Organization and Basis of Presentation Organization and Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidation, Policy [Policy Text Block]	PRINCIPLES OF CONSOLIDATION We include the accounts of Holdings and its subsidiaries in our consolidated financial statements. We eliminate the effects of all intercompany transactions, balances and profits in our consolidation.
Revenue Recognition, Policy [Policy Text Block]	REVENUE RECOGNITION We recognize revenue when products are shipped to our customers and title transfers under standard commercial terms or when realizable in accordance with our commercial agreements. If we are uncertain as to whether we will be successful collecting a balance in accordance with our understanding of a commercial agreement, we do not recognize the revenue or cost recovery until such time as the uncertainty is removed. During 2016, we reached an agreement with a customer to increase installed capacity for a program we support. In 2017, we received $5.0 million, and in 2016 we received $20.0 million, associated with this capacity increase and recorded the payments as deferred revenue, of which approximately $3.7 million is classified as a current liability, and $21.3 million is classified as a noncurrent liability, on our Consolidated Balance Sheet. We expect to begin recognizing this deferred revenue in 2018 into revenue on a straight-line basis over a period of approximately five years, which is the period that we expect the customer to benefit from this increase in installed capacity. At December 31, 2017 and 2016, we had deferred revenue of $34.1 million and $24.6 million, respectively, classified as a current liability and $78.8 million and $70.8 million, respectively, classified as a noncurrent liability in our Consolidated Balance Sheets. These amounts were primarily related to cash receipts from customers for various settlements and commercial agreements that are associated with a future benefit to these customers. We recognize this deferred revenue into revenue over the period that we expect the customer to benefit. We recognized $26.8 million, $24.9 million and $23.4 million of revenue related to deferred revenue for the years ended December 31, 2017, 2016 and 2015, respectively.
Research and Development Expense, Policy [Policy Text Block]	RESEARCH AND DEVELOPMENT (R&D) COSTS We expense R&D, as incurred, in selling, general and administrative expenses on our Consolidated Statement of Income. R&D spending was $161.5 million, $139.8 million and $113.9 million in 2017, 2016 and 2015, respectively.
Cash and Cash Equivalents, Policy [Policy Text Block]	CASH AND CASH EQUIVALENTS Cash and cash equivalents include all cash balances, savings accounts, sweep accounts, and highly liquid investments in money market funds and certificates of deposit with maturities of 90 days or less at the time of purchase.
Trade and Other Accounts Receivable, Policy [Policy Text Block]	ACCOUNTS RECEIVABLE The majority of our accounts receivable are due from original equipment manufacturers (OEMs) in the automotive industry and are past due when payment is not received within the stated terms. Trade accounts receivable for our customers are generally due within approximately 50 days from the date our customers receive our product. Amounts due from customers are stated net of allowances for doubtful accounts. We determine our allowances by considering factors such as the length of time accounts are past due, our previous loss history, the customer's ability to pay its obligation to us, and the condition of the general economy and the industry as a whole. The allowance for doubtful accounts was $7.0 million and $3.1 million as of December 31, 2017 and 2016, respectively. We write-off accounts receivable when they become uncollectible.
Property, Plant and Equipment, Preproduction Design and Development Costs [Policy Text Block]	CUSTOMER TOOLING AND PRE-PRODUCTION COSTS RELATED TO LONG-TERM SUPPLY AGREEMENTS Engineering, R&D, and other pre-production design and development costs for products sold on long-term supply arrangements are expensed as incurred unless we have a contractual guarantee for reimbursement from the customer. Reimbursements received for pre-production costs relating to awarded programs are deferred and recognized into revenue over the life of the associated program. Reimbursements received for pre-production costs relating to future programs that have not been awarded, or amounts received for programs that become discontinued prior to production, are recorded as a reduction of expense. Costs for tooling used to make products sold on long-term supply arrangements for which we have either title to the assets or the noncancelable right to use the assets during the term of the supply arrangement are capitalized in property, plant and equipment. Reimbursable costs for tooling assets for which our customer has title and we do not have a noncancelable right to use during the term of the supply arrangement, are recorded in accounts receivable in our consolidated balance sheets. The reimbursement for the customer-owned tooling is recorded as a reduction of accounts receivable upon collection. Capitalized items and customer receipts in excess of tooling costs specifically related to a supply arrangement are amortized over the shorter of the term of the arrangement or over the estimated useful lives of the related assets.
Inventory, Policy [Policy Text Block]	INVENTORIES We state our inventories at the lower of cost or net realizable value. The cost of our inventories is determined using the FIFO method. When we determine that our gross inventories exceed usage requirements, or if inventories become obsolete or otherwise not saleable, we record a provision for such loss as a component of our inventory accounts.
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Effective April 1, 2017, we changed our method of accounting for indirect inventory from capitalizing and recording as expense when the inventory was consumed to now expensing indirect inventory at the time of purchase. We believe that expensing indirect inventory at the time of purchase is preferable as the change (1) aligns purchase patterns of indirect inventory with our current operational strategies, (2) reduces administrative burden associated with record keeping for indirect inventory, and (3) results in a uniform accounting policy across our global operations as MPG's accounting method had been to expense indirect inventory upon purchase. Based on the guidance in Accounting Standards Codification (ASC) 250 Accounting Changes and Error Corrections we applied this change in accounting principle retrospectively. As a result of the change, we have decreased previously reported inventories, net by $37.2 million, decreased previously reported retained earnings by $25.8 million and increased previously reported deferred tax assets by $11.4 million as of January 1, 2016 and December 31, 2016. The cumulative impact of the change in accounting principle from January 1, 2015 to March 31, 2017, which covers the periods in which we would be required to retrospectively revise our Statements of Income, is an increase to income of $2.4 million, net of tax. We have determined that the quarterly impact of this adjustment would not be material in any required prior period nor is the impact of recording the cumulative impact of $2.4 million, net of tax material to the current period. As such, we recorded the $2.4 million, net of tax related to prior periods in the second quarter of 2017. The impact of this $2.4 million, net of tax adjustment to income resulted in an increase in basic and diluted earnings per share of $0.02 per share for the year ended December 31, 2017. The impact on the current period income for the year ended December 31, 2017 was immaterial in comparison to accounting for indirect inventory under our historical accounting policy. Based on this change in accounting principle, Raw materials and work-in-progress, and Inventory valuation reserves as of December 31, 2016 reflect decreases of $49.4 million and $12.2 million, respectively.
Property, Plant and Equipment, Policy [Policy Text Block]	PROPERTY, PLANT AND EQUIPMENT We state property, plant and equipment, including amortizable tooling, at historical cost, as adjusted for impairments. Construction in progress includes costs incurred for the construction of buildings and building improvements, and machinery and equipment in process. Repair and maintenance costs that do not extend the useful life or otherwise improve the utility of the asset beyond its existing useful state are expensed in the period incurred. We record depreciation and tooling amortization using the straight-line method over the estimated useful lives of the depreciable assets. Depreciation and tooling amortization amounted to $301.6 million, $160.4 million and $163.6 million in 2017, 2016 and 2015, respectively.
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	IMPAIRMENT OF LONG-LIVED ASSETS When impairment indicators exist, we evaluate the carrying value of long-lived assets for potential impairment. We consider projected future undiscounted cash flows, trends and other circumstances in making such estimates and evaluations. If impairment is deemed to exist, the carrying amount of the asset is adjusted based on its fair value. Recoverability of assets “held for use” is determined by comparing the forecasted undiscounted cash flows of the operations to which the assets relate to their carrying amount. When the carrying value of an asset group exceeds its fair value and is therefore nonrecoverable, those assets are written down to fair value. Fair value is determined based on market prices, when available, or a discounted cash flow analysis performed using management estimates.
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]	GOODWILL We record goodwill when the purchase price of acquired businesses exceeds the value of their identifiable net tangible and intangible assets acquired. We test our goodwill annually as of October 1, or more frequently if necessary, for impairment in accordance with the accounting guidance for goodwill and other indefinite-lived intangibles. We completed impairment tests in 2017 and 2016 and concluded that there was no impairment of our goodwill. See Note 4 - Goodwill and Intangible Assets, for more detail on our goodwill.
Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]	OTHER INTANGIBLE ASSETS In connection with our acquisitions of USM Mexico Manufacturing LLC (USM Mexico) and MPG, we recognized $1,254.8 million of amortizable intangible assets for customer platforms, customer relationships, developed technology and licensing agreements. These intangible assets will be amortized over a period ranging from five to 17 years. The intangible assets were valued using primarily the relief from royalty method or the multi-period excess earnings method, both of which utilize significant unobservable inputs. These inputs are defined in the fair value hierarchy as Level 3 inputs, which require management to make estimates and assumptions regarding certain financial measures using forecasted or projected information. See Note 4 - Goodwill and Intangible Assets, for more detail on our intangible assets.
Debt, Policy [Policy Text Block]	DEBT ISSUANCE COSTS The costs related to the issuance or modification of long-term debt are deferred and amortized into interest expense over the expected life of the borrowings. As of December 31, 2017 and December 31, 2016, our unamortized debt issuance costs were $93.1 million and $16.7 million, respectively. Debt issuance costs associated with our senior unsecured notes, as well as our Term Loan A Facility and Term Loan B Facility (as defined in Note 5 - Long-Term Debt and Lease Obligations), are recorded as a reduction to the related debt liability. Debt issuance costs of $17.5 million and $5.0 million related to our Revolving Credit Facility (also as defined in Note 5 - Long-Term Debt and Lease Obligations), are classified as Other assets and deferred charges on our Consolidated Balance Sheets as of December 31, 2017 and December 31, 2016, respectively. Unamortized debt issuance costs that exist upon the extinguishment of debt are expensed and classified as debt refinancing and redemption costs on our Consolidated Statement of Income.
Derivatives, Policy [Policy Text Block]	DERIVATIVES We recognize all derivatives on the balance sheet at fair value and we are not subject to master netting agreements. If a derivative qualifies under the accounting guidance as a hedge, depending on the nature of the hedge, changes in the fair value of the derivative are either offset against the change in fair value of the hedged asset, liability or firm commitment through earnings or recognized in other comprehensive income until the hedged item is recognized in earnings. The ineffective portion of a derivative's change in fair value, and changes in the fair value of derivatives that do not qualify as hedges, are immediately recognized in earnings. See Note 6 - Derivatives and Risk Management, for more detail on our derivatives.
Foreign Currency Transactions and Translations Policy [Policy Text Block]	CURRENCY TRANSLATION AND REMEASUREMENT We translate the assets and liabilities of our foreign subsidiaries to U.S. dollars at end-of-period exchange rates. We translate the income statement elements of our foreign subsidiaries to U.S. dollars at average-period exchange rates. We report the effect of translation for our foreign subsidiaries that use the local currency as their functional currency as a separate component of stockholders' equity. Gains and losses resulting from the remeasurement of assets and liabilities in a currency other than the functional currency of a subsidiary are reported in current period income. We also report any gains and losses arising from transactions denominated in a currency other than the functional currency of a subsidiary in current period income. These foreign currency gains and losses resulted in a net loss of $7.3 million in 2017, and net gains of $5.8 million and $9.5 million for the years 2016 and 2015, respectively, in Other income (expense).
Postemployment Benefit Plans, Policy [Policy Text Block]	PENSION AND OTHER POSTRETIREMENT DEFINED BENEFIT PLANS Net pension and postretirement benefit expenses and the related liabilities are determined on an actuarial basis. These plan expenses and obligations are dependent on management's assumptions developed in consultation with our actuaries. We review these actuarial assumptions at least annually and make modifications when appropriate. See Note 8 - Employee Benefit Plans, for more detail on our pension and other postretirement defined benefit plans.
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	STOCK-BASED COMPENSATION We have stock-based compensation in the form of restricted stock units (RSUs) and performance shares. For non-performance based awards, the grant date fair value is measured as the stock price at the date of grant. For performance based awards, fair value is estimated using valuation techniques that require management to use estimates and assumptions. Certain awards require that management's estimates and assumptions be evaluated at each reporting date to determine if compensation expense related to the award should be adjusted, both on a catch-up and go-forward basis. Compensation expense is recognized over the period during which the requisite service is provided, referred to as the vesting period. See Note 9 - Stock-Based Compensation, for more detail on our accounting for stock-based compensation.
Income Tax, Policy [Policy Text Block]	DEFERRED INCOME TAX ASSETS AND LIABILITIES AND VALUATION ALLOWANCES Our deferred income tax assets and liabilities reflect the impact of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the basis of such assets and liabilities as measured by tax laws. In accordance with the accounting guidance for income taxes, we estimate whether recoverability of our deferred tax assets is “more likely than not,” based on forecasts of taxable income in the related tax jurisdictions. In this estimate, we use historical results, projected future operating results based upon approved business plans, eligible carryforward periods, tax planning opportunities and other relevant considerations. This includes the consideration of tax law changes, prior profitability performance and the uncertainty of future projected profitability. We record a valuation allowance to reduce our deferred tax assets to the amount that is "more likely than not," to be realized. We record uncertain tax positions on the basis of a two-step process whereby: (1) we determine whether it is "more likely than not" that the tax positions will be sustained based on the technical merits of the position: and (2) for those positions that meet the "more likely than not" recognition threshold, we recognize the largest amount of tax benefit that is greater than 50% likely to be realized upon ultimate settlement with the related tax authority. We record interest and penalties on uncertain tax positions in income tax expense (benefit). See Note 10 - Income Taxes, for more detail on our accounting for income taxes.
Earnings Per Share, Policy [Policy Text Block]	EARNINGS PER SHARE (EPS) We present EPS using the two-class method. This method allocates undistributed earnings between common shares and non-vested share based payment awards that entitle the holder to non-forfeitable dividend rights. Our participating securities include non-vested restricted stock units. See Note 11 - Earnings Per Share (EPS), for more detail on our accounting for EPS.
Authorized Share Repurchase Program [Policy Text Block]	SHARE REPURCHASE PROGRAM In 2016, AAM's Board of Directors authorized a share repurchase program of up to $100 million of AAM's common shares through December 31, 2018 as part of AAM's overall capital allocation strategy. The repurchase of shares may be made in the open market or in privately negotiated transactions and will be funded through available cash balances and cash flow from operations. The timing and amount of any share repurchases will be determined based on market and economic conditions, share price, alternative uses of capital and other factors. We did not repurchase any shares under the share repurchase program during 2017. As of December 31, 2017 there is approximately $98.5 million available for repurchase.
Standard Product Warranty, Policy [Policy Text Block]	PRODUCT WARRANTY See Note 12 - Commitments and Contingencies, for more detail on our accounting for product warranties.
Use of Estimates, Policy [Policy Text Block]	USE OF ESTIMATES In order to prepare consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP), we are required to make estimates and assumptions that affect the reported amounts and disclosures in our consolidated financial statements. Actual results could differ from those estimates.
New Accounting Pronouncements, Policy [Policy Text Block]	EFFECT OF NEW ACCOUNTING STANDARDS Accounting Standards Update 2017-12 On August 28, 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2017-12 - Targeted Improvements to Accounting for Hedging Activities (Topic 815). ASU 2017-12 is intended to better align the risk management activities of a company with the company's financial reporting for hedging relationships. This guidance expands and refines several aspects of hedge accounting. The most applicable changes to AAM as a result of the new guidance are as follows: 1) the concept of risk component hedging is introduced in ASU 2017-12, which could allow us to hedge contractually specified components in a contract; 2) the guidance now allows entities to utilize a 31-day period in assessing whether the critical terms of a forecasted transaction match the maturity of the hedging derivative, which could allow for expanded use of hedging instruments for certain sales and purchases; and 3) we may now qualitatively assess hedge effectiveness on a quarterly basis when the facts and circumstances related to the hedging relationship have not changed significantly. This guidance becomes effective at the beginning of our 2019 fiscal year, however early adoption is permitted, and we have adopted this guidance effective January 1, 2018. The adoption of this guidance will not have any impact on the measurement or presentation of our existing hedging relationships. Accounting Standards Update 2017-07 On March 10, 2017, the FASB issued ASU 2017-07 - Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendments in this update require that an employer disaggregate the service cost component from the other components of defined benefit pension cost and postretirement benefit cost (net benefit cost). Subsequent to the adoption of this guidance, only the service cost component of net benefit cost will be included in the subtotal operating income in our Consolidated Statements of Income and only the service cost component will be eligible for capitalization. This guidance became effective at the beginning of our 2018 fiscal year and requires a retrospective transition method for the income statement classification of the net benefit cost components and a prospective transition method for the capitalization of the service cost component in assets. The adoption of this guidance is not expected to have a material impact on our consolidated financial statements. Accounting Standards Update 2017-04 On January 26, 2017, the FASB issued ASU 2017-04 - Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. The amendments in this update modify the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. An entity no longer will determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination, or what is referred to under existing guidance as "Step 2." Instead, under the amendments in this update, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. This guidance becomes effective at the beginning of our 2020 fiscal year and early adoption is permitted. The guidance requires a prospective transition method. We do not expect the adoption of this guidance to have a material effect on our consolidated financial statements, however, goodwill could be more susceptible to impairment in periods subsequent to adoption. Accounting Standards Update 2016-16 On October 24, 2016, the FASB issued Accounting Standards Update (ASU) 2016-16 - Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. Existing income tax guidance prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party. This existing guidance is deemed an exception to the principle of comprehensive recognition of current and deferred income taxes under accounting principles generally accepted in the United States of America (GAAP). Due to the limited authoritative guidance about this exception, diversity in practice exists. ASU 2016-16 eliminates this exception for intra-entity transfers of assets other than inventory and requires that entities recognize the income tax consequences when the transfers occur. This guidance was effective January 1, 2018 and requires a modified retrospective transition method. The adoption of this guidance did not have a significant impact on our consolidated financial statements. Accounting Standards Update 2016-02 On February 25, 2016, the FASB issued ASU 2016-02 - Leases (Topic 842), and has subsequently issued ASU 2017-13 - Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840) and Leases (Topic 842) (collectively the Lease ASUs) which supersede the existing lease accounting guidance and establish new criteria for recognizing lease assets and liabilities. The most significant impact of the updates, to AAM, is that a lessee will be required to recognize a "right-of-use" asset and lease liability for operating lease agreements that were not previously included on the balance sheet under the existing lease guidance. A lessee will be permitted to make a policy election, excluding recognition of the right-of-use asset and associated liability for lease terms of 12 months or less. Expense recognition in the statement of income along with cash flow statement classification for both financing (capital) and operating leases under the new standard will not be significantly changed from existing lease guidance. This guidance becomes effective for AAM at the beginning of our 2019 fiscal year and requires transition under a modified retrospective method. We are currently assessing the impact that this standard will have on our consolidated financial statements. Accounting Standards Update 2014-09 In 2014, the FASB issued ASU 2014-09 - Revenue from Contracts with Customers (Topic 606), and has subsequently issued ASUs 2015-14 - Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, 2016-08 - Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross Versus Net), 2016-10 - Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, 2016-12 - Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, 2016-20 - Revenue from Contracts with Customers (Topic 606): Technical Corrections and Improvements to Topic 606 and 2017-13 - Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840) and Leases (Topic 842) (collectively, the Revenue Recognition ASUs). The Revenue Recognition ASUs outline a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersede most current revenue recognition guidance, including industry-specific guidance. The guidance is based on the principle that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to fulfill a contract. This guidance became effective for AAM on January 1, 2018 and we have adopted this guidance using the modified retrospective approach. We have evaluated each of the five steps in the new revenue recognition model, which are as follows: 1) Identify the contract with the customer; 2) Identify the performance obligations in the contract; 3) Determine the transaction price; 4) Allocate the transaction price to the performance obligations; and 5) Recognize revenue when (or as) performance obligations are satisfied. We do not expect the impact of implementing the Revenue Recognition ASUs to be material to our financial statements, nor do we expect our method and timing for recognizing revenue subsequent to the implementation of the Revenue Recognition ASUs to vary significantly from our revenue recognition practices under current GAAP. There are also certain considerations related to internal control over financial reporting that are associated with implementing the new guidance under Topic 606 and we have designed and implemented the necessary changes to our control framework for the new guidance. Specifically, disclosure requirements under the new guidance in Topic 606 have been significantly expanded in comparison to the disclosure requirements under the current guidance. We have completed our assessment of the new disclosure requirements and are completing the process of drafting our disclosures for both interim and annual periods under Topic 606.