Organization and Basis of Presentation (Policies)	3 Months Ended
Organization and Basis of Presentation (Policies)	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting, Policy [Policy Text Block]	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, 2020 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 and the semiconductor supply shortage that is impacting the automotive industry. 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 and the semiconductor shortage 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, 2020.
New Accounting Pronouncements and Other Regulatory Pronouncements, Policy [Policy Text Block]	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), and has subsequently issued ASU 2021-01 - 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 expect to utilize certain of the optional expedients and exceptions available under ASU 2020-04 and ASU 2021-01 and we do not expect the adoption of this guidance to have a material impact on our financial statements. 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 became effective and we adopted this guidance on January 1, 2021. The adoption of this guidance did not have a material impact on our consolidated financial statements. 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 they remain 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. We recognized a tax benefit of $14.4 million for the year ended December 31, 2020 related to our ability to carry back prior year losses, as well as projected current year losses, under the CARES Act to years with the previous 35% tax rate. We received an income tax refund of approximately $6.0 million during the first quarter of 2021 as a result of this provision of the CARES Act. •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. At March 31, 2021, we had deferred $15.2 million of social security taxes that will be paid in the fourth quarter of 2021 and the fourth quarter of 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 applied to qualified wages paid or incurred during the period March 13, 2020 through December 31, 2020 and was 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. At March 31, 2021, we have a refundable ERC amount of $6.7 million included in Prepaid expenses and other in our Condensed Consolidated Balance Sheet.