Aleris 10-Q 5 Aug 14 2014 Q2 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	6 Months Ended
	Jun. 30, 2014
Document And Entity Information [Abstract]	'
Entity Registrant Name	'Aleris Corporation
Entity Central Index Key	'0001518587
Current Fiscal Year End Date	'--12-31
Entity Filer Category	'Non-accelerated Filer
Document Type	'10-Q
Document Period End Date	30-Jun-14
Document Fiscal Year Focus	'2014
Document Fiscal Period Focus	'Q2
Amendment Flag	'false
Entity Common Stock, Shares Outstanding	31,256,999

Consolidated_Balance_Sheet

Consolidated Balance Sheet (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current Assets	'	'
Cash and cash equivalents	$51.90	$60.10
Accounts receivable (net of allowances of $8.9 and $7.7 at June 30, 2014 and December 31, 2013, respectively)	517.6	376.9
Inventories	784.6	683.4
Deferred income taxes	7.1	7.1
Prepaid expense and other assets, current	33.2	31.5
Total Current Assets	1,394.40	1,159
Property, plant and equipment, net	1,202.20	1,157.70
Intangible assets, net	45.2	43.5
Deferred income taxes	45.2	45.2
Other long-term assets	75.5	67.5
Total Assets	2,762.50	2,472.90
Current Liabilities	'	'
Accounts payable	422.9	303.2
Accrued liabilities	214.6	200.9
Deferred income taxes	3.9	3.9
Current portion of long-term debt	11.5	8.3
Total Current Liabilities	652.9	516.3
Long-term debt	1,411.30	1,229.10
Deferred income taxes	6.7	4.4
Accrued pension benefits	224	228.5
Accrued postretirement benefits	40.5	40.9
Other long-term liabilities	85.6	79.3
Total Long-Term Liabilities	1,768.10	1,582.20
Redeemable noncontrolling interest	5.7	5.7
Common stock; par value $.01; 45,000,000 shares authorized and 31,256,999 and 31,229,064 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively	0.3	0.3
Preferred stock; par value $.01; 1,000,000 shares authorized; none issued	0	0
Additional paid-in capital	409.4	401.9
Retained deficit	-82.8	-47.6
Accumulated other comprehensive income	8.2	13.8
Total Aleris Corporation Equity	335.1	368.4
Noncontrolling interest	0.7	0.3
Total Equity	335.8	368.7
Total Liabilities and Equity	$2,762.50	$2,472.90

Consolidated_Balance_Sheet_Par

Consolidated Balance Sheet (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Allowance for doubtful accounts receivable	$8.90	$7.70
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized	45,000,000	45,000,000
Common stock, shares issued	31,256,999	31,229,064
Redeemable preferred stock, par value (in dollars per share)	$0.01	$0.01
Redeemable preferred stock, shares authorized	1,000,000	1,000,000
Redeemable preferred stock, shares issued	0	0

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]	'	'	'	'
Revenues	$1,226.20	$1,127.60	$2,280.40	$2,237.70
Cost of sales	1,134.20	1,053.40	2,113.30	2,074.50
Gross profit	92	74.2	167.1	163.2
Selling, general and administrative expenses	68.9	58.5	130.9	120
Restructuring charges	2.2	9.5	2.7	10.3
Losses (gains) on derivative financial instruments	1.8	-9.9	1.3	-19.1
Other operating expense (income), net	2.6	0.4	2.8	-0.4
Operating income	16.5	15.7	29.4	52.4
Interest expense, net	27	24.6	53.3	45.6
Other (income) expense, net	-0.4	1.3	-0.8	-0.6
(Loss) income before income taxes	-10.1	-10.2	-23.1	7.4
Provision for income taxes	7	1.2	11.3	7.6
Net loss	-17.1	-11.4	-34.4	-0.2
Net income attributable to noncontrolling interest	0.4	0.3	0.7	0.6
Net loss attributable to Aleris Corporation	-17.5	-11.7	-35.1	-0.8
Comprehensive loss	-20.7	-0.2	-40	-5.6
Comprehensive income attributable to noncontrolling interest	0.4	0.3	0.7	0.6
Comprehensive loss attributable to Aleris Corporation	($21.10)	($0.50)	($40.70)	($6.20)

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Operating activities	'	'
Net loss	($34.40)	($0.20)
Depreciation and amortization	70.7	61.9
Provision for deferred income taxes	2.3	1.8
Stock-based compensation expense	8.2	5.4
Unrealized losses (gains) on derivative financial instruments	8.5	-0.3
Currency exchange gains on debt	-0.1	-0.4
Amortization of debt issuance costs	3.9	3.9
Other	3.5	-0.7
Change in accounts receivable	-104.6	-112.1
Change in inventories	-56.7	-24.3
Change in other assets	0.5	-15.1
Change in accounts payable	89.1	53
Change in accrued liabilities	1.8	-23.7
Net cash used by operating activities	-7.3	-50.8
Investing activities	'	'
Payments for property, plant and equipment	-78.4	-142.2
Purchase of a business	-110	0
Other	5.9	1.6
Net cash used by investing activities	-182.5	-140.6
Financing activities	'	'
Proceeds from the ABL facility	240	0
Payments on the ABL facility	-69	0
Proceeds from the Zhenjiang term loans	0	0.2
Proceeds from Zhenjiang revolver	11.5	4.1
Net proceeds from (payments on) other long-term debt	0.6	-1.8
Redemption of noncontrolling interest	0	-8.9
Dividends paid	0	-313
Other	-1	-3.1
Net cash provided (used) by financing activities	182.1	-322.5
Effect of exchange rate differences on cash and cash equivalents	-0.5	-0.5
Net decrease in cash and cash equivalents	-8.2	-514.4
Cash and cash equivalents at beginning of period	60.1	592.9
Cash and cash equivalents at end of period	$51.90	$78.50

Basis_Of_Presentation_Notes

Basis Of Presentation (Notes)	6 Months Ended
	Jun. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Basis Of Presentation	'
	1. BASIS OF PRESENTATION AND RECENT ACCOUNTING PRONOUNCEMENTS
	Basis of Presentation
	The accompanying unaudited Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles for interim financial information. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles in the United States for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. The operating results for interim periods contained herein are not necessarily indicative of the results that may be expected for any other interim period or for the full year. The accompanying Consolidated Financial Statements include the accounts of Aleris Corporation and all of its subsidiaries (collectively, except where the context otherwise requires, referred to as “Aleris,” “we,” “us,” “our,” “Company” or similar terms). Aleris Corporation is a holding company and currently conducts its business and operations through its direct wholly owned subsidiary, Aleris International, Inc. and its consolidated subsidiaries. Aleris International, Inc. is referred to herein as “Aleris International.”
	Recent Accounting Pronouncements
	In April 2014, the FASB issued ASU No. 2014-08, “Presentation of Financial Statements (Topic 205) and Property, Plant and Equipment (Topic 360)” (“ASU No. 2014-08”). This guidance amends the requirements for reporting discontinued operations and requires additional disclosures about discontinued operations. Under the new guidance, only disposals representing a strategic shift in operations or that have a major effect on the Company’s operations and financial results should be presented as discontinued operations. ASU No. 2014-08 also requires expanded disclosures about discontinued operations that will provide financial statement users with more information about the assets, liabilities, income and expenses of discontinued operations. This new accounting guidance is effective for annual periods beginning after December 15, 2014. We have determined that the adoption of these changes will need to be considered in the Company’s financial condition or results of operations in the event the Company initiates any of the transactions described above.
	In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“ASU No. 2014-09”), which was the result of a joint project by the FASB and International Accounting Standards Board to clarify the principles for recognizing revenue and to develop a common revenue standard for GAAP and International Financial Reporting Standards. The issuance of a comprehensive and converged standard on revenue recognition is expected to enable financial statement users to better understand and consistently analyze an entity’s revenue across industries, transactions and geographies. The standard will require additional disclosures to help financial statement users better understand the nature, amount, timing, and potential uncertainty of the revenue that is recognized. ASU No. 2014-09 will be effective for the Company on January 1, 2017, and will require either retrospective application to each prior reporting period presented or retrospective application with the cumulative effect of initially applying the standard recognized at the date of adoption. We are currently evaluating the impact the application of ASU No. 2014-09 will have on the Company’s financial statements and disclosures.

Inventories_Notes

Inventories (Notes)	6 Months Ended
	Jun. 30, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	2. INVENTORIES
	The components of our “Inventories” as of June 30, 2014 and December 31, 2013 are as follows:
		June 30, 2014		December 31, 2013
	Raw materials	$	275.8	$	265.9
	Work in process	261.7		203
	Finished goods	206.1		185.6
	Supplies	41		28.9
	Total inventories	$	784.6	$	683.4

LongTerm_Debt_Notes

Long-Term Debt (Notes)	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	3. LONG-TERM DEBT
	Our debt as of June 30, 2014 and December 31, 2013 is summarized as follows:
		June 30, 2014		December 31, 2013
	ABL facility	$	171	$	—
	7 5/8% senior notes due 2018, net of discount of $5.2 and $5.9 at June 30, 2014 and December 31, 2013, respectively	494.8		494.1
	7 7/8% senior notes due 2020, net of discount of $6.9 and $7.5 at June 30, 2014 and December 31, 2013, respectively	493.1		492.5
	Exchangeable notes, net of discount of $0.6 and $0.7 at June 30, 2014 and December 31, 2013, respectively	44.2		44.2
	Zhenjiang term loans, net of discount of $1.0 at June 30, 2014 and December 31, 2013, respectively	191.1		192.2
	Zhenjiang revolver, net of discount of $0.2 at June 30, 2014	11.3		—
	Other	17.3		14.4
	Total debt	1,422.80		1,237.40
	Less: Current portion of long-term debt	11.5		8.3
	Total long-term debt	$	1,411.30	$	1,229.10

Commitments_And_Contingencies_

Commitments And Contingencies (Notes)	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	4. COMMITMENTS AND CONTINGENCIES
	Environmental Proceedings
	Our operations are subject to environmental laws and regulations governing air emissions, wastewater discharges, the handling, disposal and remediation of hazardous substances and wastes and employee health and safety. These laws can impose joint and several liabilities for releases or threatened releases of hazardous substances upon statutorily defined parties, including us, regardless of fault or the lawfulness of the original activity or disposal. Given the changing nature of environmental legal requirements, we may be required, from time to time, to take environmental control measures at some of our facilities to meet future requirements.
	We have been named as a potentially responsible party in certain proceedings initiated pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act and similar stated statutes and may be named a potentially responsible party in other similar proceedings in the future. It is not anticipated that the costs incurred in connection with the presently pending proceedings will, individually or in the aggregate, have a material adverse effect on our financial position, results of operations or cash flows.
	We are performing operations and maintenance at two Superfund sites for matters arising out of past waste disposal activity associated with closed facilities. We are also under orders to perform environmental remediation by agencies in five states and one non-U.S. country at eight sites.
	Our reserves for environmental remediation liabilities totaled $46.9 and $35.3 at June 30, 2014 and December 31, 2013, respectively, and have been classified as “Other long-term liabilities” and “Accrued liabilities” in the Consolidated Balance Sheet. Of the environmental liabilities recorded at June 30, 2014 and December 31, 2013, $17.1 and $6.3, respectively, are indemnified by third parties.
	In addition to environmental liabilities, we have recorded asset retirement obligations associated with legal requirements related primarily to the normal operation of our landfills and the retirement of the related assets. Our total asset retirement obligations were $12.4 at June 30, 2014 and December 31, 2013. The amounts represent the most probable costs of remedial actions. We estimate the costs related to currently identified remedial actions will be paid out primarily over the next 10 years.
	Legal Proceedings
	On July 11, 2014, we were named in a civil complaint by the Boilermaker-Blacksmith National Pension Fund (the “Pension Trust”) for withdrawal liability from a multi-employer pension plan in the amount of $4.2 plus accrued interest. We did not participate in the pension plan following emergence from bankruptcy in 2010. The claims relate to matters existing prior to and during the Aleris International, Inc. bankruptcy filing. The Pension Trust did not assert any prepetition or administrative claims in the bankruptcy proceedings. We intend to vigorously defend the matter. The litigation is in its preliminary stage, and we are unable to reasonably predict an outcome or to estimate a range of reasonably possible loss.
	In addition, we are party to routine litigation and proceedings as part of the ordinary course of business and do not believe that the outcome of any existing proceedings would have a material adverse effect on our financial position, results of operations or cash flows. We have established accruals for those loss contingencies, including litigation and environmental contingencies, for which it has been determined that a loss is probable; none of such loss contingencies is material. Except as disclosed above, for those loss contingencies, including litigation and environmental contingencies, which have been determined to be reasonably possible, an estimate of the possible loss or range of loss cannot be determined because the claims, amount claimed, facts or legal status are not sufficiently developed or advanced in order to make such a determination. While we cannot estimate the loss or range of loss at this time, we do not believe that the outcome of any of these existing proceedings would be material to our financial position, results of operations or cash flows.

Stockholders_Equity_and_Redeem

Stockholders' Equity and Redeemable Noncontrolling Interest (Notes)	6 Months Ended
	Jun. 30, 2014
Stockholders' Equity Note [Abstract]	'
Stockholders' Equity and Redeemable Noncontrolling Interest	'
	5. STOCKHOLDERS’ EQUITY AND REDEEMABLE NONCONTROLLING INTEREST
	The following table summarizes the activity within stockholders’ equity and redeemable noncontrolling interest for the six months ended June 30, 2014:
		Aleris Corporation equity			Noncontrolling interest			Total equity			Redeemable noncontrolling interest
	Total equity at January 1, 2014	$	368.4		$	0.3		$	368.7		$	5.7
	Net (loss) income	(35.1		)	0.7			(34.4		)	—
	Other comprehensive loss	(5.6		)	—			(5.6		)	—
	Stock-based compensation activity	7.6			—			7.6			—
	Other	(0.2		)	(0.3		)	(0.5		)	—
	Total equity at June 30, 2014	$	335.1		$	0.7		$	335.8		$	5.7
	The following table shows changes in the number of our outstanding shares of common stock:
		Outstanding shares of common stock
	Balance at January 1, 2014	31,229,064
	Issuance associated with options exercised	3,434
	Issuance associated with vested restricted stock units	23,294
	Issuance upon conversion of exchangeable notes	1,207
	Balance at June 30, 2014	31,256,999

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income (Notes)	6 Months Ended
	Jun. 30, 2014
Accumulated Other Comprehesive Income [Abstract]	'
Accumulated Other Comprehensive Income	'
	6. ACCUMULATED OTHER COMPREHENSIVE INCOME
	The following table summarizes the activity within accumulated other comprehensive income for the six months ended June 30, 2014:
		Currency translation				Pension and other postretirement			Total
	Balance at January 1, 2014	$	45.8			$	(32.0	)	$	13.8
	Current period currency translation adjustments	(6.1		)		—			(6.1		)
	Amortization of net actuarial losses	—				0.5			0.5
	Balance at June 30, 2014	$	39.7			$	(31.5	)	$	8.2
	A summary of reclassifications out of accumulated other comprehensive income for the six months ended June 30, 2014 is provided below:
	Description of reclassifications out of accumulated other comprehensive income	Amount reclassified
	Amortization of defined benefit pension and other postretirement benefit items:
	Amortization of net actuarial losses, net of tax	$	(0.5	)	(a)
	Losses reclassified into earnings, net of tax	$	(0.5	)
	(a) This component of accumulated other comprehensive income is included in the computation of net periodic benefit expense and net postretirement benefit expense (see Note 10, “Employee Benefit Plans,” for additional detail).

Segment_Information_Notes

Segment Information (Notes)	6 Months Ended
	Jun. 30, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	7. SEGMENT INFORMATION
	We report six operating segments based on the organizational structure that is used by the chief operating decision maker to evaluate performance, make decisions on resource allocation and for which discrete financial information is available.
	The Company’s operating segments are:
	▪	Rolled Products North America (“RPNA”);
	▪	Rolled Products Europe (“RPEU”);
	▪	Rolled Products Asia Pacific (“RPAP”);
	▪	Extrusions;
	▪	Recycling and Specification Alloys North America (“RSAA”); and
	▪	Recycling and Specification Alloys Europe (“RSEU”).
	Measurement of Segment Income or Loss and Segment Assets
	The accounting policies of the reportable segments are the same as those described in the summary of significant accounting policies in the Consolidated Financial Statements for the year ended December 31, 2013. Our measure of profitability for our operating segments is referred to as segment income and loss. Segment income and loss includes gross profits, segment specific realized gains and losses on derivative financial instruments, segment specific other income and expense, segment specific selling, general and administrative (“SG&A”) expense and an allocation of certain regional and global functional SG&A expenses. Segment income and loss excludes provisions for and benefits from income taxes, restructuring items, interest, depreciation and amortization, unrealized and certain realized gains and losses on derivative financial instruments, corporate general and administrative costs, start-up expenses, gains and losses on asset sales, currency exchange gains and losses on debt and certain other gains and losses. Intersegment sales and transfers are recorded at market value. Consolidated cash, net capitalized debt costs, deferred tax assets and assets related to our headquarters offices are not allocated to the segments.
	Reportable Segment Information
	The following table shows our revenues and segment income (loss) for the periods presented in our Consolidated Statements of Comprehensive Loss:
	Three months ended June 30, 2014		RPNA			RPEU			RPAP			Extrusions			RSAA		RSEU		Intersegment Revenues			Total
	Revenues to external customers		$	418.4		$	321.3		$	9.7		$	91		$	245.7	$	140.1				$	1,226.20
	Intersegment revenues		0.7			30.9			1.6			1.6			1		7.7		$	(43.5	)	—
	Total revenues		$	419.1		$	352.2		$	11.3		$	92.6		$	246.7	$	147.8	$	(43.5	)	$	1,226.20
	Segment income		$	22.4		$	34.4		$	—		$	3.9		$	17.3	$	5.6				$	83.6
	Three months ended June 30, 2013		RPNA			RPEU			RPAP			Extrusions			RSAA		RSEU		Intersegment Revenues			Total
	Revenues to external customers		$	322.8		$	347.1		$	1.8		$	92		$	233.8	$	130.1				$	1,127.60
	Intersegment revenues		0.4			31.5			3.2			2			0.8		9.5		$	(47.4	)	—
	Total revenues		$	323.2		$	378.6		$	5		$	94		$	234.6	$	139.6	$	(47.4	)	$	1,127.60
	Segment income		$	32.7		$	39.4		$	—		$	4.5		$	13	$	3.1				$	92.7
	Six months ended June 30, 2014		RPNA			RPEU			RPAP			Extrusions			RSAA		RSEU		Intersegment Revenues			Total
	Revenues to external customers		$	679.2		$	644.5		$	16.6		$	182.4		$	479.4	$	278.3				$	2,280.40
	Intersegment revenues		1.2			62.5			4.6			3.6			2.6		12.8		$	(87.3	)	—
	Total revenues		$	680.4		$	707		$	21.2		$	186		$	482	$	291.1	$	(87.3	)	$	2,280.40
	Segment income		$	49.3		$	72.5		$	—		$	6.9		$	26.3	$	9.9				$	164.9
	Six months ended June 30, 2013		RPNA			RPEU			RPAP			Extrusions			RSAA		RSEU		Intersegment Revenues			Total
	Revenues to external customers		$	636.5		$	674		$	2.6		$	178.7		$	470	$	275.9				$	2,237.70
	Intersegment revenues		0.9			73.8			3.1			4.3			3		19.4		$	(104.5	)	—
	Total revenues		$	637.4		$	747.8		$	5.7		$	183		$	473	$	295.3	$	(104.5	)	$	2,237.70
	Segment income (loss)		$	56.2		$	77.9		$	(0.3	)	$	7.5		$	23.4	$	6.4				$	171.1
	The following table reconciles total segment income to “(Loss) income before income taxes” as reported in our Consolidated Statements of Comprehensive Loss:
			For the three months ended						For the six months ended
			June 30, 2014			June 30, 2013			June 30, 2014			June 30, 2013
	Total segment income		$	83.6		$	92.7		$	164.9		$	171.1
	Unallocated amounts:
	Depreciation and amortization		(37.5		)	(34.7		)	(70.7		)	(61.9		)
	Corporate general and administrative expenses, excluding depreciation, amortization, start-up expenses and other expenses		(18.6		)	(10.0		)	(33.6		)	(21.3		)
	Restructuring charges		(2.2		)	(9.5		)	(2.7		)	(10.3		)
	Interest expense, net		(27.0		)	(24.6		)	(53.3		)	(45.6		)
	Unallocated gains (losses) on derivative financial instruments		0.8			(10.0		)	(8.5		)	0.2
	Unallocated currency exchange gains (losses)		0.7			—			(0.8		)	—
	Start-up expenses		(7.0		)	(12.0		)	(15.4		)	(23.3		)
	Other expense, net		(2.9		)	(2.1		)	(3.0		)	(1.5		)
	(Loss) income before income taxes		$	(10.1	)	$	(10.2	)	$	(23.1	)	$	7.4
	The following table shows our reportable segment assets as of June 30, 2014 and December 31, 2013:
			June 30, 2014			December 31, 2013
	Assets
	RPNA		$	765.1		$	524.7
	RPEU		733			699.2
	RPAP		427			439.4
	Extrusions		154.1			141.8
	RSAA		316.6			294.5
	RSEU		192.1			183.7
	Unallocated assets		174.6			189.6
	Total consolidated assets		$	2,762.50		$	2,472.90

StockBased_Compensation_Notes

Stock-Based Compensation (Notes)	6 Months Ended
	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock-Based Compensation	'
	8. STOCK-BASED COMPENSATION
	On June 1, 2010, the Board of Directors of Aleris Corporation approved the Aleris Corporation 2010 Equity Incentive Plan, which has been amended from time to time (the “2010 Equity Plan”). Stock options, restricted stock units and restricted shares have been granted under the 2010 Equity Plan to certain members of management of the Company and directors. All stock options granted have a life not to exceed ten years and generally vest over a period not to exceed four years. Shares of common stock are issued upon stock option exercises from available shares. The restricted stock units and restricted shares also vest over a period not to exceed four years. A portion of the stock options, as well as a portion of the restricted stock units and restricted shares, may vest upon a change in control event should the event occur prior to full vesting of these awards, depending on the amount of vesting that has already occurred at the time of the event in comparison to the change in our largest stockholders’ overall level of beneficial ownership that results from the event.
	During the six months ended June 30, 2014, we granted 1,007,533 stock options and 342,764 restricted stock units to certain members of our management and directors. We recorded compensation expense associated with stock options, restricted stock units and restricted shares of $4.0 and $8.2 during the three and six months ended June 30, 2014, respectively, and $2.7 and $5.4 during the three and six months ended June 30, 2013, respectively.

Income_Taxes_Notes

Income Taxes (Notes)	6 Months Ended
	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	9. INCOME TAXES
	Our effective tax rates were (69.1)% and (48.9)% for the three and six months ended June 30, 2014, respectively, and (11.6)% and 102.3% for the three and six months ended June 30, 2013, respectively. The effective tax rate for the three and six months ended June 30, 2014 and 2013 differed from the federal statutory rate applied to income and losses before income taxes primarily as a result of the mix of income, losses and tax rates between tax jurisdictions and valuation allowances.
	We have valuation allowances recorded to reduce certain deferred tax assets to amounts that are more likely than not to be realized. The valuation allowances relate to the potential inability to realize our deferred tax assets associated with amortization and net operating loss carryforwards in the U.S. and depreciation and net operating loss carryforwards in non-U.S. jurisdictions. We intend to maintain our valuation allowances until sufficient positive evidence exists (such as cumulative positive earnings and estimated future taxable income) to support their reversal.
	As of June 30, 2014, we have $2.6 of unrecognized tax benefits. The majority of the gross unrecognized tax benefits, if recognized, would affect the annual effective tax rate. We recognize interest and penalties related to uncertain tax positions within the “Provision for income taxes” in the Consolidated Statements of Comprehensive Loss. As of June 30, 2014, we had approximately $0.2 of accrued interest related to uncertain tax positions.
	The 2009 through 2013 tax years remain open to examination. During the first quarter of 2013, the IRS commenced an examination of our tax returns for the years ended December 31, 2011 and 2010 that is anticipated to be completed within three months of the reporting date. During the fourth quarter of 2013, a non-U.S. taxing jurisdiction commenced an examination of our tax returns for the tax years ended December 31, 2012, 2011, 2010 and 2009 that is anticipated to be completed within six months of the reporting date.

Employee_Benefit_Plans_Notes

Employee Benefit Plans (Notes)	6 Months Ended
	Jun. 30, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]	'
Employee Benefit Plans	'
	10. EMPLOYEE BENEFIT PLANS
	Defined Benefit Pension Plans
	The components of the net periodic benefit expense are as follows:
		U.S. pension benefits
		For the three months ended						For the six months ended
		June 30, 2014			June 30, 2013			June 30, 2014			June 30, 2013
	Service cost	$	0.8		$	0.9		$	1.6		$	1.8
	Interest cost	1.8			1.6			3.6			3.2
	Amortization of net actuarial losses	—			0.4			—			0.8
	Expected return on plan assets	(2.6		)	(2.3		)	(5.2		)	(4.6		)
	Net periodic benefit expense	$	—		$	0.6		$	—		$	1.2
		Non U.S. pension benefits
		For the three months ended						For the six months ended
		30-Jun-14			30-Jun-13			30-Jun-14			30-Jun-13
	Service cost	$	1		$	1		$	1.9		$	2
	Interest cost	1.9			1.7			3.9			3.5
	Amortization of net actuarial losses	0.3			0.4			0.7			0.8
	Expected return on plan assets	—			—			(0.1		)	(0.1		)
	Net periodic benefit expense	$	3.2		$	3.1		$	6.4		$	6.2
	Other Postretirement Benefit Plans
	The components of net postretirement benefit expense are as follows:
		For the three months ended						For the six months ended
		June 30, 2014			June 30, 2013			June 30, 2014			June 30, 2013
	Service cost	$	—		$	0.1		$	0.1		$	0.1
	Interest cost	0.5			0.4			0.9			0.9
	Amortization of net actuarial (gains) losses	(0.1		)	0.1			(0.2		)	0.2
	Net postretirement benefit expense	$	0.4		$	0.6		$	0.8		$	1.2

Derivative_And_Other_Financial

Derivative And Other Financial Instruments (Notes)	6 Months Ended
	Jun. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative and Other Financial Instruments	'
	11. DERIVATIVE AND OTHER FINANCIAL INSTRUMENTS
	We use forward contracts and options, as well as contractual price escalators, to reduce the risks associated with our metal, natural gas and other supply requirements and certain currency exposures. Generally, we enter into master netting arrangements with our counterparties and offset net derivative positions with the same counterparties against amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral under those arrangements in our Consolidated Balance Sheet. For classification purposes, we record the net fair value of each type of derivative position that is expected to settle in less than one year with each counterparty as a net current asset or liability and each type of long-term position as a net long-term asset or liability. At June 30, 2014 and December 31, 2013, no cash collateral was posted. The amounts shown in the table below represent the gross amounts of recognized assets and liabilities, the amounts offset in the Consolidated Balance Sheet and the net amounts of assets and liabilities presented therein. As of June 30, 2014 and December 31, 2013, there were no amounts subject to an enforceable master netting arrangement or similar agreement that have not been offset in the Consolidated Balance Sheet.
		Fair Value of Derivatives as of
		June 30, 2014								December 31, 2013
	Derivatives by Type	Asset				Liability				Asset			Liability
	Metal	$	8.4			$	(20.4	)		$	13.3		$	(17.0	)
	Natural gas	0.3				—				0.4			—
	Total	8.7				(20.4		)		13.7			(17.0		)
	Effect of counterparty netting	(7.9		)		7.9				(12.3		)	12.3
	Net derivatives as classified in the balance sheet	$	0.8			$	(12.5	)		$	1.4		$	(4.7	)
	The fair value of our derivative financial instruments at June 30, 2014 and December 31, 2013 are recorded in the Consolidated Balance Sheet as follows:
	Asset Derivatives	Balance Sheet Location		June 30, 2014				December 31, 2013
	Metal	Prepaid expenses and other current assets		$	—			$	1
		Other long-term assets		0.5				—
	Natural gas	Prepaid expenses and other current assets		0.3				0.4
	Total			$	0.8			$	1.4
	Liability Derivatives	Balance Sheet Location		June 30, 2014				December 31, 2013
	Metal	Accrued liabilities		$	11			$	1.7
		Other long-term liabilities		1.5				3
	Total			$	12.5			$	4.7
	Derivative contracts are recorded at fair value under Financial Accounting Standards Board Accounting Standards Codification 820, “Fair Value Measurements and Disclosures,” using quoted market prices and significant other observable inputs. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy distinguishes between (1) market participant assumptions developed based on market data obtained from independent sources (observable inputs) and (2) an entity’s own assumptions about market participant assumptions developed based on the best information available in the circumstances (unobservable inputs). The fair value hierarchy consists of three broad levels, which gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). The three levels of the fair value hierarchy are described below:
	Level 1—Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.
	Level 2—Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly, including quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in markets that are not active; inputs other than quoted prices that are observable for the asset or liability (e.g., interest rates); and inputs that are derived principally from or corroborated by observable market data by correlation or other means.
	Level 3—Inputs that are both significant to the fair value measurement and unobservable.
	We endeavor to utilize the best available information in measuring fair value. Where appropriate, valuations are adjusted for various factors such as liquidity, bid/offer spreads, and credit considerations. Such adjustments are generally based on available market evidence and unobservable inputs. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables set forth our financial assets and liabilities that are accounted for at fair value on a recurring basis as of June 30, 2014 and December 31, 2013 and the level in the fair value hierarchy:
		Fair value measurements at June 30, 2014 using:
	Description	Total carrying value				Quoted prices in				Significant			Significant
		in the Consolidated				active markets for				other observable			unobservable
		Balance Sheet				identical assets				inputs (Level 2)			inputs
						(Level 1)							(Level 3)
	Derivative assets	$	8.7			$	—			$	8.7		$	—
	Derivative liabilities	(20.4		)		—				(20.4		)	—
	Net derivative liabilities	$	(11.7	)		$	—			$	(11.7	)	$	—
		Fair value measurements at December 31, 2013 using:
	Description	Total carrying value				Quoted prices in				Significant			Significant
		in the Consolidated				active markets for				other observable			unobservable
		Balance Sheet				identical assets				inputs (Level 2)			inputs
						(Level 1)							(Level 3)
	Derivative assets	$	13.7			$	—			$	13.7		$	—
	Derivative liabilities	(17.0		)		—				(17.0		)	—
	Net derivative liabilities	$	(3.3	)		$	—			$	(3.3	)	$	—
	Both realized and unrealized gains and losses on derivative financial instruments are included within “Losses (gains) on derivative financial instruments” in the Consolidated Statements of Comprehensive Loss. Realized losses (gains) on derivative financial instruments totaled the following:
		For the three months ended								For the six months ended
		June 30, 2014				June 30, 2013				June 30, 2014			June 30, 2013
	Metal	$	3.2			$	(19.6	)		$	(5.0	)	$	(18.7	)
	Natural gas	(0.5		)		(0.3		)		(2.2		)	(0.1		)
	Metal Hedging
	The selling prices of the majority of the orders for our rolled and extruded products are established at the time of order entry or, for certain customers, under long-term contracts. As the related raw materials used to produce these orders are purchased several months or years after the selling prices are fixed, margins are subject to the risk of changes in the purchase price of the raw materials used for these fixed price sales. In order to manage this transactional exposure, LME future, swaps or forward purchase contracts are purchased at the time the selling prices are fixed. As metal is purchased to fill these fixed price sales orders, LME future, swaps or forward contracts are then sold. We also maintain a significant amount of inventory on-hand to meet anticipated and unpriced future sales. In order to preserve the value of this inventory, LME future or forward contracts are sold at the time inventory is purchased. As sales orders are priced, LME future or forward contracts are purchased. These derivatives generally settle within three months. We can also buy put option contracts for managing metal price exposures. Option contracts require the payment of a premium which is recorded as a realized loss upon settlement or expiration of the option contract. Upon settlement of a put option contract, we receive cash and recognize a related gain if the LME closing price is less than the strike price of the put option. If the put option strike price is less than the LME closing price, no amount is paid and the option expires. As of June 30, 2014 and December 31, 2013, we had 0.2 metric tons and 0.2 metric tons of metal buy and sell derivative contracts, respectively.
	Natural Gas Hedging
	To manage our price exposure for natural gas purchases, we fix the future price of a portion of our natural gas requirements by entering into financial hedge agreements. Under these agreements, payments are made or received based on the differential between the monthly closing price on the New York Mercantile Exchange (“NYMEX”) and the contractual hedge price. We can also use a combination of call option contracts and put option contracts for managing the exposure to increasing prices while maintaining our ability to benefit from declining prices. Upon settlement of call option contracts, we receive cash and recognize a related gain if the NYMEX closing price exceeds the strike price of the call option. If the call option strike price exceeds the NYMEX closing price, no amount is received and the option expires unexercised. Upon settlement of a put option contract, we pay cash and recognize a related loss if the NYMEX closing price is lower than the strike price of the put option. If the put option strike price is less than the NYMEX closing price, no amount is paid and the option expires unexercised. Option contracts require the payment of a premium which is recorded as a realized loss upon settlement or expiration of the option contract. Natural gas cost can also be managed through the use of cost escalators included in some of our long-term supply contracts with customers, which limits exposure to natural gas price risk. As of June 30, 2014 and December 31, 2013, we had 0.9 trillion and 2.9 trillion of British thermal unit swap contracts, respectively.
	Currency Exchange Hedging
	From time to time, we may enter into currency forwards, futures, call options and similar derivative financial instruments to limit our exposure to fluctuations in currency exchange rates. As of June 30, 2014 and December 31, 2013, no currency derivative contracts were outstanding.
	Credit Risk
	We are exposed to losses in the event of non-performance by the counterparties to the derivative financial instruments discussed above; however, we do not anticipate any non-performance by the counterparties. The counterparties are evaluated for creditworthiness and risk assessment prior to initiating trading activities with the brokers and periodically throughout each year while actively trading.
	Other Financial Instruments
	The carrying amount and fair values of our other financial instruments at June 30, 2014 and December 31, 2013 are as follows:
		June 30, 2014								December 31, 2013
		Carrying				Fair				Carrying			Fair
		Amount				Value				Amount			Value
	Cash and cash equivalents	$	51.9			$	51.9			$	60.1		$	60.1
	ABL facility	171				171				—			—
	Exchangeable notes	44.2				72.7				44.2			72.7
	7 5/8% senior notes	494.8				518.8				494.1			530
7 7/8% senior notes	493.1				525				492.5			531.3
Zhenjiang term loans	191.1				192.1				192.2			193.2
Zhenjiang revolver	11.3				11.5				—			—
The following tables set forth our other financial instruments for which fair value is disclosed and the level in the fair value hierarchy within which the fair value measurements are categorized as of June 30, 2014 and December 31, 2013:
	Fair value measurements at June 30, 2014 using:
Description	Total estimated fair value				Quoted prices in				Significant			Significant
					active markets for				other observable			unobservable
					identical assets				inputs (Level 2)			inputs
					(Level 1)							(Level 3)
Cash and cash equivalents	$	51.9			$	51.9			$	—		$	—
ABL facility	171				—				171			—
Exchangeable notes	72.7				—				—			72.7
7 5/8% senior notes	518.8				518.8				—			—
7 7/8% senior notes	525				525				—			—
Zhenjiang term loans	192.1				—				—			192.1
Zhenjiang revolver	11.5				—				—			11.5
	Fair value measurements at December 31, 2013 using:
Description	Total estimated fair value				Quoted prices in				Significant			Significant
					active markets for				other observable			unobservable
					identical assets				inputs			inputs
					(Level 1)				(Level 2)			(Level 3)
Cash and cash equivalents	$	60.1			$	60.1			$	—		$	—
Exchangeable notes	72.7				—				—			72.7
7 5/8% senior notes	530				530				—			—
7 7/8% senior notes	531.3				531.3				—			—
Zhenjiang term loans	193.2				—				—			193.2
The principal amount of the ABL facility approximates fair value because the interest rate paid is variable and there have been no significant changes in the credit risk of Aleris International subsequent to the borrowings. The fair value of Aleris International’s exchangeable notes was estimated using a binomial lattice pricing model based on the fair value of our common stock, a risk-free interest rate of 1.9% as of June 30, 2014 and 2.3% as of December 31, 2013 and expected equity volatility of 55%. Expected equity volatility was determined based on historical stock prices and implied and stated volatilities of our peer companies. The fair values of the 7 5/8% senior notes and the 7 7/8% senior notes were estimated using market quotations. The principal amount of the Zhenjiang term loans and Zhenjiang revolver approximates fair value because the interest rate paid is variable, is set for periods of six months or less and there have been no significant changes in the credit risk of Aleris Zhenjiang subsequent to the inception of the China loan facility.

Business_Combinations_Notes

Business Combinations (Notes)	6 Months Ended
	Jun. 30, 2014
Business Combinations [Abstract]	'
Business Combinations	'
	12. BUSINESS COMBINATIONS
	On April 1, 2014, we acquired Nichols Aluminum, LLC (“Nichols”), a wholly owned subsidiary of Quanex Building Products Corporation, and a producer of aluminum sheet for the transportation, building and construction, machinery and equipment, consumer durables and electrical industries in North America for cash consideration of $110.0, less an adjustment of $2.6 based upon the net current assets delivered (the purchase price adjustment was finalized and we received the adjustment amount in cash in July 2014). The acquisition includes casting and finishing operations at two facilities in Davenport, Iowa, as well as finishing operations in Decatur, Alabama and Lincolnshire, Illinois.
	We incurred transaction related expenses totaling approximately $2.9, which were recorded in “Selling, general and administrative expenses” in the Consolidated Statements of Comprehensive Loss.
	The acquisition was accounted for as a business combination, with the purchase price allocated based on the fair values of the assets acquired and liabilities assumed. The following table presents the preliminary allocation of the Nichols acquisition purchase price. The purchase price allocation remains preliminary as management continues to evaluate the valuation of intangible assets and the environmental remediation liabilities and the related receivables associated with the acquired operations.
	Accounts receivable	$	40
	Inventories	47.8
	Property, plant and equipment	71.3
	Intangible assets	2.8
	Other assets	12.2
	Total assets acquired	174.1
	Accounts payable	46.3
	Accrued expenses and other liabilities	22.3
	Total liabilities assumed	68.6
	Net assets acquired	105.5
	Goodwill resulting from purchase	1.9
	Total consideration transferred	$	107.4
	Recognized goodwill of $1.9 is attributable to anticipated synergies with Nichols, and is deductible for tax purposes. Intangible assets include estimated amounts recognized for the fair value of customer relationships. These intangible assets have a weighted average useful life of approximately 15 years. The valuation of the intangible assets acquired was based on management’s estimates, available information, and reasonable and supportable assumptions. The fair value of these assets was estimated using the income approach.
	The liabilities assumed include $12.0 of estimated costs to perform environmental remediation at the Decatur, Alabama facility, which has been recognized based on the guidance in ASC 450, “Contingencies” and ASC 410-30, “Environmental Obligations.” Refer to Note 4, “Commitments and Contingencies,” for additional detail regarding environmental proceedings. The Company is indemnified for the costs of these remedial activities by Blue Point Capital Partners, the successor to the former owners of the Decatur facility, in an amount estimated to be $10.8 at the acquisition date, which has been recorded in “Prepaid expenses and other current assets” and “Other long-term assets” on the Consolidated Balance Sheet.
	The operating results of Nichols were reported within the RPNA segment from the date of acquisition, which includes revenues of $115.5. The pro forma effects of this acquisition would not materially impact the Company’s reported results for any period presented, and as a result no pro forma financial statements are included herein.

Condensed_Consolidating_Financ

Condensed Consolidating Financial Statements (Notes)	6 Months Ended
	Jun. 30, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]	'
Condensed Consolidating Financial Statements	'
	13. CONDENSED CONSOLIDATING FINANCIAL STATEMENTS
	On February 9, 2011 and October 23, 2012, Aleris International issued the 7 5/8% senior notes and the 7 7/8% senior notes (collectively, the “Senior Notes”), respectively. Aleris Corporation, the direct parent of Aleris International, and certain of its subsidiaries (collectively, the “Guarantor Subsidiaries”) are guarantors of the indebtedness under the Senior Notes. Aleris Corporation and each of the Guarantor Subsidiaries have fully and unconditionally guaranteed (subject, in the case of the Guarantor Subsidiaries, to customary release provisions as described below), on a joint and several basis, to pay principal and interest related to the Senior Notes and Aleris International and each of the Guarantor Subsidiaries are directly or indirectly 100% owned subsidiaries of Aleris Corporation. For purposes of complying with the reporting requirements of Aleris International and the Guarantor Subsidiaries, presented below are condensed consolidating financial statements of Aleris Corporation, Aleris International, the Guarantor Subsidiaries, and those other subsidiaries of Aleris Corporation that are not guaranteeing the indebtedness under the Senior Notes (the “Non-Guarantor Subsidiaries”). The condensed consolidating balance sheets are presented as of June 30, 2014 and December 31, 2013. The condensed consolidating statements of comprehensive (loss) income are presented for the three and six months ended June 30, 2014 and 2013. The condensed consolidating statements of cash flows are presented for the six months ended June 30, 2014 and 2013.
	The guarantee of a Guarantor Subsidiary will be automatically and unconditionally released and discharged in the event of:
	▪	any sale of the Guarantor Subsidiary or of all or substantially all of its assets;
	▪	a Guarantor Subsidiary being designated as an “unrestricted subsidiary” in accordance with the indentures governing the Senior Notes;
	▪	the release or discharge of a Guarantor Subsidiary from its guarantee under the ABL facility or other indebtedness that resulted in the obligation of the Guarantor Subsidiary under the indentures governing the Senior Notes; and
	▪	the requirements for legal defeasance or covenant defeasance or discharge of the indentures governing the Senior Notes having been satisfied.
	The condensed consolidating statement of cash flows for the six months ended June 30, 2013 has been restated to revise the presentation of cash flows related to intercompany loans. The revisions significantly changed the classification of certain intercompany cash flows as operating, investing and financing activities; however, there was no change in the total net cash flows of Aleris Corporation, Aleris International, Inc. or the Guarantor Subsidiaries. There was no impact to the condensed consolidating statements of comprehensive (loss) income or to the consolidated financial statements for the three and six months ended June 30, 2013 as a result of these presentation changes.
			As of June 30, 2014
			Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	ASSETS
	Current Assets
	Cash and cash equivalents		$	—		$	3		$	2.9		$	46		$	—		$	51.9
	Accounts receivable, net		—			0.1			197			320.5			—			517.6
	Inventories		—			—			327.9			456.7			—			784.6
	Deferred income taxes		—			—			0.2			6.9			—			7.1
	Prepaid expenses and other current assets		—			3.1			14.9			15.2			—			33.2
	Intercompany receivables		—			523.7			493.4			186			(1,203.1		)	—
	Total Current Assets		—			529.9			1,036.30			1,031.30			(1,203.1		)	1,394.40
	Property, plant and equipment, net		—			—			417			785.2			—			1,202.20
	Intangible assets, net		—			—			29.3			15.9			—			45.2
	Deferred income taxes		—			—			—			45.2			—			45.2
	Other long-term assets		—			10.4			6.1			59			—			75.5
	Intercompany receivables		—			3.8			—			—			(3.8		)	—
	Investments in subsidiaries		338.9			1,577.40			118.2			—			(2,034.5		)	—
	Total Assets		$	338.9		$	2,121.50		$	1,606.90		$	1,936.60		$	(3,241.4	)	$	2,762.50
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Current Liabilities
	Accounts payable		$	—		$	5.7		$	195.7		$	221.5		$	—		$	422.9
	Accrued liabilities		—			21.7			66.8			126.1			—			214.6
	Deferred income taxes		—			—			—			3.9			—			3.9
	Current portion of long-term debt		—			—			0.5			11			—			11.5
	Intercompany payables		—			546.4			580.6			76.1			(1,203.1		)	—
	Total Current Liabilities		—			573.8			843.6			438.6			(1,203.1		)	652.9
	Long-term debt		—			1,203.10			0.6			207.6			—			1,411.30
	Deferred income taxes		—			—			0.2			6.5			—			6.7
	Accrued pension benefits		—			—			29			195			—			224
	Accrued postretirement benefits		—			—			40.5			—			—			40.5
	Other long-term liabilities		—			—			32.9			52.7			—			85.6
	Intercompany payables		3.8			—			—			—			(3.8		)	—
	Total Long-Term Liabilities		3.8			1,203.10			103.2			461.8			(3.8		)	1,768.10
	Redeemable noncontrolling interest		—			5.7			—			—			—			5.7
	Total equity		335.1			338.9			660.1			1,035.50			(2,034.5		)	335.1
	Noncontrolling interest		—			—			—			0.7			—			0.7
	Total Liabilities and Equity		$	338.9		$	2,121.50		$	1,606.90		$	1,936.60		$	(3,241.4	)	$	2,762.50
			As of December 31, 2013
			Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	ASSETS
	Current Assets
	Cash and cash equivalents		$	—		$	3.7		$	—		$	58.9		$	(2.5	)	$	60.1
	Accounts receivable, net		—			—			125.7			251.2			—			376.9
	Inventories		—			—			245.1			438.3			—			683.4
	Deferred income taxes		—			—			0.2			6.9			—			7.1
	Prepaid expenses and other current assets		—			0.5			16.1			14.9			—			31.5
	Intercompany receivables		—			362.4			378.3			192.4			(933.1		)	—
	Total Current Assets		—			366.6			765.4			962.6			(935.6		)	1,159.00
	Property, plant and equipment, net		—			—			377.8			779.9			—			1,157.70
	Intangible assets, net		—			—			27.6			15.9			—			43.5
	Deferred income taxes		—			—			—			45.2			—			45.2
	Other long-term assets		—			12.3			3.3			51.9			—			67.5
	Intercompany receivables		—			3.4			—			—			(3.4		)	—
	Investments in subsidiaries		371.8			1,510.60			117.7			—			(2,000.1		)	—
	Total Assets		$	371.8		$	1,892.90		$	1,291.80		$	1,855.50		$	(2,939.1	)	$	2,472.90
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities
Accounts payable		$	—		$	0.4		$	117.1		$	188.2		$	(2.5	)	$	303.2
Accrued liabilities		—			21.7			67			112.2			—			200.9
Deferred income taxes		—			—			—			3.9			—			3.9
Current portion of long-term debt		—			—			0.5			7.8			—			8.3
Intercompany payables		—			462.4			371.7			99			(933.1		)	—
Total Current Liabilities		—			484.5			556.3			411.1			(935.6		)	516.3
Long-term debt		—			1,030.90			0.8			197.4			—			1,229.10
Deferred income taxes		—			—			0.2			4.2			—			4.4
Accrued pension benefits		—			—			33.8			194.7			—			228.5
Accrued postretirement benefits		—			—			40.9			—			—			40.9
Other long-term liabilities		—			—			32.7			46.6			—			79.3
Intercompany payables		3.4			—			—			—			(3.4		)	—
Total Long-Term Liabilities		3.4			1,030.90			108.4			442.9			(3.4		)	1,582.20
Redeemable noncontrolling interest		—			5.7			—			—			—			5.7
Total equity		368.4			371.8			627.1			1,001.20			(2,000.1		)	368.4
Noncontrolling interest		—			—			—			0.3			—			0.3
Total Liabilities and Equity		$	371.8		$	1,892.90		$	1,291.80		$	1,855.50		$	(2,939.1	)	$	2,472.90
		For the three months ended June 30, 2014
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues		$	—		$	—		$	610.1		$	649.6		$	(33.5	)	$	1,226.20
Cost of sales		—			—			573.7			594			(33.5		)	1,134.20
Gross profit		—			—			36.4			55.6			—			92
Selling, general and administrative expenses		—			0.1			35.2			33.6			—			68.9
Restructuring charges		—			—			0.1			2.1			—			2.2
Losses (gains) on derivative financial instruments		—			—			1.9			(0.1		)	—			1.8
Other operating expense, net		—			—			0.2			2.4			—			2.6
Operating (loss) income		—			(0.1		)	(1.0		)	17.6			—			16.5
Interest expense, net		—			—			23.1			3.9			—			27
Other (income) expense, net		—			—			(1.7		)	1.3			—			(0.4		)
Equity in net loss (earnings) of affiliates		17.5			17.4			(0.6		)	—			(34.3		)	—
(Loss) income before income taxes		(17.5		)	(17.5		)	(21.8		)	12.4			34.3			(10.1		)
Provision for income taxes		—			—			—			7			—			7
Net (loss) income		(17.5		)	(17.5		)	(21.8		)	5.4			34.3			(17.1		)
Net income attributable to noncontrolling interest		—			—			—			0.4			—			0.4
Net (loss) income attributable to Aleris Corporation		$	(17.5	)	$	(17.5	)	$	(21.8	)	$	5		$	34.3		$	(17.5	)
Comprehensive (loss) income		$	(21.1	)	$	(21.1	)	$	(21.8	)	$	2		$	41.3		$	(20.7	)
Comprehensive income attributable to noncontrolling interest		—			—			—			0.4			—			0.4
Comprehensive (loss) income attributable to Aleris Corporation		$	(21.1	)	$	(21.1	)	$	(21.8	)	$	1.6		$	41.3		$	(21.1	)
		For the six months ended June 30, 2014
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues		$	—		$	—		$	1,049.80		$	1,267.10		$	(36.5	)	$	2,280.40
Cost of sales		—			—			990.6			1,159.20			(36.5		)	2,113.30
Gross profit		—			—			59.2			107.9			—			167.1
Selling, general and administrative expenses		—			0.1			65.5			65.3			—			130.9
Restructuring charges		—			—			0.7			2			—			2.7
(Gains) losses on derivative financial instruments		—			—			(1.8		)	3.1			—			1.3
Other operating expense, net		—			—			0.7			2.1			—			2.8
Operating (loss) income		—			(0.1		)	(5.9		)	35.4			—			29.4
Interest expense, net		—			—			45.4			7.9			—			53.3
Other (income) expense, net		—			—			(5.4		)	4.6			—			(0.8		)
Equity in net loss (earnings) of affiliates		35.1			35			(1.2		)	—			(68.9		)	—
(Loss) income before income taxes		(35.1		)	(35.1		)	(44.7		)	22.9			68.9			(23.1		)
Provision for income taxes		—			—			—			11.3			—			11.3
Net (loss) income		(35.1		)	(35.1		)	(44.7		)	11.6			68.9			(34.4		)
Net income attributable to noncontrolling interest		—			—			—			0.7			—			0.7
Net (loss) income attributable to Aleris Corporation		$	(35.1	)	$	(35.1	)	$	(44.7	)	$	10.9		$	68.9		$	(35.1	)
Comprehensive (loss) income		$	(40.7	)	$	(40.7	)	$	(44.8	)	$	6.1		$	80.1		$	(40.0	)
Comprehensive income attributable to noncontrolling interest		—			—			—			0.7			—			0.7
Comprehensive (loss) income attributable to Aleris Corporation		$	(40.7	)	$	(40.7	)	$	(44.8	)	$	5.4		$	80.1		$	(40.7	)
		For the three months ended June 30, 2013
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues		$	—		$	—		$	510.4		$	619.7		$	(2.5	)	$	1,127.60
Cost of sales		—			—			483.8			572.1			(2.5		)	1,053.40
Gross profit		—			—			26.6			47.6			—			74.2
Selling, general and administrative expenses		—			0.1			24.1			34.3			—			58.5
Restructuring charges		—			—			1.1			8.4			—			9.5
Gains on derivative financial instruments		—			—			(5.2		)	(4.7		)	—			(9.9		)
Other operating expense, net		—			—			0.3			0.1			—			0.4
Operating (loss) income		—			(0.1		)	6.3			9.5			—			15.7
Interest expense, net		—			—			21.9			2.7			—			24.6
Other (income) expense, net		—			—			(0.3		)	1.6			—			1.3
Equity in net loss (earnings) of affiliates		11.7			11.6			(0.5		)	—			(22.8		)	—
(Loss) income before income taxes		(11.7		)	(11.7		)	(14.8		)	5.2			22.8			(10.2		)
Provision for income taxes		—			—			—			1.2			—			1.2
Net (loss) income		(11.7		)	(11.7		)	(14.8		)	4			22.8			(11.4		)
Net income attributable to noncontrolling interest		—			—			—			0.3			—			0.3
Net income attributable to Aleris Corporation		$	(11.7	)	$	(11.7	)	$	(14.8	)	$	3.7		$	22.8		$	(11.7	)
Comprehensive (loss) income		$	(0.5	)	$	(0.5	)	$	(14.5	)	$	14.7		$	0.6		$	(0.2	)
Comprehensive income attributable to noncontrolling interest		—			—			—			0.3			—			0.3
Comprehensive (loss) income attributable to Aleris Corporation		$	(0.5	)	$	(0.5	)	$	(14.5	)	$	14.4		$	0.6		$	(0.5	)
		For the six months ended June 30, 2013
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues		$	—		$	—		$	1,018.30		$	1,223.60		$	(4.2	)	$	2,237.70
Cost of sales		—			—			959.2			1,119.50			(4.2		)	2,074.50
Gross profit		—			—			59.1			104.1			—			163.2
Selling, general and administrative expenses		—			0.1			52			67.9			—			120
Restructuring charges		—			—			2.2			8.1			—			10.3
Gains on derivative financial instruments		—			—			(13.8		)	(5.3		)	—			(19.1		)
Other operating expense (income), net		—			—			0.4			(0.8		)	—			(0.4		)
Operating (loss) income		—			(0.1		)	18.3			34.2			—			52.4
Interest expense (income), net		—			—			44			1.6			—			45.6
Other (income) expense, net		—			—			(1.1		)	0.5			—			(0.6		)
Equity in net loss (earnings) of affiliates		0.8			0.7			(1.0		)	—			(0.5		)	—
(Loss) income before income taxes		(0.8		)	(0.8		)	(23.6		)	32.1			0.5			7.4
Provision for income taxes		—			—			—			7.6			—			7.6
Net (loss) income		(0.8		)	(0.8		)	(23.6		)	24.5			0.5			(0.2		)
Net income attributable to noncontrolling interest		—			—			—			0.6			—			0.6
Net income (loss) attributable to Aleris Corporation		$	(0.8	)	$	(0.8	)	$	(23.6	)	$	23.9		$	0.5		$	(0.8	)
Comprehensive (loss) income		$	(6.2	)	$	(6.2	)	$	(22.3	)	$	18		$	11.1		$	(5.6	)
Comprehensive income attributable to noncontrolling interest		—			—			—			0.6			—			0.6
Comprehensive (loss) income attributable to Aleris Corporation		$	(6.2	)	$	(6.2	)	$	(22.3	)	$	17.4		$	11.1		$	(6.2	)
		For the six months ended June 30, 2014
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net cash provided (used) by operating activities		$	0.4		$	(81.4	)	$	36.4		$	35.5		$	1.8		$	(7.3	)
Investing activities
Payments for property, plant and equipment		—			—			(32.2		)	(46.2		)	—			(78.4		)
Purchase of a business		—			(2.6		)	(77.8		)	(29.6		)	—			(110.0		)
Disbursements of intercompany loans		—			(15.0		)	(10.4		)	(45.0		)	70.4			—
Repayments from intercompany loans		—			5			9.5			15			(29.5		)	—
Equity contributions in subsidiaries		—			(107.4		)	—			—			107.4			—
Other		—			—			(0.1		)	6			—			5.9
Net cash used by investing activities		—			(120.0		)	(111.0		)	(99.8		)	148.3			(182.5		)
Financing activities
Proceeds from the ABL facility		—			225			—			15			—			240
Payments on the ABL facility		—			(54.0		)	—			(15.0		)	—			(69.0		)
Proceeds from Zhenjiang revolver		—			—			—			11.5			—			11.5
Net (payments on) proceeds from other long-term debt		—			—			(0.3		)	0.9			—			0.6
Dividend paid		—			—			—			(0.7		)	0.7			—
Proceeds from intercompany loans		—			45			—			25.4			(70.4		)	—
Repayments on intercompany loans		—			(15.0		)	—			(14.5		)	29.5			—
Proceeds from intercompany equity contributions		—			—			77.8			29.6			(107.4		)	—
Other		(0.4		)	(0.3		)	—			(0.3		)	—			(1.0		)
Net cash (used) provided by financing activities		(0.4		)	200.7			77.5			51.9			(147.6		)	182.1
Effect of exchange rate differences on cash and cash equivalents		—			—			—			(0.5		)	—			(0.5		)
Net (decrease) increase in cash and cash equivalents		—			(0.7		)	2.9			(12.9		)	2.5			(8.2		)
Cash and cash equivalents at beginning of period		—			3.7			—			58.9			(2.5		)	60.1
Cash and cash equivalents at end of period		$	—		$	3		$	2.9		$	46		$	—		$	51.9
		For the six months ended June 30, 2013
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net cash provided (used) by operating activities		$	315.6		$	(52.0	)	$	58.8		$	(59.2	)	$	(314.0	)	$	(50.8	)
Investing activities
Payments for property, plant and equipment		—			—			(33.8		)	(108.4		)	—			(142.2		)
Disbursements of intercompany loans		—			(30.0		)	(44.4		)	—			74.4			—
Repayments from intercompany loans		—			8			19.4			—			(27.4		)	—
Equity contributions in subsidiaries		—			(81.9		)	(4.2		)	—			86.1			—
Other		—			—			—			1.6			—			1.6
Net cash used by investing activities		—			(103.9		)	(63.0		)	(106.8		)	133.1			(140.6		)
Financing activities
Proceeds from Zhenjiang term loans		—			—			—			0.2			—			0.2
Proceeds from Zhenjiang revolver		—			—			—			4.1			—			4.1
Net proceeds from other long-term debt		—			—			—			(1.8		)	—			(1.8		)
Redemption of noncontrolling interest		—			—			—			(8.9		)	—			(8.9		)
Dividends paid		(313.0		)	(313.0		)	—			(0.7		)	313.7			(313.0		)
Proceeds from intercompany loans		—			—			—			74.4			(74.4		)	—
Repayments on intercompany loans		—			—			—			(27.4		)	27.4			—
Proceeds from intercompany equity contributions		—			—			4.2			81.9			(86.1		)	—
Other		(2.6		)	(0.2		)	—			(0.3		)	—			(3.1		)
Net cash (used) provided by financing activities		(315.6		)	(313.2		)	4.2			121.5			180.6			(322.5		)
Effect of exchange rate differences on cash and cash equivalents		—			—			—			(0.5		)	—			(0.5		)
Net decrease in cash and cash equivalents		—			(469.1		)	—			(45.0		)	(0.3		)	(514.4		)
Cash and cash equivalents at beginning of period		—			472.4			—			121.6			(1.1		)	592.9
Cash and cash equivalents at end of period		$	—		$	3.3		$	—		$	76.6		$	(1.4	)	$	78.5

Basis_Of_Presentation_Policies

Basis Of Presentation (Policies)	6 Months Ended
	Jun. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Basis of Presentation	'
	The accompanying unaudited Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles for interim financial information. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles in the United States for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included.

Inventories_Tables

Inventories (Tables)	6 Months Ended
	Jun. 30, 2014
Inventory Disclosure [Abstract]	'
Schedule of Inventory, Current	'
	The components of our “Inventories” as of June 30, 2014 and December 31, 2013 are as follows:
		June 30, 2014		December 31, 2013
	Raw materials	$	275.8	$	265.9
	Work in process	261.7		203
	Finished goods	206.1		185.6
	Supplies	41		28.9
	Total inventories	$	784.6	$	683.4

LongTerm_Debt_Tables

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Schedule of Debt	'
	Our debt as of June 30, 2014 and December 31, 2013 is summarized as follows:
		June 30, 2014		December 31, 2013
	ABL facility	$	171	$	—
	7 5/8% senior notes due 2018, net of discount of $5.2 and $5.9 at June 30, 2014 and December 31, 2013, respectively	494.8		494.1
	7 7/8% senior notes due 2020, net of discount of $6.9 and $7.5 at June 30, 2014 and December 31, 2013, respectively	493.1		492.5
	Exchangeable notes, net of discount of $0.6 and $0.7 at June 30, 2014 and December 31, 2013, respectively	44.2		44.2
	Zhenjiang term loans, net of discount of $1.0 at June 30, 2014 and December 31, 2013, respectively	191.1		192.2
	Zhenjiang revolver, net of discount of $0.2 at June 30, 2014	11.3		—
	Other	17.3		14.4
	Total debt	1,422.80		1,237.40
	Less: Current portion of long-term debt	11.5		8.3
	Total long-term debt	$	1,411.30	$	1,229.10

Stockholders_Equity_and_Redeem1

Stockholders' Equity and Redeemable Noncontrolling Interest (Tables)	6 Months Ended
	Jun. 30, 2014
Stockholders' Equity Note [Abstract]	'
Schedule of Stockholders Equity	'
	The following table summarizes the activity within stockholders’ equity and redeemable noncontrolling interest for the six months ended June 30, 2014:
		Aleris Corporation equity			Noncontrolling interest			Total equity			Redeemable noncontrolling interest
	Total equity at January 1, 2014	$	368.4		$	0.3		$	368.7		$	5.7
	Net (loss) income	(35.1		)	0.7			(34.4		)	—
	Other comprehensive loss	(5.6		)	—			(5.6		)	—
	Stock-based compensation activity	7.6			—			7.6			—
	Other	(0.2		)	(0.3		)	(0.5		)	—
	Total equity at June 30, 2014	$	335.1		$	0.7		$	335.8		$	5.7
Changes in the Number of Outstanding Common Shares	'
	The following table shows changes in the number of our outstanding shares of common stock:
		Outstanding shares of common stock
	Balance at January 1, 2014	31,229,064
	Issuance associated with options exercised	3,434
	Issuance associated with vested restricted stock units	23,294
	Issuance upon conversion of exchangeable notes	1,207
	Balance at June 30, 2014	31,256,999

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2014
Accumulated Other Comprehesive Income [Abstract]	'
Schedule of Accumulated Other Comprehensive Income	'
	The following table summarizes the activity within accumulated other comprehensive income for the six months ended June 30, 2014:
		Currency translation				Pension and other postretirement			Total
	Balance at January 1, 2014	$	45.8			$	(32.0	)	$	13.8
	Current period currency translation adjustments	(6.1		)		—			(6.1		)
	Amortization of net actuarial losses	—				0.5			0.5
	Balance at June 30, 2014	$	39.7			$	(31.5	)	$	8.2
Schedule of Amounts Recognized in Other Comprehensive Income	'
	A summary of reclassifications out of accumulated other comprehensive income for the six months ended June 30, 2014 is provided below:
	Description of reclassifications out of accumulated other comprehensive income	Amount reclassified
	Amortization of defined benefit pension and other postretirement benefit items:
	Amortization of net actuarial losses, net of tax	$	(0.5	)	(a)
	Losses reclassified into earnings, net of tax	$	(0.5	)
	(a) This component of accumulated other comprehensive income is included in the computation of net periodic benefit expense and net postretirement benefit expense (see Note 10, “Employee Benefit Plans,” for additional detail).

Segment_Information_Tables

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2014
Segment Reporting [Abstract]	'
Reconciliation of Revenue from Segments to Consolidated	'
	The following table shows our revenues and segment income (loss) for the periods presented in our Consolidated Statements of Comprehensive Loss:
	Three months ended June 30, 2014	RPNA			RPEU			RPAP			Extrusions			RSAA		RSEU		Intersegment Revenues			Total
	Revenues to external customers	$	418.4		$	321.3		$	9.7		$	91		$	245.7	$	140.1				$	1,226.20
	Intersegment revenues	0.7			30.9			1.6			1.6			1		7.7		$	(43.5	)	—
	Total revenues	$	419.1		$	352.2		$	11.3		$	92.6		$	246.7	$	147.8	$	(43.5	)	$	1,226.20
	Segment income	$	22.4		$	34.4		$	—		$	3.9		$	17.3	$	5.6				$	83.6
	Three months ended June 30, 2013	RPNA			RPEU			RPAP			Extrusions			RSAA		RSEU		Intersegment Revenues			Total
	Revenues to external customers	$	322.8		$	347.1		$	1.8		$	92		$	233.8	$	130.1				$	1,127.60
	Intersegment revenues	0.4			31.5			3.2			2			0.8		9.5		$	(47.4	)	—
	Total revenues	$	323.2		$	378.6		$	5		$	94		$	234.6	$	139.6	$	(47.4	)	$	1,127.60
	Segment income	$	32.7		$	39.4		$	—		$	4.5		$	13	$	3.1				$	92.7
	Six months ended June 30, 2014	RPNA			RPEU			RPAP			Extrusions			RSAA		RSEU		Intersegment Revenues			Total
	Revenues to external customers	$	679.2		$	644.5		$	16.6		$	182.4		$	479.4	$	278.3				$	2,280.40
	Intersegment revenues	1.2			62.5			4.6			3.6			2.6		12.8		$	(87.3	)	—
	Total revenues	$	680.4		$	707		$	21.2		$	186		$	482	$	291.1	$	(87.3	)	$	2,280.40
	Segment income	$	49.3		$	72.5		$	—		$	6.9		$	26.3	$	9.9				$	164.9
	Six months ended June 30, 2013	RPNA			RPEU			RPAP			Extrusions			RSAA		RSEU		Intersegment Revenues			Total
	Revenues to external customers	$	636.5		$	674		$	2.6		$	178.7		$	470	$	275.9				$	2,237.70
	Intersegment revenues	0.9			73.8			3.1			4.3			3		19.4		$	(104.5	)	—
	Total revenues	$	637.4		$	747.8		$	5.7		$	183		$	473	$	295.3	$	(104.5	)	$	2,237.70
	Segment income (loss)	$	56.2		$	77.9		$	(0.3	)	$	7.5		$	23.4	$	6.4				$	171.1
Schedule of Segment Reporting Information, by Segment	'
	The following table reconciles total segment income to “(Loss) income before income taxes” as reported in our Consolidated Statements of Comprehensive Loss:
		For the three months ended						For the six months ended
		June 30, 2014			June 30, 2013			June 30, 2014			June 30, 2013
	Total segment income	$	83.6		$	92.7		$	164.9		$	171.1
	Unallocated amounts:
	Depreciation and amortization	(37.5		)	(34.7		)	(70.7		)	(61.9		)
	Corporate general and administrative expenses, excluding depreciation, amortization, start-up expenses and other expenses	(18.6		)	(10.0		)	(33.6		)	(21.3		)
	Restructuring charges	(2.2		)	(9.5		)	(2.7		)	(10.3		)
	Interest expense, net	(27.0		)	(24.6		)	(53.3		)	(45.6		)
	Unallocated gains (losses) on derivative financial instruments	0.8			(10.0		)	(8.5		)	0.2
	Unallocated currency exchange gains (losses)	0.7			—			(0.8		)	—
	Start-up expenses	(7.0		)	(12.0		)	(15.4		)	(23.3		)
	Other expense, net	(2.9		)	(2.1		)	(3.0		)	(1.5		)
	(Loss) income before income taxes	$	(10.1	)	$	(10.2	)	$	(23.1	)	$	7.4
Reconciliation of Assets from Segment to Consolidated	'
	The following table shows our reportable segment assets as of June 30, 2014 and December 31, 2013:
		June 30, 2014			December 31, 2013
	Assets
	RPNA	$	765.1		$	524.7
	RPEU	733			699.2
	RPAP	427			439.4
	Extrusions	154.1			141.8
	RSAA	316.6			294.5
	RSEU	192.1			183.7
	Unallocated assets	174.6			189.6
	Total consolidated assets	$	2,762.50		$	2,472.90

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]	'
Schedule of Net Benefit Costs	'
	Defined Benefit Pension Plans
	The components of the net periodic benefit expense are as follows:
		U.S. pension benefits
		For the three months ended						For the six months ended
		June 30, 2014			June 30, 2013			June 30, 2014			June 30, 2013
	Service cost	$	0.8		$	0.9		$	1.6		$	1.8
	Interest cost	1.8			1.6			3.6			3.2
	Amortization of net actuarial losses	—			0.4			—			0.8
	Expected return on plan assets	(2.6		)	(2.3		)	(5.2		)	(4.6		)
	Net periodic benefit expense	$	—		$	0.6		$	—		$	1.2
		Non U.S. pension benefits
		For the three months ended						For the six months ended
		30-Jun-14			30-Jun-13			30-Jun-14			30-Jun-13
	Service cost	$	1		$	1		$	1.9		$	2
	Interest cost	1.9			1.7			3.9			3.5
	Amortization of net actuarial losses	0.3			0.4			0.7			0.8
	Expected return on plan assets	—			—			(0.1		)	(0.1		)
	Net periodic benefit expense	$	3.2		$	3.1		$	6.4		$	6.2
	Other Postretirement Benefit Plans
	The components of net postretirement benefit expense are as follows:
		For the three months ended						For the six months ended
		June 30, 2014			June 30, 2013			June 30, 2014			June 30, 2013
	Service cost	$	—		$	0.1		$	0.1		$	0.1
	Interest cost	0.5			0.4			0.9			0.9
	Amortization of net actuarial (gains) losses	(0.1		)	0.1			(0.2		)	0.2
	Net postretirement benefit expense	$	0.4		$	0.6		$	0.8		$	1.2

Derivative_And_Other_Financial1

Derivative And Other Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of Derivative Instruments	'
	The amounts shown in the table below represent the gross amounts of recognized assets and liabilities, the amounts offset in the Consolidated Balance Sheet and the net amounts of assets and liabilities presented therein. As of June 30, 2014 and December 31, 2013, there were no amounts subject to an enforceable master netting arrangement or similar agreement that have not been offset in the Consolidated Balance Sheet.
		Fair Value of Derivatives as of
		June 30, 2014								December 31, 2013
	Derivatives by Type	Asset				Liability				Asset			Liability
	Metal	$	8.4			$	(20.4	)		$	13.3		$	(17.0	)
	Natural gas	0.3				—				0.4			—
	Total	8.7				(20.4		)		13.7			(17.0		)
	Effect of counterparty netting	(7.9		)		7.9				(12.3		)	12.3
	Net derivatives as classified in the balance sheet	$	0.8			$	(12.5	)		$	1.4		$	(4.7	)
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	'
	The fair value of our derivative financial instruments at June 30, 2014 and December 31, 2013 are recorded in the Consolidated Balance Sheet as follows:
	Asset Derivatives	Balance Sheet Location		June 30, 2014				December 31, 2013
	Metal	Prepaid expenses and other current assets		$	—			$	1
		Other long-term assets		0.5				—
	Natural gas	Prepaid expenses and other current assets		0.3				0.4
	Total			$	0.8			$	1.4
	Liability Derivatives	Balance Sheet Location		June 30, 2014				December 31, 2013
	Metal	Accrued liabilities		$	11			$	1.7
		Other long-term liabilities		1.5				3
	Total			$	12.5			$	4.7
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	'
	The carrying amount and fair values of our other financial instruments at June 30, 2014 and December 31, 2013 are as follows:
		June 30, 2014								December 31, 2013
		Carrying				Fair				Carrying			Fair
		Amount				Value				Amount			Value
	Cash and cash equivalents	$	51.9			$	51.9			$	60.1		$	60.1
	ABL facility	171				171				—			—
	Exchangeable notes	44.2				72.7				44.2			72.7
	7 5/8% senior notes	494.8				518.8				494.1			530
	7 7/8% senior notes	493.1				525				492.5			531.3
	Zhenjiang term loans	191.1				192.1				192.2			193.2
	Zhenjiang revolver	11.3				11.5				—			—
	The following tables set forth our financial assets and liabilities that are accounted for at fair value on a recurring basis as of June 30, 2014 and December 31, 2013 and the level in the fair value hierarchy:
		Fair value measurements at June 30, 2014 using:
	Description	Total carrying value				Quoted prices in				Significant			Significant
		in the Consolidated				active markets for				other observable			unobservable
		Balance Sheet				identical assets				inputs (Level 2)			inputs
						(Level 1)							(Level 3)
	Derivative assets	$	8.7			$	—			$	8.7		$	—
	Derivative liabilities	(20.4		)		—				(20.4		)	—
	Net derivative liabilities	$	(11.7	)		$	—			$	(11.7	)	$	—
		Fair value measurements at December 31, 2013 using:
	Description	Total carrying value				Quoted prices in				Significant			Significant
		in the Consolidated				active markets for				other observable			unobservable
		Balance Sheet				identical assets				inputs (Level 2)			inputs
						(Level 1)							(Level 3)
	Derivative assets	$	13.7			$	—			$	13.7		$	—
	Derivative liabilities	(17.0		)		—				(17.0		)	—
	Net derivative liabilities	$	(3.3	)		$	—			$	(3.3	)	$	—
	The following tables set forth our other financial instruments for which fair value is disclosed and the level in the fair value hierarchy within which the fair value measurements are categorized as of June 30, 2014 and December 31, 2013:
		Fair value measurements at June 30, 2014 using:
	Description	Total estimated fair value				Quoted prices in				Significant			Significant
						active markets for				other observable			unobservable
						identical assets				inputs (Level 2)			inputs
						(Level 1)							(Level 3)
	Cash and cash equivalents	$	51.9			$	51.9			$	—		$	—
	ABL facility	171				—				171			—
	Exchangeable notes	72.7				—				—			72.7
	7 5/8% senior notes	518.8				518.8				—			—
	7 7/8% senior notes	525				525				—			—
	Zhenjiang term loans	192.1				—				—			192.1
	Zhenjiang revolver	11.5				—				—			11.5
		Fair value measurements at December 31, 2013 using:
	Description	Total estimated fair value				Quoted prices in				Significant			Significant
						active markets for				other observable			unobservable
						identical assets				inputs			inputs
						(Level 1)				(Level 2)			(Level 3)
	Cash and cash equivalents	$	60.1			$	60.1			$	—		$	—
	Exchangeable notes	72.7				—				—			72.7
	7 5/8% senior notes	530				530				—			—
	7 7/8% senior notes	531.3				531.3				—			—
	Zhenjiang term loans	193.2				—				—			193.2
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	'
	Realized losses (gains) on derivative financial instruments totaled the following:
		For the three months ended								For the six months ended
		June 30, 2014				June 30, 2013				June 30, 2014			June 30, 2013
	Metal	$	3.2			$	(19.6	)		$	(5.0	)	$	(18.7	)
	Natural gas	(0.5		)		(0.3		)		(2.2		)	(0.1		)

Business_Combinations_Tables

Business Combinations (Tables)	6 Months Ended
	Jun. 30, 2014
Business Combinations [Abstract]	'
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	'
	Accounts receivable	$	40
	Inventories	47.8
	Property, plant and equipment	71.3
	Intangible assets	2.8
	Other assets	12.2
	Total assets acquired	174.1
	Accounts payable	46.3
	Accrued expenses and other liabilities	22.3
	Total liabilities assumed	68.6
	Net assets acquired	105.5
	Goodwill resulting from purchase	1.9
	Total consideration transferred	$	107.4

Condensed_Consolidating_Financ1

Condensed Consolidating Financial Statements (Tables)	6 Months Ended
	Jun. 30, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]	'
Schedule of Condensed Balance Sheet	'
		As of June 30, 2014
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	ASSETS
	Current Assets
	Cash and cash equivalents	$	—		$	3		$	2.9		$	46		$	—		$	51.9
	Accounts receivable, net	—			0.1			197			320.5			—			517.6
	Inventories	—			—			327.9			456.7			—			784.6
	Deferred income taxes	—			—			0.2			6.9			—			7.1
	Prepaid expenses and other current assets	—			3.1			14.9			15.2			—			33.2
	Intercompany receivables	—			523.7			493.4			186			(1,203.1		)	—
	Total Current Assets	—			529.9			1,036.30			1,031.30			(1,203.1		)	1,394.40
	Property, plant and equipment, net	—			—			417			785.2			—			1,202.20
	Intangible assets, net	—			—			29.3			15.9			—			45.2
	Deferred income taxes	—			—			—			45.2			—			45.2
	Other long-term assets	—			10.4			6.1			59			—			75.5
	Intercompany receivables	—			3.8			—			—			(3.8		)	—
	Investments in subsidiaries	338.9			1,577.40			118.2			—			(2,034.5		)	—
	Total Assets	$	338.9		$	2,121.50		$	1,606.90		$	1,936.60		$	(3,241.4	)	$	2,762.50
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Current Liabilities
	Accounts payable	$	—		$	5.7		$	195.7		$	221.5		$	—		$	422.9
	Accrued liabilities	—			21.7			66.8			126.1			—			214.6
	Deferred income taxes	—			—			—			3.9			—			3.9
	Current portion of long-term debt	—			—			0.5			11			—			11.5
	Intercompany payables	—			546.4			580.6			76.1			(1,203.1		)	—
	Total Current Liabilities	—			573.8			843.6			438.6			(1,203.1		)	652.9
	Long-term debt	—			1,203.10			0.6			207.6			—			1,411.30
	Deferred income taxes	—			—			0.2			6.5			—			6.7
	Accrued pension benefits	—			—			29			195			—			224
	Accrued postretirement benefits	—			—			40.5			—			—			40.5
	Other long-term liabilities	—			—			32.9			52.7			—			85.6
	Intercompany payables	3.8			—			—			—			(3.8		)	—
	Total Long-Term Liabilities	3.8			1,203.10			103.2			461.8			(3.8		)	1,768.10
	Redeemable noncontrolling interest	—			5.7			—			—			—			5.7
	Total equity	335.1			338.9			660.1			1,035.50			(2,034.5		)	335.1
	Noncontrolling interest	—			—			—			0.7			—			0.7
	Total Liabilities and Equity	$	338.9		$	2,121.50		$	1,606.90		$	1,936.60		$	(3,241.4	)	$	2,762.50
		As of December 31, 2013
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	ASSETS
	Current Assets
	Cash and cash equivalents	$	—		$	3.7		$	—		$	58.9		$	(2.5	)	$	60.1
	Accounts receivable, net	—			—			125.7			251.2			—			376.9
	Inventories	—			—			245.1			438.3			—			683.4
	Deferred income taxes	—			—			0.2			6.9			—			7.1
	Prepaid expenses and other current assets	—			0.5			16.1			14.9			—			31.5
	Intercompany receivables	—			362.4			378.3			192.4			(933.1		)	—
	Total Current Assets	—			366.6			765.4			962.6			(935.6		)	1,159.00
	Property, plant and equipment, net	—			—			377.8			779.9			—			1,157.70
	Intangible assets, net	—			—			27.6			15.9			—			43.5
	Deferred income taxes	—			—			—			45.2			—			45.2
	Other long-term assets	—			12.3			3.3			51.9			—			67.5
	Intercompany receivables	—			3.4			—			—			(3.4		)	—
	Investments in subsidiaries	371.8			1,510.60			117.7			—			(2,000.1		)	—
	Total Assets	$	371.8		$	1,892.90		$	1,291.80		$	1,855.50		$	(2,939.1	)	$	2,472.90
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Current Liabilities
	Accounts payable	$	—		$	0.4		$	117.1		$	188.2		$	(2.5	)	$	303.2
	Accrued liabilities	—			21.7			67			112.2			—			200.9
	Deferred income taxes	—			—			—			3.9			—			3.9
	Current portion of long-term debt	—			—			0.5			7.8			—			8.3
	Intercompany payables	—			462.4			371.7			99			(933.1		)	—
	Total Current Liabilities	—			484.5			556.3			411.1			(935.6		)	516.3
Long-term debt	—			1,030.90			0.8			197.4			—			1,229.10
Deferred income taxes	—			—			0.2			4.2			—			4.4
Accrued pension benefits	—			—			33.8			194.7			—			228.5
Accrued postretirement benefits	—			—			40.9			—			—			40.9
Other long-term liabilities	—			—			32.7			46.6			—			79.3
Intercompany payables	3.4			—			—			—			(3.4		)	—
Total Long-Term Liabilities	3.4			1,030.90			108.4			442.9			(3.4		)	1,582.20
Redeemable noncontrolling interest	—			5.7			—			—			—			5.7
Total equity	368.4			371.8			627.1			1,001.20			(2,000.1		)	368.4
Noncontrolling interest	—			—			—			0.3			—			0.3
Total Liabilities and Equity	$	371.8		$	1,892.90		$	1,291.80		$	1,855.50		$	(2,939.1	)	$	2,472.90
Schedule of Condensed Income Statement	'
		For the three months ended June 30, 2014
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Revenues	$	—		$	—		$	610.1		$	649.6		$	(33.5	)	$	1,226.20
	Cost of sales	—			—			573.7			594			(33.5		)	1,134.20
	Gross profit	—			—			36.4			55.6			—			92
	Selling, general and administrative expenses	—			0.1			35.2			33.6			—			68.9
	Restructuring charges	—			—			0.1			2.1			—			2.2
	Losses (gains) on derivative financial instruments	—			—			1.9			(0.1		)	—			1.8
	Other operating expense, net	—			—			0.2			2.4			—			2.6
	Operating (loss) income	—			(0.1		)	(1.0		)	17.6			—			16.5
	Interest expense, net	—			—			23.1			3.9			—			27
	Other (income) expense, net	—			—			(1.7		)	1.3			—			(0.4		)
	Equity in net loss (earnings) of affiliates	17.5			17.4			(0.6		)	—			(34.3		)	—
	(Loss) income before income taxes	(17.5		)	(17.5		)	(21.8		)	12.4			34.3			(10.1		)
	Provision for income taxes	—			—			—			7			—			7
	Net (loss) income	(17.5		)	(17.5		)	(21.8		)	5.4			34.3			(17.1		)
	Net income attributable to noncontrolling interest	—			—			—			0.4			—			0.4
	Net (loss) income attributable to Aleris Corporation	$	(17.5	)	$	(17.5	)	$	(21.8	)	$	5		$	34.3		$	(17.5	)
	Comprehensive (loss) income	$	(21.1	)	$	(21.1	)	$	(21.8	)	$	2		$	41.3		$	(20.7	)
	Comprehensive income attributable to noncontrolling interest	—			—			—			0.4			—			0.4
	Comprehensive (loss) income attributable to Aleris Corporation	$	(21.1	)	$	(21.1	)	$	(21.8	)	$	1.6		$	41.3		$	(21.1	)
		For the six months ended June 30, 2014
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Revenues	$	—		$	—		$	1,049.80		$	1,267.10		$	(36.5	)	$	2,280.40
	Cost of sales	—			—			990.6			1,159.20			(36.5		)	2,113.30
	Gross profit	—			—			59.2			107.9			—			167.1
	Selling, general and administrative expenses	—			0.1			65.5			65.3			—			130.9
	Restructuring charges	—			—			0.7			2			—			2.7
	(Gains) losses on derivative financial instruments	—			—			(1.8		)	3.1			—			1.3
	Other operating expense, net	—			—			0.7			2.1			—			2.8
	Operating (loss) income	—			(0.1		)	(5.9		)	35.4			—			29.4
	Interest expense, net	—			—			45.4			7.9			—			53.3
	Other (income) expense, net	—			—			(5.4		)	4.6			—			(0.8		)
	Equity in net loss (earnings) of affiliates	35.1			35			(1.2		)	—			(68.9		)	—
	(Loss) income before income taxes	(35.1		)	(35.1		)	(44.7		)	22.9			68.9			(23.1		)
	Provision for income taxes	—			—			—			11.3			—			11.3
	Net (loss) income	(35.1		)	(35.1		)	(44.7		)	11.6			68.9			(34.4		)
	Net income attributable to noncontrolling interest	—			—			—			0.7			—			0.7
	Net (loss) income attributable to Aleris Corporation	$	(35.1	)	$	(35.1	)	$	(44.7	)	$	10.9		$	68.9		$	(35.1	)
	Comprehensive (loss) income	$	(40.7	)	$	(40.7	)	$	(44.8	)	$	6.1		$	80.1		$	(40.0	)
	Comprehensive income attributable to noncontrolling interest	—			—			—			0.7			—			0.7
	Comprehensive (loss) income attributable to Aleris Corporation	$	(40.7	)	$	(40.7	)	$	(44.8	)	$	5.4		$	80.1		$	(40.7	)
		For the three months ended June 30, 2013
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Revenues	$	—		$	—		$	510.4		$	619.7		$	(2.5	)	$	1,127.60
	Cost of sales	—			—			483.8			572.1			(2.5		)	1,053.40
	Gross profit	—			—			26.6			47.6			—			74.2
	Selling, general and administrative expenses	—			0.1			24.1			34.3			—			58.5
	Restructuring charges	—			—			1.1			8.4			—			9.5
	Gains on derivative financial instruments	—			—			(5.2		)	(4.7		)	—			(9.9		)
	Other operating expense, net	—			—			0.3			0.1			—			0.4
	Operating (loss) income	—			(0.1		)	6.3			9.5			—			15.7
	Interest expense, net	—			—			21.9			2.7			—			24.6
	Other (income) expense, net	—			—			(0.3		)	1.6			—			1.3
	Equity in net loss (earnings) of affiliates	11.7			11.6			(0.5		)	—			(22.8		)	—
	(Loss) income before income taxes	(11.7		)	(11.7		)	(14.8		)	5.2			22.8			(10.2		)
	Provision for income taxes	—			—			—			1.2			—			1.2
	Net (loss) income	(11.7		)	(11.7		)	(14.8		)	4			22.8			(11.4		)
	Net income attributable to noncontrolling interest	—			—			—			0.3			—			0.3
	Net income attributable to Aleris Corporation	$	(11.7	)	$	(11.7	)	$	(14.8	)	$	3.7		$	22.8		$	(11.7	)
	Comprehensive (loss) income	$	(0.5	)	$	(0.5	)	$	(14.5	)	$	14.7		$	0.6		$	(0.2	)
	Comprehensive income attributable to noncontrolling interest	—			—			—			0.3			—			0.3
	Comprehensive (loss) income attributable to Aleris Corporation	$	(0.5	)	$	(0.5	)	$	(14.5	)	$	14.4		$	0.6		$	(0.5	)
	For the six months ended June 30, 2013
	Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues	$	—		$	—		$	1,018.30		$	1,223.60		$	(4.2	)	$	2,237.70
Cost of sales	—			—			959.2			1,119.50			(4.2		)	2,074.50
Gross profit	—			—			59.1			104.1			—			163.2
Selling, general and administrative expenses	—			0.1			52			67.9			—			120
Restructuring charges	—			—			2.2			8.1			—			10.3
Gains on derivative financial instruments	—			—			(13.8		)	(5.3		)	—			(19.1		)
Other operating expense (income), net	—			—			0.4			(0.8		)	—			(0.4		)
Operating (loss) income	—			(0.1		)	18.3			34.2			—			52.4
Interest expense (income), net	—			—			44			1.6			—			45.6
Other (income) expense, net	—			—			(1.1		)	0.5			—			(0.6		)
Equity in net loss (earnings) of affiliates	0.8			0.7			(1.0		)	—			(0.5		)	—
(Loss) income before income taxes	(0.8		)	(0.8		)	(23.6		)	32.1			0.5			7.4
Provision for income taxes	—			—			—			7.6			—			7.6
Net (loss) income	(0.8		)	(0.8		)	(23.6		)	24.5			0.5			(0.2		)
Net income attributable to noncontrolling interest	—			—			—			0.6			—			0.6
Net income (loss) attributable to Aleris Corporation	$	(0.8	)	$	(0.8	)	$	(23.6	)	$	23.9		$	0.5		$	(0.8	)
Comprehensive (loss) income	$	(6.2	)	$	(6.2	)	$	(22.3	)	$	18		$	11.1		$	(5.6	)
Comprehensive income attributable to noncontrolling interest	—			—			—			0.6			—			0.6
Comprehensive (loss) income attributable to Aleris Corporation	$	(6.2	)	$	(6.2	)	$	(22.3	)	$	17.4		$	11.1		$	(6.2	)
Schedule of Condensed Cash Flow Statement	'
		For the six months ended June 30, 2014
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Net cash provided (used) by operating activities	$	0.4		$	(81.4	)	$	36.4		$	35.5		$	1.8		$	(7.3	)
	Investing activities
	Payments for property, plant and equipment	—			—			(32.2		)	(46.2		)	—			(78.4		)
	Purchase of a business	—			(2.6		)	(77.8		)	(29.6		)	—			(110.0		)
	Disbursements of intercompany loans	—			(15.0		)	(10.4		)	(45.0		)	70.4			—
	Repayments from intercompany loans	—			5			9.5			15			(29.5		)	—
	Equity contributions in subsidiaries	—			(107.4		)	—			—			107.4			—
	Other	—			—			(0.1		)	6			—			5.9
	Net cash used by investing activities	—			(120.0		)	(111.0		)	(99.8		)	148.3			(182.5		)
	Financing activities
	Proceeds from the ABL facility	—			225			—			15			—			240
	Payments on the ABL facility	—			(54.0		)	—			(15.0		)	—			(69.0		)
	Proceeds from Zhenjiang revolver	—			—			—			11.5			—			11.5
	Net (payments on) proceeds from other long-term debt	—			—			(0.3		)	0.9			—			0.6
	Dividend paid	—			—			—			(0.7		)	0.7			—
	Proceeds from intercompany loans	—			45			—			25.4			(70.4		)	—
	Repayments on intercompany loans	—			(15.0		)	—			(14.5		)	29.5			—
	Proceeds from intercompany equity contributions	—			—			77.8			29.6			(107.4		)	—
	Other	(0.4		)	(0.3		)	—			(0.3		)	—			(1.0		)
	Net cash (used) provided by financing activities	(0.4		)	200.7			77.5			51.9			(147.6		)	182.1
	Effect of exchange rate differences on cash and cash equivalents	—			—			—			(0.5		)	—			(0.5		)
	Net (decrease) increase in cash and cash equivalents	—			(0.7		)	2.9			(12.9		)	2.5			(8.2		)
	Cash and cash equivalents at beginning of period	—			3.7			—			58.9			(2.5		)	60.1
	Cash and cash equivalents at end of period	$	—		$	3		$	2.9		$	46		$	—		$	51.9
		For the six months ended June 30, 2013
		Aleris Corporation (Parent)			Aleris International, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Net cash provided (used) by operating activities	$	315.6		$	(52.0	)	$	58.8		$	(59.2	)	$	(314.0	)	$	(50.8	)
	Investing activities
	Payments for property, plant and equipment	—			—			(33.8		)	(108.4		)	—			(142.2		)
	Disbursements of intercompany loans	—			(30.0		)	(44.4		)	—			74.4			—
	Repayments from intercompany loans	—			8			19.4			—			(27.4		)	—
	Equity contributions in subsidiaries	—			(81.9		)	(4.2		)	—			86.1			—
	Other	—			—			—			1.6			—			1.6
	Net cash used by investing activities	—			(103.9		)	(63.0		)	(106.8		)	133.1			(140.6		)
	Financing activities
	Proceeds from Zhenjiang term loans	—			—			—			0.2			—			0.2
	Proceeds from Zhenjiang revolver	—			—			—			4.1			—			4.1
	Net proceeds from other long-term debt	—			—			—			(1.8		)	—			(1.8		)
	Redemption of noncontrolling interest	—			—			—			(8.9		)	—			(8.9		)
	Dividends paid	(313.0		)	(313.0		)	—			(0.7		)	313.7			(313.0		)
	Proceeds from intercompany loans	—			—			—			74.4			(74.4		)	—
	Repayments on intercompany loans	—			—			—			(27.4		)	27.4			—
	Proceeds from intercompany equity contributions	—			—			4.2			81.9			(86.1		)	—
	Other	(2.6		)	(0.2		)	—			(0.3		)	—			(3.1		)
	Net cash (used) provided by financing activities	(315.6		)	(313.2		)	4.2			121.5			180.6			(322.5		)
	Effect of exchange rate differences on cash and cash equivalents	—			—			—			(0.5		)	—			(0.5		)
	Net decrease in cash and cash equivalents	—			(469.1		)	—			(45.0		)	(0.3		)	(514.4		)
	Cash and cash equivalents at beginning of period	—			472.4			—			121.6			(1.1		)	592.9
	Cash and cash equivalents at end of period	$	—		$	3.3		$	—		$	76.6		$	(1.4	)	$	78.5

Inventories_Details

Inventories (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Raw materials	$275.80	$265.90
Work in process	261.7	203
Finished goods	206.1	185.6
Supplies	41	28.9
Total inventories	$784.60	$683.40

LongTerm_Debt_Details

Long-Term Debt (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Debt Instrument [Line Items]	'	'
Other Long-term Debt	$17.30	$14.40
Long-term debt	1,422.80	1,237.40
Current portion of long-term debt	11.5	8.3
Total long-term debt	1,411.30	1,229.10
Line of Credit | ABL Facility	'	'
Debt Instrument [Line Items]	'	'
Long-term Line of Credit	171	0
Senior Notes | 7 5/8% Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Senior Notes	494.8	494.1
Debt discount	5.2	5.9
Stated interest rate	7.63%	'
Senior Notes | 7 7/8% Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Senior Notes	493.1	492.5
Debt discount	6.9	7.5
Stated interest rate	7.88%	'
Senior Subordinated Notes | Senior Subordinated Exchangeable Notes	'	'
Debt Instrument [Line Items]	'	'
Debt discount	0.6	0.7
Convertible Subordinated Debt	44.2	44.2
Notes Payable to Banks | Zhenjiang term loans	'	'
Debt Instrument [Line Items]	'	'
Debt discount	1	1
Notes Payable to Bank, Noncurrent	191.1	192.2
Foreign Line of Credit | Zhenjiang revolver	'	'
Debt Instrument [Line Items]	'	'
Long-term Line of Credit	11.3	0
Debt discount	$0.20	$0

Commitments_And_Contingencies_1

Commitments And Contingencies (Details) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
	Site
	States
	Foreign_Countries
Loss Contingencies [Line Items]	'	'
Site Contingency, Number of Superfund Sites with Operations and Maintenance	2	'
Number of States in which Entity Performs Environmental Remediation	5	'
Number of Foreign Countries with Environmental Remediations	1	'
Number of Sites with Environmental Remediations	8	'
Portion of environmental liabilities indemnified by Corus Group Ltd.	$17.10	$6.30
Asset retirement obligations	12.4	12.4
Asset Retirement Obligation, Description, Estimated Timeframe of Disbursements	'10 years	'
Loss Contingency, Estimate of Possible Loss	4.2	'
Other Long-Term Liabilities and Accrued Liabilities	'	'
Loss Contingencies [Line Items]	'	'
Accrual for Environmental Loss Contingencies	$46.90	$35.30

Stockholders_Equity_and_Redeem2

Stockholders' Equity and Redeemable Noncontrolling Interest (Schedule of Stockholders' Equity) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Increase (Decrease) in Stockholders' Equity Disclosure [Roll Forward]	'	'	'	'
Aleris Corporation equity	'	'	$368.40	'
Noncontrolling interest	'	'	0.3	'
Total Equity at January 1, 2014	'	'	368.7	'
Net (loss) income attributable to Aleris Corporation	-17.5	-11.7	-35.1	-0.8
Net income attributable to noncontrolling interest	0.4	0.3	0.7	0.6
Net loss	-17.1	-11.4	-34.4	-0.2
Other Comprehensive Loss, Net of Tax	'	'	-5.6	'
Stock-based compensation activity	'	'	7.6	'
Stockholders' Equity, Other	'	'	-0.5	'
Aleris Corporation equity	335.1	'	335.1	'
Noncontrolling interest	0.7	'	0.7	'
Total Equity at June 30, 2014	335.8	'	335.8	'
Aleris Corporation	'	'	'	'
Increase (Decrease) in Stockholders' Equity Disclosure [Roll Forward]	'	'	'	'
Aleris Corporation equity	'	'	368.4	'
Net (loss) income attributable to Aleris Corporation	'	'	-35.1	'
Other Comprehensive Loss, Net of Tax	'	'	-5.6	'
Stock-based compensation activity	'	'	7.6	'
Stockholders' Equity, Other	'	'	-0.2	'
Aleris Corporation equity	335.1	'	335.1	'
Noncontrolling Interest	'	'	'	'
Increase (Decrease) in Stockholders' Equity Disclosure [Roll Forward]	'	'	'	'
Noncontrolling interest	'	'	0.3	'
Net income attributable to noncontrolling interest	'	'	0.7	'
Other Comprehensive Loss, Net of Tax	'	'	0	'
Stock-based compensation activity	'	'	0	'
Stockholders' Equity, Other	'	'	-0.3	'
Noncontrolling interest	0.7	'	0.7	'
Redeemable Noncontrolling Interest	'	'	'	'
Increase (Decrease) in Stockholders' Equity Disclosure [Roll Forward]	'	'	'	'
Redeemable Noncontrolling Interest, Equity, Carrying Amount	'	'	5.7	'
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest	'	'	0	'
Other Comprehensive Loss, Net of Tax	'	'	0	'
Stock-based compensation activity	'	'	0	'
Stockholders' Equity, Other	'	'	0	'
Redeemable Noncontrolling Interest, Equity, Carrying Amount	$5.70	'	$5.70	'

Stockholders_Equity_and_Redeem3

Stockholders' Equity and Redeemable Noncontrolling Interest (Changes in the Number of Outstanding Common Stock) (Details)	6 Months Ended
	Jun. 30, 2014
Outstanding Shares of Common Stock [Roll Forward]	'
Common Stock, Shares, Outstanding at beginning of period	31,229,064
Stock Issued During Period, Shares, Conversion of Convertible Securities	1,207
Common Stock, Shares, Outstanding at end of period	31,256,999
Stock Options	'
Outstanding Shares of Common Stock [Roll Forward]	'
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	3,434
Restricted Stock	'
Outstanding Shares of Common Stock [Roll Forward]	'
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	23,294

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Details) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014
Accumulated Other Comprehensive Income [Roll Forward]	'
Balance at January 1, 2014	$13.80
Balance at June 30, 2014	8.2
Amortization of net actuarial losses, net of tax	-0.5	[1]
Losses reclassified into earnings, net of tax	-0.5
Accumulated Translation Adjustment	'
Accumulated Other Comprehensive Income [Roll Forward]	'
Balance at January 1, 2014	45.8
Current period currency translation adjustments	-6.1
Amortization of net actuarial loss	0
Balance at June 30, 2014	39.7
Defined Benefit Plans and Other Postretirement Benefit Plans	'
Accumulated Other Comprehensive Income [Roll Forward]	'
Balance at January 1, 2014	-32
Current period currency translation adjustments	0
Amortization of net actuarial loss	0.5
Balance at June 30, 2014	-31.5
Accumulated Net Adjustment	'
Accumulated Other Comprehensive Income [Roll Forward]	'
Balance at January 1, 2014	13.8
Current period currency translation adjustments	-6.1
Amortization of net actuarial loss	0.5
Balance at June 30, 2014	$8.20
[1]	This component of accumulated other comprehensive income is included in the computation of net periodic benefit expense and net postretirement benefit expense (see Note 10, bEmployee Benefit Plans,b for additional detail).

Segment_Information_Narratives

Segment Information (Narratives) (Details)	6 Months Ended
	Jun. 30, 2014
	Operating_Segment
Segment Reporting [Abstract]	'
Number of Operating Segments (in segments)	6

Segment_Information_Schedule_o

Segment Information (Schedule of Revenues and Segment Income) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	$1,226.20	$1,127.60	$2,280.40	$2,237.70
Segment income	83.6	92.7	164.9	171.1
RPNA	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	419.1	323.2	680.4	637.4
Segment income	22.4	32.7	49.3	56.2
RPEU	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	352.2	378.6	707	747.8
Segment income	34.4	39.4	72.5	77.9
RPAP	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	11.3	5	21.2	5.7
Segment income	0	0	0	-0.3
Extrusions	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	92.6	94	186	183
Segment income	3.9	4.5	6.9	7.5
RSAA	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	246.7	234.6	482	473
Segment income	17.3	13	26.3	23.4
RSEU	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	147.8	139.6	291.1	295.3
Segment income	5.6	3.1	9.9	6.4
External Customers [Member]	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	1,226.20	1,127.60	2,280.40	2,237.70
External Customers [Member] | RPNA	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	418.4	322.8	679.2	636.5
External Customers [Member] | RPEU	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	321.3	347.1	644.5	674
External Customers [Member] | RPAP	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	9.7	1.8	16.6	2.6
External Customers [Member] | Extrusions	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	91	92	182.4	178.7
External Customers [Member] | RSAA	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	245.7	233.8	479.4	470
External Customers [Member] | RSEU	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	140.1	130.1	278.3	275.9
Intersegment Eliminations	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	0	0	0	0
Intersegment Eliminations | RPNA	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	0.7	0.4	1.2	0.9
Intersegment Eliminations | RPEU	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	30.9	31.5	62.5	73.8
Intersegment Eliminations | RPAP	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	1.6	3.2	4.6	3.1
Intersegment Eliminations | Extrusions	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	1.6	2	3.6	4.3
Intersegment Eliminations | RSAA	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	1	0.8	2.6	3
Intersegment Eliminations | RSEU	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	7.7	9.5	12.8	19.4
Intersegment Eliminations | Intersegment Eliminations	'	'	'	'
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'	'	'	'
Revenues	($43.50)	($47.40)	($87.30)	($104.50)

Segment_Information_Reconcilia

Segment Information (Reconciliation of Segment Income to Consolidated Statements of Comprehensive Loss) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Total segment income	$83.60	$92.70	$164.90	$171.10
Depreciation and amortization	'	'	-70.7	-61.9
Restructuring charges	-2.2	-9.5	-2.7	-10.3
Interest expense, net	27	24.6	53.3	45.6
Unallocated gains (losses) on derivative financial instruments	-1.8	9.9	-1.3	19.1
(Loss) income before income taxes	-10.1	-10.2	-23.1	7.4
Unallocated Amounts	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Depreciation and amortization	-37.5	-34.7	-70.7	-61.9
Corporate general and administrative expenses, excluding depreciation, amortization, start-up expenses and other expenses	-18.6	-10	-33.6	-21.3
Restructuring charges	-2.2	-9.5	-2.7	-10.3
Interest expense, net	-27	-24.6	-53.3	-45.6
Unallocated gains (losses) on derivative financial instruments	0.8	-10	-8.5	0.2
Unallocated currency exchange gains (losses)	0.7	0	-0.8	0
Start-up expenses	-7	-12	-15.4	-23.3
Other expense, net	($2.90)	($2.10)	($3)	($1.50)

Segment_Information_Reconcilia1

Segment Information (Reconciliation of Reportable Segment Assets) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	$2,762.50	$2,472.90
RPNA	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	765.1	524.7
RPEU	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	733	699.2
RPAP	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	427	439.4
Extrusions	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	154.1	141.8
RSAA	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	316.6	294.5
RSEU	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	192.1	183.7
Unallocated Amounts	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	$174.60	$189.60

StockBased_Compensation_Detail

Stock-Based Compensation (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Life of award (in years)	'	'	'10 years	'
Award vesting period (in years)	'	'	'4 years	'
2010 Equity Incentive Plan | Certain Members of Management and Directors	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock options granted (in shares)	'	'	1,007,533	'
Stock-based compensation expense	$4	$2.70	$8.20	$5.40
2010 Equity Incentive Plan | Restricted Stock Units (RSUs) | Certain Members of Management and Directors	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Restricted stock units granted (in shares)	'	'	342,764	'

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'	'
Effective tax rate (percent)	-69.10%	-11.60%	-48.90%	102.30%
Unrecognized tax benefits	$2.60	'	$2.60	'
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$0.20	'	$0.20	'

Employee_Benefit_Plans_Details

Employee Benefit Plans (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
U.S. Pension Benefits	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	$0.80	$0.90	$1.60	$1.80
Interest cost	1.8	1.6	3.6	3.2
Amortization of net actuarial loss	0	0.4	0	0.8
Expected return on plan assets	-2.6	-2.3	-5.2	-4.6
Net periodic benefit expense	0	0.6	0	1.2
European Pension Benefits	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	1	1	1.9	2
Interest cost	1.9	1.7	3.9	3.5
Amortization of net actuarial loss	0.3	0.4	0.7	0.8
Expected return on plan assets	0	0	-0.1	-0.1
Net periodic benefit expense	3.2	3.1	6.4	6.2
Other Postretirement Benefit Plans	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	0	0.1	0.1	0.1
Interest cost	0.5	0.4	0.9	0.9
Amortization of net actuarial loss	-0.1	0.1	-0.2	0.2
Net periodic benefit expense	$0.40	$0.60	$0.80	$1.20

Derivative_And_Other_Financial2

Derivative And Other Financial Instruments (Narratives) (Details) (USD $)	6 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivative [Line Items]	'	'
Collateral Already Posted, Aggregate Fair Value	0	0
Metal	'	'
Derivative [Line Items]	'	'
Maximum settlement period of derivatives (in months)	'3 months	'
Tons of metal in forward contracts with the right to buy (in tons)	200,000	200,000
Tons of metal in forward contracts with the right to sell (in tons)	200,000	200,000
Natural Gas	'	'
Derivative [Line Items]	'	'
British thermal units in forward buy contracts (in British thermal units)	900,000,000,000	2,900,000,000,000
Currency	'	'
Derivative [Line Items]	'	'
Derivative, Notional Amount	0	'
Convertible Notes Payable	'	'
Derivative [Line Items]	'	'
Risk-free interest rate (percent)	1.90%	2.30%
Expected equity volatility rate (percent)	55.00%	'
Zhenjiang term loans	'	'
Derivative [Line Items]	'	'
Maximum period for variable interest rate paid (in months)	'6 months	'
Senior Notes | 7 5/8% Senior Notes	'	'
Derivative [Line Items]	'	'
Stated interest rate	7.63%	'
Senior Notes | 7 7/8% Senior Notes	'	'
Derivative [Line Items]	'	'
Stated interest rate	7.88%	'

Derivative_And_Other_Financial3

Derivative And Other Financial Instruments (Schedule of Derivative Instruments) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value of Derivative Assets	'	'
Fair value	$8.70	$13.70
Effect of counterparty netting	-7.9	-12.3
Net derivatives as classified in the balance sheet	0.8	1.4
Fair Value of Derivative Liabilities	'	'
Fair value	-20.4	-17
Effect of counterparty netting	7.9	12.3
Net derivatives as classified in the balance sheet	-12.5	-4.7
Metal	'	'
Fair Value of Derivative Assets	'	'
Fair value	8.4	13.3
Fair Value of Derivative Liabilities	'	'
Fair value	-20.4	-17
Natural Gas	'	'
Fair Value of Derivative Assets	'	'
Fair value	0.3	0.4
Fair Value of Derivative Liabilities	'	'
Fair value	$0	$0

Derivative_And_Other_Financial4

Derivative And Other Financial Instruments (Schedule of Derivative Instruments in Balance Sheet by Contract Type) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Prepaid expense and other assets, current	$33.20	$31.50
Other long-term assets	75.5	67.5
Total Asset Derivatives	0.8	1.4
Accrued liabilities	214.6	200.9
Other long-term liabilities	85.6	79.3
Total Liability Derivatives	12.5	4.7
Metal	'	'
Derivatives, Fair Value [Line Items]	'	'
Prepaid expense and other assets, current	0	1
Other long-term assets	0.5	0
Accrued liabilities	11	1.7
Other long-term liabilities	1.5	3
Natural Gas	'	'
Derivatives, Fair Value [Line Items]	'	'
Prepaid expense and other assets, current	$0.30	$0.40

Derivative_And_Other_Financial5

Derivative And Other Financial Instruments (Schedule of Realized (Gains) Losses on Derivatives) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Metal	'	'	'	'
Derivative Instruments, Loss [Line Items]	'	'	'	'
Realized (gains) losses on derivative financial instruments	$3.20	($19.60)	($5)	($18.70)
Natural Gas	'	'	'	'
Derivative Instruments, Loss [Line Items]	'	'	'	'
Realized (gains) losses on derivative financial instruments	($0.50)	($0.30)	($2.20)	($0.10)

Derivative_And_Other_Financial6

Derivative And Other Financial Instruments (Schedule of Fair Value for Assets and Liabilities Measured on Recurring Basis) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value	$8.70	$13.70
Derivative Liability, Fair Value, Gross Liability	-20.4	-17
Fair Value	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	51.9	60.1
Lines of Credit	171	193.2
Exchangeable Notes	72.7	72.7
Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	51.9	60.1
Lines of Credit	0	'
Exchangeable Notes	0	0
Zhenjiang term loan	'	0
Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Lines of Credit	171	'
Exchangeable Notes	0	0
Zhenjiang term loan	'	0
Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Lines of Credit	0	'
Exchangeable Notes	72.7	72.7
Zhenjiang term loan	'	193.2
Recurring Basis	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value	8.7	13.7
Derivative Liability, Fair Value, Gross Liability	-20.4	-17
Derivative, Fair Value, Net	-11.7	-3.3
Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Fair Value, Net	0	0
Recurring Basis | Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value	8.7	13.7
Derivative Liability, Fair Value, Gross Liability	-20.4	-17
Derivative, Fair Value, Net	-11.7	-3.3
Recurring Basis | Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Fair Value, Net	0	0
7 5/8% Senior Notes | Fair Value	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	518.8	530
7 5/8% Senior Notes | Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	518.8	530
7 5/8% Senior Notes | Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	0	0
7 5/8% Senior Notes | Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	0	0
7 7/8% Senior Notes | Fair Value	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	525	531.3
7 7/8% Senior Notes | Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	525	531.3
7 7/8% Senior Notes | Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	0	0
7 7/8% Senior Notes | Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	0	0
Zhenjiang term loans | Fair Value	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Zhenjiang term loan	192.1	'
Zhenjiang term loans | Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Zhenjiang term loan	0	'
Zhenjiang term loans | Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Zhenjiang term loan	0	'
Zhenjiang term loans | Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Zhenjiang term loan	192.1	'
Zhenjiang revolver | Fair Value	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Lines of Credit	11.5	'
Zhenjiang revolver | Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Lines of Credit	0	'
Zhenjiang revolver | Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Lines of Credit	0	'
Zhenjiang revolver | Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Lines of Credit	11.5	'
Fair Value	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	51.9	60.1
Lines of Credit	171	0
Exchangeable Notes	72.7	72.7
Fair Value | 7 5/8% Senior Notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	518.8	530
Fair Value | 7 7/8% Senior Notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	525	531.3
Fair Value | Zhenjiang term loans	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Zhenjiang term loan	192.1	193.2
Fair Value | Zhenjiang revolver	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Lines of Credit	11.5	0
Carrying Amount	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	51.9	60.1
Lines of Credit	171	0
Exchangeable Notes	44.2	44.2
Carrying Amount | 7 5/8% Senior Notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	494.8	494.1
Carrying Amount | 7 7/8% Senior Notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Notes Payable, Fair Value Disclosure	493.1	492.5
Carrying Amount | Zhenjiang term loans	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Zhenjiang term loan	191.1	192.2
Carrying Amount | Zhenjiang revolver	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Lines of Credit	$11.30	$0

Business_Combinations_Narrativ

Business Combinations (Narratives) (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2014	Apr. 01, 2014	Apr. 01, 2014
					Nichols Aluminum, LLC	Nichols Aluminum, LLC	Nichols Aluminum, LLC	Reserve for Environmental Costs
								Nichols Aluminum, LLC
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'
Goodwill resulting from purchase	'	'	'	'	'	'	$1.90	'
Purchase of a business	'	'	110	0	110	'	'	'
Proceeds from purchase price adjustment	'	'	'	'	2.6	'	'	'
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed	'	'	'	'	'	2.9	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities	'	'	'	'	'	'	'	12
Business Combination, Indemnification Assets, Amount as of Acquisition Date	'	'	'	'	'	'	10.8	'
Revenues	$1,226.20	$1,127.60	$2,280.40	$2,237.70	'	$115.50	'	'

Business_Combinations_Schedule

Business Combinations Schedule Of Recognized Identified Assets Acquired And Liabilities Assumed (Details) (Nichols Aluminum, LLC, USD $)	3 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Apr. 01, 2014
Nichols Aluminum, LLC	'	'
Business Acquisition [Line Items]	'	'
Accounts receivable	'	$40
Inventories	'	47.8
Property, plant and equipment	'	71.3
Intangible assets	'	2.8
Other assets	'	12.2
Total assets acquired	'	174.1
Accounts payable	'	46.3
Accrued expenses and other liabilities	'	22.3
Total liabilities assumed	'	68.6
Net assets acquired	'	105.5
Goodwill resulting from purchase	'	1.9
Total consideration transferred	$107.40	'

Condensed_Consolidating_Financ2

Condensed Consolidating Financial Statements (Condensed Balance Sheet) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Current Assets	'	'	'	'
Cash and cash equivalents	$51.90	$60.10	$78.50	$592.90
Accounts receivable (net of allowances of $8.9 and $7.7 at June 30, 2014 and December 31, 2013, respectively)	517.6	376.9	'	'
Inventories	784.6	683.4	'	'
Deferred income taxes	7.1	7.1	'	'
Prepaid expense and other assets, current	33.2	31.5	'	'
Due from Affiliate, Current	0	0	'	'
Total Current Assets	1,394.40	1,159	'	'
Property, plant and equipment, net	1,202.20	1,157.70	'	'
Intangible assets, net	45.2	43.5	'	'
Deferred income taxes	45.2	45.2	'	'
Other long-term assets	75.5	67.5	'	'
Due from Affiliate, Noncurrent	0	0	'	'
Investments in subsidiaries/intercompany receivables, net	0	0	'	'
Total Assets	2,762.50	2,472.90	'	'
Current Liabilities	'	'	'	'
Accounts payable	422.9	303.2	'	'
Accrued liabilities	214.6	200.9	'	'
Deferred income taxes	3.9	3.9	'	'
Current portion of long-term debt	11.5	8.3	'	'
Due to Affiliate, Current	0	0	'	'
Total Current Liabilities	652.9	516.3	'	'
Long-term debt	1,411.30	1,229.10	'	'
Deferred income taxes	6.7	4.4	'	'
Accrued pension benefits	224	228.5	'	'
Accrued postretirement benefits	40.5	40.9	'	'
Other long-term liabilities	85.6	79.3	'	'
Due to Affiliate, Noncurrent	0	0	'	'
Total Long-Term Liabilities	1,768.10	1,582.20	'	'
Redeemable noncontrolling interest	5.7	5.7	'	'
Total Aleris Corporation Equity	335.1	368.4	'	'
Noncontrolling interest	0.7	0.3	'	'
Total Liabilities and Equity	2,762.50	2,472.90	'	'
Aleris Corporation (Parent)	'	'	'	'
Current Assets	'	'	'	'
Cash and cash equivalents	0	0	0	0
Accounts receivable (net of allowances of $8.9 and $7.7 at June 30, 2014 and December 31, 2013, respectively)	0	0	'	'
Inventories	0	0	'	'
Deferred income taxes	0	0	'	'
Prepaid expense and other assets, current	0	0	'	'
Due from Affiliate, Current	0	0	'	'
Total Current Assets	0	0	'	'
Property, plant and equipment, net	0	0	'	'
Intangible assets, net	0	0	'	'
Deferred income taxes	0	0	'	'
Other long-term assets	0	0	'	'
Due from Affiliate, Noncurrent	0	0	'	'
Investments in subsidiaries/intercompany receivables, net	338.9	371.8	'	'
Total Assets	338.9	371.8	'	'
Current Liabilities	'	'	'	'
Accounts payable	0	0	'	'
Accrued liabilities	0	0	'	'
Deferred income taxes	0	0	'	'
Current portion of long-term debt	0	0	'	'
Due to Affiliate, Current	0	0	'	'
Total Current Liabilities	0	0	'	'
Long-term debt	0	0	'	'
Deferred income taxes	0	0	'	'
Accrued pension benefits	0	0	'	'
Accrued postretirement benefits	0	0	'	'
Other long-term liabilities	0	0	'	'
Due to Affiliate, Noncurrent	3.8	3.4	'	'
Total Long-Term Liabilities	3.8	3.4	'	'
Redeemable noncontrolling interest	0	0	'	'
Total Aleris Corporation Equity	335.1	368.4	'	'
Noncontrolling interest	0	0	'	'
Total Liabilities and Equity	338.9	371.8	'	'
Aleris International, Inc.	'	'	'	'
Current Assets	'	'	'	'
Cash and cash equivalents	3	3.7	3.3	472.4
Accounts receivable (net of allowances of $8.9 and $7.7 at June 30, 2014 and December 31, 2013, respectively)	0.1	0	'	'
Inventories	0	0	'	'
Deferred income taxes	0	0	'	'
Prepaid expense and other assets, current	3.1	0.5	'	'
Due from Affiliate, Current	523.7	362.4	'	'
Total Current Assets	529.9	366.6	'	'
Property, plant and equipment, net	0	0	'	'
Intangible assets, net	0	0	'	'
Deferred income taxes	0	0	'	'
Other long-term assets	10.4	12.3	'	'
Due from Affiliate, Noncurrent	3.8	3.4	'	'
Investments in subsidiaries/intercompany receivables, net	1,577.40	1,510.60	'	'
Total Assets	2,121.50	1,892.90	'	'
Current Liabilities	'	'	'	'
Accounts payable	5.7	0.4	'	'
Accrued liabilities	21.7	21.7	'	'
Deferred income taxes	0	0	'	'
Current portion of long-term debt	0	0	'	'
Due to Affiliate, Current	546.4	462.4	'	'
Total Current Liabilities	573.8	484.5	'	'
Long-term debt	1,203.10	1,030.90	'	'
Deferred income taxes	0	0	'	'
Accrued pension benefits	0	0	'	'
Accrued postretirement benefits	0	0	'	'
Other long-term liabilities	0	0	'	'
Due to Affiliate, Noncurrent	0	0	'	'
Total Long-Term Liabilities	1,203.10	1,030.90	'	'
Redeemable noncontrolling interest	5.7	5.7	'	'
Total Aleris Corporation Equity	338.9	371.8	'	'
Noncontrolling interest	0	0	'	'
Total Liabilities and Equity	2,121.50	1,892.90	'	'
Guarantors	'	'	'	'
Current Assets	'	'	'	'
Cash and cash equivalents	2.9	0	0	0
Accounts receivable (net of allowances of $8.9 and $7.7 at June 30, 2014 and December 31, 2013, respectively)	197	125.7	'	'
Inventories	327.9	245.1	'	'
Deferred income taxes	0.2	0.2	'	'
Prepaid expense and other assets, current	14.9	16.1	'	'
Due from Affiliate, Current	493.4	378.3	'	'
Total Current Assets	1,036.30	765.4	'	'
Property, plant and equipment, net	417	377.8	'	'
Intangible assets, net	29.3	27.6	'	'
Deferred income taxes	0	0	'	'
Other long-term assets	6.1	3.3	'	'
Due from Affiliate, Noncurrent	0	0	'	'
Investments in subsidiaries/intercompany receivables, net	118.2	117.7	'	'
Total Assets	1,606.90	1,291.80	'	'
Current Liabilities	'	'	'	'
Accounts payable	195.7	117.1	'	'
Accrued liabilities	66.8	67	'	'
Deferred income taxes	0	0	'	'
Current portion of long-term debt	0.5	0.5	'	'
Due to Affiliate, Current	580.6	371.7	'	'
Total Current Liabilities	843.6	556.3	'	'
Long-term debt	0.6	0.8	'	'
Deferred income taxes	0.2	0.2	'	'
Accrued pension benefits	29	33.8	'	'
Accrued postretirement benefits	40.5	40.9	'	'
Other long-term liabilities	32.9	32.7	'	'
Due to Affiliate, Noncurrent	0	0	'	'
Total Long-Term Liabilities	103.2	108.4	'	'
Redeemable noncontrolling interest	0	0	'	'
Total Aleris Corporation Equity	660.1	627.1	'	'
Noncontrolling interest	0	0	'	'
Total Liabilities and Equity	1,606.90	1,291.80	'	'
Non-Guarantors	'	'	'	'
Current Assets	'	'	'	'
Cash and cash equivalents	46	58.9	76.6	121.6
Accounts receivable (net of allowances of $8.9 and $7.7 at June 30, 2014 and December 31, 2013, respectively)	320.5	251.2	'	'
Inventories	456.7	438.3	'	'
Deferred income taxes	6.9	6.9	'	'
Prepaid expense and other assets, current	15.2	14.9	'	'
Due from Affiliate, Current	186	192.4	'	'
Total Current Assets	1,031.30	962.6	'	'
Property, plant and equipment, net	785.2	779.9	'	'
Intangible assets, net	15.9	15.9	'	'
Deferred income taxes	45.2	45.2	'	'
Other long-term assets	59	51.9	'	'
Due from Affiliate, Noncurrent	0	0	'	'
Investments in subsidiaries/intercompany receivables, net	0	0	'	'
Total Assets	1,936.60	1,855.50	'	'
Current Liabilities	'	'	'	'
Accounts payable	221.5	188.2	'	'
Accrued liabilities	126.1	112.2	'	'
Deferred income taxes	3.9	3.9	'	'
Current portion of long-term debt	11	7.8	'	'
Due to Affiliate, Current	76.1	99	'	'
Total Current Liabilities	438.6	411.1	'	'
Long-term debt	207.6	197.4	'	'
Deferred income taxes	6.5	4.2	'	'
Accrued pension benefits	195	194.7	'	'
Accrued postretirement benefits	0	0	'	'
Other long-term liabilities	52.7	46.6	'	'
Due to Affiliate, Noncurrent	0	0	'	'
Total Long-Term Liabilities	461.8	442.9	'	'
Redeemable noncontrolling interest	0	0	'	'
Total Aleris Corporation Equity	1,035.50	1,001.20	'	'
Noncontrolling interest	0.7	0.3	'	'
Total Liabilities and Equity	1,936.60	1,855.50	'	'
Eliminations	'	'	'	'
Current Assets	'	'	'	'
Cash and cash equivalents	0	-2.5	-1.4	-1.1
Accounts receivable (net of allowances of $8.9 and $7.7 at June 30, 2014 and December 31, 2013, respectively)	0	0	'	'
Inventories	0	0	'	'
Deferred income taxes	0	0	'	'
Prepaid expense and other assets, current	0	0	'	'
Due from Affiliate, Current	-1,203.10	-933.1	'	'
Total Current Assets	-1,203.10	-935.6	'	'
Property, plant and equipment, net	0	0	'	'
Intangible assets, net	0	0	'	'
Deferred income taxes	0	0	'	'
Other long-term assets	0	0	'	'
Due from Affiliate, Noncurrent	-3.8	-3.4	'	'
Investments in subsidiaries/intercompany receivables, net	-2,034.50	-2,000.10	'	'
Total Assets	-3,241.40	-2,939.10	'	'
Current Liabilities	'	'	'	'
Accounts payable	0	-2.5	'	'
Accrued liabilities	0	0	'	'
Deferred income taxes	0	0	'	'
Current portion of long-term debt	0	0	'	'
Due to Affiliate, Current	-1,203.10	-933.1	'	'
Total Current Liabilities	-1,203.10	-935.6	'	'
Long-term debt	0	0	'	'
Deferred income taxes	0	0	'	'
Accrued pension benefits	0	0	'	'
Accrued postretirement benefits	0	0	'	'
Other long-term liabilities	0	0	'	'
Due to Affiliate, Noncurrent	-3.8	-3.4	'	'
Total Long-Term Liabilities	-3.8	-3.4	'	'
Redeemable noncontrolling interest	0	0	'	'
Total Aleris Corporation Equity	-2,034.50	-2,000.10	'	'
Noncontrolling interest	0	0	'	'
Total Liabilities and Equity	($3,241.40)	($2,939.10)	'	'

Condensed_Consolidating_Financ3

Condensed Consolidating Financial Statements (Condensed Income Statement) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	$1,226.20	$1,127.60	$2,280.40	$2,237.70
Cost of sales	1,134.20	1,053.40	2,113.30	2,074.50
Gross profit	92	74.2	167.1	163.2
Selling, general and administrative expenses	68.9	58.5	130.9	120
Restructuring charges (gains)	2.2	9.5	2.7	10.3
Losses (gains) on derivative financial instruments	1.8	-9.9	1.3	-19.1
Other operating expense (income), net	2.6	0.4	2.8	-0.4
Operating (loss) income	16.5	15.7	29.4	52.4
Interest expense, net	27	24.6	53.3	45.6
Other (income) expense, net	-0.4	1.3	-0.8	-0.6
Equity in net loss (earnings) of affiliates	0	0	0	0
(Loss) income before income taxes	-10.1	-10.2	-23.1	7.4
Provision for income taxes	7	1.2	11.3	7.6
Net loss (income)	-17.1	-11.4	-34.4	-0.2
Net income attributable to noncontrolling interest	0.4	0.3	0.7	0.6
Net (loss) income attributable to Aleris Corporation	-17.5	-11.7	-35.1	-0.8
Comprehensive (loss) income	-20.7	-0.2	-40	-5.6
Comprehensive income attributable to noncontrolling interest	0.4	0.3	0.7	0.6
Comprehensive (loss) income attributable to Aleris Corporation	-21.1	-0.5	-40.7	-6.2
Aleris Corporation (Parent)	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	0	0	0	0
Cost of sales	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Restructuring charges (gains)	0	0	0	0
Losses (gains) on derivative financial instruments	0	0	0	0
Other operating expense (income), net	0	0	0	0
Operating (loss) income	0	0	0	0
Interest expense, net	0	0	0	0
Other (income) expense, net	0	0	0	0
Equity in net loss (earnings) of affiliates	17.5	11.7	35.1	0.8
(Loss) income before income taxes	-17.5	-11.7	-35.1	-0.8
Provision for income taxes	0	0	0	0
Net loss (income)	-17.5	-11.7	-35.1	-0.8
Net income attributable to noncontrolling interest	0	0	0	0
Net (loss) income attributable to Aleris Corporation	-17.5	-11.7	-35.1	-0.8
Comprehensive (loss) income	-21.1	-0.5	-40.7	-6.2
Comprehensive income attributable to noncontrolling interest	0	0	0	0
Comprehensive (loss) income attributable to Aleris Corporation	-21.1	-0.5	-40.7	-6.2
Aleris International, Inc.	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	0	0	0	0
Cost of sales	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	0.1	0.1	0.1	0.1
Restructuring charges (gains)	0	0	0	0
Losses (gains) on derivative financial instruments	0	0	0	0
Other operating expense (income), net	0	0	0	0
Operating (loss) income	-0.1	-0.1	-0.1	-0.1
Interest expense, net	0	0	0	0
Other (income) expense, net	0	0	0	0
Equity in net loss (earnings) of affiliates	17.4	11.6	35	0.7
(Loss) income before income taxes	-17.5	-11.7	-35.1	-0.8
Provision for income taxes	0	0	0	0
Net loss (income)	-17.5	-11.7	-35.1	-0.8
Net income attributable to noncontrolling interest	0	0	0	0
Net (loss) income attributable to Aleris Corporation	-17.5	-11.7	-35.1	-0.8
Comprehensive (loss) income	-21.1	-0.5	-40.7	-6.2
Comprehensive income attributable to noncontrolling interest	0	0	0	0
Comprehensive (loss) income attributable to Aleris Corporation	-21.1	-0.5	-40.7	-6.2
Guarantors	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	610.1	510.4	1,049.80	1,018.30
Cost of sales	573.7	483.8	990.6	959.2
Gross profit	36.4	26.6	59.2	59.1
Selling, general and administrative expenses	35.2	24.1	65.5	52
Restructuring charges (gains)	0.1	1.1	0.7	2.2
Losses (gains) on derivative financial instruments	1.9	-5.2	-1.8	-13.8
Other operating expense (income), net	0.2	0.3	0.7	0.4
Operating (loss) income	-1	6.3	-5.9	18.3
Interest expense, net	23.1	21.9	45.4	44
Other (income) expense, net	-1.7	-0.3	-5.4	-1.1
Equity in net loss (earnings) of affiliates	-0.6	-0.5	-1.2	-1
(Loss) income before income taxes	-21.8	-14.8	-44.7	-23.6
Provision for income taxes	0	0	0	0
Net loss (income)	-21.8	-14.8	-44.7	-23.6
Net income attributable to noncontrolling interest	0	0	0	0
Net (loss) income attributable to Aleris Corporation	-21.8	-14.8	-44.7	-23.6
Comprehensive (loss) income	-21.8	-14.5	-44.8	-22.3
Comprehensive income attributable to noncontrolling interest	0	0	0	0
Comprehensive (loss) income attributable to Aleris Corporation	-21.8	-14.5	-44.8	-22.3
Non-Guarantors	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	649.6	619.7	1,267.10	1,223.60
Cost of sales	594	572.1	1,159.20	1,119.50
Gross profit	55.6	47.6	107.9	104.1
Selling, general and administrative expenses	33.6	34.3	65.3	67.9
Restructuring charges (gains)	2.1	8.4	2	8.1
Losses (gains) on derivative financial instruments	-0.1	-4.7	3.1	-5.3
Other operating expense (income), net	2.4	0.1	2.1	-0.8
Operating (loss) income	17.6	9.5	35.4	34.2
Interest expense, net	3.9	2.7	7.9	1.6
Other (income) expense, net	1.3	1.6	4.6	0.5
Equity in net loss (earnings) of affiliates	0	0	0	0
(Loss) income before income taxes	12.4	5.2	22.9	32.1
Provision for income taxes	7	1.2	11.3	7.6
Net loss (income)	5.4	4	11.6	24.5
Net income attributable to noncontrolling interest	0.4	0.3	0.7	0.6
Net (loss) income attributable to Aleris Corporation	5	3.7	10.9	23.9
Comprehensive (loss) income	2	14.7	6.1	18
Comprehensive income attributable to noncontrolling interest	0.4	0.3	0.7	0.6
Comprehensive (loss) income attributable to Aleris Corporation	1.6	14.4	5.4	17.4
Eliminations	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	-33.5	-2.5	-36.5	-4.2
Cost of sales	-33.5	-2.5	-36.5	-4.2
Gross profit	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Restructuring charges (gains)	0	0	0	0
Losses (gains) on derivative financial instruments	0	0	0	0
Other operating expense (income), net	0	0	0	0
Operating (loss) income	0	0	0	0
Interest expense, net	0	0	0	0
Other (income) expense, net	0	0	0	0
Equity in net loss (earnings) of affiliates	-34.3	-22.8	-68.9	-0.5
(Loss) income before income taxes	34.3	22.8	68.9	0.5
Provision for income taxes	0	0	0	0
Net loss (income)	34.3	22.8	68.9	0.5
Net income attributable to noncontrolling interest	0	0	0	0
Net (loss) income attributable to Aleris Corporation	34.3	22.8	68.9	0.5
Comprehensive (loss) income	41.3	0.6	80.1	11.1
Comprehensive income attributable to noncontrolling interest	0	0	0	0
Comprehensive (loss) income attributable to Aleris Corporation	$41.30	$0.60	$80.10	$11.10

Condensed_Consolidating_Financ4

Condensed Consolidating Financial Statements (Condensed Cash Flow Statement) (Details) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided (used) by operating activities	($7.30)	($50.80)
Investing activities	'	'
Payments for property, plant and equipment	-78.4	-142.2
Purchase of a business	-110	0
Disbursements of intercompany loans	0	0
Repayments from intercompany loans	0	0
Equity contributions in subsidiaries	0	0
Other	5.9	1.6
Net cash used by investing activities	-182.5	-140.6
Financing activities	'	'
Proceeds from the ABL facility	240	0
Payments on the ABL facility	-69	0
Proceeds from the Zhenjiang term loans	0	0.2
Proceeds from Zhenjiang revolver	11.5	4.1
Net (payments on) proceeds from other long-term debt	0.6	-1.8
Redemption of noncontrolling interest	0	-8.9
Dividends paid	0	-313
Proceeds from intercompany loans	0	0
Repayments of intercompany loans	0	0
Proceeds from intercompany equity contributions	0	0
Other	-1	-3.1
Net cash (used) provided by financing activities	182.1	-322.5
Effect of exchange rate differences on cash and cash equivalents	-0.5	-0.5
Net decrease in cash and cash equivalents	-8.2	-514.4
Cash and cash equivalents at beginning of period	60.1	592.9
Cash and cash equivalents at end of period	51.9	78.5
Aleris Corporation (Parent)	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided (used) by operating activities	0.4	315.6
Investing activities	'	'
Payments for property, plant and equipment	0	0
Purchase of a business	0	'
Disbursements of intercompany loans	0	0
Repayments from intercompany loans	0	0
Equity contributions in subsidiaries	0	0
Other	0	0
Net cash used by investing activities	0	0
Financing activities	'	'
Proceeds from the ABL facility	0	'
Payments on the ABL facility	0	'
Proceeds from the Zhenjiang term loans	'	0
Net (payments on) proceeds from other long-term debt	0	0
Redemption of noncontrolling interest	'	0
Dividends paid	0	-313
Proceeds from intercompany loans	0	0
Repayments of intercompany loans	0	0
Proceeds from intercompany equity contributions	0	0
Other	-0.4	-2.6
Net cash (used) provided by financing activities	-0.4	-315.6
Effect of exchange rate differences on cash and cash equivalents	0	0
Net decrease in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Aleris International, Inc.	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided (used) by operating activities	-81.4	-52
Investing activities	'	'
Payments for property, plant and equipment	0	0
Purchase of a business	-2.6	'
Disbursements of intercompany loans	-15	-30
Repayments from intercompany loans	5	8
Equity contributions in subsidiaries	-107.4	-81.9
Other	0	0
Net cash used by investing activities	-120	-103.9
Financing activities	'	'
Proceeds from the ABL facility	225	'
Payments on the ABL facility	-54	'
Proceeds from the Zhenjiang term loans	'	0
Net (payments on) proceeds from other long-term debt	0	0
Redemption of noncontrolling interest	'	0
Dividends paid	0	-313
Proceeds from intercompany loans	45	0
Repayments of intercompany loans	-15	0
Proceeds from intercompany equity contributions	0	0
Other	-0.3	-0.2
Net cash (used) provided by financing activities	200.7	-313.2
Effect of exchange rate differences on cash and cash equivalents	0	0
Net decrease in cash and cash equivalents	-0.7	-469.1
Cash and cash equivalents at beginning of period	3.7	472.4
Cash and cash equivalents at end of period	3	3.3
Guarantors	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided (used) by operating activities	36.4	58.8
Investing activities	'	'
Payments for property, plant and equipment	-32.2	-33.8
Purchase of a business	-77.8	'
Disbursements of intercompany loans	-10.4	-44.4
Repayments from intercompany loans	9.5	19.4
Equity contributions in subsidiaries	0	-4.2
Other	-0.1	0
Net cash used by investing activities	-111	-63
Financing activities	'	'
Proceeds from the ABL facility	0	'
Payments on the ABL facility	0	'
Proceeds from the Zhenjiang term loans	'	0
Net (payments on) proceeds from other long-term debt	-0.3	0
Redemption of noncontrolling interest	'	0
Dividends paid	0	0
Proceeds from intercompany loans	0	0
Repayments of intercompany loans	0	0
Proceeds from intercompany equity contributions	77.8	4.2
Other	0	0
Net cash (used) provided by financing activities	77.5	4.2
Effect of exchange rate differences on cash and cash equivalents	0	0
Net decrease in cash and cash equivalents	2.9	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	2.9	0
Non-Guarantors	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided (used) by operating activities	35.5	-59.2
Investing activities	'	'
Payments for property, plant and equipment	-46.2	-108.4
Purchase of a business	-29.6	'
Disbursements of intercompany loans	-45	0
Repayments from intercompany loans	15	0
Equity contributions in subsidiaries	0	0
Other	6	1.6
Net cash used by investing activities	-99.8	-106.8
Financing activities	'	'
Proceeds from the ABL facility	15	'
Payments on the ABL facility	-15	'
Proceeds from the Zhenjiang term loans	'	0.2
Net (payments on) proceeds from other long-term debt	0.9	-1.8
Redemption of noncontrolling interest	'	-8.9
Dividends paid	-0.7	-0.7
Proceeds from intercompany loans	25.4	74.4
Repayments of intercompany loans	-14.5	27.4
Proceeds from intercompany equity contributions	29.6	81.9
Other	-0.3	-0.3
Net cash (used) provided by financing activities	51.9	121.5
Effect of exchange rate differences on cash and cash equivalents	-0.5	-0.5
Net decrease in cash and cash equivalents	-12.9	-45
Cash and cash equivalents at beginning of period	58.9	121.6
Cash and cash equivalents at end of period	46	76.6
Eliminations	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided (used) by operating activities	1.8	-314
Investing activities	'	'
Payments for property, plant and equipment	0	0
Purchase of a business	0	'
Disbursements of intercompany loans	70.4	74.4
Repayments from intercompany loans	-29.5	-27.4
Equity contributions in subsidiaries	107.4	86.1
Other	0	0
Net cash used by investing activities	148.3	133.1
Financing activities	'	'
Proceeds from the ABL facility	0	'
Payments on the ABL facility	0	'
Proceeds from the Zhenjiang term loans	'	0
Net (payments on) proceeds from other long-term debt	0	0
Redemption of noncontrolling interest	'	0
Dividends paid	0.7	313.7
Proceeds from intercompany loans	-70.4	-74.4
Repayments of intercompany loans	29.5	-27.4
Proceeds from intercompany equity contributions	-107.4	-86.1
Other	0	0
Net cash (used) provided by financing activities	-147.6	180.6
Effect of exchange rate differences on cash and cash equivalents	0	0
Net decrease in cash and cash equivalents	2.5	-0.3
Cash and cash equivalents at beginning of period	-2.5	-1.1
Cash and cash equivalents at end of period	0	-1.4
Revolving Credit Facility [Member] | Zhenjiang revolver | Aleris Corporation (Parent)	'	'
Financing activities	'	'
Proceeds from Zhenjiang revolver	0	0
Revolving Credit Facility [Member] | Zhenjiang revolver | Aleris International, Inc.	'	'
Financing activities	'	'
Proceeds from Zhenjiang revolver	0	0
Revolving Credit Facility [Member] | Zhenjiang revolver | Guarantors	'	'
Financing activities	'	'
Proceeds from Zhenjiang revolver	0	0
Revolving Credit Facility [Member] | Zhenjiang revolver | Non-Guarantors	'	'
Financing activities	'	'
Proceeds from Zhenjiang revolver	11.5	4.1
Revolving Credit Facility [Member] | Zhenjiang revolver | Eliminations	'	'
Financing activities	'	'
Proceeds from Zhenjiang revolver	$0	$0