturities	0
2018 debt maturities	380
2019 debt maturities	700
2020 debt maturities	537.1
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
2019 debt maturities	$ 550

Credit Facility and Other Finan

Credit Facility and Other Financing Information (Details 3) - Revolving Credit Facility [Member] - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,500,000,000
Line of credit facility, expiration date	Mar. 31, 2019
Debt Instrument, Covenant Description	The Credit Facility contains common restrictions, including limitations on, among other things, distributions and dividends, acquisitions and investments, indebtedness, liens and affiliate transactions. The Credit Facility requires that we maintain a minimum fixed charge coverage ratio of one to one if availability under the Credit Facility is less than $150.0. The Credit Facility’s current availability significantly exceeds $150.0. Availability is calculated as the lesser of the Credit Facility commitment or our eligible collateral after advance rates, less in either case outstanding borrowings and letters of credit. We secure our Credit Facility obligations with our inventory and accounts receivable, and the Credit Facility’s availability fluctuates monthly based on the varying levels of eligible collateral.
Minimum amount of borrowing capacity before a fixed charge coverage ratio applies	$ 150,000,000
Line of credit, current borrowing capacity based on eligible collateral	1,275,200,000
Current borrowings on credit facility	550,000,000	$ 605,000,000
Letters of credit, outstanding	72,900,000
Line of credit facility, remaining borrowing capacity	$ 652,300,000
Line of credit facility, Weighted Average Interest Rate (in hundredths)	2.10%	2.20%

Pension and Other Postretirem69

Pension and Other Postretirement Benefits (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Contributions to pension trust		$ 24.1	$ 196.5	$ 181.1
Amounts recognized in the consolidated balance sheets:
Current liabilities	$ (55.6)	(77.7)	(55.6)
Noncurrent liabilities	(1,225.3)	(1,146.9)	(1,225.3)
Amounts recognized in accumulated other comprehensive income, before tax:
Defined Benefit Plan, Expected Future Benefit Payments Net Of Prescription Drug Subsidy Receipts, Next Twelve Months		46.5
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Future pension contributions in next fiscal year		0
Defined Benefit Plans, Estimated Future Employer Contributions, Year Two		50
Defined Benefit Plans, Estimated Future Employer Contributions, Year Three		75
Change in benefit obligations:
Benefit obligations at beginning of year		3,545.2	3,380.6
Service cost		2.2	1.7	2.4
Interest cost		130	146	138.8
Plan participants' contributions		0	0
Actuarial loss (gain)		147.8	(432.1)
Amendments		13.3	2
Dearborn acquisition		0	0
Contributions to retirees VEBAs		0	0
Benefits paid		(295.1)	(416.6)
Medicare subsidy reimbursement received		0	0
Foreign currency exchange rate changes		(0.4)	(0.6)
Benefit obligations at end of year	3,545.2	3,247.4	3,545.2	3,380.6
Change in plan assets:
Fair value of plan assets at beginning of year		2,863.6	2,808.5
Actual gain (loss) on plan assets		(93.6)	257.8
Employer contributions		36.5	213.9
Plan participants' contributions		0	0
Benefits paid		(295.1)	(416.6)
Medicare subsidy reimbursement received		0	0
Fair value of plan assets at end of year	2,863.6	2,511.4	2,863.6	2,808.5
Funded status	(681.6)	(736)	(681.6)
Amounts recognized in the consolidated balance sheets:
Current liabilities	(2.1)	(31.2)	(2.1)
Noncurrent liabilities	(679.5)	(704.8)	(679.5)
Net amount recognized	(681.6)	(736)	(681.6)
Amounts recognized in accumulated other comprehensive income, before tax:
Actuarial loss (gain)	355.7	323.5	355.7
Prior service cost (credit)	16.3	25.1	16.3
Net amount recognized	372	348.6	372
Aggregate accumulated benefit obligation	3,513.7	3,222	3,513.7
Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in benefit obligations:
Benefit obligations at beginning of year		599.3	479.2
Service cost		7.1	4.9	4.7
Interest cost		22.5	21.7	21
Plan participants' contributions		24.9	25.4
Actuarial loss (gain)		83.3	(45.1)
Amendments		(5.6)	(12.8)
Dearborn acquisition		0	128.2
Benefits paid		(76.5)	(96.6)
Medicare subsidy reimbursement received		3.3	7.3
Foreign currency exchange rate changes		0	0
Benefit obligations at end of year	599.3	488.6	599.3	479.2
Change in plan assets:
Fair value of plan assets at beginning of year		0	0
Actual gain (loss) on plan assets		0	0
Employer contributions		48.3	63.9
Plan participants' contributions		24.9	25.4
Benefits paid		(76.5)	(96.6)
Medicare subsidy reimbursement received		3.3	7.3
Fair value of plan assets at end of year	0	0	0	$ 0
Funded status	(599.3)	(488.6)	(599.3)
Amounts recognized in the consolidated balance sheets:
Current liabilities	(53.5)	(46.5)	(53.5)
Noncurrent liabilities	(545.8)	(442.1)	(545.8)
Net amount recognized	(599.3)	(488.6)	(599.3)
Amounts recognized in accumulated other comprehensive income, before tax:
Actuarial loss (gain)	23.1	(48.8)	23.1
Prior service cost (credit)	(258.1)	(199)	(258.1)
Net amount recognized	(235)	(247.8)	(235)
Zanesville Works Retiree Healthcare Benefits Litigation [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions to retirees VEBAs		3.1
Change in benefit obligations:
Contributions to retirees VEBAs		(3.1)	(3.1)
Correction of Census Data [Member] | Pension Plans, Defined Benefit [Member]
Change in benefit obligations:
Actuarial loss (gain)			25.8
Change in Assumptions for Pension Plans [Member] | Pension Plans, Defined Benefit [Member]
Change in benefit obligations:
Actuarial loss (gain)		7	(233.5)
Change In Assumptions For Other Postretirement Benefit Plans [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in benefit obligations:
Actuarial loss (gain)		$ 58	$ (12)
Postretirement Plan Obligation Settlement [Member] | Pension Plans, Defined Benefit [Member]
Change in benefit obligations:
Actuarial loss (gain)	20
Amounts recognized in accumulated other comprehensive income, before tax:
Defined Benefit Plan, Settlements, Plan Assets	$ 105

Pension and Other Postretirem70

Pension and Other Postretirement Benefits - Assumptions (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plans, Defined Benefit [Member]
Assumptions used to determine benefit obligations at December 31:
Discount rate	4.15%	3.82%	4.53%
Rate of compensation increase	4.00%	4.00%	4.00%
Assumptions used to determine pension and OPEB expense (income) for the year ended December 31:
Discount rate	3.82%	4.53%	3.85%
Expected return on plan assets	7.25%	7.25%	7.25%
Rate of compensation increase	4.00%	4.00%	4.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Assumptions used to determine benefit obligations at December 31:
Discount rate	4.22%	3.90%	4.48%
Rate of compensation increase	4.00%	4.00%	4.00%
Subsequent year healthcare cost trend rate	7.00%	7.00%	7.00%
Ultimate healthcare cost trend rate	4.50%	4.50%	4.50%
Year ultimate healthcare cost trend rate begins	2,024	2,020	2,019
Assumptions used to determine pension and OPEB expense (income) for the year ended December 31:
Discount rate	3.90%	4.48%	3.77%
Rate of compensation increase	4.00%	4.00%	4.00%
Effect of one percentage point increase on total service and interest cost components	$ 0.1
Effect of one percentage point decrease on total service and interest cost components	(0.1)
Effect of one percentage point increase on postretirement benefit obligation	3.3
Effect of one percentage point decrease on postretirement benefit obligation	$ (3.1)

Pension and Other Postretirem71

Pension and Other Postretirement Benefits - Expected Benefit Payments (Details 3) $ in Millions	Dec. 31, 2015USD ($)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected Future Benefit Payments in 2016	$ 330.4
Expected Future Benefit Payments in 2017	293
Expected Future Benefit Payments in 2018	279.1
Expected Future Benefit Payments in 2019	272
Expected Future Benefit Payments in 2020	259
Expected Future Benefit Payments in 2021 through 2025	1,159.6
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected Future Benefit Payments in 2016	47.9
Expected Future Benefit Payments in 2017	44.8
Expected Future Benefit Payments in 2018	42.6
Expected Future Benefit Payments in 2019	40.8
Expected Future Benefit Payments in 2020	39
Expected Future Benefit Payments in 2021 through 2025	171.7
Expected Medicare Subsidy Receipts in 2016	(1.4)
Expected Medicare Subsidy Receipts in 2017	(1.4)
Expected Medicare Subsidy Receipts in 2018	(1.5)
Expected Medicare Subsidy Receipts in 2019	(1.5)
Expected Medicare Subsidy Receipts in 2020	(1.5)
Expected Medicare Subsidy Receipts in 2021 through 2025	$ (9.1)

Pension and Other Postretirem72

Pension and Other Postretirement Benefits - Plan Assets (Details 4) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		$ 2,511.4	$ 2,863.6	$ 2,808.5
Equity Securities [Member]
Defined Benefit Plan, Target Allocation, Percentages of Assets [Abstract]
Target plan asset allocations percentage		60.00%
Fixed Income Securities [Member]
Defined Benefit Plan, Target Allocation, Percentages of Assets [Abstract]
Target plan asset allocations percentage		38.00%
Cash and Cash Equivalents [Member]
Defined Benefit Plan, Target Allocation, Percentages of Assets [Abstract]
Target plan asset allocations percentage		2.00%
Fair Value, Measurements, Recurring [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		$ 2,511.4	2,863.6
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		175.7	239
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		2,335.2	2,623.7
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0.5	0.9
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		37.3	39.6
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		37.3	39.6
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | US Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		138.4	199.4
Fair Value, Measurements, Recurring [Member] | US Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		138.4	199.4
Fair Value, Measurements, Recurring [Member] | US Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | US Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | U.S. Equity Securities Common/Collective Trusts [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		814.5	862.4
Fair Value, Measurements, Recurring [Member] | U.S. Equity Securities Common/Collective Trusts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | U.S. Equity Securities Common/Collective Trusts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		814.5	862.4
Fair Value, Measurements, Recurring [Member] | U.S. Equity Securities Common/Collective Trusts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | EAFE Equity Securities Common/Collective Trusts [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		261.5	272.9
Fair Value, Measurements, Recurring [Member] | EAFE Equity Securities Common/Collective Trusts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | EAFE Equity Securities Common/Collective Trusts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		261.5	272.9
Fair Value, Measurements, Recurring [Member] | EAFE Equity Securities Common/Collective Trusts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Emerging Market Equity Securities Common/Collective Trusts [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		103.9	125.7
Fair Value, Measurements, Recurring [Member] | Emerging Market Equity Securities Common/Collective Trusts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Emerging Market Equity Securities Common/Collective Trusts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		103.9	125.7
Fair Value, Measurements, Recurring [Member] | Emerging Market Equity Securities Common/Collective Trusts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Global Equity Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		179.6	210.7
Fair Value, Measurements, Recurring [Member] | Global Equity Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Global Equity Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		179.6	210.7
Fair Value, Measurements, Recurring [Member] | Global Equity Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | U.S. Investment-Grade Corporate Fixed Income Investments Common/Collective Trusts [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		391	421.8
Fair Value, Measurements, Recurring [Member] | U.S. Investment-Grade Corporate Fixed Income Investments Common/Collective Trusts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | U.S. Investment-Grade Corporate Fixed Income Investments Common/Collective Trusts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		391	421.8
Fair Value, Measurements, Recurring [Member] | U.S. Investment-Grade Corporate Fixed Income Investments Common/Collective Trusts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | U.S. Treasuries Fixed Income Investments Common/Collective Trusts [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		85.3	98.4
Fair Value, Measurements, Recurring [Member] | U.S. Treasuries Fixed Income Investments Common/Collective Trusts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | U.S. Treasuries Fixed Income Investments Common/Collective Trusts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		85.3	98.4
Fair Value, Measurements, Recurring [Member] | U.S. Treasuries Fixed Income Investments Common/Collective Trusts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Mortgage-Backed Fixed Income Investments Common/Collective Trusts [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	18
Fair Value, Measurements, Recurring [Member] | Mortgage-Backed Fixed Income Investments Common/Collective Trusts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Mortgage-Backed Fixed Income Investments Common/Collective Trusts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	18
Fair Value, Measurements, Recurring [Member] | Mortgage-Backed Fixed Income Investments Common/Collective Trusts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Global Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		389.7	435.4
Fair Value, Measurements, Recurring [Member] | Global Fixed Income Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Global Fixed Income Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		389.7	435.4
Fair Value, Measurements, Recurring [Member] | Global Fixed Income Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | U.S. High-Yield Corporate Fixed Income Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		109.7	178.4
Fair Value, Measurements, Recurring [Member] | U.S. High-Yield Corporate Fixed Income Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | U.S. High-Yield Corporate Fixed Income Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		109.7	178.4
Fair Value, Measurements, Recurring [Member] | U.S. High-Yield Corporate Fixed Income Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	[1]	0.5	0.9
Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets		0	0
Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	[1]	$ 0.5	$ 0.9
[1]	Consists of private equity funds that have no remaining capital commitments.

Pension and Other Postretirem73

Pension and Other Postretirement Benefits - Benefit Costs (Details 5) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended			36 Months Ended
	Dec. 31, 2012	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2013
Recognized net actuarial loss (gain):
Pension/OPEB corridor charge/credit				$ 131.2	$ 2	$ 0
Expense for defined contribution plans				14.5	12.1	11.5
Pension Plans, Defined Benefit [Member]
Components of pension and OPEB expense (income):
Service cost				2.2	1.7	2.4
Interest cost				130	146	138.8
Expected return on plan assets				(198.4)	(202.8)	(184.5)
Amortization of prior service cost (credit)				4.4	4.3	3.8
Recognized net actuarial loss (gain):
Annual amortization				31.2	2.5	23.6
Pension/OPEB corridor charge/credit		$ 144.3	$ 2	144.3	2	0
Settlement (gain) loss				1	0.2	(0.8)
Pension and OPEB expense (income)				114.7	(46.1)	(16.7)
Estimated net loss (gain) expected to be amortized into pension and OPEB expense (income) in the next year				27.9
Estimated net prior service cost (credit) expected to be amortized into pension and OPEB expense (income) in the next year				5.2
Other Postretirement Benefit Plans, Defined Benefit [Member]
Components of pension and OPEB expense (income):
Service cost				7.1	4.9	4.7
Interest cost				22.5	21.7	21
Expected return on plan assets				0	0	0
Amortization of prior service cost (credit)				(64.6)	(73.2)	(80)
Recognized net actuarial loss (gain):
Annual amortization				1.6	(1.3)	2.4
Pension/OPEB corridor charge/credit		$ (13.1)		(13.1)	0	0
Pension and OPEB expense (income)				(46.5)	(44.4)	(51.9)
Estimated net loss (gain) expected to be amortized into pension and OPEB expense (income) in the next year				(4.3)
Estimated net prior service cost (credit) expected to be amortized into pension and OPEB expense (income) in the next year				(60.3)
Zanesville Works Retiree Healthcare Benefits Litigation [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Recognized net actuarial loss (gain):
Payments for Legal Settlements	$ 10.6
Contributions to retirees VEBAs				3.1
Butler Works Retiree Healthcare Benefits Litigation [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Recognized net actuarial loss (gain):
Settlement (gain) loss				$ 0	$ 3.5	$ 0
Payments for Legal Settlements							$ 91

Pension and Other Postretirem74

Pension and Other Postretirement Benefits - Multiemployer Plans (Details 6) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)employees	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Multiemployer Plans [Line Items]
Contributions to multiemployer plans | $	$ 23.3	$ 24.6	$ 22.1
Number of Employees	8,500
Steelworkers Pension Trust [Member]
Multiemployer Plans [Line Items]
Contributions to multiemployer plans | $	$ 7.3	8.1	7.3
IAM National Pension Fund's National Pension Plan [Member]
Multiemployer Plans [Line Items]
Contributions to multiemployer plans | $	$ 16	$ 16.5	$ 14.8
Mansfield Works [Member] | Steelworkers Pension Trust [Member]
Multiemployer Plans [Line Items]
Number of Employees	300
Walbridge Tube [Member] | Steelworkers Pension Trust [Member]
Multiemployer Plans [Line Items]
Number of Employees	85
Ashland Works [Member] | Steelworkers Pension Trust [Member]
Multiemployer Plans [Line Items]
Number of Employees	820
Middletown Works [Member] | IAM National Pension Fund's National Pension Plan [Member]
Multiemployer Plans [Line Items]
Number of Employees	1,725
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] | Butler Works [Member] | IAM National Pension Fund's National Pension Plan [Member]
Multiemployer Plans [Line Items]
Number of Employees	1,240
Workforce Subject to Collective Bargaining Arrangements [Member]
Multiemployer Plans [Line Items]
Number of Employees	6,300
Workforce Subject to Collective Bargaining Arrangements [Member] | Zanesville Works [Member] | IAM National Pension Fund's National Pension Plan [Member]
Multiemployer Plans [Line Items]
Number of Employees	140

Operating Leases (Details)

Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Leases [Abstract]
Rental Expense	$ 44	$ 35.7	$ 27
Minimum Lease Payments 2016	20.7
Minimum Lease Payments 2017	17.9
Minimum Lease Payments 2018	16.9
Minimum Lease Payments 2019	13
Minimum Lease Payments 2020	10
Minimum Lease Payments 2021 and thereafter	56.5
Total minimum lease payments	$ 135

Commitments (Details)

Commitments (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Capital Investment Commitments [Member]
Long-term Purchase Commitment [Line Items]
Commitments for future capital investments	$ 45.7
Research And Innovation Center Middletown OH [Member]
Long-term Purchase Commitment [Line Items]
Estimated cost of construction projects	$ 36

Environmental and Legal Conti77

Environmental and Legal Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Environmental-related capital investments	$ 7.1	$ 7.2	$ 1.6
Environmental compliance costs	$ 133.2	$ 112.4	$ 101.1

Environmental and Legal Conti78

Environmental and Legal Contingencies (Details 2) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Other Current Liabilities [Member]
Accrued liabilities	$ 5.6	$ 17.6
Other Noncurrent Liabilities [Member]
Other non-current liabilities	$ 41.1	$ 32.7

Environmental and Legal Conti79

Environmental and Legal Contingencies (Details 3) - USD ($) $ in Millions	Dec. 31, 2015	Mar. 23, 2015	Oct. 17, 2012
Hamilton Plant [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	$ 0.7
Mansfield Works [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	1.1
Proposed civil penalty related to environmental issue		$ 0.1	$ 0.3
Ashland coke plant [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	0.5
Ambridge Works [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	5.5
Dicks Creek [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	$ 16.2

Environmental and Legal Conti80

Environmental and Legal Contingencies (Details 4)	12 Months Ended
	Dec. 31, 2015USD ($)defendantsplaintiffsclaims-lawsuits
Asbestos Claims With Specific Dollar Claim For Damages [Member]
Information on pending asbestos cases [Line Items]
Total asbestos cases pending | claims-lawsuits	131	[1]
Claims with specific dollar claims for damages [Abstract]
Asbestos Lawsuits Pending With Dollars Number Of Plaintiffs | plaintiffs	2,331
Asbestos Lawsuits Pending With Dollars Number Of Defendants | defendants	17,116
Asbestos Claims With Specific Dollar Claim For Damages [Member] | Asbestos claims up to $0.2 [Member]
Information on pending asbestos cases [Line Items]
Total asbestos cases pending | claims-lawsuits	122
Claims with specific dollar claims for damages [Abstract]
Asbestos Lawsuits Pending With Dollars Lower Range	$ 0
Asbestos Lawsuits Pending With Dollars Upper Range	$ 200,000
Asbestos Claims With Specific Dollar Claim For Damages [Member] | Asbestos claims above $0.2 to $5.0 [Member]
Information on pending asbestos cases [Line Items]
Total asbestos cases pending | claims-lawsuits	5
Claims with specific dollar claims for damages [Abstract]
Asbestos Lawsuits Pending With Dollars Lower Range	$ 200,000
Asbestos Lawsuits Pending With Dollars Upper Range	$ 5,000,000
Asbestos Claims With Specific Dollar Claim For Damages [Member] | Asbestos claims above $5.0 to $15.0 [Member]
Information on pending asbestos cases [Line Items]
Total asbestos cases pending | claims-lawsuits	2
Claims with specific dollar claims for damages [Abstract]
Asbestos Lawsuits Pending With Dollars Lower Range	$ 5,000,000
Asbestos Lawsuits Pending With Dollars Upper Range	$ 15,000,000
Asbestos Claims With Specific Dollar Claim For Damages [Member] | Asbestos claims above $15.0 to $20.0 [Member]
Information on pending asbestos cases [Line Items]
Total asbestos cases pending | claims-lawsuits	2
Claims with specific dollar claims for damages [Abstract]
Asbestos Lawsuits Pending With Dollars Lower Range	$ 15,000,000
Asbestos Lawsuits Pending With Dollars Upper Range	$ 20,000,000
Asbestos Claims Without Specific Dollar Claim For Damages [Member]
Information on pending asbestos cases [Line Items]
Total asbestos cases pending | claims-lawsuits	252
Asbestos Issue [Member]
Information on pending asbestos cases [Line Items]
Total asbestos cases pending | claims-lawsuits	383
[1]	Involve a total of 2,331 plaintiffs and 17,116 defendants

Environmental and Legal Conti81

Environmental and Legal Contingencies (Details 5) - Asbestos Issue [Member] $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)claims-lawsuits	Dec. 31, 2014USD ($)claims-lawsuits	Dec. 31, 2013USD ($)claims-lawsuits
Loss Contingency, Claims Quantities [Abstract]
New Claims Filed	52	50	42
Pending Claims Disposed Of	68	90	39
Liability for Asbestos and Environmental Claims, Net, Claims Paid | $	$ 1.9	$ 0.7	$ 1

Environmental and Legal Conti82

Environmental and Legal Contingencies (Details 6) - USD ($) $ in Millions	1 Months Ended
	Mar. 31, 2014	Jan. 11, 2016	Dec. 23, 2015	Dec. 16, 2015	Nov. 02, 2015
Antitrust Case [Member]
Loss Contingencies [Line Items]
Payments for Legal Settlements	$ 5.8
US Trade Case - CORE [Member] | Countervailing Duty [Member] | Preliminary [Member] | CHINA | Minimum [Member]
Loss Contingencies [Line Items]
Duty Rate					26.26%
US Trade Case - CORE [Member] | Countervailing Duty [Member] | Preliminary [Member] | CHINA | Maximum [Member]
Loss Contingencies [Line Items]
Duty Rate					235.66%
US Trade Case - CORE [Member] | Countervailing Duty [Member] | Preliminary [Member] | INDIA | Minimum [Member]
Loss Contingencies [Line Items]
Duty Rate					2.85%
US Trade Case - CORE [Member] | Countervailing Duty [Member] | Preliminary [Member] | INDIA | Maximum [Member]
Loss Contingencies [Line Items]
Duty Rate					7.71%
US Trade Case - CORE [Member] | Countervailing Duty [Member] | Preliminary [Member] | ITALY | Minimum [Member]
Loss Contingencies [Line Items]
Duty Rate					0.00%
US Trade Case - CORE [Member] | Countervailing Duty [Member] | Preliminary [Member] | ITALY | Maximum [Member]
Loss Contingencies [Line Items]
Duty Rate					38.41%
US Trade Case - CORE [Member] | Countervailing Duty [Member] | Preliminary [Member] | KOREA, REPUBLIC OF | Minimum [Member]
Loss Contingencies [Line Items]
Duty Rate					0.00%
US Trade Case - CORE [Member] | Countervailing Duty [Member] | Preliminary [Member] | KOREA, REPUBLIC OF | Maximum [Member]
Loss Contingencies [Line Items]
Duty Rate					1.37%
US Trade Case - CORE [Member] | Antidumping Duty [Member] | Preliminary [Member] | CHINA
Loss Contingencies [Line Items]
Duty Rate			255.80%
US Trade Case - CORE [Member] | Antidumping Duty [Member] | Preliminary [Member] | INDIA | Minimum [Member]
Loss Contingencies [Line Items]
Duty Rate			6.64%
US Trade Case - CORE [Member] | Antidumping Duty [Member] | Preliminary [Member] | INDIA | Maximum [Member]
Loss Contingencies [Line Items]
Duty Rate			6.92%
US Trade Case - CORE [Member] | Antidumping Duty [Member] | Preliminary [Member] | ITALY | Minimum [Member]
Loss Contingencies [Line Items]
Duty Rate			0.00%
US Trade Case - CORE [Member] | Antidumping Duty [Member] | Preliminary [Member] | ITALY | Maximum [Member]
Loss Contingencies [Line Items]
Duty Rate			3.11%
US Trade Case - CORE [Member] | Antidumping Duty [Member] | Preliminary [Member] | KOREA, REPUBLIC OF | Minimum [Member]
Loss Contingencies [Line Items]
Duty Rate			2.99%
US Trade Case - CORE [Member] | Antidumping Duty [Member] | Preliminary [Member] | KOREA, REPUBLIC OF | Maximum [Member]
Loss Contingencies [Line Items]
Duty Rate			3.51%
US Trade Case - ColdRolled [Member] | Countervailing Duty [Member] | Preliminary [Member] | CHINA
Loss Contingencies [Line Items]
Duty Rate				227.29%
US Trade Case - ColdRolled [Member] | Countervailing Duty [Member] | Preliminary [Member] | INDIA
Loss Contingencies [Line Items]
Duty Rate				4.45%
US Trade Case - ColdRolled [Member] | Countervailing Duty [Member] | Preliminary [Member] | BRAZIL
Loss Contingencies [Line Items]
Duty Rate				7.42%
US Trade Case - ColdRolled [Member] | Countervailing Duty [Member] | Preliminary [Member] | SOVIET UNION | Minimum [Member]
Loss Contingencies [Line Items]
Duty Rate				0.00%
US Trade Case - ColdRolled [Member] | Countervailing Duty [Member] | Preliminary [Member] | SOVIET UNION | Maximum [Member]
Loss Contingencies [Line Items]
Duty Rate				6.33%
Subsequent Event [Member] | US Trade Case - HotRolled [Member] | Countervailing Duty [Member] | Preliminary [Member] | BRAZIL
Loss Contingencies [Line Items]
Duty Rate		7.42%

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Sep. 16, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 31, 2008
Summary of Stockholders' Equity Disclosure [Line Items]
Line of Credit Facility, Dividend Restrictions		However, our Credit Facility restricts dividend payments. Dividends are permitted if (i) availability under the Credit Facility exceeds $337.5 or (ii) availability exceeds $262.5 and we meet a fixed charge coverage ratio of one to one as of the most recently ended fiscal quarter. If we cannot meet either of these thresholds, dividends would be limited to $12.0 annually.
Preferred stock authorized (in shares)		25,000,000
Preferred stock issued (in shares)		0
Preferred stock outstanding (in shares)		0
Stock Issued During Period, Shares, New Issues	40,250,000
Shares Issued, Price Per Share	$ 9
Proceeds from issuance of common stock	$ 345.3	$ 0	$ 345.3	$ 0
Stock Repurchase Program, Authorized Amount					$ 150
Stock Repurchase Program, Remaining Authorized Repurchase Amount		125.6
Revolving Credit Facility [Member]
Summary of Stockholders' Equity Disclosure [Line Items]
Amount Of Threshold Under Credit Facility, Dividend Restriction, Unlimited		337.5
Amount Of Threshold Under Credit Facility, Dividend Restriction, Unlimited with Financial Covenant Compliance		262.5
Availability under credit facility exceeds		337.5
Maximum [Member] | Revolving Credit Facility [Member]
Summary of Stockholders' Equity Disclosure [Line Items]
Dividends would be limited to this amount annually		$ 12

Share-based Compensation (Detai

Share-based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum issuable shares under Stock Incentive Plan	23,000,000
Shares available for future grant under Stock Incentive Plan	4,000,000
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	$ 7.7	$ 8.9	$ 9.5
Stock Options [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	$ 1.7	$ 1.7	$ 1.5
Maximum term of stock option awards (in number of years)	10 years
Share based compensation estimated to be forfeited (in hundredths)	5.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility, minimum (in hundredths)	67.60%	58.30%	57.80%
Expected volatility, maximum (in hundredths)	75.90%	68.20%	68.80%
Weighted-average volatility (in hundredths)	69.40%	62.60%	65.20%
Risk-free interest rate, minimum (in hundredths)	1.00%	0.90%	0.40%
Risk-free interest rate, maximum (in hundredths)	1.70%	2.30%	1.10%
Dividend yield (in hundredths)	0.00%	0.00%	0.00%
Weighted-average grant-date fair value per share of options granted	$ 2.36	$ 3.50	$ 2.44
Summary of changes in shares outstanding under all long-term incentive plans [Rollforward]
Number of options outstanding, beginning balance (in shares)	2,696,595
Number of options granted (in shares)	906,700
Number of options exercised (in shares)	(2,733)
Number of options canceled (in shares)	(296,570)
Number of options outstanding, ending balance (in shares)	3,303,992	2,696,595
Number of exercisable options (in shares)	1,959,959
Number of unvested options (in shares)	1,344,033
Number of unvested options that are expected to vest (in shares)	1,276,831
Weighted average exercise price per option, outstanding, beginning of period (dollars per share)	$ 11.16
Weighted average exercise price per option granted (dollars per share)	4.08
Weighted average exercise price per option exercised (dollars per share)	4.59
Weighted average exercise price per option canceled (dollars per share)	10.81
Weighted average exercise price per option, outstanding, end of period (dollars per share)	9.26	$ 11.16
Weighted average exercise price per exercisable option (dollars per share)	12.33
Weighted average exercise price per unvested options (dollars per share)	4.77
Weighted average exercise price per unvested options that expected to vest (dollars per share)	$ 4.77
Remaining average contractual life of options outstanding (in years)	4 years 7 months 6 days
Remaining average contractual life of options exercisable (in years)	3 years 3 months 18 days
Remaining average contractual life of unvested options (in years)	6 years 6 months
Remaining average contractual life of unvested options that are expected to vest (in years)	6 years 6 months
Aggregate intrinsic value of options outstanding, outstanding	$ 0
Aggregate intrinsic value of options outstanding, exercisable	0
Aggregate intrinsic value of options outstanding, unvested	0
Aggregate intrinsic value of options outstanding, unvested and expected to vest	0
Amount of unrecognized compensation costs	$ 0.7
Weighted average period of recognition (in years)	1 year 8 months 12 days
Restricted Stock [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	$ 3.2	$ 3.2	$ 2.9
Summary of changes in shares outstanding under all long-term incentive plans [Rollforward]
Amount of unrecognized compensation costs	$ 1.5
Weighted average period of recognition (in years)	1 year 7 months
Summary of nonvested shares [Roll Forward]
Nonvested, beginning of period (in shares)	502,413
Granted (in shares)	886,060
Vested/restrictions lapsed/earned (in shares)	(719,955)
Canceled (in shares)	(69,203)
Nonvested, end of period (in shares)	599,315	502,413
Weighted average grant date fair value, nonvested, beginning of period (dollars per share)	$ 5.97
Weighted average grant date fair value, granted (dollars per share)	4.06	$ 6.66	$ 4.43
Weighted average grant date fair value, vested/restrictions lapsed/earned (dollars per share)	4.90
Weighted average grant date fair value, canceled (dollars per share)	5.06
Weighted average grant date fair value, nonvested, end of period (dollars per share)	$ 4.54	$ 5.97
Intrinsic value of shares vested/restrictions lapsed during the period	$ 2.9	$ 2.9	$ 2.1
Restricted Stock Units Issued to Directors [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	$ 0.9	1.1	1
Summary of nonvested shares [Roll Forward]
Share Based Compensation Arrangement By Share Based Payment Award, Award Period Until Settlement	1 year
Deferred Compensation Arrangement With Individual, Period To Defer Settlement Following Termination Of Service	6 months
Deferred Compensation Arrangement with Individual, Maximum Period to Receive Installments	15 years
Performance Share Awards [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	$ 1.9	$ 2.9	$ 4.1
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Weighted-average volatility (in hundredths)	56.40%	59.10%	59.20%
Weighted-average volatility S&P MidCap 400 Index (in hundredths)	27.00%	32.40%	34.70%
Risk-free interest rate (in hundredths)	0.90%	0.90%	0.40%
Dividend yield (in hundredths)	0.00%	0.00%	0.00%
Summary of changes in shares outstanding under all long-term incentive plans [Rollforward]
Amount of unrecognized compensation costs	$ 2.1
Weighted average period of recognition (in years)	1 year 7 months 6 days
Summary of nonvested shares [Roll Forward]
Nonvested, beginning of period (in shares)	978,952
Granted (in shares)	890,700
Vested/restrictions lapsed/earned (in shares)	0
Canceled (in shares)	(865,358)
Nonvested, end of period (in shares)	1,004,294	978,952
Weighted average grant date fair value, nonvested, beginning of period (dollars per share)	$ 5.56
Weighted average grant date fair value, granted (dollars per share)	3.09	$ 6.40	$ 4.68
Weighted average grant date fair value, vested/restrictions lapsed/earned (dollars per share)	0
Weighted average grant date fair value, canceled (dollars per share)	4.36
Weighted average grant date fair value, nonvested, end of period (dollars per share)	$ 4.40	$ 5.56
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	3 years
Minimum [Member] | Stock Options [Member]
Share-based Compensation Expense [Abstract]
Minimum vesting period for stock option awards (in number of months)	6 months
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected term (in years)	3 years 1 month	3 years	2 years 10 months 24 days
Maximum [Member] | Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected term (in years)	6 years 7 months	6 years 6 months	6 years 4 months 24 days

Comprehensive Income (Loss) (De

Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Foreign currency translation
Balance at beginning of period		$ 1	$ 4.7	$ 3.5
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract]
Foreign currency translation gain (loss)		(3.1)	(3.7)	1.2
Balance at end of period		(2.1)	1	4.7
Cash flow hedges
Balance at beginning of period		(32.2)	18.3	31.7
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax [Abstract]
Gains (losses) arising in period		(64.2)	(51.6)	3.5
Income tax expense		24.9	0	1.3
Gains (losses) arising in period, net of tax		(89.1)	(51.6)	2.2
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax [Abstract]
Reclassification of losses (gains) to net income (loss)		61.4	1.1	(25.2)
Income tax expense	[1]	(25.9)	0	(9.6)
Net amount of reclassification of losses (gains) to net income (loss)		87.3	1.1	(15.6)
Total other comprehensive income (loss), (Derivatives Qualifying as Hedges), net of tax		(1.8)	(50.5)	(13.4)
Balance at end of period		(34)	(32.2)	18.3
Unrealized holding gains (losses) on securities
Balance at beginning of period		0.4	0.4	0.3
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax [Abstract]
Unrealized holding gains (losses) arising in period		0	0	0.2
Income tax expense		0	0	0.1
Unrealized holding gains (losses) arising in period, net of tax		0	0	0.1
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	[1]	0.4	0	0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax		(0.4)	0	0.1
Balance at end of period		0	0.4	0.4
Pension and OPEB Plans
Balance at beginning of period		(173.6)	300	(34.4)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax [Abstract]
Prior service credit (cost) arising in period		(7.7)	10.9	(6.1)
Gains (losses) arising in period		(60.8)	(422.5)	422.3
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments and Tax		(68.5)	(411.6)	416.2
Income tax expense (benefit)	[1]	(26)	0	50.3
Gains (losses) arising in period, net of tax		(42.5)	(411.6)	365.9
Other Comprehensive Income (Loss), Reclassification Adjustment, Pension and Other Postretirement Benefit Plans, Included in Net Income, before Tax [Abstract]
Reclassification of prior service cost (credits) included in net income (loss)		(60.2)	(68.9)	(76.2)
Reclassification of actuarial (gains) losses included in net income (loss)		165	6.9	25.3
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax		104.8	(62)	(50.9)
Income tax (expense) benefit	[1]	39.8	0	(19.4)
Amount of reclassification to net income (loss), net of tax		65	(62)	(31.5)
Total other comprehensive income (loss), net of tax		22.5	(473.6)	334.4
Balance at end of period		(151.1)	(173.6)	300
Pension and OPEB Expense (Income) [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment, Pension and Other Postretirement Benefit Plans, Included in Net Income, before Tax [Abstract]
Reclassification of prior service cost (credits) included in net income (loss)	[2]	(60.2)	(68.9)	(76.2)
Reclassification of actuarial (gains) losses included in net income (loss)	[2]	165	6.9	25.3
Commodity Contract [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax [Abstract]
Reclassification of losses (gains) to net income (loss)		61.4	1.1	(25.2)
Commodity Contract [Member] | Sales [Member] | Hot Roll Carbon Steel Coils [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax [Abstract]
Reclassification of losses (gains) to net income (loss)	[3]	0	0	(0.4)
Commodity Contract [Member] | Cost of Products Sold [Member] | Other Contract [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax [Abstract]
Reclassification of losses (gains) to net income (loss)	[4]	$ 61.4	$ 1.1	$ (24.8)
[1]	Included in income tax expense (benefit)
[2]	Included in pension and OPEB expense (income)
[3]	Included in net sales
[4]	Included in cost of products sold

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net income (loss) attributable to AK Steel Holding Corporation	$ (145.4)	$ 6.7	$ (64)	$ (306.3)	$ 13.5	$ (7.2)	$ (17.1)	$ (86.1)	$ (509)	$ (96.9)	$ (46.8)
Less: distributed earnings to common stockholders and holders of certain stock compensation awards									0	0	0
Undistributed earnings (loss)									(509)	(96.9)	(46.8)
Common stockholders earnings - basic [Abstract]
Distributed earnings to common stockholders									0	0	0
Undistributed earnings (loss) to common stockholders - basic									(507.3)	(96.6)	(46.6)
Common stockholders earnings (loss) - basic									(507.3)	(96.6)	(46.6)
Common stockholders earnings - diluted [Abstract]
Distributed earnings to common stockholders									0	0	0
Undistributed earnings to common stockholders - diluted									(507.3)	(96.6)	(46.6)
Common stockholders earnings - diluted									$ (507.3)	$ (96.6)	$ (46.6)
Common shares outstanding (weighted-average shares in millions) [Abstract]
Common shares outstanding for basic earnings per share (in shares)									177.2	148.1	135.8
Effect of exchangeable debt									0	0	0
Effect of dilutive stock-based compensation (in shares)									0	0	0
Common shares outstanding for diluted earnings per share (in shares)									177.2	148.1	135.8
Basic earnings per share [Abstract]
Distributed earnings - basic (in dollars per share)									$ 0	$ 0	$ 0
Undistributed earnings (loss) - basic (in dollars per share)									(2.86)	(0.65)	(0.34)
Basic earnings (loss) per share (in dollars per share)					$ 0.08	$ (0.05)	$ (0.13)	$ (0.63)	(2.86)	(0.65)	(0.34)
Diluted earnings per share [Abstract]
Distributed earnings - diluted (in dollars per share)									0	0	0
Undistributed earnings (loss) - diluted (in dollars per share)									(2.86)	(0.65)	(0.34)
Diluted earnings (loss) per share (in dollars per share)					$ 0.07	$ (0.05)	$ (0.13)	$ (0.63)	$ (2.86)	$ (0.65)	$ (0.34)
Potentially issuable common shares excluded from earnings per share calculation due to anti-dilutive effect (in millions of shares)									3.6	9.7	2.6

Variable Interest Entities (Det

Variable Interest Entities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Income before income taxes	$ (382.8)	$ (26.4)	$ 7
SunCoke Middletown [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable interest entity, ownership percentage	0.00%
Income before income taxes	$ 62.6	$ 63	$ 64.3
Vicksmetal Armco Associates [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable interest entity, ownership percentage	50.00%

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Estimate of Fair Value Measurement [Member] | Long-term Debt [Member]
Liabilities measured at fair value
Long-term debt, including current maturities	$ (1,573.3)	$ (2,478.3)
Estimate of Fair Value Measurement [Member] | Long-term Debt [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
Long-term debt, including current maturities	0	0
Estimate of Fair Value Measurement [Member] | Long-term Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities measured at fair value
Long-term debt, including current maturities	(1,573.3)	(2,478.3)
Reported Value Measurement [Member] | Long-term Debt [Member]
Liabilities measured at fair value
Long-term debt, including current maturities	(2,354.1)	(2,422)
Reported Value Measurement [Member] | Long-term Debt [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
Long-term debt, including current maturities	0	0
Reported Value Measurement [Member] | Long-term Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities measured at fair value
Long-term debt, including current maturities	(2,354.1)	(2,422)
Fair Value, Measurements, Recurring [Member]
Assets measured at fair value
Assets measured at fair value	58.5	80.1
Liabilities measured at fair value
Liabilities measured at fair value	(50.7)	(41.9)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Assets measured at fair value	56.6	73.5
Liabilities measured at fair value
Liabilities measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Assets measured at fair value	1.9	6.6
Liabilities measured at fair value
Liabilities measured at fair value	(50.7)	(41.9)
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member]
Assets measured at fair value
Cash and cash equivalents	56.6	70.2
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Cash and cash equivalents	56.6	70.2
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Cash and cash equivalents	0	0
Fair Value, Measurements, Recurring [Member] | Other Noncurrent Assets [Member]
Assets measured at fair value
Available for sale investments-cash and cash equivalents	0	3.3
Commodity hedge contracts-noncurrent	0.3	1.8
Fair Value, Measurements, Recurring [Member] | Other Noncurrent Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Available for sale investments-cash and cash equivalents	0	3.3
Commodity hedge contracts-noncurrent	0	0
Fair Value, Measurements, Recurring [Member] | Other Noncurrent Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Available for sale investments-cash and cash equivalents	0	0
Commodity hedge contracts-noncurrent	0.3	1.8
Foreign Exchange Contract [Member] | Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member]
Assets measured at fair value
Foreign exchange contracts	1.1	1.2
Foreign Exchange Contract [Member] | Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Foreign exchange contracts	0	0
Foreign Exchange Contract [Member] | Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Foreign exchange contracts	1.1	1.2
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member]
Assets measured at fair value
Commodity hedge contracts-current	0.5	3.6
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Commodity hedge contracts-current	0	0
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Commodity hedge contracts-current	0.5	3.6
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member]
Liabilities measured at fair value
Commodity hedge contracts-current	(41.2)	(36.2)
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
Commodity hedge contracts-current	0	0
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities measured at fair value
Commodity hedge contracts-current	(41.2)	(36.2)
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member] | Other Noncurrent Liabilities [Member]
Liabilities measured at fair value
Commodity hedge contracts-noncurrent	(9.5)	(5.7)
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member] | Other Noncurrent Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
Commodity hedge contracts-noncurrent	0	0
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member] | Other Noncurrent Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities measured at fair value
Commodity hedge contracts-noncurrent	$ (9.5)	$ (5.7)
Liability [Member] | Maximum [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Benchmark interest rates for contracts (in hundredths)	3.60%
Assets [Member] | Maximum [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Benchmark interest rates for contracts (in hundredths)	1.50%

Derivative Instruments and He89

Derivative Instruments and Hedging Activities (Details)	Dec. 31, 2015EUR (€)MMBTUTMWtlb	Dec. 31, 2014EUR (€)MMBTUTMWtlb
Commodity Contract [Member] | Nickel [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives	164,800	259,300
Commodity Contract [Member] | Natural Gas [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | MMBTU	36,972,500	33,992,500
Commodity Contract [Member] | Zinc [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives	54,173,800	61,800,000
Commodity Contract [Member] | Iron Ore [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | t	2,795,000	2,335,000
Commodity Contract [Member] | Electricity [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | MW	1,386,400	1,182,800
Commodity Contract [Member] | Hot Roll Carbon Steel Coils [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | T	0	15,000
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount | €	€ 55,500,000	€ 23,675,000

Derivative Instruments and He90

Derivative Instruments and Hedging Activities (Details 2) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative, Collateral, Right to Reclaim Cash	$ 17.9
Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, current	0.3	$ 2.1
Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Noncurrent	0.3	1.8
Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities, current	(40.9)	(32)
Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities, noncurrent	(9.5)	(5.7)
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, current	1.1	1.2
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, current	0.2	1.5
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities, current	$ (0.3)	$ (4.2)

Derivative Instruments and He91

Derivative Instruments and Hedging Activities (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Natural Gas [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Investment Contract Settlement Date Range Start	Jan. 1, 2016
Investment Contract Settlement Date Range End	Dec. 31, 2017
Gains (losses) before tax expected to be reclassified into earnings within the next twelve months	$ (17.1)
Electricity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Investment Contract Settlement Date Range Start	Jan. 1, 2016
Investment Contract Settlement Date Range End	Dec. 31, 2017
Gains (losses) before tax expected to be reclassified into earnings within the next twelve months	$ (1.9)
Iron Ore [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Investment Contract Settlement Date Range Start	Jan. 1, 2016
Investment Contract Settlement Date Range End	Nov. 30, 2017
Gains (losses) before tax expected to be reclassified into earnings within the next twelve months	$ (7.8)
Zinc [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Investment Contract Settlement Date Range Start	Jan. 1, 2016
Investment Contract Settlement Date Range End	Dec. 31, 2017
Gains (losses) before tax expected to be reclassified into earnings within the next twelve months	$ (11.2)
Foreign Exchange Contract [Member] | Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Recognized gains (losses) in consolidated statement of operations	(0.1)	$ 1.9	$ (0.1)
Commodity Contract [Member] | Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Recognized gains (losses) in consolidated statement of operations	2.2	(5.1)	(3.1)
Commodity Contract [Member] | Cost of Products Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Recognized gains (losses) in consolidated statement of operations	(2)	(35)	1.7
Cash Flow Hedging [Member] | Commodity Contract [Member] | Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification of losses (gains) from accumulated other comprehensive income to net income (loss)	0	0	0.4
Cash Flow Hedging [Member] | Commodity Contract [Member] | Cost of Products Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification of losses (gains) from accumulated other comprehensive income to net income (loss)	(61.4)	(1.1)	24.8
Recognized in cost of products sold (ineffective portion and amount excluded from effectiveness testing)	$ (23.6)	$ (0.8)	$ 3.3

Supplementary Cash Flow Infor92

Supplementary Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Cash Flow Information [Abstract]
Interest, net of capitalized interest	$ 161.3	$ 121.9	$ 116.2
Income taxes	0.7	(0.3)	1.2
Supplementary Cash Flow [Line Items]
Net cash flows from operating activities	200.3	(322.8)	(110.2)
Cash and Cash Equivalents, at Carrying Value	56.6	70.2	45.3	$ 227
Supplementary cash flow, noncash investing and financing activities [Abstract]
Capital investments	37.4	29.5	10.2
Variable Interest Entity, Primary Beneficiary [Member] | SunCoke Middletown [Member]
Supplementary Cash Flow [Line Items]
Net cash flows from operating activities	87.4	66.4	82.6
Cash and Cash Equivalents, at Carrying Value	7.6	18.2
Restricted stock and RSUs [Member]
Supplementary cash flow, noncash investing and financing activities [Abstract]
Issuance of restricted stock and restricted stock units	$ 4.1	$ 4.5	$ 3

Quarterly Information (Unaudi93

Quarterly Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Impairment of Magnetation investment				$ 256.3					$ 256.3	$ 0	$ 0
Impairment of AFSG investment									41.6	0	0
Charge for facility idling									28.1	0	0
Pension/OPEB corridor charge/credit									131.2	2	0
Net sales	$ 1,542.7	$ 1,709.9	$ 1,689.4	1,750.9	$ 1,997.6	$ 1,593.8	$ 1,530.8	$ 1,383.5	6,692.9	6,505.7	5,570.4
Operating profit (loss)	(34.4)	80.2	7.1	33.8	74.5	63.7	36.5	(35.3)	86.7	139.4	135.8
Net income (loss) attributable to AK Holding	$ (145.4)	$ 6.7	$ (64)	$ (306.3)	$ 13.5	$ (7.2)	$ (17.1)	$ (86.1)	$ (509)	$ (96.9)	$ (46.8)
Basic and diluted earnings (loss) per share (in dollars per share)	$ (0.82)	$ 0.04	$ (0.36)	$ (1.72)					$ (2.86)	$ (0.65)	$ (0.34)
Basic earnings (loss) per share					$ 0.08	$ (0.05)	$ (0.13)	$ (0.63)	(2.86)	(0.65)	(0.34)
Diluted earnings (loss) per share					$ 0.07	$ (0.05)	$ (0.13)	$ (0.63)	$ (2.86)	$ (0.65)	$ (0.34)
Severstal Dearborn [Member]
Business Acquisition [Line Items]
Business Combination, Additional Disclosures, Acquisition Related Costs					$ 7.1	$ 23.6	$ 1			$ 31.7
Pension Plans, Defined Benefit [Member]
Business Acquisition [Line Items]
Pension/OPEB corridor charge/credit	$ 144.3				$ 2				$ 144.3	2	$ 0
Other Postretirement Benefit Plans, Defined Benefit [Member]
Business Acquisition [Line Items]
Pension/OPEB corridor charge/credit	(13.1)								$ (13.1)	$ 0	$ 0
AFSG Holdings Inc [Member]
Business Acquisition [Line Items]
Impairment of AFSG investment	$ 41.6

Supplementary Guarantor Infor94

Supplementary Guarantor Information (Details) - USD ($) $ in Millions	Sep. 16, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Statements of Operations [Abstract]
Net sales		$ 1,542.7	$ 1,709.9	$ 1,689.4	$ 1,750.9	$ 1,997.6	$ 1,593.8	$ 1,530.8	$ 1,383.5	$ 6,692.9	$ 6,505.7	$ 5,570.4
Cost of products sold (exclusive of items shown separately below)										6,032	6,007.7	5,107.8
Selling and administrative expenses (exclusive of items shown separately below)										261.9	247.2	205.3
Depreciation										216	201.9	190.1
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										(63)	(92.5)	(68.6)
Pension and OPEB net corridor charge										131.2	2	0
Charge for facility idling										28.1	0	0
Total operating costs										6,606.2	6,366.3	5,434.6
Operating profit (loss)		(34.4)	80.2	7.1	33.8	74.5	63.7	36.5	(35.3)	86.7	139.4	135.8
Interest expense										173	144.7	127.4
Impairment of Magnetation investment					(256.3)					(256.3)	0	0
Impairment of AFSG investment										(41.6)	0	0
Other income (expense)										1.4	(21.1)	(1.4)
Income (loss) before income taxes										(382.8)	(26.4)	7
Income tax expense (benefit)										63.4	7.7	(10.4)
Equity in net income (loss) of subsidiaries										0	0	0
Net income (loss)										(446.2)	(34.1)	17.4
Less: Net income attributable to noncontrolling interests										62.8	62.8	64.2
Net income (loss) attributable to AK Steel Holding Corporation		(145.4)	$ 6.7	$ (64)	(306.3)	13.5	$ (7.2)	$ (17.1)	(86.1)	(509)	(96.9)	(46.8)
Other comprehensive income (loss)										17.2	(527.8)	322.3
Comprehensive income (loss) attributable to AK Steel Holding Corporation										(491.8)	(624.7)	275.5
Current assets:
Cash and cash equivalents		56.6			70.2	70.2			45.3	70.2	45.3	227	$ 56.6	$ 70.2	$ 45.3	$ 227
Accounts receivable, net													444.9	644.3
Inventory, net													1,226.3	1,172.1
Other current assets													78.4	71.4
Total current assets													1,806.2	1,958
Property, plant and equipment													6,466	6,388.4
Accumulated depreciation													(4,379.5)	(4,175.2)
Property, plant and equipment, net													2,086.5	2,213.2
Other non-current assets:
Investments in affiliates													70.7	388.7
Investment in subsidiaries													0	0
Inter-company accounts													0	0
Other non-current assets													121	268.1
TOTAL ASSETS													4,084.4	4,828
Current liabilities:
Accounts payable													703.4	803.1
Accrued liabilities													261.5	266.5
Current portion of pension and other postretirement benefit obligations													77.7	55.6
Total current liabilities													1,042.6	1,125.2
Non-current liabilities:
Long-term debt													2,354.1	2,422
Pension and other postretirement benefit obligations													1,146.9	1,225.3
Other non-current liabilities													136.4	132.5
TOTAL LIABILITIES													4,680	4,905
Equity (deficit):
Total stockholders' equity (deficit)													(977.6)	(492.5)
Noncontrolling interests													382	415.5
TOTAL EQUITY (DEFICIT)													(595.6)	(77)	192.7	(91)
TOTAL LIABILITIES AND EQUITY (DEFICIT)													4,084.4	4,828
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										200.3	(322.8)	(110.2)
Cash flows from investing activities:
Capital investments										(99)	(81.1)	(63.6)
Investments in Magnetation joint venture										0	(100)	(50)
Investments in acquired business, net of cash acquired										0	(690.3)	0
Proceeds from sale of equity investee										25	0	0
Proceeds from AFSG Holdings, Inc. distribution										14	0	0
Other investing items, net										12.5	13.6	15.1
Net cash flows from investing activities										(47.5)	(857.8)	(98.5)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										(55)	515	90
Proceeds from issuance of long-term debt										0	427.1	31.9
Redemption of long-term debt										(14.1)	(0.8)	(27.4)
Proceeds from issuance of common stock	$ 345.3									0	345.3	0
Debt issuance costs										0	(15.5)	(3.4)
Inter-company activity										0	0	0
SunCoke Middletown distributions to noncontrolling interest owners										(96.3)	(61)	(64.8)
Other financing items, net										(1)	(4.6)	0.7
Net cash flows from financing activities										(166.4)	1,205.5	27
Net increase (decrease) in cash and cash equivalents										(13.6)	24.9	(181.7)
Cash and cash equivalents, beginning of year					70.2				45.3	70.2	45.3	227
Cash and cash equivalents, end of year		56.6				70.2				56.6	70.2	45.3
AK Holding [Member]
Condensed Statements of Operations [Abstract]
Net sales										0	0	0
Cost of products sold (exclusive of items shown separately below)										0	0	0
Selling and administrative expenses (exclusive of items shown separately below)										4.9	4.6	4.4
Depreciation										0	0	0
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										0	0	0
Pension and OPEB net corridor charge										0	0
Charge for facility idling										0
Total operating costs										4.9	4.6	4.4
Operating profit (loss)										(4.9)	(4.6)	(4.4)
Interest expense										0	0	0
Impairment of Magnetation investment										0
Impairment of AFSG investment										0
Other income (expense)										0	0	0
Income (loss) before income taxes										(4.9)	(4.6)	(4.4)
Income tax expense (benefit)										0	0	0
Equity in net income (loss) of subsidiaries										(504.1)	(92.3)	(42.4)
Net income (loss)										(509)	(96.9)	(46.8)
Less: Net income attributable to noncontrolling interests										0	0	0
Net income (loss) attributable to AK Steel Holding Corporation										(509)	(96.9)	(46.8)
Other comprehensive income (loss)										17.2	(527.8)	322.3
Comprehensive income (loss) attributable to AK Steel Holding Corporation										(491.8)	(624.7)	275.5
Current assets:
Cash and cash equivalents		0			0	0			0	0	0	0	0	0	0	0
Accounts receivable, net													0	0
Inventory, net													0	0
Other current assets													0	0.3
Total current assets													0	0.3
Property, plant and equipment													0	0
Accumulated depreciation													0	0
Property, plant and equipment, net													0	0
Other non-current assets:
Investments in affiliates													0	0
Investment in subsidiaries													(3,541)	(2,970.9)
Inter-company accounts													2,563.4	2,478.1
Other non-current assets													0	0
TOTAL ASSETS													(977.6)	(492.5)
Current liabilities:
Accounts payable													0	0
Accrued liabilities													0	0
Current portion of pension and other postretirement benefit obligations													0	0
Total current liabilities													0	0
Non-current liabilities:
Long-term debt													0	0
Pension and other postretirement benefit obligations													0	0
Other non-current liabilities													0	0
TOTAL LIABILITIES													0	0
Equity (deficit):
Total stockholders' equity (deficit)													(977.6)	(492.5)
Noncontrolling interests													0	0
TOTAL EQUITY (DEFICIT)													(977.6)	(492.5)
TOTAL LIABILITIES AND EQUITY (DEFICIT)													(977.6)	(492.5)
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										(3.7)	(3.4)	(3.5)
Cash flows from investing activities:
Capital investments										0	0	0
Investments in Magnetation joint venture											0	0
Investments in acquired business, net of cash acquired											0
Proceeds from sale of equity investee										0
Proceeds from AFSG Holdings, Inc. distribution										0
Other investing items, net										0	0	0
Net cash flows from investing activities										0	0	0
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										0	0	0
Proceeds from issuance of long-term debt											0	0
Redemption of long-term debt										0	0	0
Proceeds from issuance of common stock											345.3
Debt issuance costs											0	0
Inter-company activity										4.7	(341)	4.1
SunCoke Middletown distributions to noncontrolling interest owners										0	0	0
Other financing items, net										(1)	(0.9)	(0.6)
Net cash flows from financing activities										3.7	3.4	3.5
Net increase (decrease) in cash and cash equivalents										0	0	0
Cash and cash equivalents, beginning of year					0				0	0	0	0
Cash and cash equivalents, end of year		0				0				0	0	0
AK Steel [Member]
Condensed Statements of Operations [Abstract]
Net sales										6,498.2	6,284.2	5,339.3
Cost of products sold (exclusive of items shown separately below)										5,984.9	5,937.6	5,012.1
Selling and administrative expenses (exclusive of items shown separately below)										270.4	251	205
Depreciation										187.7	176.1	169.4
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										(63)	(92.5)	(68.6)
Pension and OPEB net corridor charge										131.2	2
Charge for facility idling										28.1
Total operating costs										6,539.3	6,274.2	5,317.9
Operating profit (loss)										(41.1)	10	21.4
Interest expense										171	142.1	125.9
Impairment of Magnetation investment										0
Impairment of AFSG investment										0
Other income (expense)										6.4	(17.7)	(5.9)
Income (loss) before income taxes										(205.7)	(149.8)	(110.4)
Income tax expense (benefit)										39.6	(19.2)	(27.8)
Equity in net income (loss) of subsidiaries										(258.8)	38.3	40.2
Net income (loss)										(504.1)	(92.3)	(42.4)
Less: Net income attributable to noncontrolling interests										0	0	0
Net income (loss) attributable to AK Steel Holding Corporation										(504.1)	(92.3)	(42.4)
Other comprehensive income (loss)										17.2	(527.8)	322.3
Comprehensive income (loss) attributable to AK Steel Holding Corporation										(486.9)	(620.1)	279.9
Current assets:
Cash and cash equivalents		27			28.5	28.5			16.8	28.5	16.8	203.6	27	28.5	16.8	203.6
Accounts receivable, net													411.9	606.2
Inventory, net													1,149.6	1,080.5
Other current assets													75.6	67.9
Total current assets													1,664.1	1,783.1
Property, plant and equipment													5,763.8	5,695.8
Accumulated depreciation													(4,218)	(4,040.8)
Property, plant and equipment, net													1,545.8	1,655
Other non-current assets:
Investments in affiliates													42.6	84.5
Investment in subsidiaries													1,346	1,582.4
Inter-company accounts													(3,600.9)	(3,420.4)
Other non-current assets													83	174.4
TOTAL ASSETS													1,080.6	1,859
Current liabilities:
Accounts payable													669	754.9
Accrued liabilities													242.3	244.6
Current portion of pension and other postretirement benefit obligations													77.3	55.3
Total current liabilities													988.6	1,054.8
Non-current liabilities:
Long-term debt													2,354.1	2,422
Pension and other postretirement benefit obligations													1,143.6	1,221.3
Other non-current liabilities													135.3	131.8
TOTAL LIABILITIES													4,621.6	4,829.9
Equity (deficit):
Total stockholders' equity (deficit)													(3,541)	(2,970.9)
Noncontrolling interests													0	0
TOTAL EQUITY (DEFICIT)													(3,541)	(2,970.9)
TOTAL LIABILITIES AND EQUITY (DEFICIT)													1,080.6	1,859
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										49	(447.2)	(251.1)
Cash flows from investing activities:
Capital investments										(85)	(63.1)	(39.2)
Investments in Magnetation joint venture											0	0
Investments in acquired business, net of cash acquired											(690.3)
Proceeds from sale of equity investee										25
Proceeds from AFSG Holdings, Inc. distribution										0
Other investing items, net										12.5	13.6	8.5
Net cash flows from investing activities										(47.5)	(739.8)	(30.7)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										(55)	515	90
Proceeds from issuance of long-term debt											427.1	31.9
Redemption of long-term debt										(14.1)	(0.8)	(27.4)
Proceeds from issuance of common stock											0
Debt issuance costs											(15.5)	(3.4)
Inter-company activity										66.1	272.9	3.9
SunCoke Middletown distributions to noncontrolling interest owners										0	0	0
Other financing items, net										0	0	0
Net cash flows from financing activities										(3)	1,198.7	95
Net increase (decrease) in cash and cash equivalents										(1.5)	11.7	(186.8)
Cash and cash equivalents, beginning of year					28.5				16.8	28.5	16.8	203.6
Cash and cash equivalents, end of year		27				28.5				27	28.5	16.8
Guarantor Subsidiaries of the Senior Notes [Member]
Condensed Statements of Operations [Abstract]
Net sales										250.9	280.7	261.5
Cost of products sold (exclusive of items shown separately below)										167.5	199.3	189
Selling and administrative expenses (exclusive of items shown separately below)										10.7	11.3	10.5
Depreciation										3.6	3.9	4.3
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										0	0	0
Pension and OPEB net corridor charge										0	0
Charge for facility idling										0
Total operating costs										181.8	214.5	203.8
Operating profit (loss)										69.1	66.2	57.7
Interest expense										0	0	0
Impairment of Magnetation investment										0
Impairment of AFSG investment										0
Other income (expense)										6.6	6.5	6.1
Income (loss) before income taxes										75.7	72.7	63.8
Income tax expense (benefit)										28.7	29.1	20.1
Equity in net income (loss) of subsidiaries										0	0	0
Net income (loss)										47	43.6	43.7
Less: Net income attributable to noncontrolling interests										0	0	0
Net income (loss) attributable to AK Steel Holding Corporation										47	43.6	43.7
Other comprehensive income (loss)										0	0	0
Comprehensive income (loss) attributable to AK Steel Holding Corporation										47	43.6	43.7
Current assets:
Cash and cash equivalents		0			0.5	0.5			0	0.5	0	0	0	0.5	0	0
Accounts receivable, net													23.5	27.6
Inventory, net													26.1	26.2
Other current assets													0.3	0.2
Total current assets													49.9	54.5
Property, plant and equipment													103.1	97.3
Accumulated depreciation													(75.4)	(71.8)
Property, plant and equipment, net													27.7	25.5
Other non-current assets:
Investments in affiliates													0	0
Investment in subsidiaries													0	0
Inter-company accounts													1,403	1,325.5
Other non-current assets													33	33
TOTAL ASSETS													1,513.6	1,438.5
Current liabilities:
Accounts payable													6.3	6.9
Accrued liabilities													2.8	3
Current portion of pension and other postretirement benefit obligations													0	0
Total current liabilities													9.1	9.9
Non-current liabilities:
Long-term debt													0	0
Pension and other postretirement benefit obligations													0	0
Other non-current liabilities													0	0
TOTAL LIABILITIES													9.1	9.9
Equity (deficit):
Total stockholders' equity (deficit)													1,504.5	1,428.6
Noncontrolling interests													0	0
TOTAL EQUITY (DEFICIT)													1,504.5	1,428.6
TOTAL LIABILITIES AND EQUITY (DEFICIT)													1,513.6	1,438.5
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										53.9	39.2	50.4
Cash flows from investing activities:
Capital investments										(5.8)	(2.8)	(1.7)
Investments in Magnetation joint venture											0	0
Investments in acquired business, net of cash acquired											0
Proceeds from sale of equity investee										0
Proceeds from AFSG Holdings, Inc. distribution										0
Other investing items, net										0	0	0.3
Net cash flows from investing activities										(5.8)	(2.8)	(1.4)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										0	0	0
Proceeds from issuance of long-term debt											0	0
Redemption of long-term debt										0	0	0
Proceeds from issuance of common stock											0
Debt issuance costs											0	0
Inter-company activity										(48.6)	(35.9)	(49)
SunCoke Middletown distributions to noncontrolling interest owners										0	0	0
Other financing items, net										0	0	0
Net cash flows from financing activities										(48.6)	(35.9)	(49)
Net increase (decrease) in cash and cash equivalents										(0.5)	0.5	0
Cash and cash equivalents, beginning of year					0.5				0	0.5	0	0
Cash and cash equivalents, end of year		0				0.5				0	0.5	0
Other Non-Guarantor Subsidiaries [Member]
Condensed Statements of Operations [Abstract]
Net sales										538.3	599.6	568.8
Cost of products sold (exclusive of items shown separately below)										423.3	484.7	463.3
Selling and administrative expenses (exclusive of items shown separately below)										25	28.3	26.2
Depreciation										24.7	21.9	16.4
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										0	0	0
Pension and OPEB net corridor charge										0	0
Charge for facility idling										0
Total operating costs										473	534.9	505.9
Operating profit (loss)										65.3	64.7	62.9
Interest expense										2	2.6	1.5
Impairment of Magnetation investment										(256.3)
Impairment of AFSG investment										(41.6)
Other income (expense)										(11.6)	(9.9)	(1.6)
Income (loss) before income taxes										(246.2)	52.2	59.8
Income tax expense (benefit)										(4.2)	(3.4)	(2)
Equity in net income (loss) of subsidiaries										0	0	0
Net income (loss)										(242)	55.6	61.8
Less: Net income attributable to noncontrolling interests										62.8	62.8	64.2
Net income (loss) attributable to AK Steel Holding Corporation										(304.8)	(7.2)	(2.4)
Other comprehensive income (loss)										(3.1)	(3.7)	1.2
Comprehensive income (loss) attributable to AK Steel Holding Corporation										(307.9)	(10.9)	(1.2)
Current assets:
Cash and cash equivalents		29.6			41.2	41.2			28.5	41.2	28.5	23.4	29.6	41.2	28.5	23.4
Accounts receivable, net													32	37.3
Inventory, net													60.6	73.5
Other current assets													2.5	3
Total current assets													124.7	155
Property, plant and equipment													599.1	595.3
Accumulated depreciation													(86.1)	(62.6)
Property, plant and equipment, net													513	532.7
Other non-current assets:
Investments in affiliates													28.1	304.2
Investment in subsidiaries													0	0
Inter-company accounts													(390.8)	(412.4)
Other non-current assets													5	60.7
TOTAL ASSETS													280	640.2
Current liabilities:
Accounts payable													29.1	42
Accrued liabilities													16.4	18.9
Current portion of pension and other postretirement benefit obligations													0.4	0.3
Total current liabilities													45.9	61.2
Non-current liabilities:
Long-term debt													0	0
Pension and other postretirement benefit obligations													3.3	4
Other non-current liabilities													1.1	0.7
TOTAL LIABILITIES													50.3	65.9
Equity (deficit):
Total stockholders' equity (deficit)													(152.3)	158.8
Noncontrolling interests													382	415.5
TOTAL EQUITY (DEFICIT)													229.7	574.3
TOTAL LIABILITIES AND EQUITY (DEFICIT)													280	640.2
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										104.8	91.3	129.6
Cash flows from investing activities:
Capital investments										(8.2)	(15.2)	(22.7)
Investments in Magnetation joint venture											(100)	(50)
Investments in acquired business, net of cash acquired											0
Proceeds from sale of equity investee										0
Proceeds from AFSG Holdings, Inc. distribution										14
Other investing items, net										0	0	6.3
Net cash flows from investing activities										5.8	(115.2)	(66.4)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										0	0	0
Proceeds from issuance of long-term debt											0	0
Redemption of long-term debt										0	0	0
Proceeds from issuance of common stock											0
Debt issuance costs											0	0
Inter-company activity										(25.9)	101.3	5.4
SunCoke Middletown distributions to noncontrolling interest owners										(96.3)	(61)	(64.8)
Other financing items, net										0	(3.7)	1.3
Net cash flows from financing activities										(122.2)	36.6	(58.1)
Net increase (decrease) in cash and cash equivalents										(11.6)	12.7	5.1
Cash and cash equivalents, beginning of year					41.2				28.5	41.2	28.5	23.4
Cash and cash equivalents, end of year		29.6				41.2				29.6	41.2	28.5
Eliminations [Member]
Condensed Statements of Operations [Abstract]
Net sales										(594.5)	(658.8)	(599.2)
Cost of products sold (exclusive of items shown separately below)										(543.7)	(613.9)	(556.6)
Selling and administrative expenses (exclusive of items shown separately below)										(49.1)	(48)	(40.8)
Depreciation										0	0	0
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										0	0	0
Pension and OPEB net corridor charge										0	0
Charge for facility idling										0
Total operating costs										(592.8)	(661.9)	(597.4)
Operating profit (loss)										(1.7)	3.1	(1.8)
Interest expense										0	0	0
Impairment of Magnetation investment										0
Impairment of AFSG investment										0
Other income (expense)										0	0	0
Income (loss) before income taxes										(1.7)	3.1	(1.8)
Income tax expense (benefit)										(0.7)	1.2	(0.7)
Equity in net income (loss) of subsidiaries										762.9	54	2.2
Net income (loss)										761.9	55.9	1.1
Less: Net income attributable to noncontrolling interests										0	0	0
Net income (loss) attributable to AK Steel Holding Corporation										761.9	55.9	1.1
Other comprehensive income (loss)										(14.1)	531.5	(323.5)
Comprehensive income (loss) attributable to AK Steel Holding Corporation										747.8	587.4	(322.4)
Current assets:
Cash and cash equivalents		0			0	0			0	0	0	0	0	0	$ 0	$ 0
Accounts receivable, net													(22.5)	(26.8)
Inventory, net													(10)	(8.1)
Other current assets													0	0
Total current assets													(32.5)	(34.9)
Property, plant and equipment													0	0
Accumulated depreciation													0	0
Property, plant and equipment, net													0	0
Other non-current assets:
Investments in affiliates													0	0
Investment in subsidiaries													2,195	1,388.5
Inter-company accounts													25.3	29.2
Other non-current assets													0	0
TOTAL ASSETS													2,187.8	1,382.8
Current liabilities:
Accounts payable													(1)	(0.7)
Accrued liabilities													0	0
Current portion of pension and other postretirement benefit obligations													0	0
Total current liabilities													(1)	(0.7)
Non-current liabilities:
Long-term debt													0	0
Pension and other postretirement benefit obligations													0	0
Other non-current liabilities													0	0
TOTAL LIABILITIES													(1)	(0.7)
Equity (deficit):
Total stockholders' equity (deficit)													2,188.8	1,383.5
Noncontrolling interests													0	0
TOTAL EQUITY (DEFICIT)													2,188.8	1,383.5
TOTAL LIABILITIES AND EQUITY (DEFICIT)													$ 2,187.8	$ 1,382.8
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										(3.7)	(2.7)	(35.6)
Cash flows from investing activities:
Capital investments										0	0	0
Investments in Magnetation joint venture											0	0
Investments in acquired business, net of cash acquired											0
Proceeds from sale of equity investee										0
Proceeds from AFSG Holdings, Inc. distribution										0
Other investing items, net										0	0	0
Net cash flows from investing activities										0	0	0
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										0	0	0
Proceeds from issuance of long-term debt											0	0
Redemption of long-term debt										0	0	0
Proceeds from issuance of common stock											0
Debt issuance costs											0	0
Inter-company activity										3.7	2.7	35.6
SunCoke Middletown distributions to noncontrolling interest owners										0	0	0
Other financing items, net										0	0	0
Net cash flows from financing activities										3.7	2.7	35.6
Net increase (decrease) in cash and cash equivalents										0	0	0
Cash and cash equivalents, beginning of year					$ 0				$ 0	0	0	0
Cash and cash equivalents, end of year		$ 0				$ 0				$ 0	$ 0	$ 0
Senior Secured Notes Due December 2018 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)													8.75%	8.75%
Senior Notes Due May 2020 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)													7.625%	7.625%
Senior Notes Due October 2021 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)	7.625%												7.625%	7.625%
Senior Notes Due April 2022 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)													8.375%	8.375%
Exchangeable Senior Notes Due November 2019 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)													5.00%	5.00%