Organization and Basis of Presentation (Notes)	9 Months Ended
Organization and Basis of Presentation (Notes)	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	1. ORGANIZATION AND BASIS OF PRESENTATION Organization We are a global Tier 1 supplier to the automotive industry. We design, engineer and manufacture driveline and metal forming products that are making the next generation of vehicles smarter, lighter, safer and more efficient. We employ approximately 20,000 associates, operating at nearly 80 facilities in 17 countries, to support our customers on global and regional platforms with a continued focus on delivering quality, operational excellence and technology leadership. Basis of Presentation We have prepared the accompanying interim condensed consolidated financial statements in accordance with the instructions to Form 10-Q under the Securities Exchange Act of 1934. These condensed consolidated financial statements are unaudited but include all normal recurring adjustments, which we consider necessary for a fair presentation of the information set forth herein. Results of operations for the periods presented are not necessarily indicative of the results for the full fiscal year. The balance sheet at December 31, 2019 presented herein has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States of America (GAAP) for complete consolidated financial statements. In order to prepare the accompanying interim condensed consolidated financial statements, we are required to make estimates and assumptions that affect the reported amounts and disclosures in our interim condensed consolidated financial statements. These estimates and assumptions are impacted by risks and uncertainties, including those associated with the Novel Coronavirus (COVID-19) pandemic that began in the first quarter of 2020. While we have made estimates and assumptions based on the facts and circumstances available as of the date of this report, the full impact of COVID-19 cannot be predicted, and actual results could differ materially from those estimates and assumptions. For further information, refer to the audited consolidated financial statements and notes included in our Annual Report on Form 10-K for the year ended December 31, 2019. Manufacturing Facility Fire and Insurance Recovery On September 22, 2020, a significant industrial fire occurred at our Malvern Manufacturing Facility in Ohio (Malvern Fire). All associates were evacuated safely and without injury. We continue to focus on managing this disruption and protecting continuity of supply to our customers, including utilizing production capacity and resources at other AAM facilities. Our insurance policies are expected to cover the repair, replacement or actual cash value of the assets that incurred loss or damage, less our applicable deductible of $1 million. In addition, our insurance policies are expected to provide coverage for interruption to our business, including lost or reduced profits and reimbursement for certain expenses and costs that are incurred relating to the fire. In the third quarter of 2020, we recorded $28.4 million of charges primarily related to the write-down of property, plant and equipment (PP&E) as a result of damage from the fire. We also recorded an insurance recovery receivable primarily associated with the write-down of PP&E of $19.8 million in the third quarter of 2020, which is included in Prepaid expenses and other in our Condensed Consolidated Balance Sheet as of September 30, 2020. This resulted in a net pre-tax impact to our Condensed Consolidated Statement of Operations of approximately $8.6 million in Cost of goods sold for the three and nine months ended September 30, 2020, which includes our applicable deductible. We continue to assess the extent of the damage caused by the fire. As such, we cannot estimate the total impact, including potential insurance recoveries, on our results of operations, financial position or cash flows, or the timing of such impact. Sale of U.S. Casting - Classification of Assets and Liabilities as Held-for-Sale In the fourth quarter of 2019, we completed the sale of the U.S operations of our former Casting segment (the Casting Sale). In conjunction with the Casting Sale, the assets and liabilities associated with this business met the criteria to be classified as held-for-sale in our Condensed Consolidated Balance Sheet as of September 30, 2019. Upon reclassification to held-for-sale in the third quarter of 2019, we recorded a pre-tax impairment charge of $225.0 million to reduce the carrying value of this business to fair value less cost to sell. Effect of New Accounting Standards and Other Regulatory Pronouncements Accounting Standard Update 2020-04 On March 12, 2020, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2020-04 - Reference Rate Reform (Topic 848). This guidance provides optional expedients and exceptions that are intended to ease the burden of updating contracts to contain a new reference rate due to the discontinuation of the London Inter-Bank Offered Rate (LIBOR). This guidance is available immediately and may be implemented in any period prior to the guidance expiration on December 31, 2022. We are currently assessing which of our various contracts will require an update for a new reference rate and will determine the timing for our implementation of this guidance at the completion of that analysis. Accounting Standard Update 2019-12 On December 18, 2019, the FASB issued ASU 2019-12 - Income Taxes (Topic 740). This guidance is intended to simplify the accounting and disclosure requirements for income taxes by removing various exceptions and requires that the effect of an enacted change in tax laws or rates be included in the annual effective tax rate computation in the interim period of the enactment. This guidance becomes effective at the beginning of our 2021 fiscal year. We expect to adopt this guidance on January 1, 2021 and we do not expect that this standard will have a material impact on our consolidated financial statements. Accounting Standards Update 2016-13 On June 16, 2016, the FASB issued 2016-13 - Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 replaces the incurred loss model under previous guidance, and requires entities to consider expected credit losses, in addition to past events and current conditions when measuring credit losses. This guidance applies to certain of our financial instruments and is primarily applicable to our trade accounts receivable. We adopted this guidance on January 1, 2020, using a modified-retrospective transition method and the adoption of this standard did not have a material impact on our condensed consolidated financial statements. See the Statement of Stockholders' Equity for the implementation impact of ASU 2016-13. Securities and Exchange Commission (SEC) Rule In the first quarter of 2020, the SEC adopted "Financial Disclosures about Guarantors and Issuers of Guaranteed Securities and Affiliates Whose Securities Collateralize a Registrant's Securities," a rule that amends the financial disclosure requirements for guarantors and issuers of registered guaranteed securities. This rule eliminates the previous requirement to present guarantor financial statement information in the notes to the financial statements and allows for the disclosure of summarized financial information for the most recent year and interim period, as well as expanded non-financial disclosures, in Management's Discussion and Analysis (MD&A). The effective date for this rule is January 4, 2021, however, the SEC permitted voluntary compliance prior to this date and we elected to adopt the new disclosure requirements in the first quarter of 2020. As such, we no longer present guarantor financial statement information in the notes to the condensed consolidated financial statements in this Quarterly Report on Form 10-Q, but instead present the required information within MD&A. Coronavirus Aid, Relief, and Economic Security Act The Coronavirus Aid, Relief, and Economic Security Act (the CARES Act) was enacted on March 27, 2020 in the United States. The key provisions of the CARES Act, as applicable to AAM, include the following: •The ability to use net operating losses (NOLs) to offset income without the 80% taxable income limitation enacted as part of the Tax Cuts and Jobs Act (TCJA) of 2017, and to carry back NOLs to offset prior year income for five years. These are temporary provisions that apply to NOLs incurred in 2018, 2019 or 2020 tax years. •The ability to claim a current deduction for interest expense up to 50% of Adjusted Taxable Income (ATI) for tax years 2019 and 2020. This limitation was previously 30% of ATI pursuant to the TCJA, and will revert to 30% after 2020. •The ability to defer the payment of the employer portion of social security taxes incurred between March 27, 2020 and December 31, 2020, with 50% of the deferred amount to be paid by December 31, 2021 and the remaining 50% to be paid by December 31, 2022. •The ability to claim an Employee Retention Credit (ERC), which is a refundable payroll tax credit, for 50% of qualified wages or benefits, subject to certain limitations, that are paid to an employee when they are not providing services due to COVID-19. The ERC applies to qualified wages paid or incurred during the period March 13, 2020 through December 31, 2020 and is available to eligible employers whose operations were fully or partially suspended due to COVID-19, or whose gross receipts declined by more than 50% when compared to the applicable period in the prior year.