American Axle & Manufacturing (AXL) 10-Q 3 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	9 Months Ended
	Sep. 30, 2017	Nov. 01, 2017
Entity Registrant Name	AMERICAN AXLE & MANUFACTURING HOLDINGS INC
Entity Central Index Key	1,062,231
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Document Type	10-Q
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		111,290,072
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net sales	$ 1,724.4	$ 1,006.9	$ 4,532.1	$ 3,001.5
Cost of goods sold	1,426.7	825.7	3,707.3	2,454.9
Gross profit	297.7	181.2	824.8	546.6
Selling, general and administrative expenses	102.3	78.6	289.1	231.8
Amortization of intangible assets	24.4	1.3	50.8	3.6
Restructuring and acquisition-related costs	22.8	0	90.5	0
Operating income	148.2	101.3	394.4	311.2
Interest expense	(57.5)	(23.2)	(139.9)	(70.2)
Investment income	0.8	0.5	2.2	2.6
Debt refinancing and redemption costs	0	0	(2.7)	0
Other income (expense), net	0.5	0.9	(7.4)	4
Income before income taxes	92	79.5	246.6	247.6
Income tax expense	5.7	17.8	15.6	53.8
Net income	86.3	61.7	231	193.8
Net income attributable to noncontrolling interests	(0.1)	0	(0.2)	0
Net income attributable to AAM	$ 86.2	$ 61.7	$ 230.8	$ 193.8
Basic earnings per share	$ 0.76	$ 0.79	$ 2.28	$ 2.48
Diluted earnings per share	$ 0.75	$ 0.78	$ 2.27	$ 2.47

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 86.3	$ 61.7	$ 231	$ 193.8
Other comprehensive income (loss)
Defined benefit plans, net of tax (a)	3.1	0.6	3.7	5.3
Foreign currency translation adjustments	42.8	(0.8)	79.3	15
Changes in cash flow hedges, net of tax (b)	1.1	(4.1)	21.5	(6.4)
Other comprehensive income (loss)	47	(4.3)	104.5	13.9
Comprehensive income	133.3	57.4	335.5	207.7
Net income attributable to noncontrolling interests	(0.1)	0	(0.2)	0
Comprehensive income attributable to AAM	$ 133.2	$ 57.4	$ 335.3	$ 207.7

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other comprehensive income (loss), pension and other postretirement benefit plans, tax	$ (1)	$ (0.1)	$ (1.2)	$ (2.8)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	$ 0	$ 0	$ 0.7	$ 0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 549.6	$ 481.2
Accounts receivable, net	1,122	560
Inventories, net	396.6	182.3
Prepaid expenses and other	144.5	75.8
Total current assets	2,212.7	1,299.3
Property, plant and equipment, net	2,302.7	1,093.7
Deferred income taxes	39.9	369.4
Goodwill	1,654.6	154
Intangible assets, net	1,236.6	28.5
GM postretirement cost sharing asset	232.2	236.1
Other assets and deferred charges	379.6	242.9
Total assets	8,058.3	3,423.9
Current liabilities
Current portion of long-term debt	6.8	3.3
Accounts payable	856.4	382.3
Accrued compensation and benefits	200	139.3
Deferred revenue	28.5	24.6
Accrued expenses and other	193.3	102
Total current liabilities	1,285	651.5
Long-term debt, net	4,169.3	1,400.9
Deferred revenue	79.7	70.8
Deferred income taxes	233.5	15
Postretirement benefits and other long-term liabilities	854.2	779.9
Total liabilities	6,621.7	2,918.1
Stockholders' equity
118.2 million shares issued as of September 30, 2017 and 83.0 million shares issued as of December 31, 2016	1.2	0.9
Paid-in capital	1,258.5	660.1
Retained earnings	656.3	425.5
Treasury stock at cost, 6.9 million shares as of September 30, 2017 and 6.5 million shares as of December 31, 2016	(198.1)	(191.1)
Accumulated other comprehensive loss
Defined benefit plans, net of tax	(239.8)	(243.5)
Foreign currency translation adjustments	(43.1)	(122.4)
Unrecognized loss on cash flow hedges, net of tax	(2.2)	(23.7)
Total AAM stockholders' equity	1,432.8	505.8
Noncontrolling interests in subsidiaries	3.8	0
Total stockholders' equity	1,436.6	505.8
Total liabilities and stockholders' equity	$ 8,058.3	$ 3,423.9

Condensed Consolidated Balance6

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Millions	Sep. 30, 2017	Dec. 31, 2016
Common stock, par or stated value per share	$ 0.01	$ 0.01
Treasury stock, shares	6.9	6.5
Common Stock, Shares, Issued	118.2	83

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 231	$ 193.8
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	303.4	150.4
Asset Impairment Charges	0	3.4
Deferred income taxes	(43.8)	32.3
Stock-based compensation	37.2	15.8
Pensions and other postretirement benefits, net of contributions	0.6	(5.7)
Loss on disposal of property, plant and equipment, net	0.7	2.2
Undistributed earnings in affiliate	(2)	(2.2)
Debt refinancing and redemption costs	2.7	0
Changes in operating assets and liabilities, net of amounts acquired
Accounts receivable	(131)	(140)
Inventories	(3.3)	13.7
Accounts payable and accrued expenses	65.3	98.1
Deferred revenue	10.1	(8.9)
Other assets and liabilities	(50.2)	(61.9)
Net cash provided by operating activities	420.7	291
Investing activities
Purchases of property, plant and equipment	(278.7)	(158.7)
Proceeds from sale of property, plant and equipment	1.7	0.7
Proceeds from government grants	0	2.8
Purchase buyouts of leased equipment	(12.6)	0
Final distribution of Reserve Yield Plus Fund	0	1
Proceeds from sale of business, net	5.9	0
Acquisition of business, net of cash acquired	(895.5)	(5.6)
Net cash used in investing activities	(1,179.2)	(159.8)
Financing activities
Payments of long-term debt and capital lease obligations	(1,944.6)	(6.2)
Proceeds from issuance of long-term debt	2,858.1	28.8
Debt issuance costs	(90.8)	0
Purchase of treasury stock	(7)	(5.3)
Employee stock option exercises	0.9	0.3
Net cash provided by financing activities	816.6	17.6
Effect of exchange rate changes on cash	10.3	2.6
Net increase in cash and cash equivalents	68.4	151.4
Cash and cash equivalents at beginning of period	481.2	282.5
Cash and cash equivalents at end of period	549.6	433.9
Supplemental cash flow information
Interest paid	108.9	61.3
Income taxes paid, net of refunds	30.2	42.5
Non-cash investing activities: AAM common shares issued for acquisition of MPG	$ 576.7	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2017
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 On April 6, 2017, Alpha SPV I, Inc., a wholly-owned subsidiary of American Axle & Manufacturing Holdings, Inc. (Holdings), merged with and into Metaldyne Performance Group, Inc. (MPG), with MPG as the surviving corporation in the merger. Upon completion of the merger, MPG became a wholly-owned subsidiary of Holdings. As a result, we are now a global Tier I supplier to the automotive, commercial and industrial markets. We design, engineer, validate and manufacture driveline, metal forming, powertrain and casting products, employing over 25,000 associates, operating at more than 90 facilities in 17 countries, to support our customers on global and regional platforms with a continued focus on delivering operational excellence, technology leadership and quality. 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, 2016 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. Actual results could differ from those estimates. 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, 2016 . Change in Accounting Principle 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 the administrative burden associated with recordkeeping 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 $24.2 million and increased previously reported deferred tax assets by $13.0 million as of January 1, 2016 and December 31, 2016. The cumulative impact of the change in accounting principle from January 1, 2016 to March 31, 2017, which covers the periods in which we would be required to retrospectively revise our Statements of Income and Balance Sheets, 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 adjustment 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 nine months ended September 30, 2017. The impact on current period income for the quarter ended September 30, 2017 was immaterial in comparison to accounting for indirect inventory under our historical accounting policy. See Note 5 - Inventories for further discussion. 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 expect to adopt this guidance effective January 1, 2018. The adoption of this guidance is not expected to 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). The amendments also provide explicit guidance on how to present the service cost component and the other components of net benefit cost in the income statement and allow only the service cost component of net benefit cost to be eligible for capitalization. This guidance becomes 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. We are currently assessing the impact that this standard will have 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, however early adoption is permitted. The guidance requires a prospective transition method. We are currently assessing the impact that this standard will have on our consolidated financial statements. Accounting Standards Update 2016-16 On October 24, 2016, the FASB issued 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 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 becomes effective at the beginning of our 2018 fiscal year and requires a modified retrospective transition method. We are currently assessing the impact that this standard will have on our consolidated financial statements. Accounting Standards Update 2016-02 On February 25, 2016, the FASB issued ASU 2016-02 - Leases (Topic 842) , which supersedes the existing lease accounting guidance and establishes new criteria for recognizing lease assets and liabilities. The most significant impact of the update, 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 , and 2016-20 - Revenue from Contracts with Customers (Topic 606): Technical Corrections and Improvements to Topic 606 (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 is effective for AAM beginning on January 1, 2018 and entities have the option of using either a full retrospective or a modified retrospective approach for the adoption of the new standard. We expect to adopt this guidance using the modified retrospective approach. We are concluding the assessment phase of implementing this guidance. 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. Our preliminary conclusion is that the impact of implementing the Revenue Recognition ASUs will be immaterial to our financial statements and that our method for recognizing revenue subsequent to the implementation of the Revenue Recognition ASUs will not vary significantly from our revenue recognition practices under current GAAP. There are certain considerations related to internal control over financial reporting that are associated with implementing the new guidance under Topic 606 and we are currently implementing the necessary changes to our control framework for revenue recognition. Disclosure requirements under the new guidance in Topic 606 have been significantly expanded in comparison to the disclosure requirements under the current guidance. We are currently concluding our assessment of the new disclosure requirements and we are in the process of drafting our disclosures for both interim and annual periods under Topic 606. 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. Approximately $1.5 million of shares have been repurchased under the authorized share repurchase program, leaving approximately $98.5 million available for repurchase. There were no repurchases under the program in the first nine months of 2017.

Restructuring and Acquisition-R

Restructuring and Acquisition-Related Costs	9 Months Ended
	Sep. 30, 2017
Restructuring and Related Activities [Abstract]
Business Acquisition, Integration, Restructuring and Other Related Costs [Text Block]	2. RESTRUCTURING AND ACQUISITION-RELATED COSTS In the fourth quarter of 2016, AAM initiated actions under a global restructuring program focused on creating a more streamlined organization in addition to reducing our cost structure and preparing for acquisition integration activities. A summary of this activity for the first nine months of 2017 is shown below: Severance Charges Implementation Costs Total (in millions) Accrual as of December 31, 2016 $ 0.6 $ 9.2 $ 9.8 Charges 1.7 13.5 15.2 Cash utilization (2.3 ) (17.8 ) (20.1 ) Non-cash utilization — — — Accrual adjustments — — — Accrual as of September 30, 2017 $ — $ 4.9 $ 4.9 As part of our restructuring actions, we incurred severance charges of approximately $1.7 million , as well as implementation costs, including professional expenses, of approximately $13.5 million during the nine months ended September 30, 2017. Since the inception of our global restructuring program, we have incurred severance charges totaling $2.3 million and implementation costs totaling $23.7 million . We expect to incur up to $5 million of additional charges under our global restructuring program in 2017. On March 1, 2017, we completed the acquisition of USM Mexico Manufacturing LLC (USM Mexico) and on April 6, 2017, we completed the acquisition of MPG. During the nine months ended September 30, 2017, we incurred the following charges related to these acquisitions: Acquisition-Related Costs Severance Charges Integration Expenses Total (in millions) Charges $ 40.7 $ 5.6 $ 29.0 $ 75.3 Total restructuring and acquisition-related charges $ 90.5 Acquisition-related costs primarily consist of advisory, legal, accounting, valuation and certain other professional or consulting fees incurred. Also included in acquisition-related costs is a one-time charge of approximately $20 million for MPG stock-based compensation that was accelerated and settled as a result of the acquisition. Integration expenses reflect costs incurred for information technology systems, ongoing operational activities, and consulting fees incurred in conjunction with the acquisitions. Total charges associated with our global restructuring program and acquisition-related charges of $22.8 million and $90.5 million are shown on a separate line item titled "Restructuring and Acquisition-Related Costs" in our Condensed Consolidated Statements of Income for the three and nine months ended September 30, 2017, respectively.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	3. BUSINESS COMBINATIONS Acquisition of MPG On April 6, 2017, AAM completed its acquisition of 100% of the equity interests of MPG for a total purchase price of approximately $1.5 billion plus the assumption of approximately $1.7 billion in net debt (comprised of approximately $1.9 billion in debt less approximately $0.2 billion of MPG cash and cash equivalents). Under the terms of the agreement and plan of merger (Merger Agreement), each share of MPG common stock (other than MPG excluded shares as defined in the Merger Agreement) was converted into the right to receive (a) $13.50 in cash, without interest, and (b) 0.5 of a share of AAM common stock (Merger Consideration). Further, MPG stock options outstanding immediately prior to the effective time of the merger were accelerated and holders of the stock options received the Merger Consideration less the per share exercise price of the MPG stock options. All MPG restricted shares and restricted stock unit awards outstanding under an MPG equity plan were also accelerated and each holder thereof received the Merger Consideration for each restricted share or restricted stock unit award of MPG common stock. MPG provides highly-engineered components for use in powertrain and safety-critical platforms for the global light, commercial and industrial markets. MPG produces these components using complex metal-forming manufacturing technologies and processes for a global customer base of OEMs and Tier I suppliers, which help their customers meet fuel economy, performance and safety standards. Our acquisition of MPG contributes significantly to diversifying our global customer base and end markets, while also allowing us to expand our presence as a global Tier I supplier to the commercial and industrial markets, in addition to our existing presence as a global Tier I supplier to the automotive industry. The aggregate cash consideration for the acquisition of MPG was financed using (i) net proceeds from the issuance in March 2017 by AAM of $1.2 billion of new senior notes consisting of $700.0 million aggregate principal amount of 6.25% senior notes due 2025, and $500.0 million aggregate principal amount of 6.50% senior notes due 2027, and on April 6, 2017: (ii) borrowings by AAM of $100.0 million under a term loan that matures in 2022, (iii) borrowings by AAM of $1.55 billion under a term loan that matures in 2024, and (iv) cash on hand. The acquisition of MPG was accounted for under the acquisition method under Accounting Standards Codification 805 Business Combinations (ASC 805) with the purchase price allocated to the identifiable assets and liabilities of the acquired company based on the respective fair values of the assets and liabilities. The following represents the preliminary fair values of the assets acquired and liabilities assumed resulting from the acquisition, as well as the calculation of goodwill: (in millions) April 6, 2017 Cash consideration $ 953.5 Share consideration 576.7 Total consideration transferred $ 1,530.2 Fair value of MPG noncontrolling interests 3.6 Total fair value of MPG $ 1,533.8 Cash and cash equivalents $ 202.1 Accounts receivable 403.2 Inventories 199.0 Prepaid expenses and other long-term assets 121.0 Property, plant and equipment 985.7 Intangible assets 1,223.1 Total assets acquired $ 3,134.1 Accounts payable 287.8 Accrued expenses and other 137.2 Deferred income tax liabilities 596.4 Debt 1,918.7 Postretirement benefits and other long-term liabilities 54.5 Net assets acquired $ 139.5 Goodwill $ 1,394.3 The preliminary allocation of the purchase price to the assets acquired and liabilities assumed, including the residual amount recognized as goodwill, is based upon estimated information and is subject to change within the measurement period. Under the guidance in ASC 805, the measurement period is a period not to exceed one year from the acquisition date during which we may adjust estimated or provisional amounts recorded during purchase accounting if new information is obtained about facts and circumstances that existed as of the acquisition date that, if known, would have resulted in revised estimated values of those assets or liabilities as of that date. Measurement period adjustments are recorded in the period identified with an offsetting entry to goodwill. Any adjustments to amounts recorded in purchase accounting that do not qualify as measurement period adjustments will be included in earnings in the period identified. In the third quarter of 2017, we made measurement period adjustments to reflect changes to facts and circumstances that existed as of the acquisition date, which resulted in a net increase in Goodwill of $18.0 million . These adjustments related primarily to Intangible assets and the corresponding offset to Deferred income tax liabilities as a result of changes to our third-party valuation and customary post-closing reviews. The resulting impact to amortization expense in our Condensed Consolidated Statements of Income for the three and nine months ended September 30, 2017 of adjusting our intangible assets was immaterial. The primary areas of the preliminary purchase price allocation that are not yet finalized relate to the fair value of property, plant and equipment and intangible assets, as well as deferred income tax assets and liabilities, and contingent liabilities. The fair values of the assets acquired and liabilities assumed are based on our preliminary estimates and assumptions, as well as other information compiled by management, including valuations that utilize customary valuation procedures and techniques. While we believe that these preliminary estimates provide a reasonable basis for estimating the fair value of the assets acquired and liabilities assumed, we will continue to evaluate available information prior to finalization of the amounts. Goodwill resulting from the acquisition is primarily attributable to anticipated synergies and economies of scale from which we expect to benefit as a combined entity. None of the goodwill is expected to be deductible for tax purposes. We recognized $1,223.1 million of amortizable intangible assets for customer platforms, customer relationships, developed technology and licensing agreements as a result of the acquisition of MPG. 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. AAM had an existing accounts payable balance of $12.4 million with MPG as of the date of acquisition. As a result of the acquisition, this pre-existing accounts payable balance was settled and AAM accounted for this settlement separately from the acquisition. This resulted in a $12.4 million reduction in the purchase price and this portion of the cash paid to acquire MPG has been reflected as an operating cash outflow in our Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2017. Included in net sales and net income attributable to AAM for the period from the acquisition date on April 6, 2017 through September 30, 2017 was approximately $1,351 million and $42 million , respectively, attributable to MPG. Unaudited Pro Forma Financial Information Unaudited pro forma net sales for AAM, on a combined basis with MPG for the nine months ended September 30, 2017 and September 30, 2016, were $5.3 billion and $5.1 billion , respectively, excluding MPG sales to AAM during those periods. Unaudited pro forma net income amounts for the nine months ended September 30, 2017 and September 30, 2016 were approximately $290 million and $170 million , respectively. Unaudited pro forma earnings per share amounts for the nine months ended September 30, 2017 and September 30, 2016 were $2.57 per share and $1.64 per share, respectively. The unaudited pro forma net income amounts for the nine months ended September 30, 2017 and September 30, 2016 have been adjusted by approximately $20 million for a one-time charge for MPG stock-based compensation that was accelerated and settled on the date of acquisition, approximately $25 million related to the step-up of inventory to fair value as a result of the acquisition, and approximately $55 million in acquisition-related costs. This adjustment resulted in a reclassification of approximately $65 million , net of tax, from unaudited pro forma net income for the first nine months of 2017 into pro forma net income for the first nine months of 2016, as we are required to disclose the unaudited pro forma amounts as if the acquisition of MPG had been completed on January 1, 2016. The disclosure of unaudited pro forma net sales and earnings is for informational purposes only and does not purport to indicate the results that would actually have been obtained had the merger been completed on the assumed date for the periods presented, or which may be realized in the future. Acquisition of USM Mexico On March 1, 2017, AAM completed the acquisition of 100% of USM Mexico, a former subsidiary of U.S. Manufacturing Corporation (USM). The purchase price was funded entirely with available cash and the acquisition was accounted for under the acquisition method. USM Mexico includes USM's operations in Guanajuato, Mexico, which has historically been one of the largest suppliers to AAM's Guanajuato Manufacturing Complex. This acquisition allows AAM to vertically integrate the supply chain and helps ensure continuity of supply for certain parts to our largest manufacturing facility. The following represents the estimated fair value of the assets acquired and liabilities assumed resulting from the acquisition, as well as the calculation of goodwill: (in millions) March 1, 2017 Contractual purchase price $ 162.5 Adjustments to contractual purchase price for capital equipment 4.9 Adjustment to contractual purchase price for settlement of existing accounts payable balance (22.8 ) Cash acquired (0.5 ) Adjusted purchase price, net of cash acquired $ 144.1 Accounts receivable 1.1 Inventories 4.8 Prepaid expenses and other 2.4 Property, plant and equipment 38.4 Intangible assets 31.7 Total assets acquired $ 78.4 Accounts payable 10.8 Accrued expenses and other 2.7 Deferred income tax liabilities 1.2 Net assets acquired $ 63.7 Goodwill $ 80.4 The purchase agreement specifies a period of time subsequent to the acquisition date for calculating the final working capital amount of USM Mexico as of the acquisition date. As a result, the purchase price, working capital and goodwill amounts as included in the table above are considered provisional and are subject to adjustment. We expect these provisional amounts to be finalized in the fourth quarter of 2017. None of the goodwill is expected to be deductible for tax purposes. AAM had an existing accounts payable balance of $22.8 million with USM Mexico as of the date of acquisition. As a result of the acquisition, this pre-existing accounts payable balance was settled and AAM accounted for this settlement separately from the acquisition. This resulted in a $22.8 million reduction in the purchase price and this portion of the cash paid to acquire USM Mexico has been reflected as an operating cash outflow in our Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2017. The operating results of USM Mexico from the acquisition date through September 30, 2017 were insignificant to AAM's Condensed Consolidated Statement of Income for the three months and nine months ended September 30, 2017. Further, we have not included pro forma revenue and earnings for the nine months ended September 30, 2017 and September 30, 2016 as the inclusion of USM Mexico would be insignificant to AAM's consolidated results for these periods.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets Disclosure [Text Block]	4. GOODWILL AND INTANGIBLE ASSETS Goodwill The following table provides a reconciliation of changes in goodwill for the nine months ended September 30, 2017: Driveline Metal Forming Powertrain Casting Consolidated (in millions) Balance as of December 31, 2016 $ 130.1 $ 23.9 $ — $ — $ 154.0 Acquisition of MPG — 516.0 472.3 406.0 1,394.3 Acquisition of USM Mexico 80.4 — — — 80.4 Foreign currency translation 0.4 16.6 8.9 — 25.9 Balance as of September 30, 2017 $ 210.9 $ 556.5 $ 481.2 $ 406.0 $ 1,654.6 Intangible Assets As a result of the acquisitions of MPG and USM Mexico, AAM identified and recognized certain intangible assets that are subject to amortization. The weighted-average amortization period for all intangible assets recognized as a result of these acquisitions is 13.6 years . The following table provides a breakout of the major intangible assets acquired by class: Estimated September 30, Useful Lives 2017 (years) (in millions) MPG Customer platforms 14 $ 950.0 Customer relationships 16-17 151.8 Technology and other 5-13 121.3 Total MPG $ 1,223.1 USM Mexico Technology 13 $ 29.5 Customer platforms 13 2.2 Total USM Mexico $ 31.7 Total $ 1,254.8 In the third quarter of 2017, we made measurement period adjustments related to the acquisition of MPG to reflect changes to facts and circumstances that existed as of the acquisition date. These adjustments resulted in a decrease to customer platforms of $20.0 million and a decrease in customer relationships of $1.5 million as a result of changes to our third-party valuation and customary post-closing reviews. The impact to amortization expense in our Condensed Consolidated Statements of Income for the three and nine months ended September 30, 2017 as a result of adjusting our intangible assets was immaterial. The following table provides a reconciliation of the gross carrying amount and associated accumulated amortization for AAM's total intangible assets, which are all subject to amortization: September 30, December 31, 2017 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in millions) Capitalized computer software $ 35.2 $ (12.8 ) $ 22.4 $ 31.7 $ (8.5 ) $ 23.2 e-AAM in-process research and development 5.9 — 5.9 5.3 — 5.3 Customer platforms 952.2 (35.3 ) 916.9 — — — Customer relationships 151.8 (4.9 ) 146.9 — — — Technology and other 150.8 (6.3 ) 144.5 — — — Total $ 1,295.9 $ (59.3 ) $ 1,236.6 $ 37.0 $ (8.5 ) $ 28.5 Amortization expense for these intangible assets was $24.4 million and $50.8 million for the three and nine months ended September 30, 2017, respectively, and $1.3 million and $3.6 million for the three and nine months ended September 30, 2016, respectively. Estimated amortization expense for each of the next five years is as follows: approximately $75 million in 2017 and approximately $100 million in each of the years 2018 through 2021.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2017
Inventory Disclosure [Abstract]
Inventory Disclosure [Text Block]	5. INVENTORIES We state our inventories at the lower of cost or net realizable value. The cost of our inventories is determined using the first-in first-out 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. Inventories consist of the following: September 30, 2017 December 31, 2016 (in millions) Raw materials and work-in-progress $ 331.4 $ 163.3 Finished goods 90.0 33.8 Gross inventories 421.4 197.1 Inventory valuation reserves (24.8 ) (14.8 ) Inventories, net $ 396.6 $ 182.3 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. Based on the guidance in ASC 250 Accounting Changes and Error Corrections, we have adjusted retained earnings to reflect the retrospective application of this change in accounting principle. Refer to Note 1 - Organization and Basis of Presentation for further detail. Based on this change in accounting principle, Raw materials and work-in-progress and Inventory valuation reserves, as of December 31, 2016, reflect a decrease of $49.4 million and a decrease of $12.2 million , respectively.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Long-term Debt [Text Block]	6. LONG-TERM DEBT Long-term debt consists of the following: September 30, 2017 December 31, 2016 (in millions) Revolving Credit Facility $ — $ — Term Loan A Facility 93.8 — Term Loan B Facility 1,530.6 — 7.75% Notes due 2019 200.0 200.0 6.625% Notes due 2022 550.0 550.0 6.50% Notes due 2027 500.0 — 6.25% Notes due 2025 700.0 — 6.25% Notes due 2021 400.0 400.0 5.125% Notes due 2019 200.0 200.0 Foreign credit facilities 52.3 60.4 Capital lease obligations 28.6 5.5 Total debt 4,255.3 1,415.9 Less: Current portion of long-term debt 6.8 3.3 Long-term debt 4,248.5 1,412.6 Less: Debt issuance costs 79.2 11.7 Long-term debt, net $ 4,169.3 $ 1,400.9 New Senior Secured Credit Facilities In connection with our acquisition of MPG (the Acquisition) on April 6, 2017, Holdings and American Axle & Manufacturing, Inc. (AAM, Inc.) entered into a credit agreement (the Credit Agreement), among AAM, Inc., as borrower, Holdings, each financial institution party thereto as a lender (the Lenders) and administrative agent, pursuant to which Holdings and certain of its restricted subsidiaries (including certain subsidiaries of MPG acquired as part of the Acquisition) are required to guarantee the borrowings of AAM, Inc. thereunder and Holdings, AAM, Inc. and certain of their restricted subsidiaries are required to pledge their assets (including, without limitation, after-acquired assets), subject to certain exceptions and limitations. In connection with the Credit Agreement, Holdings, AAM, Inc. and certain of their restricted subsidiaries entered into a Collateral Agreement and Guarantee Agreement with the financial institutions party thereto as collateral agent and administrative agent. Pursuant to the Credit Agreement, the Lenders agreed to provide a $100.0 million term loan A facility (the Term Loan A Facility), a $1.55 billion term loan B facility (the Term Loan B Facility) and a $900 million multi-currency revolving credit facility (the Revolving Credit Facility, and together with the Term Loan A Facility and the Term Loan B Facility, the New Senior Secured Credit Facilities). The proceeds of the Term Loan A Facility and the Term Loan B Facility were used to finance a portion of the consideration for the Acquisition, pay transaction costs, redeem in full MPG Holdco I Inc.’s 7.375% Senior Notes due 2022, and repay the existing indebtedness of AAM, Inc. under its Amended and Restated Credit Agreement, dated as of January 9, 2004, amended and restated as of September 13, 2013 and as further amended, among AAM, Inc., as borrower, Holdings, and each financial institution party thereto as a lender and administrative agent, as well as repay existing indebtedness of MPG under its Credit Agreement, dated as of October 20, 2014 and as amended as of May 8, 2015, among MPG Holdco I Inc., as guarantor, MPG, the subsidiary guarantors party thereto, and each financial institution party thereto as a lender and administrative agent. The proceeds of the Revolving Credit Facility will be used for general corporate purposes. We paid debt issuance costs of $53.9 million in the first nine months of 2017 related to the New Senior Secured Credit Facilities. The Term Loan A Facility and the Revolving Credit Facility will mature on April 6, 2022, and the Term Loan B Facility will mature on April 6, 2024. Borrowings under the New Senior Secured Credit Facilities bear interest at rates based on the applicable Eurodollar rate or alternate base rate, as AAM may elect, in each case plus an applicable margin determined based on AAM’s total net leverage ratio. The alternate base rate is the greatest of (a) the prime rate of a major United States financial institution, (b) the Federal Reserve Bank of New York rate plus 0.50% and (c) the adjusted Eurodollar rate plus 1.00%. The applicable margin for Eurodollar-based loans under the New Senior Secured Credit Facilities will be between 1.25% and 2.25% with respect to any loan under the Term Loan A Facility, 2.25% with respect to any loan under the Term Loan B Facility, and between 2.00% and 3.00% with respect to any loan under the Revolving Credit Facility. The applicable margin for loans subject to alternate base rate will be between 0.25% and 1.25% with respect to any loan under the Term Loan A Facility, 1.25% with respect to any loan under the Term Loan B Facility, and between 1.00% and 2.00% with respect to any loan under the Revolving Credit Facility. The Credit Agreement requires certain mandatory prepayments of outstanding loans under the Term Loan A Facility and the Term Loan B Facility, subject to certain exceptions, based on a percentage of the annual excess cash flow of Holdings and its restricted subsidiaries (with step-downs to 0% based upon the total net leverage ratio, and with no prepayment required if annual excess cash flow is under a specified minimum threshold), the net cash proceeds of certain asset sales and casualty and condemnation events, subject to reinvestment rights and certain other exceptions, and the net cash proceeds of any issuance of debt not otherwise permitted under the Credit Agreement. The Credit Agreement permits AAM, Inc. to incur incremental term loan borrowings and/or increase commitments under the Revolving Credit Facility, subject to certain limitations and the satisfaction of certain conditions, in an aggregate amount not to exceed (i) $600 million, plus (ii) certain voluntary prepayments, plus (iii) additional amounts subject to pro forma compliance with a first lien net leverage ratio for Holdings and its restricted subsidiaries. The Credit Agreement contains customary affirmative and negative covenants, including, among others, financial covenants based on total net leverage and cash interest expense coverage ratios and limitations on the ability of Holdings, AAM, Inc. or their restricted subsidiaries to make certain investments, declare or pay dividends or distributions on capital stock, redeem or repurchase capital stock and certain debt obligations, incur liens, incur indebtedness, or merge, make certain acquisitions or certain sales of assets. The Credit Agreement includes customary events of default, the occurrence of which would permit the lenders to, among other things, declare the principal, accrued interest and other obligations to be immediately due and payable. Upon such default, the lenders may also seek customary remedies with respect to the collateral under the Collateral Agreement. As of September 30, 2017, we have prepaid $5.0 million of the outstanding principal on our Term Loan A Facility and $15.5 million of the outstanding principal on our Term Loan B Facility. These payments satisfy our obligation for principal payments under the Term Loan A Facility and Term Loan B Facility for the next four quarters. As a result, there are no amounts related to the Term Loan A Facility or Term Loan B Facility in the Current portion of long-term debt line item in our Condensed Consolidated Balance Sheet as of September 30, 2017. At September 30, 2017 , we had $869.1 million available under the Revolving Credit Facility. This availability reflects a reduction of $30.9 million for standby letters of credit issued against the facility. The New Senior Secured Credit Facilities provide back-up liquidity for our foreign credit facilities. We intend to use the availability of long-term financing under the New Senior Secured Credit Facilities to refinance any current maturities related to such debt agreements that are not otherwise refinanced on a long-term basis in their local markets, except where otherwise reclassified to current portion of long-term debt on our Condensed Consolidated Balance Sheet. 6.50% Notes due 2027 and 6.25% Notes due 2025 On March 23, 2017, we issued $700.0 million in aggregate principal amount of 6.25% senior notes due 2025 and $500.0 million in aggregate principal amount of 6.50% senior notes due 2027 (the Notes). Proceeds from the Notes were used primarily to fund the cash consideration related to AAM's acquisition of MPG, related fees and expenses, refinancing certain existing indebtedness of MPG and borrowings under our previous revolving credit facility, which has been replaced by our new Revolving Credit Facility, together with borrowings under the New Senior Secured Credit Facilities. We paid debt issuance costs of $36.9 million in the first nine months of 2017 related to the Notes. Repayment of MPG Indebtedness Upon the acquisition of MPG, we assumed approximately $1.9 billion of existing MPG indebtedness, which we repaid in its entirety on the date of acquisition. This indebtedness was comprised of approximately $0.2 billion of a Euro denominated term loan, approximately $1.0 billion of a U.S. dollar denominated term loan and approximately $0.7 billion of outstanding MPG bonds. Upon settlement of the debt, we paid approximately $24.6 million of accrued interest. In addition, we expensed $2.7 million of prepayment premiums related to the extinguishment of MPG's debt, which has been presented in the Debt refinancing and redemption costs line item within our condensed consolidated statements of income for both the three and nine months ended September 30, 2017. Foreign credit facilities We utilize local currency credit facilities to finance the operations of certain foreign subsidiaries. At September 30, 2017 , $52.3 million was outstanding under our foreign credit facilities and an additional $99.9 million was available. The weighted-average interest rate of our long-term debt outstanding was 5.7% at September 30, 2017 and 6.6% at December 31, 2016 .

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	7. FAIR VALUE Accounting Standards Codification 820 - Fair Value Measurement defines fair value 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 definition is based on an exit price rather than an entry price, regardless of whether the entity plans to hold or sell the asset. This guidance also establishes a fair value hierarchy to prioritize inputs used in measuring fair value as follows: • Level 1: Observable inputs such as quoted prices in active markets; • Level 2: Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and • Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Financial instruments The estimated fair value of our financial assets and liabilities that are recognized at fair value on a recurring basis, using available market information and other observable data, are as follows: September 30, 2017 December 31, 2016 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Balance Sheet Classification Cash equivalents $ 126.1 $ 126.1 $ 187.2 $ 187.2 Level 1 Prepaid expenses and other Cash flow hedges - currency forward contracts 1.1 1.1 — — Level 2 Nondesignated - currency forward contracts 1.0 1.0 — — Level 2 Nondesignated - currency option contracts 1.5 1.5 — — Level 2 Other assets and deferred charges Cash flow hedges - currency forward contracts 2.1 2.1 — — Level 2 Cash flow hedges - variable-to-fixed interest rate swap 0.3 0.3 — — Level 2 Accrued expenses and other Cash flow hedges - currency forward contracts 3.8 3.8 12.3 12.3 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 0.2 0.2 — — Level 2 Nondesignated - currency forward contracts 0.2 0.2 1.4 1.4 Level 2 Postretirement benefits and other long-term liabilities Cash flow hedges - currency forward contracts 0.5 0.5 11.4 11.4 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 2.1 2.1 — — Level 2 The carrying values of our cash, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the short-term maturities of these instruments. The carrying values of our borrowings under the foreign credit facilities approximate their fair value due to the frequent resetting of the interest rates. We estimated the fair value of the amounts outstanding on our debt using available market information and other observable data, to be as follows: September 30, 2017 December 31, 2016 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Revolving Credit Facility $ — $ — $ — $ — Level 2 Term Loan A Facility 93.8 93.3 — — Level 2 Term Loan B Facility 1,530.6 1,521.1 — — Level 2 7.75% Notes due 2019 200.0 219.0 200.0 221.0 Level 2 6.625% Notes due 2022 550.0 567.2 550.0 566.1 Level 2 6.50% Notes due 2027 500.0 502.8 — — Level 2 6.25% Notes due 2025 700.0 711.7 — — Level 2 6.25% Notes due 2021 400.0 411.0 400.0 412.0 Level 2 5.125% Notes due 2019 200.0 200.5 200.0 201.7 Level 2

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	8. DERIVATIVES Our business and financial results are affected by fluctuations in world financial markets, including interest rates and currency exchange rates. Our hedging policy has been developed to manage these risks to an acceptable level based on management’s judgment of the appropriate trade-off between risk, opportunity and cost. We do not hold financial instruments for trading or speculative purposes. Currency derivative contracts From time to time, we use foreign currency forward and option contracts to reduce the effects of fluctuations in exchange rates relating to the Mexican Peso, Euro, Brazilian Real, British Pound Sterling, Thai Baht, Swedish Krona, Chinese Yuan, Polish Zloty and Indian Rupee. As of September 30, 2017 , we have currency forward and option contracts outstanding with a notional amount of $218.1 million that hedge our exposure to changes in foreign currency exchange rates for certain payroll expenses into the second quarter of 2020 and certain direct and indirect inventory and other working capital items into the second quarter of 2018. Variable-to-fixed interest rate swap In the second quarter of 2017, we entered into a variable-to-fixed interest rate swap to reduce the variability of cash flows associated with interest payments on our variable rate debt. We have the following notional amounts hedged in relation to our variable-to-fixed interest rate swap: $750.0 million through May 2018, $600.0 million through May 2019, $450.0 million through May 2020 and $200.0 million through May 2021. The following table summarizes the reclassification of derivative losses into net income from accumulated other comprehensive loss for those derivative instruments designated as cash flow hedges under Accounting Standards Codification 815 - Derivatives and Hedging (ASC 815): Loss Reclassified During Loss Expected to Location of Loss Three Months Ended Nine Months Ended be Reclassified Reclassified into September 30, September 30, During the Net Income 2017 2016 2017 2016 Next 12 Months (in millions) Currency forward contracts Cost of Goods Sold $ (0.7 ) $ (2.6 ) $ (4.6 ) $ (6.9 ) $ (2.6 ) Variable-to-fixed interest rate swap Interest Expense — — — — (0.1 ) See Note 13 - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (AOCI) for amounts recognized in other comprehensive income (loss) during the three and nine months ended September 30, 2017 and 2016. The following table summarizes the amount and location of gains (losses) recognized in the Condensed Consolidated Statements of Income for those derivative instruments not designated as hedging instruments under ASC 815: Gain (Loss) Recognized During Location of Gain (Loss) Three Months Ended Nine Months Ended Recognized in September 30, September 30, Net Income 2017 2016 2017 2016 (in millions) Currency forward contracts Cost of Goods Sold $ 0.4 $ (1.3 ) $ 6.1 $ (4.0 ) Currency forward contracts Other Income, Net — — — (0.7 ) Currency option contracts Cost of Goods Sold 0.3 — 1.4 —

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Pension and Other Postretirement Benefits Disclosure [Text Block]	9. EMPLOYEE BENEFIT PLANS The components of net periodic benefit cost (credit) are as follows: Pension Benefits Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 (in millions) Service cost $ 0.7 $ 0.8 $ 2.6 $ 2.3 Interest cost 7.2 7.3 21.4 21.9 Expected asset return (11.1 ) (10.7 ) (32.7 ) (32.1 ) Amortized loss 1.9 1.3 5.4 4.1 Amortized prior service cost (credit) (0.1 ) — (0.1 ) — Settlement 2.9 — 2.9 — Net periodic benefit cost (credit) $ 1.5 $ (1.3 ) $ (0.5 ) $ (3.8 ) Other Postretirement Benefits Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 (in millions) Service cost $ 0.1 $ 0.1 $ 0.3 $ 0.3 Interest cost 3.3 3.5 9.9 10.5 Amortized loss 0.2 0.1 0.5 0.3 Amortized prior service credit (0.8 ) (0.7 ) (2.1 ) (2.0 ) Net periodic benefit cost $ 2.8 $ 3.0 $ 8.6 $ 9.1 The noncurrent liabilities associated with our pension and other postretirement benefit plans are classified as postretirement benefits and other long-term liabilities on our Condensed Consolidated Balance Sheets. As of September 30, 2017 and December 31, 2016 , we have a noncurrent pension liability of $141.0 million and $113.5 million , respectively. As of September 30, 2017 and December 31, 2016 , we have a noncurrent other postretirement benefits liability of $540.3 million and $542.6 million , respectively. Due to the availability of our pre-funded pension balances (previous contributions in excess of prior required pension contributions) related to our U.S. pension plans, as well as contributions we made in 2015 for one of our U.K. pension plans, the cash payments to our pension trusts will be insignificant in 2017. We expect our cash payments for other postretirement benefit obligations in 2017, net of GM cost sharing, to be approximately $16 million .

Product Warranties

Product Warranties	9 Months Ended
	Sep. 30, 2017
Product Warranties Disclosures [Abstract]
Product Warranty Disclosure [Text Block]	10. PRODUCT WARRANTIES We record a liability for estimated warranty obligations at the dates our products are sold. These estimates are established using sales volumes and internal and external warranty data where there is no payment history and historical information about the average cost of warranty claims for customers with prior claims. We estimate our costs based on the contractual arrangements with our customers, existing customer warranty terms and internal and external warranty data, which includes a determination of our warranty claims and actions taken to improve product quality and minimize warranty claims. We continuously evaluate these estimates and our customers' administration of their warranty programs. We closely monitor actual warranty claim data and adjust the liability, as necessary, on a quarterly basis. The following table provides a reconciliation of changes in the product warranty liability: Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 (in millions) Beginning balance $ 47.9 $ 37.9 $ 42.9 $ 36.6 Accruals 4.4 4.4 14.0 12.4 Payments (2.1 ) (3.0 ) (4.5 ) (6.7 ) Adjustment to prior period accruals (3.7 ) — (6.3 ) (3.1 ) Foreign currency translation 0.2 — 0.6 0.1 Ending balance $ 46.7 $ 39.3 $ 46.7 $ 39.3

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	11. INCOME TAXES We are required to adjust our effective tax rate each quarter to estimate our annual effective tax rate. We must also record the tax impact of certain discrete, unusual or infrequently occurring items, including changes in judgment about valuation allowances and effects of changes in tax laws or rates, in the interim period in which they occur. In addition, jurisdictions with a projected loss for the year or a year-to-date loss where no tax benefit can be recognized are excluded from the estimated annual effective tax rate. The impact of such an exclusion could result in a higher or lower effective tax rate during a particular quarter, based upon the mix and timing of actual earnings versus annual projections. Income tax expense was $5.7 million in the three months ended September 30, 2017 as compared to $17.8 million in the three months ended September 30, 2016 . Our effective income tax rate was 6.2% in the third quarter of 2017 as compared to 22.4% in the third quarter of 2016 . Income tax expense was $15.6 million in the nine months ended September 30, 2017 as compared to $53.8 million in the nine months ended September 30, 2016 . Our effective income tax rate was 6.3% in the first nine months of 2017 as compared to 21.7% in the first nine months of 2016. Our effective income tax rate for the three months ended September 30, 2017 is lower than our effective income tax rate for the three months ended September 30, 2016 as a result of an increase in the proportionate share of income attributable to lower tax rate jurisdictions. In addition, subsequent to the acquisition of MPG, we re-evaluated our valuation allowance position with regard to jurisdictions in which consolidated state tax returns are filed and recorded an income tax benefit for the three months ended September 30, 2017. Our effective income tax rate for the nine months ended September 30, 2017 is lower than our effective income tax rate for the nine months ended September 30, 2016 as a result of an increase in the proportionate share of income attributable to lower tax rate jurisdictions. In addition, subsequent to the acquisition of MPG, we re-evaluated our valuation allowance position with regard to jurisdictions in which consolidated state tax returns are filed and recorded an income tax benefit for the nine months ended September 30, 2017. This was partially offset by a discrete tax adjustment related to certain non-deductible transaction and acquisition-related costs. Our income tax expense and effective tax rate for the three and nine months ended September 30, 2017 , and September 30, 2016 , reflect the impact of favorable foreign tax rates, partially offset by our inability to realize a tax benefit for current foreign losses. Based on the status of audits outside the U.S., and the protocol of finalizing audits by the relevant tax authorities, it is not possible to estimate the timing or impact of changes, if any, to previously recorded uncertain tax positions. As of September 30, 2017 and December 31, 2016, we have recorded a liability for unrecognized income tax benefits and related interest and penalties of $54.4 million and $30.7 million , respectively. In January 2016, we completed negotiations with the Mexican tax authorities to settle transfer pricing audits. Including these settlements, we made payments of $26.1 million in the first nine months of 2016 to the Mexican tax authorities related to transfer pricing matters. Although it is difficult to estimate with certainty the amount of our tax liabilities for the years that remain subject to audit, we do not expect the settlements will be materially different from what we have recorded in unrecognized tax benefits. We will continue to monitor the progress and conclusions of current and future audits and will adjust our estimated liability as necessary.

Earnings Per Share (EPS)

Earnings Per Share (EPS)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	12. EARNINGS PER SHARE (EPS) We present earnings per share 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. The following table sets forth the computation of our basic and diluted EPS available to shareholders of common stock (excluding participating securities): Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 (in millions, except per share data) Numerator Net income attributable to AAM $ 86.2 $ 61.7 $ 230.8 $ 193.8 Less: Net income attributable to participating securities (1.9 ) (1.4 ) (5.1 ) (4.4 ) Net income attributable to common shareholders - Basic and Dilutive $ 84.3 $ 60.3 $ 225.7 $ 189.4 Denominators Basic common shares outstanding - Weighted-average shares outstanding 113.9 78.3 101.5 78.2 Less: Participating securities (2.6 ) (1.8 ) (2.3 ) (1.8 ) Weighted-average common shares outstanding 111.3 76.5 99.2 76.4 Effect of dilutive securities - Dilutive stock-based compensation 0.4 0.5 0.4 0.4 Diluted shares outstanding - Adjusted weighted-average shares after assumed conversions 111.7 77.0 99.6 76.8 Basic EPS $ 0.76 $ 0.79 $ 2.28 $ 2.48 Diluted EPS $ 0.75 $ 0.78 $ 2.27 $ 2.47 Certain exercisable stock options were excluded from the computations of diluted EPS because the exercise price of these options was greater than the average period market prices. There were no stock options excluded from the calculation of diluted EPS at September 30, 2017 . The number of stock options outstanding, which were not included in the calculation of diluted EPS, was 0.2 million , with an exercise price of $26.02 , at September 30, 2016 .

Reclassifications out of Accumu

Reclassifications out of Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2017
Reclassifications out of Accumulated Other Comprehensive Income (Loss) [Abstract]
Disclosure of Reclassification Amount [Text Block]	13. RECLASSIFICATIONS OUT OF ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (AOCI) Reclassification adjustments and other activity impacting accumulated other comprehensive income (loss) during the three months ended September 30, 2017 and September 30, 2016 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at June 30, 2017 $ (242.9 ) $ (85.9 ) $ (3.3 ) $ (332.1 ) Other comprehensive income before reclassifications — 42.8 0.4 43.2 Income tax effect of other comprehensive income before reclassifications — — — — Amounts reclassified from accumulated other comprehensive loss 4.1 (a) — 0.7 (b) 4.8 Income tax benefit reclassified into net income (1.0 ) — — (1.0 ) Net current period other comprehensive income 3.1 42.8 1.1 47.0 Balance at September 30, 2017 $ (239.8 ) $ (43.1 ) $ (2.2 ) $ (285.1 ) Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at June 30, 2016 $ (219.2 ) $ (103.4 ) $ (15.7 ) $ (338.3 ) Other comprehensive loss before reclassifications — (0.8 ) (6.7 ) (7.5 ) Income tax effect of other comprehensive loss before reclassifications — — — — Amounts reclassified from accumulated other comprehensive loss 0.7 (a) — 2.6 (b) 3.3 Income tax benefit reclassified into net income (0.1 ) — — (0.1 ) Net current period other comprehensive income (loss) 0.6 (0.8 ) (4.1 ) (4.3 ) Balance at September 30, 2016 $ (218.6 ) $ (104.2 ) $ (19.8 ) $ (342.6 ) (a) The amount reclassified from AOCI included $4.2 million in cost of goods sold (COGS) and $(0.1) million in selling, general & administrative expenses (SG&A) for the three months ended September 30, 2017 and $1.0 million in COGS and $(0.3) million in SG&A for the three months ended September 30, 2016. (b) The amounts reclassified from AOCI are included in COGS. Reclassification adjustments and other activity impacting accumulated other comprehensive income (loss) during the nine months ended September 30, 2017 and September 30, 2016 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at December 31, 2016 $ (243.5 ) $ (122.4 ) $ (23.7 ) $ (389.6 ) Other comprehensive income (loss) before reclassifications (1.7 ) 79.3 16.2 93.8 Income tax effect of other comprehensive income (loss) before reclassifications 0.6 — 0.7 1.3 Amounts reclassified from accumulated other comprehensive loss 6.6 (a) — 4.6 (b) 11.2 Income tax benefit reclassified into net income (1.8 ) — — (1.8 ) Net current period other comprehensive income 3.7 79.3 21.5 104.5 Balance at September 30, 2017 $ (239.8 ) $ (43.1 ) $ (2.2 ) $ (285.1 ) Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at December 31, 2015 $ (223.9 ) (119.2 ) $ (13.4 ) $ (356.5 ) Other comprehensive income (loss) before reclassifications 5.7 15.0 (13.3 ) 7.4 Income tax effect of other comprehensive income (loss) before reclassifications (2.0 ) — — (2.0 ) Amounts reclassified from accumulated other comprehensive loss 2.4 (a) — 6.9 (b) 9.3 Income tax benefit reclassified into net income (0.8 ) — — (0.8 ) Net current period other comprehensive income (loss) 5.3 15.0 (6.4 ) 13.9 Balance at September 30, 2016 $ (218.6 ) $ (104.2 ) $ (19.8 ) $ (342.6 ) (a) The amount reclassified from AOCI included $7.0 million in COGS and $(0.4) million in SG&A for the nine months ended September 30, 2017 and $3.3 million in COGS and $(0.9) million in SG&A for the nine months ended September 30, 2016. (b) The amounts reclassified from AOCI are included in COGS.

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Reporting Disclosure [Text Block]	14. SEGMENT REPORTING Prior to the acquisition of MPG on April 6, 2017, we operated in one reportable segment: the manufacture, engineer, design and validation of driveline systems and related components and chassis modules for light trucks, sport utility vehicles (SUVs), crossover vehicles, passenger cars and commercial vehicles. Subsequent to the acquisition of MPG, our business was organized into four business units, each representing a reportable segment under ASC 280 Segment Reporting . The four segments are Driveline, Metal Forming, Powertrain and Casting. The results of each segment are regularly reviewed by the chief operating decision maker to assess the performance of the segment and make decisions regarding the allocation of resources to the segments. Our product offerings by segment are as follows: • Driveline products consist primarily of axles, driveshafts, power transfer units, rear drive modules, and electric and hybrid driveline products and systems for light trucks, SUVs, crossover vehicles, passenger cars and commercial vehicles; • Metal Forming products consist primarily of axle shafts, ring and pinion gears, differential gears, transmission gears and shafts and suspension components for OEMs and Tier 1 automotive suppliers; • The Powertrain segment products consist primarily of transmission module and differential assemblies, transmission valve bodies, connecting rod forging and assemblies, torsional vibration dampers, and variable valve timing products for OEMs and Tier I automotive suppliers; and • The Casting segment produces both thin wall castings and high strength ductile iron castings, as well as differential cases, steering knuckles, control arms, and turbo charger housings for the global light, commercial and industrial markets. We use Segment Adjusted EBITDA as the measure of earnings to assess the performance of each segment and determine the resources to be allocated to the segments. Segment Adjusted EBITDA is defined as earnings before interest expense, income taxes, depreciation and amortization for our reportable segments, excluding the impact of restructuring and acquisition-related costs, debt refinancing and redemption costs and non-recurring items. The following tables represent information by reportable segment for the three months ended September 30, 2017 and 2016: Three Months Ended September 30, 2017 Driveline Metal Forming Powertrain Casting Total Sales $ 1,007.9 $ 368.2 $ 260.9 $ 226.6 $ 1,863.6 Less: intersegment sales 0.2 106.8 3.8 28.4 139.2 Net external sales $ 1,007.7 $ 261.4 $ 257.1 $ 198.2 $ 1,724.4 Segment Adjusted EBITDA $ 181.4 $ 70.7 $ 36.8 $ 8.8 $ 297.7 Three Months Ended September 30, 2016 Driveline Metal Forming Powertrain Casting Total Sales $ 956.1 $ 137.2 $ — $ — $ 1,093.3 Less: intersegment sales 0.1 86.3 — — 86.4 Net external sales $ 956.0 $ 50.9 $ — $ — $ 1,006.9 Segment Adjusted EBITDA $ 134.4 $ 22.3 $ — $ — $ 156.7 The following tables represent information by reportable segment for the nine months ended September 30, 2017 and 2016: Nine Months Ended September 30, 2017 Driveline Metal Forming Powertrain Casting Total Sales $ 3,028.7 $ 887.5 $ 544.5 $ 452.2 $ 4,912.9 Less: intersegment sales 1.1 315.1 6.0 58.6 380.8 Net external sales $ 3,027.6 $ 572.4 $ 538.5 $ 393.6 $ 4,532.1 Segment Adjusted EBITDA $ 513.5 $ 170.5 $ 88.7 $ 34.3 $ 807.0 Nine Months Ended September 30, 2016 Driveline Metal Forming Powertrain Casting Total Sales $ 2,840.4 $ 414.4 $ — $ — $ 3,254.8 Less: intersegment sales 3.8 249.5 — — 253.3 Net external sales $ 2,836.6 $ 164.9 $ — $ — $ 3,001.5 Segment Adjusted EBITDA $ 391.9 $ 79.4 $ — $ — $ 471.3 Total assets by reportable segment as of September 30, 2017 and December 31, 2016 were as follows: September 30, 2017 Driveline Metal Forming Powertrain Casting Corporate and Eliminations Total Total assets $ 2,362.7 $ 2,155.8 $ 1,825.1 $ 1,018.0 $ 696.7 $ 8,058.3 December 31, 2016 Driveline Metal Forming Powertrain Casting Corporate and Eliminations Total Total assets $ 2,183.9 $ 410.3 $ — $ — $ 829.7 $ 3,423.9 Assets included in the Corporate and Eliminations column in the table above represent AAM corporate assets, as well as eliminations of intercompany assets. The following table represents a reconciliation of Segment Adjusted EBITDA to consolidated income before income taxes for the three and nine months ended September 30, 2017 and 2016. Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Segment Adjusted EBITDA $ 297.7 $ 156.7 $ 807.0 $ 471.3 Interest expense (57.5 ) (23.2 ) (139.9 ) (70.2 ) Depreciation and amortization (122.6 ) (49.9 ) (303.4 ) (150.4 ) Restructuring and acquisition-related costs (22.8 ) — (90.5 ) — Pension settlement (2.9 ) — (2.9 ) — Acquisition-related fair value inventory adjustment — — (24.9 ) — Impact of change in accounting principle — — 3.7 — Debt refinancing and redemption costs — — (2.7 ) — Asset impairment charge — (3.4 ) — (3.4 ) Investment gain related to the final distribution of the Reserve Yield Plus Fund — — — 1.0 Other 0.1 (0.7 ) 0.2 (0.7 ) Income before income taxes $ 92.0 $ 79.5 $ 246.6 $ 247.6

Supplemental Guarantor Condense

Supplemental Guarantor Condensed Consolidating Financial Statements	9 Months Ended
	Sep. 30, 2017
Supplemental Guarantor Condensed Consolidating Financial Statements [Abstract]
Supplemental Guarantor Disclosure [Text Block]	15. SUPPLEMENTAL GUARANTOR CONDENSED CONSOLIDATING FINANCIAL STATEMENTS Holdings has no significant assets other than its 100% ownership in AAM, Inc. and Metaldyne Performance Group, Inc. (MPG Inc.), and no direct subsidiaries other than AAM, Inc. and MPG Inc. The 7.75% Notes, 6.625% Notes, 6.50% Notes, 6.25% Notes (due 2025), 6.25% Notes (due 2021) and 5.125% Notes are senior unsecured obligations of AAM, Inc.; all of which are fully and unconditionally guaranteed, on a joint and several basis, by Holdings and substantially all domestic subsidiaries of AAM, Inc. and, as of May 17, 2017, MPG Inc, and substantially all domestic subsidiaries of MPG Inc. These Condensed Consolidating Financial Statements are prepared under the equity method of accounting whereby the investments in subsidiaries are recorded at cost and adjusted for the parent’s share of the subsidiaries’ cumulative results of operations, capital contributions and distributions, and other equity changes. Condensed Consolidating Statements of Income Three Months Ended September 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net sales External $ — $ 250.0 $ 529.0 $ 945.4 $ — $ 1,724.4 Intercompany — 0.2 80.0 7.0 (87.2 ) — Total net sales — 250.2 609.0 952.4 (87.2 ) 1,724.4 Cost of goods sold — 229.6 546.3 738.0 (87.2 ) 1,426.7 Gross profit — 20.6 62.7 214.4 — 297.7 Selling, general and administrative expenses — 57.8 24.7 19.8 — 102.3 Amortization of intangible assets — 1.5 22.3 0.6 — 24.4 Restructuring and acquisition-related costs — 21.6 — 1.2 — 22.8 Operating income (loss) — (60.3 ) 15.7 192.8 — 148.2 Non-operating income (expense), net — (60.8 ) 5.5 (0.9 ) — (56.2 ) Income (loss) before income taxes — (121.1 ) 21.2 191.9 — 92.0 Income tax expense (benefit) — (29.0 ) 17.8 16.9 — 5.7 Earnings from equity in subsidiaries 86.2 29.9 25.5 — (141.6 ) — Net income (loss) before royalties 86.2 (62.2 ) 28.9 175.0 (141.6 ) 86.3 Royalties — 84.9 1.3 (86.2 ) — — Net income after royalties 86.2 22.7 30.2 88.8 (141.6 ) 86.3 Net income attributable to noncontrolling interests — — — (0.1 ) — (0.1 ) Net income attributable to AAM $ 86.2 $ 22.7 $ 30.2 $ 88.7 $ (141.6 ) $ 86.2 Other comprehensive income, net of tax 47.0 16.7 42.6 51.3 (110.6 ) 47.0 Comprehensive income attributable to AAM $ 133.2 $ 39.4 $ 72.8 $ 140.0 $ (252.2 ) $ 133.2 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2016 Net sales External $ — $ 274.7 $ 49.9 $ 682.3 $ — $ 1,006.9 Intercompany — 3.7 62.7 4.4 (70.8 ) — Total net sales — 278.4 112.6 686.7 (70.8 ) 1,006.9 Cost of goods sold — 265.4 94.9 536.2 (70.8 ) 825.7 Gross profit — 13.0 17.7 150.5 — 181.2 Selling, general and administrative expenses — 71.3 — 7.3 — 78.6 Amortization of intangible assets — 1.3 — — — 1.3 Operating income (loss) — (59.6 ) 17.7 143.2 — 101.3 Non-operating income (expense), net — (24.9 ) 2.9 0.2 — (21.8 ) Income (loss) before income taxes — (84.5 ) 20.6 143.4 — 79.5 Income tax expense — 7.9 0.1 9.8 — 17.8 Earnings (loss) from equity in subsidiaries 61.7 87.4 (7.1 ) — (142.0 ) — Net income (loss) before royalties 61.7 (5.0 ) 13.4 133.6 (142.0 ) 61.7 Royalties — 66.7 — (66.7 ) — — Net income after royalties 61.7 61.7 13.4 66.9 (142.0 ) 61.7 Net income attributable to noncontrolling interests — — — — — — Net income attributable to AAM $ 61.7 $ 61.7 $ 13.4 $ 66.9 $ (142.0 ) $ 61.7 Other comprehensive income (loss), net of tax (4.3 ) (4.3 ) 1.0 (3.3 ) 6.6 (4.3 ) Comprehensive income attributable to AAM $ 57.4 $ 57.4 $ 14.4 $ 63.6 $ (135.4 ) $ 57.4 Condensed Consolidating Statements of Income Nine Months Ended September 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net sales External $ — $ 806.9 $ 1,139.8 $ 2,585.4 $ — $ 4,532.1 Intercompany — 2.4 214.7 19.9 (237.0 ) — Total net sales — 809.3 1,354.5 2,605.3 (237.0 ) 4,532.1 Cost of goods sold — 752.2 1,188.0 2,004.1 (237.0 ) 3,707.3 Gross profit — 57.1 166.5 601.2 — 824.8 Selling, general and administrative expenses — 196.0 45.7 47.4 — 289.1 Amortization of intangible assets — 4.3 45.0 1.5 — 50.8 Restructuring and acquisition-related costs — 87.0 — 3.5 90.5 Operating income (loss) — (230.2 ) 75.8 548.8 — 394.4 Non-operating income (expense), net — (148.7 ) 14.9 (14.0 ) — (147.8 ) Income (loss) before income taxes — (378.9 ) 90.7 534.8 — 246.6 Income tax expense (benefit) — (62.2 ) 42.0 35.8 — 15.6 Earnings from equity in subsidiaries 230.8 202.9 41.4 — (475.1 ) — Net income (loss) before royalties 230.8 (113.8 ) 90.1 499.0 (475.1 ) 231.0 Royalties — 253.6 2.6 (256.2 ) — — Net income after royalties 230.8 139.8 92.7 242.8 (475.1 ) 231.0 Net income attributable to noncontrolling interests — — — (0.2 ) — (0.2 ) Net income attributable to AAM $ 230.8 $ 139.8 $ 92.7 $ 242.6 $ (475.1 ) $ 230.8 Other comprehensive income, net of tax 104.5 55.3 74.7 94.8 (224.8 ) 104.5 Comprehensive income attributable to AAM $ 335.3 $ 195.1 $ 167.4 $ 337.4 $ (699.9 ) $ 335.3 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2016 Net sales External $ — $ 866.3 $ 161.4 $ 1,973.8 $ — $ 3,001.5 Intercompany — 8.1 185.7 12.2 (206.0 ) — Total net sales — 874.4 347.1 1,986.0 (206.0 ) 3,001.5 Cost of goods sold — 833.5 284.3 1,543.1 (206.0 ) 2,454.9 Gross profit — 40.9 62.8 442.9 — 546.6 Selling, general and administrative expenses — 206.8 — 25.0 — 231.8 Amortization of intangible assets — 3.5 — 0.1 — 3.6 Operating income (loss) — (169.4 ) 62.8 417.8 — 311.2 Non-operating income (expense), net — (72.7 ) 8.4 0.7 — (63.6 ) Income (loss) before income taxes — (242.1 ) 71.2 418.5 — 247.6 Income tax expense — 28.9 0.3 24.6 — 53.8 Earnings (loss) from equity in subsidiaries 193.8 266.6 (28.0 ) — (432.4 ) — Net income (loss) before royalties 193.8 (4.4 ) 42.9 393.9 (432.4 ) 193.8 Royalties — 198.2 — (198.2 ) — — Net income after royalties 193.8 193.8 42.9 195.7 (432.4 ) 193.8 Net income attributable to noncontrolling interests — — — — — — Net income attributable to AAM $ 193.8 $ 193.8 $ 42.9 $ 195.7 $ (432.4 ) $ 193.8 Other comprehensive income, net of tax 13.9 13.9 23.2 16.9 (54.0 ) 13.9 Comprehensive income attributable to AAM $ 207.7 $ 207.7 $ 66.1 $ 212.6 $ (486.4 ) $ 207.7 Condensed Consolidating Balance Sheets (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims/Reclassifications Consolidated September 30, 2017 Assets Current assets Cash and cash equivalents $ — $ 188.5 $ 0.1 $ 361.0 $ — $ 549.6 Accounts receivable, net — 134.4 320.2 667.4 — 1,122.0 Intercompany receivables — 3,559.1 465.9 8.0 (4,033.0 ) — Inventories, net — 34.0 151.2 211.4 — 396.6 Prepaid expenses and other — 27.4 12.1 105.0 — 144.5 Total current assets — 3,943.4 949.5 1,352.8 (4,033.0 ) 2,212.7 Property, plant and equipment, net — 234.1 788.5 1,280.1 — 2,302.7 Goodwill — — 1,220.2 434.4 — 1,654.6 Intangible assets, net — 21.9 1,178.1 36.6 — 1,236.6 Intercompany notes and accounts receivable 14.6 — 260.9 — (275.5 ) — Other assets and deferred charges — 717.4 137.2 129.8 (332.7 ) 651.7 Investment in subsidiaries 2,735.0 1,917.2 708.9 — (5,361.1 ) — Total assets $ 2,749.6 $ 6,834.0 $ 5,243.3 $ 3,233.7 $ (10,002.3 ) $ 8,058.3 Liabilities and Stockholders’ Equity Current liabilities Current portion of long-term debt $ — $ — $ — $ 6.8 $ — $ 6.8 Accounts payable — 130.2 238.2 488.0 — 856.4 Intercompany payables 1,313.0 499.7 2,010.2 210.1 (4,033.0 ) — Accrued expenses and other — 183.0 56.3 182.5 — 421.8 Total current liabilities 1,313.0 812.9 2,304.7 887.4 (4,033.0 ) 1,285.0 Intercompany notes and accounts payable — 76.9 — 198.6 (275.5 ) — Long-term debt, net — 4,096.3 4.6 68.4 — 4,169.3 Other long-term liabilities — 742.2 594.0 163.9 (332.7 ) 1,167.4 Total liabilities 1,313.0 5,728.3 2,903.3 1,318.3 (4,641.2 ) 6,621.7 Total AAM Stockholders’ equity 1,432.8 1,105.7 2,340.0 1,911.6 (5,357.3 ) 1,432.8 Noncontrolling interests in subsidiaries 3.8 — — 3.8 (3.8 ) 3.8 Total stockholders’ equity 1,436.6 1,105.7 2,340.0 1,915.4 (5,361.1 ) 1,436.6 Total liabilities and stockholders’ equity $ 2,749.6 $ 6,834.0 $ 5,243.3 $ 3,233.7 $ (10,002.3 ) $ 8,058.3 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated December 31, 2016 Assets Current assets Cash and cash equivalents $ — $ 84.3 $ 1.6 $ 395.3 $ — $ 481.2 Accounts receivable, net — 126.7 21.9 411.4 — 560.0 Intercompany receivables — 442.6 326.0 9.1 (777.7 ) — Inventories, net — 31.3 21.5 129.5 — 182.3 Prepaid expenses and other — 29.4 0.5 45.9 — 75.8 Total current assets — 714.3 371.5 991.2 (777.7 ) 1,299.3 Property, plant and equipment, net — 213.7 102.9 777.1 — 1,093.7 Goodwill — — 147.8 6.2 — 154.0 Intangible assets, net — 22.8 — 5.7 — 28.5 Intercompany notes and accounts receivable — 343.9 242.2 — (586.1 ) — Other assets and deferred charges — 644.9 39.8 163.7 — 848.4 Investment in subsidiaries 827.6 1,544.4 — — (2,372.0 ) — Total assets $ 827.6 $ 3,484.0 $ 904.2 $ 1,943.9 $ (3,735.8 ) $ 3,423.9 Liabilities and Stockholders’ Equity Current liabilities Current portion of long-term debt $ — $ — $ — $ 3.3 $ — $ 3.3 Accounts payable — 80.6 35.8 265.9 — 382.3 Intercompany payables — 324.8 153.4 299.5 (777.7 ) — Accrued expenses and other — 142.2 4.3 119.4 — 265.9 Total current liabilities — 547.6 193.5 688.1 (777.7 ) 651.5 Intercompany notes and accounts payable 321.8 14.6 7.5 242.2 (586.1 ) — Long-term debt, net — 1,339.7 4.1 57.1 — 1,400.9 Investment in subsidiaries obligation — — 124.7 — (124.7 ) — Other long-term liabilities — 754.5 0.6 110.6 — 865.7 Total liabilities 321.8 2,656.4 330.4 1,098.0 (1,488.5 ) 2,918.1 Total stockholders’ equity 505.8 827.6 573.8 845.9 (2,247.3 ) 505.8 Total liabilities and stockholders’ equity $ 827.6 $ 3,484.0 $ 904.2 $ 1,943.9 $ (3,735.8 ) $ 3,423.9 Condensed Consolidating Statements of Cash Flows Nine Months Ended September 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net cash provided by operating activities $ — $ 276.4 $ 9.0 $ 135.3 $ — $ 420.7 Investing activities Purchases of property, plant and equipment — (43.1 ) (73.3 ) (162.3 ) — (278.7 ) Proceeds from sale of property, plant and equipment — 0.3 0.3 1.1 — 1.7 Purchase buyouts of leased equipment — (12.6 ) — — — (12.6 ) Proceeds from sale of business, net — 7.5 (1.6 ) — — 5.9 Acquisition of business, net of cash acquired — (953.5 ) 64.6 (6.6 ) — (895.5 ) Net cash used in investing activities — (1,001.4 ) (10.0 ) (167.8 ) — (1,179.2 ) Financing activities Net debt activity — 926.1 (0.5 ) (12.1 ) — 913.5 Debt issuance costs — (90.8 ) — — — (90.8 ) Employee stock option exercises — 0.9 — — — 0.9 Purchase of treasury stock (7.0 ) — — — — (7.0 ) Intercompany activity 7.0 (7.0 ) — — — — Net cash provided by (used in) financing activities — 829.2 (0.5 ) (12.1 ) — 816.6 Effect of exchange rate changes on cash — — — 10.3 — 10.3 Net increase (decrease) in cash and cash equivalents — 104.2 (1.5 ) (34.3 ) — 68.4 Cash and cash equivalents at beginning of period — 84.3 1.6 395.3 — 481.2 Cash and cash equivalents at end of period $ — $ 188.5 $ 0.1 $ 361.0 $ — $ 549.6 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2016 Net cash provided by operating activities $ — $ 114.8 $ 20.9 $ 155.3 $ — $ 291.0 Investing activities Purchases of property, plant and equipment — (25.9 ) (12.0 ) (120.8 ) — (158.7 ) Proceeds from sale of property, plant and equipment — — 0.3 0.4 — 0.7 Proceeds from government grants — — — 2.8 — 2.8 Final distribution of Reserve Yield Plus Fund — 1.0 — — — 1.0 Acquisition of business, net of cash acquired — — (5.6 ) — — (5.6 ) Intercompany activity — — (2.0 ) — 2.0 — Net cash used in investing activities — (24.9 ) (19.3 ) (117.6 ) 2.0 (159.8 ) Financing activities Net debt activity — (0.4 ) (0.3 ) 23.3 — 22.6 Employee stock option exercises — 0.3 — — — 0.3 Purchase of treasury stock (5.3 ) — — — — (5.3 ) Intercompany activity 5.3 (5.3 ) — 2.0 (2.0 ) — Net cash provided by (used in) financing activities — (5.4 ) (0.3 ) 25.3 (2.0 ) 17.6 Effect of exchange rate changes on cash — — — 2.6 — 2.6 Net increase in cash and cash equivalents — 84.5 1.3 65.6 — 151.4 Cash and cash equivalents at beginning of period — 52.0 — 230.5 — 282.5 Cash and cash equivalents at end of period $ — $ 136.5 $ 1.3 $ 296.1 $ — $ 433.9

Organization and Basis of Pre23

Organization and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2017
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, 2016 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. Actual results could differ from those estimates. 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, 2016 .
Accounting Changes [Text Block]	Change in Accounting Principle 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 the administrative burden associated with recordkeeping 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 $24.2 million and increased previously reported deferred tax assets by $13.0 million as of January 1, 2016 and December 31, 2016. The cumulative impact of the change in accounting principle from January 1, 2016 to March 31, 2017, which covers the periods in which we would be required to retrospectively revise our Statements of Income and Balance Sheets, 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 adjustment 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 nine months ended September 30, 2017. The impact on current period income for the quarter ended September 30, 2017 was immaterial in comparison to accounting for indirect inventory under our historical accounting policy. See Note 5 - Inventories for further discussion
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 expect to adopt this guidance effective January 1, 2018. The adoption of this guidance is not expected to 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). The amendments also provide explicit guidance on how to present the service cost component and the other components of net benefit cost in the income statement and allow only the service cost component of net benefit cost to be eligible for capitalization. This guidance becomes 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. We are currently assessing the impact that this standard will have 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, however early adoption is permitted. The guidance requires a prospective transition method. We are currently assessing the impact that this standard will have on our consolidated financial statements. Accounting Standards Update 2016-16 On October 24, 2016, the FASB issued 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 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 becomes effective at the beginning of our 2018 fiscal year and requires a modified retrospective transition method. We are currently assessing the impact that this standard will have on our consolidated financial statements. Accounting Standards Update 2016-02 On February 25, 2016, the FASB issued ASU 2016-02 - Leases (Topic 842) , which supersedes the existing lease accounting guidance and establishes new criteria for recognizing lease assets and liabilities. The most significant impact of the update, 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 , and 2016-20 - Revenue from Contracts with Customers (Topic 606): Technical Corrections and Improvements to Topic 606 (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 is effective for AAM beginning on January 1, 2018 and entities have the option of using either a full retrospective or a modified retrospective approach for the adoption of the new standard. We expect to adopt this guidance using the modified retrospective approach. We are concluding the assessment phase of implementing this guidance. 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. Our preliminary conclusion is that the impact of implementing the Revenue Recognition ASUs will be immaterial to our financial statements and that our method for recognizing revenue subsequent to the implementation of the Revenue Recognition ASUs will not vary significantly from our revenue recognition practices under current GAAP. There are certain considerations related to internal control over financial reporting that are associated with implementing the new guidance under Topic 606 and we are currently implementing the necessary changes to our control framework for revenue recognition. Disclosure requirements under the new guidance in Topic 606 have been significantly expanded in comparison to the disclosure requirements under the current guidance. We are currently concluding our assessment of the new disclosure requirements and we are in the process of drafting our disclosures for both interim and annual periods under Topic 606.
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. Approximately $1.5 million of shares have been repurchased under the authorized share repurchase program, leaving approximately $98.5 million available for repurchase. There were no repurchases under the program in the first nine months of 2017.

Restructuring and Acquisition24

Restructuring and Acquisition-Related Costs (Tables)	9 Months Ended
	Sep. 30, 2017
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs [Table Text Block]	In the fourth quarter of 2016, AAM initiated actions under a global restructuring program focused on creating a more streamlined organization in addition to reducing our cost structure and preparing for acquisition integration activities. A summary of this activity for the first nine months of 2017 is shown below: Severance Charges Implementation Costs Total (in millions) Accrual as of December 31, 2016 $ 0.6 $ 9.2 $ 9.8 Charges 1.7 13.5 15.2 Cash utilization (2.3 ) (17.8 ) (20.1 ) Non-cash utilization — — — Accrual adjustments — — — Accrual as of September 30, 2017 $ — $ 4.9 $ 4.9
Business Combination, Separately Recognized Transactions [Table Text Block]	On March 1, 2017, we completed the acquisition of USM Mexico Manufacturing LLC (USM Mexico) and on April 6, 2017, we completed the acquisition of MPG. During the nine months ended September 30, 2017, we incurred the following charges related to these acquisitions: Acquisition-Related Costs Severance Charges Integration Expenses Total (in millions) Charges $ 40.7 $ 5.6 $ 29.0 $ 75.3 Total restructuring and acquisition-related charges $ 90.5

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2017
Metaldyne Performance Group, Inc. [Member]
Business Acquisition [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The acquisition of MPG was accounted for under the acquisition method under Accounting Standards Codification 805 Business Combinations (ASC 805) with the purchase price allocated to the identifiable assets and liabilities of the acquired company based on the respective fair values of the assets and liabilities. The following represents the preliminary fair values of the assets acquired and liabilities assumed resulting from the acquisition, as well as the calculation of goodwill: (in millions) April 6, 2017 Cash consideration $ 953.5 Share consideration 576.7 Total consideration transferred $ 1,530.2 Fair value of MPG noncontrolling interests 3.6 Total fair value of MPG $ 1,533.8 Cash and cash equivalents $ 202.1 Accounts receivable 403.2 Inventories 199.0 Prepaid expenses and other long-term assets 121.0 Property, plant and equipment 985.7 Intangible assets 1,223.1 Total assets acquired $ 3,134.1 Accounts payable 287.8 Accrued expenses and other 137.2 Deferred income tax liabilities 596.4 Debt 1,918.7 Postretirement benefits and other long-term liabilities 54.5 Net assets acquired $ 139.5 Goodwill $ 1,394.3
USM Mexico Manufacturing LLC [Member]
Business Acquisition [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	On March 1, 2017, AAM completed the acquisition of 100% of USM Mexico, a former subsidiary of U.S. Manufacturing Corporation (USM). The purchase price was funded entirely with available cash and the acquisition was accounted for under the acquisition method. USM Mexico includes USM's operations in Guanajuato, Mexico, which has historically been one of the largest suppliers to AAM's Guanajuato Manufacturing Complex. This acquisition allows AAM to vertically integrate the supply chain and helps ensure continuity of supply for certain parts to our largest manufacturing facility. The following represents the estimated fair value of the assets acquired and liabilities assumed resulting from the acquisition, as well as the calculation of goodwill: (in millions) March 1, 2017 Contractual purchase price $ 162.5 Adjustments to contractual purchase price for capital equipment 4.9 Adjustment to contractual purchase price for settlement of existing accounts payable balance (22.8 ) Cash acquired (0.5 ) Adjusted purchase price, net of cash acquired $ 144.1 Accounts receivable 1.1 Inventories 4.8 Prepaid expenses and other 2.4 Property, plant and equipment 38.4 Intangible assets 31.7 Total assets acquired $ 78.4 Accounts payable 10.8 Accrued expenses and other 2.7 Deferred income tax liabilities 1.2 Net assets acquired $ 63.7 Goodwill $ 80.4

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	Goodwill The following table provides a reconciliation of changes in goodwill for the nine months ended September 30, 2017: Driveline Metal Forming Powertrain Casting Consolidated (in millions) Balance as of December 31, 2016 $ 130.1 $ 23.9 $ — $ — $ 154.0 Acquisition of MPG — 516.0 472.3 406.0 1,394.3 Acquisition of USM Mexico 80.4 — — — 80.4 Foreign currency translation 0.4 16.6 8.9 — 25.9 Balance as of September 30, 2017 $ 210.9 $ 556.5 $ 481.2 $ 406.0 $ 1,654.6
Schedule of Acquired Finite-Lived Intangible Assets by Major Class [Table Text Block]	Intangible Assets As a result of the acquisitions of MPG and USM Mexico, AAM identified and recognized certain intangible assets that are subject to amortization. The weighted-average amortization period for all intangible assets recognized as a result of these acquisitions is 13.6 years . The following table provides a breakout of the major intangible assets acquired by class: Estimated September 30, Useful Lives 2017 (years) (in millions) MPG Customer platforms 14 $ 950.0 Customer relationships 16-17 151.8 Technology and other 5-13 121.3 Total MPG $ 1,223.1 USM Mexico Technology 13 $ 29.5 Customer platforms 13 2.2 Total USM Mexico $ 31.7 Total $ 1,254.8
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The following table provides a reconciliation of the gross carrying amount and associated accumulated amortization for AAM's total intangible assets, which are all subject to amortization: September 30, December 31, 2017 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in millions) Capitalized computer software $ 35.2 $ (12.8 ) $ 22.4 $ 31.7 $ (8.5 ) $ 23.2 e-AAM in-process research and development 5.9 — 5.9 5.3 — 5.3 Customer platforms 952.2 (35.3 ) 916.9 — — — Customer relationships 151.8 (4.9 ) 146.9 — — — Technology and other 150.8 (6.3 ) 144.5 — — — Total $ 1,295.9 $ (59.3 ) $ 1,236.6 $ 37.0 $ (8.5 ) $ 28.5 Amortization expense for these intangible assets was $24.4 million and $50.8 million for the three and nine months ended September 30, 2017, respectively, and $1.3 million and $3.6 million for the three and nine months ended September 30, 2016, respectively. Estimated amortization expense for each of the next five years is as follows: approximately $75 million in 2017 and approximately $100 million in each of the years 2018 through 2021.

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2017
Inventory Disclosure [Abstract]
Schedule of Inventory, Current [Table Text Block]	Inventories consist of the following: September 30, 2017 December 31, 2016 (in millions) Raw materials and work-in-progress $ 331.4 $ 163.3 Finished goods 90.0 33.8 Gross inventories 421.4 197.1 Inventory valuation reserves (24.8 ) (14.8 ) Inventories, net $ 396.6 $ 182.3

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	Long-term debt consists of the following: September 30, 2017 December 31, 2016 (in millions) Revolving Credit Facility $ — $ — Term Loan A Facility 93.8 — Term Loan B Facility 1,530.6 — 7.75% Notes due 2019 200.0 200.0 6.625% Notes due 2022 550.0 550.0 6.50% Notes due 2027 500.0 — 6.25% Notes due 2025 700.0 — 6.25% Notes due 2021 400.0 400.0 5.125% Notes due 2019 200.0 200.0 Foreign credit facilities 52.3 60.4 Capital lease obligations 28.6 5.5 Total debt 4,255.3 1,415.9 Less: Current portion of long-term debt 6.8 3.3 Long-term debt 4,248.5 1,412.6 Less: Debt issuance costs 79.2 11.7 Long-term debt, net $ 4,169.3 $ 1,400.9

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	The estimated fair value of our financial assets and liabilities that are recognized at fair value on a recurring basis, using available market information and other observable data, are as follows: September 30, 2017 December 31, 2016 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Balance Sheet Classification Cash equivalents $ 126.1 $ 126.1 $ 187.2 $ 187.2 Level 1 Prepaid expenses and other Cash flow hedges - currency forward contracts 1.1 1.1 — — Level 2 Nondesignated - currency forward contracts 1.0 1.0 — — Level 2 Nondesignated - currency option contracts 1.5 1.5 — — Level 2 Other assets and deferred charges Cash flow hedges - currency forward contracts 2.1 2.1 — — Level 2 Cash flow hedges - variable-to-fixed interest rate swap 0.3 0.3 — — Level 2 Accrued expenses and other Cash flow hedges - currency forward contracts 3.8 3.8 12.3 12.3 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 0.2 0.2 — — Level 2 Nondesignated - currency forward contracts 0.2 0.2 1.4 1.4 Level 2 Postretirement benefits and other long-term liabilities Cash flow hedges - currency forward contracts 0.5 0.5 11.4 11.4 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 2.1 2.1 — — Level 2
Fair Value, Financial Instruments not Carried at Fair Value [Table Text Block]	We estimated the fair value of the amounts outstanding on our debt using available market information and other observable data, to be as follows: September 30, 2017 December 31, 2016 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Revolving Credit Facility $ — $ — $ — $ — Level 2 Term Loan A Facility 93.8 93.3 — — Level 2 Term Loan B Facility 1,530.6 1,521.1 — — Level 2 7.75% Notes due 2019 200.0 219.0 200.0 221.0 Level 2 6.625% Notes due 2022 550.0 567.2 550.0 566.1 Level 2 6.50% Notes due 2027 500.0 502.8 — — Level 2 6.25% Notes due 2025 700.0 711.7 — — Level 2 6.25% Notes due 2021 400.0 411.0 400.0 412.0 Level 2 5.125% Notes due 2019 200.0 200.5 200.0 201.7 Level 2

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Table Text Block]	The following table summarizes the amount and location of gains (losses) recognized in the Condensed Consolidated Statements of Income for those derivative instruments not designated as hedging instruments under ASC 815: Gain (Loss) Recognized During Location of Gain (Loss) Three Months Ended Nine Months Ended Recognized in September 30, September 30, Net Income 2017 2016 2017 2016 (in millions) Currency forward contracts Cost of Goods Sold $ 0.4 $ (1.3 ) $ 6.1 $ (4.0 ) Currency forward contracts Other Income, Net — — — (0.7 ) Currency option contracts Cost of Goods Sold 0.3 — 1.4 — The following table summarizes the reclassification of derivative losses into net income from accumulated other comprehensive loss for those derivative instruments designated as cash flow hedges under Accounting Standards Codification 815 - Derivatives and Hedging (ASC 815): Loss Reclassified During Loss Expected to Location of Loss Three Months Ended Nine Months Ended be Reclassified Reclassified into September 30, September 30, During the Net Income 2017 2016 2017 2016 Next 12 Months (in millions) Currency forward contracts Cost of Goods Sold $ (0.7 ) $ (2.6 ) $ (4.6 ) $ (6.9 ) $ (2.6 ) Variable-to-fixed interest rate swap Interest Expense — — — — (0.1 )

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Schedule of Net Benefit (Credits) Costs [Table Text Block]	The components of net periodic benefit cost (credit) are as follows: Pension Benefits Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 (in millions) Service cost $ 0.7 $ 0.8 $ 2.6 $ 2.3 Interest cost 7.2 7.3 21.4 21.9 Expected asset return (11.1 ) (10.7 ) (32.7 ) (32.1 ) Amortized loss 1.9 1.3 5.4 4.1 Amortized prior service cost (credit) (0.1 ) — (0.1 ) — Settlement 2.9 — 2.9 — Net periodic benefit cost (credit) $ 1.5 $ (1.3 ) $ (0.5 ) $ (3.8 ) Other Postretirement Benefits Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 (in millions) Service cost $ 0.1 $ 0.1 $ 0.3 $ 0.3 Interest cost 3.3 3.5 9.9 10.5 Amortized loss 0.2 0.1 0.5 0.3 Amortized prior service credit (0.8 ) (0.7 ) (2.1 ) (2.0 ) Net periodic benefit cost $ 2.8 $ 3.0 $ 8.6 $ 9.1

Product Warranties (Tables)

Product Warranties (Tables)	9 Months Ended
	Sep. 30, 2017
Product Warranties Disclosures [Abstract]
Schedule of Product Warranty Liability [Table Text Block]	The following table provides a reconciliation of changes in the product warranty liability: Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 (in millions) Beginning balance $ 47.9 $ 37.9 $ 42.9 $ 36.6 Accruals 4.4 4.4 14.0 12.4 Payments (2.1 ) (3.0 ) (4.5 ) (6.7 ) Adjustment to prior period accruals (3.7 ) — (6.3 ) (3.1 ) Foreign currency translation 0.2 — 0.6 0.1 Ending balance $ 46.7 $ 39.3 $ 46.7 $ 39.3

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table sets forth the computation of our basic and diluted EPS available to shareholders of common stock (excluding participating securities): Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 (in millions, except per share data) Numerator Net income attributable to AAM $ 86.2 $ 61.7 $ 230.8 $ 193.8 Less: Net income attributable to participating securities (1.9 ) (1.4 ) (5.1 ) (4.4 ) Net income attributable to common shareholders - Basic and Dilutive $ 84.3 $ 60.3 $ 225.7 $ 189.4 Denominators Basic common shares outstanding - Weighted-average shares outstanding 113.9 78.3 101.5 78.2 Less: Participating securities (2.6 ) (1.8 ) (2.3 ) (1.8 ) Weighted-average common shares outstanding 111.3 76.5 99.2 76.4 Effect of dilutive securities - Dilutive stock-based compensation 0.4 0.5 0.4 0.4 Diluted shares outstanding - Adjusted weighted-average shares after assumed conversions 111.7 77.0 99.6 76.8 Basic EPS $ 0.76 $ 0.79 $ 2.28 $ 2.48 Diluted EPS $ 0.75 $ 0.78 $ 2.27 $ 2.47 Certain exercisable stock options were excluded from the computations of diluted EPS because the exercise price of these options was greater than the average period market prices. There were no stock options excluded from the calculation of diluted EPS at September 30, 2017 . The number of stock options outstanding, which were not included in the calculation of diluted EPS, was 0.2 million , with an exercise price of $26.02 , at September 30, 2016 .

Reclassifications out of Accu34

Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2017
Reclassifications out of Accumulated Other Comprehensive Income (Loss) [Abstract]
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]	Reclassification adjustments and other activity impacting accumulated other comprehensive income (loss) during the three months ended September 30, 2017 and September 30, 2016 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at June 30, 2017 $ (242.9 ) $ (85.9 ) $ (3.3 ) $ (332.1 ) Other comprehensive income before reclassifications — 42.8 0.4 43.2 Income tax effect of other comprehensive income before reclassifications — — — — Amounts reclassified from accumulated other comprehensive loss 4.1 (a) — 0.7 (b) 4.8 Income tax benefit reclassified into net income (1.0 ) — — (1.0 ) Net current period other comprehensive income 3.1 42.8 1.1 47.0 Balance at September 30, 2017 $ (239.8 ) $ (43.1 ) $ (2.2 ) $ (285.1 ) Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at June 30, 2016 $ (219.2 ) $ (103.4 ) $ (15.7 ) $ (338.3 ) Other comprehensive loss before reclassifications — (0.8 ) (6.7 ) (7.5 ) Income tax effect of other comprehensive loss before reclassifications — — — — Amounts reclassified from accumulated other comprehensive loss 0.7 (a) — 2.6 (b) 3.3 Income tax benefit reclassified into net income (0.1 ) — — (0.1 ) Net current period other comprehensive income (loss) 0.6 (0.8 ) (4.1 ) (4.3 ) Balance at September 30, 2016 $ (218.6 ) $ (104.2 ) $ (19.8 ) $ (342.6 ) (a) The amount reclassified from AOCI included $4.2 million in cost of goods sold (COGS) and $(0.1) million in selling, general & administrative expenses (SG&A) for the three months ended September 30, 2017 and $1.0 million in COGS and $(0.3) million in SG&A for the three months ended September 30, 2016. (b) The amounts reclassified from AOCI are included in COGS. Reclassification adjustments and other activity impacting accumulated other comprehensive income (loss) during the nine months ended September 30, 2017 and September 30, 2016 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at December 31, 2016 $ (243.5 ) $ (122.4 ) $ (23.7 ) $ (389.6 ) Other comprehensive income (loss) before reclassifications (1.7 ) 79.3 16.2 93.8 Income tax effect of other comprehensive income (loss) before reclassifications 0.6 — 0.7 1.3 Amounts reclassified from accumulated other comprehensive loss 6.6 (a) — 4.6 (b) 11.2 Income tax benefit reclassified into net income (1.8 ) — — (1.8 ) Net current period other comprehensive income 3.7 79.3 21.5 104.5 Balance at September 30, 2017 $ (239.8 ) $ (43.1 ) $ (2.2 ) $ (285.1 ) Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at December 31, 2015 $ (223.9 ) (119.2 ) $ (13.4 ) $ (356.5 ) Other comprehensive income (loss) before reclassifications 5.7 15.0 (13.3 ) 7.4 Income tax effect of other comprehensive income (loss) before reclassifications (2.0 ) — — (2.0 ) Amounts reclassified from accumulated other comprehensive loss 2.4 (a) — 6.9 (b) 9.3 Income tax benefit reclassified into net income (0.8 ) — — (0.8 ) Net current period other comprehensive income (loss) 5.3 15.0 (6.4 ) 13.9 Balance at September 30, 2016 $ (218.6 ) $ (104.2 ) $ (19.8 ) $ (342.6 ) (a) The amount reclassified from AOCI included $7.0 million in COGS and $(0.4) million in SG&A for the nine months ended September 30, 2017 and $3.3 million in COGS and $(0.9) million in SG&A for the nine months ended September 30, 2016. (b) The amounts reclassified from AOCI are included in COGS.

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	The following tables represent information by reportable segment for the three months ended September 30, 2017 and 2016: Three Months Ended September 30, 2017 Driveline Metal Forming Powertrain Casting Total Sales $ 1,007.9 $ 368.2 $ 260.9 $ 226.6 $ 1,863.6 Less: intersegment sales 0.2 106.8 3.8 28.4 139.2 Net external sales $ 1,007.7 $ 261.4 $ 257.1 $ 198.2 $ 1,724.4 Segment Adjusted EBITDA $ 181.4 $ 70.7 $ 36.8 $ 8.8 $ 297.7 Three Months Ended September 30, 2016 Driveline Metal Forming Powertrain Casting Total Sales $ 956.1 $ 137.2 $ — $ — $ 1,093.3 Less: intersegment sales 0.1 86.3 — — 86.4 Net external sales $ 956.0 $ 50.9 $ — $ — $ 1,006.9 Segment Adjusted EBITDA $ 134.4 $ 22.3 $ — $ — $ 156.7 The following tables represent information by reportable segment for the nine months ended September 30, 2017 and 2016: Nine Months Ended September 30, 2017 Driveline Metal Forming Powertrain Casting Total Sales $ 3,028.7 $ 887.5 $ 544.5 $ 452.2 $ 4,912.9 Less: intersegment sales 1.1 315.1 6.0 58.6 380.8 Net external sales $ 3,027.6 $ 572.4 $ 538.5 $ 393.6 $ 4,532.1 Segment Adjusted EBITDA $ 513.5 $ 170.5 $ 88.7 $ 34.3 $ 807.0 Nine Months Ended September 30, 2016 Driveline Metal Forming Powertrain Casting Total Sales $ 2,840.4 $ 414.4 $ — $ — $ 3,254.8 Less: intersegment sales 3.8 249.5 — — 253.3 Net external sales $ 2,836.6 $ 164.9 $ — $ — $ 3,001.5 Segment Adjusted EBITDA $ 391.9 $ 79.4 $ — $ — $ 471.3 Total assets by reportable segment as of September 30, 2017 and December 31, 2016 were as follows: September 30, 2017 Driveline Metal Forming Powertrain Casting Corporate and Eliminations Total Total assets $ 2,362.7 $ 2,155.8 $ 1,825.1 $ 1,018.0 $ 696.7 $ 8,058.3 December 31, 2016 Driveline Metal Forming Powertrain Casting Corporate and Eliminations Total Total assets $ 2,183.9 $ 410.3 $ — $ — $ 829.7 $ 3,423.9
Reconciliation of Segment Adjusted EBITDA (Non-GAAP Measure) to Income Before Income Taxes [Table Text Block]	The following table represents a reconciliation of Segment Adjusted EBITDA to consolidated income before income taxes for the three and nine months ended September 30, 2017 and 2016. Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Segment Adjusted EBITDA $ 297.7 $ 156.7 $ 807.0 $ 471.3 Interest expense (57.5 ) (23.2 ) (139.9 ) (70.2 ) Depreciation and amortization (122.6 ) (49.9 ) (303.4 ) (150.4 ) Restructuring and acquisition-related costs (22.8 ) — (90.5 ) — Pension settlement (2.9 ) — (2.9 ) — Acquisition-related fair value inventory adjustment — — (24.9 ) — Impact of change in accounting principle — — 3.7 — Debt refinancing and redemption costs — — (2.7 ) — Asset impairment charge — (3.4 ) — (3.4 ) Investment gain related to the final distribution of the Reserve Yield Plus Fund — — — 1.0 Other 0.1 (0.7 ) 0.2 (0.7 ) Income before income taxes $ 92.0 $ 79.5 $ 246.6 $ 247.6

Supplemental Guarantor Conden36

Supplemental Guarantor Condensed Consolidating Financial Statements (Tables)	9 Months Ended
	Sep. 30, 2017
Supplemental Guarantor Condensed Consolidating Financial Statements [Abstract]
Supplemental Guarantor Consolidating Income Statement [Table Text Block]	Condensed Consolidating Statements of Income Three Months Ended September 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net sales External $ — $ 250.0 $ 529.0 $ 945.4 $ — $ 1,724.4 Intercompany — 0.2 80.0 7.0 (87.2 ) — Total net sales — 250.2 609.0 952.4 (87.2 ) 1,724.4 Cost of goods sold — 229.6 546.3 738.0 (87.2 ) 1,426.7 Gross profit — 20.6 62.7 214.4 — 297.7 Selling, general and administrative expenses — 57.8 24.7 19.8 — 102.3 Amortization of intangible assets — 1.5 22.3 0.6 — 24.4 Restructuring and acquisition-related costs — 21.6 — 1.2 — 22.8 Operating income (loss) — (60.3 ) 15.7 192.8 — 148.2 Non-operating income (expense), net — (60.8 ) 5.5 (0.9 ) — (56.2 ) Income (loss) before income taxes — (121.1 ) 21.2 191.9 — 92.0 Income tax expense (benefit) — (29.0 ) 17.8 16.9 — 5.7 Earnings from equity in subsidiaries 86.2 29.9 25.5 — (141.6 ) — Net income (loss) before royalties 86.2 (62.2 ) 28.9 175.0 (141.6 ) 86.3 Royalties — 84.9 1.3 (86.2 ) — — Net income after royalties 86.2 22.7 30.2 88.8 (141.6 ) 86.3 Net income attributable to noncontrolling interests — — — (0.1 ) — (0.1 ) Net income attributable to AAM $ 86.2 $ 22.7 $ 30.2 $ 88.7 $ (141.6 ) $ 86.2 Other comprehensive income, net of tax 47.0 16.7 42.6 51.3 (110.6 ) 47.0 Comprehensive income attributable to AAM $ 133.2 $ 39.4 $ 72.8 $ 140.0 $ (252.2 ) $ 133.2 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2016 Net sales External $ — $ 274.7 $ 49.9 $ 682.3 $ — $ 1,006.9 Intercompany — 3.7 62.7 4.4 (70.8 ) — Total net sales — 278.4 112.6 686.7 (70.8 ) 1,006.9 Cost of goods sold — 265.4 94.9 536.2 (70.8 ) 825.7 Gross profit — 13.0 17.7 150.5 — 181.2 Selling, general and administrative expenses — 71.3 — 7.3 — 78.6 Amortization of intangible assets — 1.3 — — — 1.3 Operating income (loss) — (59.6 ) 17.7 143.2 — 101.3 Non-operating income (expense), net — (24.9 ) 2.9 0.2 — (21.8 ) Income (loss) before income taxes — (84.5 ) 20.6 143.4 — 79.5 Income tax expense — 7.9 0.1 9.8 — 17.8 Earnings (loss) from equity in subsidiaries 61.7 87.4 (7.1 ) — (142.0 ) — Net income (loss) before royalties 61.7 (5.0 ) 13.4 133.6 (142.0 ) 61.7 Royalties — 66.7 — (66.7 ) — — Net income after royalties 61.7 61.7 13.4 66.9 (142.0 ) 61.7 Net income attributable to noncontrolling interests — — — — — — Net income attributable to AAM $ 61.7 $ 61.7 $ 13.4 $ 66.9 $ (142.0 ) $ 61.7 Other comprehensive income (loss), net of tax (4.3 ) (4.3 ) 1.0 (3.3 ) 6.6 (4.3 ) Comprehensive income attributable to AAM $ 57.4 $ 57.4 $ 14.4 $ 63.6 $ (135.4 ) $ 57.4 Condensed Consolidating Statements of Income Nine Months Ended September 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net sales External $ — $ 806.9 $ 1,139.8 $ 2,585.4 $ — $ 4,532.1 Intercompany — 2.4 214.7 19.9 (237.0 ) — Total net sales — 809.3 1,354.5 2,605.3 (237.0 ) 4,532.1 Cost of goods sold — 752.2 1,188.0 2,004.1 (237.0 ) 3,707.3 Gross profit — 57.1 166.5 601.2 — 824.8 Selling, general and administrative expenses — 196.0 45.7 47.4 — 289.1 Amortization of intangible assets — 4.3 45.0 1.5 — 50.8 Restructuring and acquisition-related costs — 87.0 — 3.5 90.5 Operating income (loss) — (230.2 ) 75.8 548.8 — 394.4 Non-operating income (expense), net — (148.7 ) 14.9 (14.0 ) — (147.8 ) Income (loss) before income taxes — (378.9 ) 90.7 534.8 — 246.6 Income tax expense (benefit) — (62.2 ) 42.0 35.8 — 15.6 Earnings from equity in subsidiaries 230.8 202.9 41.4 — (475.1 ) — Net income (loss) before royalties 230.8 (113.8 ) 90.1 499.0 (475.1 ) 231.0 Royalties — 253.6 2.6 (256.2 ) — — Net income after royalties 230.8 139.8 92.7 242.8 (475.1 ) 231.0 Net income attributable to noncontrolling interests — — — (0.2 ) — (0.2 ) Net income attributable to AAM $ 230.8 $ 139.8 $ 92.7 $ 242.6 $ (475.1 ) $ 230.8 Other comprehensive income, net of tax 104.5 55.3 74.7 94.8 (224.8 ) 104.5 Comprehensive income attributable to AAM $ 335.3 $ 195.1 $ 167.4 $ 337.4 $ (699.9 ) $ 335.3 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2016 Net sales External $ — $ 866.3 $ 161.4 $ 1,973.8 $ — $ 3,001.5 Intercompany — 8.1 185.7 12.2 (206.0 ) — Total net sales — 874.4 347.1 1,986.0 (206.0 ) 3,001.5 Cost of goods sold — 833.5 284.3 1,543.1 (206.0 ) 2,454.9 Gross profit — 40.9 62.8 442.9 — 546.6 Selling, general and administrative expenses — 206.8 — 25.0 — 231.8 Amortization of intangible assets — 3.5 — 0.1 — 3.6 Operating income (loss) — (169.4 ) 62.8 417.8 — 311.2 Non-operating income (expense), net — (72.7 ) 8.4 0.7 — (63.6 ) Income (loss) before income taxes — (242.1 ) 71.2 418.5 — 247.6 Income tax expense — 28.9 0.3 24.6 — 53.8 Earnings (loss) from equity in subsidiaries 193.8 266.6 (28.0 ) — (432.4 ) — Net income (loss) before royalties 193.8 (4.4 ) 42.9 393.9 (432.4 ) 193.8 Royalties — 198.2 — (198.2 ) — — Net income after royalties 193.8 193.8 42.9 195.7 (432.4 ) 193.8 Net income attributable to noncontrolling interests — — — — — — Net income attributable to AAM $ 193.8 $ 193.8 $ 42.9 $ 195.7 $ (432.4 ) $ 193.8 Other comprehensive income, net of tax 13.9 13.9 23.2 16.9 (54.0 ) 13.9 Comprehensive income attributable to AAM $ 207.7 $ 207.7 $ 66.1 $ 212.6 $ (486.4 ) $ 207.7
Supplemental Guarantor Consolidating Balance Sheet [Table Text Block]	Condensed Consolidating Balance Sheets (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims/Reclassifications Consolidated September 30, 2017 Assets Current assets Cash and cash equivalents $ — $ 188.5 $ 0.1 $ 361.0 $ — $ 549.6 Accounts receivable, net — 134.4 320.2 667.4 — 1,122.0 Intercompany receivables — 3,559.1 465.9 8.0 (4,033.0 ) — Inventories, net — 34.0 151.2 211.4 — 396.6 Prepaid expenses and other — 27.4 12.1 105.0 — 144.5 Total current assets — 3,943.4 949.5 1,352.8 (4,033.0 ) 2,212.7 Property, plant and equipment, net — 234.1 788.5 1,280.1 — 2,302.7 Goodwill — — 1,220.2 434.4 — 1,654.6 Intangible assets, net — 21.9 1,178.1 36.6 — 1,236.6 Intercompany notes and accounts receivable 14.6 — 260.9 — (275.5 ) — Other assets and deferred charges — 717.4 137.2 129.8 (332.7 ) 651.7 Investment in subsidiaries 2,735.0 1,917.2 708.9 — (5,361.1 ) — Total assets $ 2,749.6 $ 6,834.0 $ 5,243.3 $ 3,233.7 $ (10,002.3 ) $ 8,058.3 Liabilities and Stockholders’ Equity Current liabilities Current portion of long-term debt $ — $ — $ — $ 6.8 $ — $ 6.8 Accounts payable — 130.2 238.2 488.0 — 856.4 Intercompany payables 1,313.0 499.7 2,010.2 210.1 (4,033.0 ) — Accrued expenses and other — 183.0 56.3 182.5 — 421.8 Total current liabilities 1,313.0 812.9 2,304.7 887.4 (4,033.0 ) 1,285.0 Intercompany notes and accounts payable — 76.9 — 198.6 (275.5 ) — Long-term debt, net — 4,096.3 4.6 68.4 — 4,169.3 Other long-term liabilities — 742.2 594.0 163.9 (332.7 ) 1,167.4 Total liabilities 1,313.0 5,728.3 2,903.3 1,318.3 (4,641.2 ) 6,621.7 Total AAM Stockholders’ equity 1,432.8 1,105.7 2,340.0 1,911.6 (5,357.3 ) 1,432.8 Noncontrolling interests in subsidiaries 3.8 — — 3.8 (3.8 ) 3.8 Total stockholders’ equity 1,436.6 1,105.7 2,340.0 1,915.4 (5,361.1 ) 1,436.6 Total liabilities and stockholders’ equity $ 2,749.6 $ 6,834.0 $ 5,243.3 $ 3,233.7 $ (10,002.3 ) $ 8,058.3 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated December 31, 2016 Assets Current assets Cash and cash equivalents $ — $ 84.3 $ 1.6 $ 395.3 $ — $ 481.2 Accounts receivable, net — 126.7 21.9 411.4 — 560.0 Intercompany receivables — 442.6 326.0 9.1 (777.7 ) — Inventories, net — 31.3 21.5 129.5 — 182.3 Prepaid expenses and other — 29.4 0.5 45.9 — 75.8 Total current assets — 714.3 371.5 991.2 (777.7 ) 1,299.3 Property, plant and equipment, net — 213.7 102.9 777.1 — 1,093.7 Goodwill — — 147.8 6.2 — 154.0 Intangible assets, net — 22.8 — 5.7 — 28.5 Intercompany notes and accounts receivable — 343.9 242.2 — (586.1 ) — Other assets and deferred charges — 644.9 39.8 163.7 — 848.4 Investment in subsidiaries 827.6 1,544.4 — — (2,372.0 ) — Total assets $ 827.6 $ 3,484.0 $ 904.2 $ 1,943.9 $ (3,735.8 ) $ 3,423.9 Liabilities and Stockholders’ Equity Current liabilities Current portion of long-term debt $ — $ — $ — $ 3.3 $ — $ 3.3 Accounts payable — 80.6 35.8 265.9 — 382.3 Intercompany payables — 324.8 153.4 299.5 (777.7 ) — Accrued expenses and other — 142.2 4.3 119.4 — 265.9 Total current liabilities — 547.6 193.5 688.1 (777.7 ) 651.5 Intercompany notes and accounts payable 321.8 14.6 7.5 242.2 (586.1 ) — Long-term debt, net — 1,339.7 4.1 57.1 — 1,400.9 Investment in subsidiaries obligation — — 124.7 — (124.7 ) — Other long-term liabilities — 754.5 0.6 110.6 — 865.7 Total liabilities 321.8 2,656.4 330.4 1,098.0 (1,488.5 ) 2,918.1 Total stockholders’ equity 505.8 827.6 573.8 845.9 (2,247.3 ) 505.8 Total liabilities and stockholders’ equity $ 827.6 $ 3,484.0 $ 904.2 $ 1,943.9 $ (3,735.8 ) $ 3,423.9
Supplemental Guarantor Consolidating Statement of Cash Flows [Table Text Block]	Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2016 Net cash provided by operating activities $ — $ 114.8 $ 20.9 $ 155.3 $ — $ 291.0 Investing activities Purchases of property, plant and equipment — (25.9 ) (12.0 ) (120.8 ) — (158.7 ) Proceeds from sale of property, plant and equipment — — 0.3 0.4 — 0.7 Proceeds from government grants — — — 2.8 — 2.8 Final distribution of Reserve Yield Plus Fund — 1.0 — — — 1.0 Acquisition of business, net of cash acquired — — (5.6 ) — — (5.6 ) Intercompany activity — — (2.0 ) — 2.0 — Net cash used in investing activities — (24.9 ) (19.3 ) (117.6 ) 2.0 (159.8 ) Financing activities Net debt activity — (0.4 ) (0.3 ) 23.3 — 22.6 Employee stock option exercises — 0.3 — — — 0.3 Purchase of treasury stock (5.3 ) — — — — (5.3 ) Intercompany activity 5.3 (5.3 ) — 2.0 (2.0 ) — Net cash provided by (used in) financing activities — (5.4 ) (0.3 ) 25.3 (2.0 ) 17.6 Effect of exchange rate changes on cash — — — 2.6 — 2.6 Net increase in cash and cash equivalents — 84.5 1.3 65.6 — 151.4 Cash and cash equivalents at beginning of period — 52.0 — 230.5 — 282.5 Cash and cash equivalents at end of period $ — $ 136.5 $ 1.3 $ 296.1 $ — $ 433.9 Condensed Consolidating Statements of Cash Flows Nine Months Ended September 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net cash provided by operating activities $ — $ 276.4 $ 9.0 $ 135.3 $ — $ 420.7 Investing activities Purchases of property, plant and equipment — (43.1 ) (73.3 ) (162.3 ) — (278.7 ) Proceeds from sale of property, plant and equipment — 0.3 0.3 1.1 — 1.7 Purchase buyouts of leased equipment — (12.6 ) — — — (12.6 ) Proceeds from sale of business, net — 7.5 (1.6 ) — — 5.9 Acquisition of business, net of cash acquired — (953.5 ) 64.6 (6.6 ) — (895.5 ) Net cash used in investing activities — (1,001.4 ) (10.0 ) (167.8 ) — (1,179.2 ) Financing activities Net debt activity — 926.1 (0.5 ) (12.1 ) — 913.5 Debt issuance costs — (90.8 ) — — — (90.8 ) Employee stock option exercises — 0.9 — — — 0.9 Purchase of treasury stock (7.0 ) — — — — (7.0 ) Intercompany activity 7.0 (7.0 ) — — — — Net cash provided by (used in) financing activities — 829.2 (0.5 ) (12.1 ) — 816.6 Effect of exchange rate changes on cash — — — 10.3 — 10.3 Net increase (decrease) in cash and cash equivalents — 104.2 (1.5 ) (34.3 ) — 68.4 Cash and cash equivalents at beginning of period — 84.3 1.6 395.3 — 481.2 Cash and cash equivalents at end of period $ — $ 188.5 $ 0.1 $ 361.0 $ — $ 549.6

Effect of Change in Accounting

Effect of Change in Accounting Principle (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2017	Sep. 30, 2017	Dec. 31, 2016	Jan. 01, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories, net		$ (396.6)	$ (182.3)
Retained earnings		$ (656.3)	(425.5)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Diluted Earnings Per Share		$ 0.02
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Basic Earnings Per Share		$ 0.02
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	$ 2.4
Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories, net			(37.2)	$ (37.2)
Retained earnings			(24.2)	(24.2)
Deferred Tax Assets, Net			$ 13	$ 13

Share Repurchase Program (Detai

Share Repurchase Program (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	May 05, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Stock Repurchase Program, Authorized Amount			$ 100
Treasury Stock, Value, Acquired, Cost Method	$ 1.5
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 98.5

Organization and Basis of Pre39

Organization and Basis of Presentation Company Information (Details)	Apr. 06, 2017EmployeesCountriesFacilities
Franchisor Disclosure [Line Items]
Entity Number of Employees | Employees	25,000
Number of Facilities | Facilities	90
Number of Countries in which Entity Operates | Countries	17

Restructuring and Acquisition40

Restructuring and Acquisition-Related Costs (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Restructuring Reserve [Roll Forward]
Restructuring Reserve	$ 9.8
Charges	15.2
Cash utilization	(20.1)
Non-cash utilization	0
Accrual adjustments	0
Restructuring Reserve	4.9	$ 4.9
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve	9.2
Charges	13.5	23.7
Cash utilization	(17.8)
Non-cash utilization	0
Accrual adjustments	0
Restructuring Reserve	4.9	4.9
Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve	0.6
Charges	1.7	2.3
Cash utilization	(2.3)
Non-cash utilization	0
Accrual adjustments	0
Restructuring Reserve	$ 0	$ 0

Restructuring Reserve Narrative

Restructuring Reserve Narrative (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2017USD ($)
Restructuring Cost and Reserve [Line Items]
Charges	$ 15.2
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Charges	1.7	$ 2.3
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Charges	13.5	23.7
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	5	5
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	$ 15	$ 15

Business Combinations, Separate

Business Combinations, Separately Recognized Transactions Table (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restructuring and Related Activities [Abstract]
Business Combination, Acquisition Related Costs			$ 40.7
Severance Costs			5.6
Business Combination, Integration Related Costs			29
Business Combination, Acquisition & Integration Related Costs			75.3
Restructuring and acquisition-related costs	$ 22.8	$ 0	90.5	$ 0
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost			$ 20

Acquisition of MPG Narrative (D

Acquisition of MPG Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 06, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Business Acquisition, Share Price	$ 13.50
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	0.5
Proceeds from Issuance of Long-term Debt								$ 2,858.1	$ 28.8
Business Acquisition, Pro Forma Earnings Per Share, Diluted								$ 2.57	$ 1.64
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost								$ 20
Acquisition-related fair value inventory adjustment		$ 0			$ 0			(24.9)	$ 0
Restructuring and acquisition-related costs		22.8			$ 0			90.5	0
Metaldyne Performance Group, Inc. [Member]
Business Acquisition [Line Items]
Contractual purchase price			$ 1,530.2
Proposed Business Acquisition Net Debt to be Assumed by Acquiring Entity			$ 1,700
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	$ 1,918.7
Cash acquired	(202.1)
Proceeds from Notes Payable				$ 1,200
Goodwill, Purchase Accounting Adjustments		$ 18
Intangible assets	1,223.1
Adjustment to contractual purchase price for settlement of existing accounts payable balance	(12.4)
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual						$ 1,351
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual						$ 42
Business Acquisition, Pro Forma Revenue								5,300	5,100
Business Acquisition, Pro Forma Net Income (Loss)								290	$ 170
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost							$ 20	20
Acquisition-related fair value inventory adjustment							24.9	24.9
Restructuring and acquisition-related costs							22	55
MPG Pro Forma Net Income Adjustment							$ 45	$ 65
6.25% Notes due 2025 [Member] | Metaldyne Performance Group, Inc. [Member]
Business Acquisition [Line Items]
Proceeds from Notes Payable				$ 700
Debt Instrument, Interest Rate, Stated Percentage				6.25%
6.50% Notes due 2027 [Member] | Metaldyne Performance Group, Inc. [Member]
Business Acquisition [Line Items]
Proceeds from Notes Payable				$ 500
Debt Instrument, Interest Rate, Stated Percentage				6.50%
Term Loan A [Member] | Metaldyne Performance Group, Inc. [Member]
Business Acquisition [Line Items]
Proceeds from Issuance of Long-term Debt	100
Term Loan B [Member] | Metaldyne Performance Group, Inc. [Member]
Business Acquisition [Line Items]
Proceeds from Issuance of Long-term Debt	$ 1,550

MPG Acquisition Table (Details)

MPG Acquisition Table (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Sep. 30, 2017	Apr. 06, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 1,654.6		$ 154
Metaldyne Performance Group, Inc. [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 953.5
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	576.7
Contractual purchase price	$ 1,530.2
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value			$ 3.6
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			1,533.8
Net assets acquired			139.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents			202.1
Accounts receivable			403.2
Inventories			199
Prepaid expenses and other			121
Property, plant and equipment			985.7
Intangible assets			1,223.1
Total assets acquired			3,134.1
Accounts payable			287.8
Accrued expenses and other			137.2
Deferred income tax liabilities			596.4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt			1,918.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other			54.5
Goodwill			$ 1,394.3

USM Acquisition Table (Details)

USM Acquisition Table (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Mar. 01, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Adjusted purchase price, net of cash acquired		$ 895.5	$ 5.6
Goodwill		$ 1,654.6			$ 154
USM Mexico Manufacturing LLC [Member]
Business Acquisition [Line Items]
Contractual purchase price	$ 162.5
Adjustments to contractual purchase price for capital equipment				$ 4.9
Adjustment to contractual purchase price for settlement of existing accounts payable balance				(22.8)
Cash acquired				(0.5)
Adjusted purchase price, net of cash acquired	$ 144.1
Accounts receivable				1.1
Inventories				4.8
Prepaid expenses and other				2.4
Property, plant and equipment				38.4
Intangible assets				31.7
Total assets acquired				78.4
Accounts payable				10.8
Accrued expenses and other				2.7
Deferred income tax liabilities				1.2
Net assets acquired				63.7
Goodwill				$ 80.4

Goodwill Rollforward (Details)

Goodwill Rollforward (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Goodwill [Roll Forward]
Goodwill	$ 154
Goodwill, Foreign Currency Translation Gain (Loss)	25.9
Goodwill	1,654.6
Driveline [Member]
Goodwill [Roll Forward]
Goodwill	130.1
Goodwill, Foreign Currency Translation Gain (Loss)	0.4
Goodwill	210.9
Metal Forming [Member]
Goodwill [Roll Forward]
Goodwill	23.9
Goodwill, Foreign Currency Translation Gain (Loss)	16.6
Goodwill	556.5
Powertrain [Member]
Goodwill [Roll Forward]
Goodwill	0
Goodwill, Foreign Currency Translation Gain (Loss)	8.9
Goodwill	481.2
Casting [Member]
Goodwill [Roll Forward]
Goodwill	0
Goodwill, Foreign Currency Translation Gain (Loss)	0
Goodwill	406
Metaldyne Performance Group, Inc. [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	1,394.3
Metaldyne Performance Group, Inc. [Member] | Driveline [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	0
Metaldyne Performance Group, Inc. [Member] | Metal Forming [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	516
Metaldyne Performance Group, Inc. [Member] | Powertrain [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	472.3
Metaldyne Performance Group, Inc. [Member] | Casting [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	406
USM Mexico Manufacturing LLC [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	80.4
USM Mexico Manufacturing LLC [Member] | Driveline [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	80.4
USM Mexico Manufacturing LLC [Member] | Metal Forming [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	0
USM Mexico Manufacturing LLC [Member] | Powertrain [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	0
USM Mexico Manufacturing LLC [Member] | Casting [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	$ 0

Intangible Assets Acquired Tabl

Intangible Assets Acquired Table (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		$ 1,254.8
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		13 years 7 months
Metaldyne Performance Group, Inc. [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		$ 1,223.1
Metaldyne Performance Group, Inc. [Member] | Customer Platforms - Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		950
Finite-Lived Intangible Assets, Purchase Accounting Adjustments	$ 20
Metaldyne Performance Group, Inc. [Member] | Customer Relationships - Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		151.8
Finite-Lived Intangible Assets, Purchase Accounting Adjustments	$ 1.5
Metaldyne Performance Group, Inc. [Member] | Technology-Based Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		121.3
USM Mexico Manufacturing LLC [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		31.7
USM Mexico Manufacturing LLC [Member] | Customer Platforms - Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		2.2
USM Mexico Manufacturing LLC [Member] | Technology-Based Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		$ 29.5

Intangible Assets Table (Detail

Intangible Assets Table (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 24.4	$ 1.3	$ 50.8	$ 3.6
Finite-Lived Intangible Assets, Gross	1,295.9		1,295.9		$ 37
Finite-Lived Intangible Assets, Accumulated Amortization	(59.3)		(59.3)		(8.5)
Finite-Lived Intangible Assets, Net	1,236.6		1,236.6		28.5
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	75		75
Finite-Lived Intangible Assets, Amortization Expense, Year Two	100		100
Finite-Lived Intangible Assets, Amortization Expense, Year Three	100		100
Finite-Lived Intangible Assets, Amortization Expense, Year Four	100		100
Finite-Lived Intangible Assets, Amortization Expense, Year Five	100		100
Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	35.2		35.2		31.7
Finite-Lived Intangible Assets, Accumulated Amortization	(12.8)		(12.8)		(8.5)
Finite-Lived Intangible Assets, Net	22.4		22.4		23.2
In Process Research and Development [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	5.9		5.9		5.3
Finite-Lived Intangible Assets, Accumulated Amortization	0		0		0
Finite-Lived Intangible Assets, Net	5.9		5.9		5.3
Customer Platforms - Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	952.2		952.2		0
Finite-Lived Intangible Assets, Accumulated Amortization	(35.3)		(35.3)		0
Finite-Lived Intangible Assets, Net	916.9		916.9		0
Customer Relationships - Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	151.8		151.8		0
Finite-Lived Intangible Assets, Accumulated Amortization	(4.9)		(4.9)		0
Finite-Lived Intangible Assets, Net	146.9		146.9		0
Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	150.8		150.8		0
Finite-Lived Intangible Assets, Accumulated Amortization	(6.3)		(6.3)		0
Finite-Lived Intangible Assets, Net	$ 144.5		$ 144.5		$ 0

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Inventory [Line Items]
Raw materials and work-in-progress	$ 331.4	$ 163.3
Finished goods	90	33.8
Gross inventories	421.4	197.1
Inventory valuation reserves	(24.8)	(14.8)
Inventories, net	$ 396.6	$ 182.3

Inventories - Change in Account

Inventories - Change in Accounting Principle (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Raw materials and work-in-progress	$ (331.4)	$ (163.3)
Inventory Valuation Reserves	$ 24.8	14.8
Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Raw materials and work-in-progress		(49.4)
Inventory Valuation Reserves		$ 12.2

Schedule of Long-Term Debt (Det

Schedule of Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt, Long-term and Short-term, Combined Amount	$ 4,255.3	$ 1,415.9
Current portion of long-term debt	6.8	3.3
Long-term debt	4,248.5	1,412.6
Long-term debt, net	4,169.3	1,400.9
Total Debt Instruments excluding Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense	79.2	11.7
Secured Debt [Member] | Term Loan A [Member]
Debt Instrument [Line Items]
Notes payable	93.8	0
Secured Debt [Member] | Term Loan B [Member]
Debt Instrument [Line Items]
Notes payable	1,530.6	0
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	0	0
Unsecured Debt [Member] | 7.75% Notes [Member]
Debt Instrument [Line Items]
Notes payable	$ 200	200
Debt Instrument, Interest Rate, Stated Percentage	7.75%
Unsecured Debt [Member] | 6.625% Notes [Member]
Debt Instrument [Line Items]
Notes payable	$ 550	550
Debt Instrument, Interest Rate, Stated Percentage	6.625%
Unsecured Debt [Member] | 6.50% Notes due 2027 [Member]
Debt Instrument [Line Items]
Notes payable	$ 500	0
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Unsecured Debt [Member] | 6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Notes payable	$ 700	0
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Unsecured Debt [Member] | 6.25% Notes Due 2021 [Member]
Debt Instrument [Line Items]
Notes payable	$ 400	400
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Unsecured Debt [Member] | 5.125% Notes [Member]
Debt Instrument [Line Items]
Notes payable	$ 200	200
Debt Instrument, Interest Rate, Stated Percentage	5.125%
Foreign Credit Facilities [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	$ 52.3	60.4
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Capital lease obligations	$ 28.6	$ 5.5

New Senior Secured Credit Facil

New Senior Secured Credit Facilities Narrative (Details) - USD ($) $ in Millions	Apr. 06, 2017	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt			$ 2,858.1	$ 28.8
Payments of Debt Issuance Costs			$ 90.8	$ 0
Line of Credit Facility, Interest Rate Description			The Term Loan A Facility and the Revolving Credit Facility will mature on April 6, 2022, and the Term Loan B Facility will mature on April 6, 2024. Borrowings under the New Senior Secured Credit Facilities bear interest at rates based on the applicable Eurodollar rate or alternate base rate, as AAM may elect, in each case plus an applicable margin determined based on AAM’s total net leverage ratio. The alternate base rate is the greatest of (a) the prime rate of a major United States financial institution, (b) the Federal Reserve Bank of New York rate plus 0.50% and (c) the adjusted Eurodollar rate plus 1.00%. The applicable margin for Eurodollar-based loans under the New Senior Secured Credit Facilities will be between 1.25% and 2.25% with respect to any loan under the Term Loan A Facility, 2.25% with respect to any loan under the Term Loan B Facility, and between 2.00% and 3.00% with respect to any loan under the Revolving Credit Facility. The applicable margin for loans subject to alternate base rate will be between 0.25% and 1.25% with respect to any loan under the Term Loan A Facility, 1.25% with respect to any loan under the Term Loan B Facility, and between 1.00% and 2.00% with respect to any loan under the Revolving Credit Facility.
Line of Credit Facility, Borrowing Capacity, Description			The Credit Agreement permits AAM, Inc. to incur incremental term loan borrowings and/or increase commitments under the Revolving Credit Facility, subject to certain limitations and the satisfaction of certain conditions, in an aggregate amount not to exceed (i) $600 million, plus (ii) certain voluntary prepayments, plus (iii) additional amounts subject to pro forma compliance with a first lien net leverage ratio for Holdings and its restricted subsidiaries.
Term Loan A [Member]
Debt Instrument [Line Items]
Payment for Debt Extinguishment or Debt Prepayment Cost		$ 5
Term Loan B [Member]
Debt Instrument [Line Items]
Payment for Debt Extinguishment or Debt Prepayment Cost		15.5
New Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs			$ 53.9
Metaldyne Performance Group, Inc. [Member] | Term Loan A [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt	$ 100
Metaldyne Performance Group, Inc. [Member] | Term Loan B [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt	1,550
Metaldyne Performance Group, Inc. [Member] | New Multi-Currency Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Line of Credit	$ 900
Metaldyne Performance Group, Inc. [Member] | 7.375% Notes - MPG [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.375%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Line of Credit			$ 0		$ 0
Line of Credit Facility, Remaining Borrowing Capacity		869.1
Line of Credit Facility, Standby Letters of Credit Issued Against the Facility		$ 30.9

Issuance of New Notes Narrative

Issuance of New Notes Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Payments of Debt Issuance Costs		$ 90.8	$ 0
6.25% Notes Due 2025 & 6.50% Notes Due 2027 [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs		$ 36.9
Metaldyne Performance Group, Inc. [Member]
Debt Instrument [Line Items]
Proceeds from Notes Payable	$ 1,200
Metaldyne Performance Group, Inc. [Member] | 6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Proceeds from Notes Payable	$ 700
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Metaldyne Performance Group, Inc. [Member] | 6.50% Notes due 2027 [Member]
Debt Instrument [Line Items]
Proceeds from Notes Payable	$ 500
Debt Instrument, Interest Rate, Stated Percentage	6.50%

Repayment of MPG Indebtedness (

Repayment of MPG Indebtedness (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Apr. 06, 2017
Debt Instrument [Line Items]
Debt refinancing and redemption costs	$ 0	$ 0	$ 2.7	$ 0
Metaldyne Performance Group, Inc. [Member]
Debt Instrument [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt					$ 1,918.7
Interest Paid			$ 24.6
Euro Denominated Term Loan [Member] | Metaldyne Performance Group, Inc. [Member]
Debt Instrument [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt					200
U.S. Dollar Denominated Term Loan [Member] [Member] | Metaldyne Performance Group, Inc. [Member]
Debt Instrument [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt					1,000
MPG Bonds [Member] | Metaldyne Performance Group, Inc. [Member]
Debt Instrument [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt					$ 700

Other Debt Disclosures Narrativ

Other Debt Disclosures Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time	5.70%	6.60%
Foreign Credit Facilities [Member]
Debt Instrument [Line Items]
Long-term Line of Credit	$ 52.3	$ 60.4
Debt Instrument, Unused Borrowing Capacity, Amount	$ 99.9

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, at carrying value	$ 126.1	$ 187.2
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, at fair value	126.1	187.2
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Prepaid expenses and other [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	1.1	0
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Prepaid expenses and other [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	1.1	0
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	2.1	0
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	2.1	0
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Accrued expenses and other [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	3.8	12.3
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Accrued expenses and other [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	3.8	12.3
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Postretirement benefits and other long-term liabilities [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	0.5	11.4
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Postretirement benefits and other long-term liabilities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	0.5	11.4
Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member] | Prepaid expenses and other [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	1	0
Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member] | Prepaid expenses and other [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	1	0
Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member] | Accrued expenses and other [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	0.2	1.4
Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member] | Accrued expenses and other [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	0.2	1.4
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	0.3	0
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	0.3	0
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Accrued expenses and other [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	0.2	0
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Accrued expenses and other [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	0.2	0
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Postretirement benefits and other long-term liabilities [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	2.1	0
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Postretirement benefits and other long-term liabilities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	2.1	0
Foreign Exchange Option [Member] | Not Designated as Hedging Instrument [Member] | Prepaid expenses and other [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	1.5	0
Foreign Exchange Option [Member] | Not Designated as Hedging Instrument [Member] | Prepaid expenses and other [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts	$ 1.5	$ 0

Fair Value of Debt (Details)

Fair Value of Debt (Details) - Fair Value, Inputs, Level 2 [Member] - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Revolving Credit Facility [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of Credit Facility, Amount Outstanding	$ 0	$ 0
Revolving Credit Facility [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of Credit Facility, Amount Outstanding	0	0
Term Loan A [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	93.8	0
Term Loan A [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	93.3	0
Term Loan B [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	1,530.6	0
Term Loan B [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	1,521.1	0
7.75% Notes [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	200	200
7.75% Notes [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	219	221
6.625% Notes [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	550	550
6.625% Notes [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	567.2	566.1
6.50% Notes due 2027 [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	500	0
6.50% Notes due 2027 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	502.8	0
6.25% Notes due 2025 [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	700	0
6.25% Notes due 2025 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	711.7	0
6.25% Notes Due 2021 [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	400	400
6.25% Notes Due 2021 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	411	412
5.125% Notes [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	200	200
5.125% Notes [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	$ 200.5	$ 201.7

Derivatives Narrative (Details)

Derivatives Narrative (Details) $ in Millions	Sep. 30, 2017USD ($)
Foreign Currency Forward & Foreign Currency Option Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	$ 218.1
Debt [Member] | Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivate, Amount of Hedged Item, Through May 2018	750
Derivative, Amount of Hedged Item, Through May 2019	600
Derivative, Amount of Hedged Item, Through May 2020	450
Derivative, Amount of Hedged Item, Through May 2021	$ 200

Schedule of Derivatives (Detail

Schedule of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2018
Foreign Exchange Forward [Member] | Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Description of Location of Loss on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments in Financial Statements			Other Income, Net
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss)	$ 0	$ 0	$ 0	$ (0.7)
Foreign Exchange Forward [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Description of Location of Loss on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments in Financial Statements			Cost of Goods Sold
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss)	0.4	(1.3)	$ 6.1	(4)
Foreign Exchange Forward [Member] | Cost of Sales [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Income Statement Location Loss Reclassified from Accumulated OCI			Cost of Goods Sold
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	(0.7)	(2.6)	$ (4.6)	(6.9)
Foreign Exchange Forward [Member] | Cost of Sales [Member] | Cash Flow Hedging [Member] | Scenario, Forecast [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash flow hedge loss to be reclassified within twelve months					$ (2.6)
Interest Rate Swap [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Income Statement Location Loss Reclassified from Accumulated OCI			Interest Expense
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0	$ 0	0
Interest Rate Swap [Member] | Interest Expense [Member] | Cash Flow Hedging [Member] | Scenario, Forecast [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash flow hedge loss to be reclassified within twelve months					$ (0.1)
Foreign Exchange Option [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Description of Location of Loss on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments in Financial Statements			Cost of Goods Sold
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss)	$ 0.3	$ 0	$ 1.4	$ 0

Schedule of Employee Benefit Pl

Schedule of Employee Benefit Plans Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 0.7	$ 0.8	$ 2.6	$ 2.3
Interest cost	7.2	7.3	21.4	21.9
Expected asset return	(11.1)	(10.7)	(32.7)	(32.1)
Amortized loss	1.9	1.3	5.4	4.1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	2.9	0	2.9	0
Net periodic benefit cost (credit)	1.5	(1.3)	(0.5)	(3.8)
Amortized prior service credit	(0.1)	0	(0.1)	0
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.1	0.1	0.3	0.3
Interest cost	3.3	3.5	9.9	10.5
Amortized loss	0.2	0.1	0.5	0.3
Amortized prior service credit	(0.8)	(0.7)	(2.1)	(2)
Net periodic benefit cost	$ 2.8	$ 3	$ 8.6	$ 9.1

Employee Benefit Plans and Othe

Employee Benefit Plans and Other Postretirement Benefit Plans Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Liability, Defined Benefit Pension Plan, Noncurrent	$ 141	$ 113.5
Liability, Other Postretirement Defined Benefit Plan, Noncurrent	540.3	$ 542.6
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	$ 16

Product Warranties (Details)

Product Warranties (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Product Warranty Rollforward
Beginning balance	$ 47.9	$ 37.9	$ 42.9	$ 36.6
Accruals	4.4	4.4	14	12.4
Payments	(2.1)	(3)	(4.5)	(6.7)
Adjustment to prior period accruals	(3.7)	0	(6.3)	(3.1)
Foreign currency translation	0.2	0	0.6	0.1
Ending balance	$ 46.7	$ 39.3	$ 46.7	$ 39.3

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income tax expense	$ 5.7	$ 17.8	$ 15.6	$ 53.8
Effective income tax rate, continuing operations	6.20%	22.40%	6.30%	21.70%
Unrecognized tax benefit liability, including penalties and accrued interest	$ 54.4		$ 54.4		$ 30.7
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities				$ 26.1

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator
Net income attributable to AAM	$ 86.2	$ 61.7	$ 230.8	$ 193.8
Less: Net income attributable to participating securities	(1.9)	(1.4)	(5.1)	(4.4)
Net income attributable to common shareholders - Basic and Dilutive	$ 84.3	$ 60.3	$ 225.7	$ 189.4
Denominators
Basic - Weighted-average shares outstanding	113.9	78.3	101.5	78.2
Basic - Less: Participating securities	(2.6)	(1.8)	(2.3)	(1.8)
Basic - Weighted-average common shares outstanding	111.3	76.5	99.2	76.4
Effect of dilutive securities - dilutive stock-based compensation	0.4	0.5	0.4	0.4
Diluted - Adjusted weighted-average shares after assumed conversions	111.7	77	99.6	76.8
Basic EPS	$ 0.76	$ 0.79	$ 2.28	$ 2.48
Diluted EPS	$ 0.75	$ 0.78	$ 2.27	$ 2.47

Earnings Per Share Narrative (D

Earnings Per Share Narrative (Details) shares in Millions	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares	0.2
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Earnings Per Share, Exercise Prices of Stock Options Excluded from the Calculation of Diluted EPS | $ / shares	$ 26.02

Reclassifications out of Accu66

Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined benefit plans - Beginning balance			$ (243.5)
Defined benefit plans, net current period other comprehensive income (loss)	$ 3.1	$ 0.6	3.7	$ 5.3
Defined benefit plans - Ending balance	(239.8)		(239.8)
Foreign currency translation adjustments - Beginning balance			(122.4)
Foreign currency translation adjustments, net current period other comprehensive income (loss)	42.8	(0.8)	79.3	15
Foreign currency translation adjustments - Ending balance	(43.1)		(43.1)
Unrecognized loss on cash flow hedges - Beginning balance			(23.7)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	0	0	(0.7)	0
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	1.1	(4.1)	21.5	(6.4)
Unrecognized loss on cash flow hedges - Ending balance	(2.2)		(2.2)
Other comprehensive income (loss)	47	(4.3)	104.5	13.9
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Defined benefit plans - Beginning balance	(242.9)	(219.2)	(243.5)	(223.9)
Defined benefit plans, other comprehensive income (loss), before reclassifications	0	0	(1.7)	5.7
Income tax effect of other comprehensive income (loss) before reclassifications	0	0	0.6	(2)
Defined benefit plans, amounts reclassified from accumulated other comprehensive loss	4.1	0.7	6.6	2.4
Income taxes reclassified into net income	(1)	(0.1)	(1.8)	(0.8)
Defined benefit plans, net current period other comprehensive income (loss)	3.1	0.6	3.7	5.3
Defined benefit plans - Ending balance	(239.8)	(218.6)	(239.8)	(218.6)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Foreign currency translation adjustments - Beginning balance	(85.9)	(103.4)	(122.4)	(119.2)
Foreign currency translation adjustments, other comprehensive income (loss) arising during period	42.8	(0.8)	79.3	15
Foreign currency translation adjustments, amounts reclassified from accumulated other comprehensive loss	0	0	0	0
Foreign currency translation adjustments, net current period other comprehensive income (loss)	42.8	(0.8)	79.3	15
Foreign currency translation adjustments - Ending balance	(43.1)	(104.2)	(43.1)	(104.2)
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Unrecognized loss on cash flow hedges - Beginning balance	(3.3)	(15.7)	(23.7)	(13.4)
Unrecognized loss on cash flow hedges, other comprehensive income (loss) arising during period	0.4	(6.7)	16.2	(13.3)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	0	0	0.7	0
Unrecognized loss on cash flow hedges, amounts reclassified from accumulated other comprehensive loss	0.7	2.6	4.6	6.9
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	1.1	(4.1)	21.5	(6.4)
Unrecognized loss on cash flow hedges - Ending balance	(2.2)	(19.8)	(2.2)	(19.8)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated other comprehensive income (loss), net of tax - Beginning balance	(332.1)	(338.3)	(389.6)	(356.5)
Other comprehensive income (loss) arising during period, total	43.2	(7.5)	93.8	7.4
Other Comprehensive Income (Loss) before Reclassifications, Tax	0	0	1.3	(2)
Reclassification from AOCI, Current Period, Tax	4.8	3.3	11.2	9.3
Reclassification from AOCI, Current Period, Tax	(1)	(0.1)	(1.8)	(0.8)
Other comprehensive income (loss)	47	(4.3)	104.5	13.9
Accumulated other comprehensive income (loss), net of tax - Ending balance	$ (285.1)	$ (342.6)	$ (285.1)	$ (342.6)

Reclassifications out of Accu67

Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Cost of Sales [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Defined benefit plans, amounts reclassified from accumulated other comprehensive income (loss)	$ 4.2	$ 1	$ 7	$ 3.3
Selling, General and Administrative Expenses [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Defined benefit plans, amounts reclassified from accumulated other comprehensive income (loss)	$ (0.1)	$ (0.3)	$ (0.4)	$ (0.9)

Segment Reporting Sales and Seg

Segment Reporting Sales and Segment Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	$ 1,863.6	$ 1,093.3	$ 4,912.9	$ 3,254.8
Sales Revenue, Goods, Net, Intersegment Sales	139.2	86.4	380.8	253.3
Net sales	1,724.4	1,006.9	4,532.1	3,001.5
Segment Adjusted EBITDA	297.7	156.7	807	471.3
Driveline [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	1,007.9	956.1	3,028.7	2,840.4
Sales Revenue, Goods, Net, Intersegment Sales	0.2	0.1	1.1	3.8
Net sales	1,007.7	956	3,027.6	2,836.6
Segment Adjusted EBITDA	181.4	134.4	513.5	391.9
Metal Forming [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	368.2	137.2	887.5	414.4
Sales Revenue, Goods, Net, Intersegment Sales	106.8	86.3	315.1	249.5
Net sales	261.4	50.9	572.4	164.9
Segment Adjusted EBITDA	70.7	22.3	170.5	79.4
Powertrain [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	260.9	0	544.5	0
Sales Revenue, Goods, Net, Intersegment Sales	3.8	0	6	0
Net sales	257.1	0	538.5	0
Segment Adjusted EBITDA	36.8	0	88.7	0
Casting [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	226.6	0	452.2	0
Sales Revenue, Goods, Net, Intersegment Sales	28.4	0	58.6	0
Net sales	198.2	0	393.6	0
Segment Adjusted EBITDA	$ 8.8	$ 0	$ 34.3	$ 0

Total Assets by Segment (Detail

Total Assets by Segment (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total assets	$ 8,058.3	$ 3,423.9
Driveline [Member]
Segment Reporting Information [Line Items]
Total assets	2,362.7	2,183.9
Metal Forming [Member]
Segment Reporting Information [Line Items]
Total assets	2,155.8	410.3
Powertrain [Member]
Segment Reporting Information [Line Items]
Total assets	1,825.1	0
Casting [Member]
Segment Reporting Information [Line Items]
Total assets	1,018	0
Other Segments [Member]
Segment Reporting Information [Line Items]
Total assets	$ 696.7	$ 829.7

Reconciliation of Segment Adjus

Reconciliation of Segment Adjusted EBITDA (Non-GAAP Measure) to Income Before Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Segment Adjusted EBITDA	$ 297.7	$ 156.7	$ 807	$ 471.3
Interest expense	(57.5)	(23.2)	(139.9)	(70.2)
Depreciation and amortization	(122.6)	(49.9)	(303.4)	(150.4)
Restructuring and acquisition-related costs	(22.8)	0	(90.5)	0
Acquisition-related fair value inventory adjustment	0	0	(24.9)	0
Impact of change in accounting principle	0	0	3.7	0
Debt refinancing and redemption costs	0	0	(2.7)	0
Asset Impairment Charges	0	(3.4)	0	(3.4)
Final distribution of Reserve Yield Plus Fund	0	0	0	1
Other	0.1	(0.7)	0.2	(0.7)
Income before income taxes	92	79.5	246.6	247.6
Pension Plan [Member]
Segment Reporting Information [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	$ (2.9)	$ 0	$ (2.9)	$ 0

Supplemental Guarantor Conden71

Supplemental Guarantor Condensed Consolidating Financial Statements Narrative (Details)	Sep. 30, 2017
Debt Instrument [Line Items]
Ownership in Subsidiary, Percentage	100.00%
Unsecured Debt [Member] | 7.75% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.75%
Unsecured Debt [Member] | 6.625% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.625%
Unsecured Debt [Member] | 6.50% Notes due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Unsecured Debt [Member] | 6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Unsecured Debt [Member] | 6.25% Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Unsecured Debt [Member] | 5.125% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.125%

Supplemental Guarantor Conden72

Supplemental Guarantor Condensed Consolidating Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net sales
External	$ 1,724.4	$ 1,006.9	$ 4,532.1	$ 3,001.5
Intercompany	0	0	0	0
Total net sales	1,724.4	1,006.9	4,532.1	3,001.5
Cost of goods sold	1,426.7	825.7	3,707.3	2,454.9
Gross profit	297.7	181.2	824.8	546.6
Selling, general and administrative expenses	102.3	78.6	289.1	231.8
Amortization of intangible assets	24.4	1.3	50.8	3.6
Restructuring and acquisition-related costs	22.8	0	90.5	0
Operating income	148.2	101.3	394.4	311.2
Non-operating income (expense), net	(56.2)	(21.8)	(147.8)	(63.6)
Income (loss) before income taxes	92	79.5	246.6	247.6
Income tax expense (benefit)	5.7	17.8	15.6	53.8
Earnings from equity in subsidiaries	0	0	0	0
Net income (loss) before royalties	86.3	61.7	231	193.8
Royalties	0	0	0	0
Net income after royalties	86.3	61.7	231	193.8
Net income attributable to noncontrolling interests	(0.1)	0	(0.2)	0
Net income attributable to AAM	86.2	61.7	230.8	193.8
Other comprehensive income (loss), net of tax	47	(4.3)	104.5	13.9
Comprehensive income attributable to AAM	133.2	57.4	335.3	207.7
Holdings [Member]
Net sales
External	0	0	0	0
Intercompany	0	0	0	0
Total net sales	0	0	0	0
Cost of goods sold	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Amortization of intangible assets	0	0	0	0
Restructuring and acquisition-related costs	0		0
Operating income	0	0	0	0
Non-operating income (expense), net	0	0	0	0
Income (loss) before income taxes	0	0	0	0
Income tax expense (benefit)	0	0	0	0
Earnings from equity in subsidiaries	86.2	61.7	230.8	193.8
Net income (loss) before royalties	86.2	61.7	230.8	193.8
Royalties	0	0	0	0
Net income after royalties	86.2	61.7	230.8	193.8
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to AAM	86.2	61.7	230.8	193.8
Other comprehensive income (loss), net of tax	47	(4.3)	104.5	13.9
Comprehensive income attributable to AAM	133.2	57.4	335.3	207.7
AAM Inc. [Member]
Net sales
External	250	274.7	806.9	866.3
Intercompany	0.2	3.7	2.4	8.1
Total net sales	250.2	278.4	809.3	874.4
Cost of goods sold	229.6	265.4	752.2	833.5
Gross profit	20.6	13	57.1	40.9
Selling, general and administrative expenses	57.8	71.3	196	206.8
Amortization of intangible assets	1.5	1.3	4.3	3.5
Restructuring and acquisition-related costs	21.6		87
Operating income	(60.3)	(59.6)	(230.2)	(169.4)
Non-operating income (expense), net	(60.8)	(24.9)	(148.7)	(72.7)
Income (loss) before income taxes	(121.1)	(84.5)	(378.9)	(242.1)
Income tax expense (benefit)	(29)	7.9	(62.2)	28.9
Earnings from equity in subsidiaries	29.9	87.4	202.9	266.6
Net income (loss) before royalties	(62.2)	(5)	(113.8)	(4.4)
Royalties	84.9	66.7	253.6	198.2
Net income after royalties	22.7	61.7	139.8	193.8
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to AAM	22.7	61.7	139.8	193.8
Other comprehensive income (loss), net of tax	16.7	(4.3)	55.3	13.9
Comprehensive income attributable to AAM	39.4	57.4	195.1	207.7
Guarantor Subsidiaries [Member]
Net sales
External	529	49.9	1,139.8	161.4
Intercompany	80	62.7	214.7	185.7
Total net sales	609	112.6	1,354.5	347.1
Cost of goods sold	546.3	94.9	1,188	284.3
Gross profit	62.7	17.7	166.5	62.8
Selling, general and administrative expenses	24.7	0	45.7	0
Amortization of intangible assets	22.3	0	45	0
Restructuring and acquisition-related costs	0		0
Operating income	15.7	17.7	75.8	62.8
Non-operating income (expense), net	5.5	2.9	14.9	8.4
Income (loss) before income taxes	21.2	20.6	90.7	71.2
Income tax expense (benefit)	17.8	0.1	42	0.3
Earnings from equity in subsidiaries	25.5	(7.1)	41.4	(28)
Net income (loss) before royalties	28.9	13.4	90.1	42.9
Royalties	1.3	0	2.6	0
Net income after royalties	30.2	13.4	92.7	42.9
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to AAM	30.2	13.4	92.7	42.9
Other comprehensive income (loss), net of tax	42.6	1	74.7	23.2
Comprehensive income attributable to AAM	72.8	14.4	167.4	66.1
Non-Guarantor Subsidiaries [Member]
Net sales
External	945.4	682.3	2,585.4	1,973.8
Intercompany	7	4.4	19.9	12.2
Total net sales	952.4	686.7	2,605.3	1,986
Cost of goods sold	738	536.2	2,004.1	1,543.1
Gross profit	214.4	150.5	601.2	442.9
Selling, general and administrative expenses	19.8	7.3	47.4	25
Amortization of intangible assets	0.6	0	1.5	0.1
Restructuring and acquisition-related costs	1.2		3.5
Operating income	192.8	143.2	548.8	417.8
Non-operating income (expense), net	(0.9)	0.2	(14)	0.7
Income (loss) before income taxes	191.9	143.4	534.8	418.5
Income tax expense (benefit)	16.9	9.8	35.8	24.6
Earnings from equity in subsidiaries	0	0	0	0
Net income (loss) before royalties	175	133.6	499	393.9
Royalties	(86.2)	(66.7)	(256.2)	(198.2)
Net income after royalties	88.8	66.9	242.8	195.7
Net income attributable to noncontrolling interests	(0.1)	0	(0.2)	0
Net income attributable to AAM	88.7	66.9	242.6	195.7
Other comprehensive income (loss), net of tax	51.3	(3.3)	94.8	16.9
Comprehensive income attributable to AAM	140	63.6	337.4	212.6
Consolidation, Eliminations [Member]
Net sales
External	0	0	0	0
Intercompany	(87.2)	(70.8)	(237)	(206)
Total net sales	(87.2)	(70.8)	(237)	(206)
Cost of goods sold	(87.2)	(70.8)	(237)	(206)
Gross profit	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Amortization of intangible assets	0	0	0	0
Restructuring and acquisition-related costs	0
Operating income	0	0	0	0
Non-operating income (expense), net	0	0	0	0
Income (loss) before income taxes	0	0	0	0
Income tax expense (benefit)	0	0	0	0
Earnings from equity in subsidiaries	(141.6)	(142)	(475.1)	(432.4)
Net income (loss) before royalties	(141.6)	(142)	(475.1)	(432.4)
Royalties	0	0	0	0
Net income after royalties	(141.6)	(142)	(475.1)	(432.4)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to AAM	(141.6)	(142)	(475.1)	(432.4)
Other comprehensive income (loss), net of tax	(110.6)	6.6	(224.8)	(54)
Comprehensive income attributable to AAM	$ (252.2)	$ (135.4)	$ (699.9)	$ (486.4)

Supplemental Guarantor Conden73

Supplemental Guarantor Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 549.6	$ 481.2	$ 433.9	$ 282.5
Accounts receivable, net	1,122	560
Intercompany receivables	0	0
Inventories, net	396.6	182.3
Prepaid expenses and other	144.5	75.8
Total current assets	2,212.7	1,299.3
Property, plant and equipment, net	2,302.7	1,093.7
Goodwill	1,654.6	154
Intangible assets, net	1,236.6	28.5
Intercompany notes and accounts receivable	0	0
Other assets and deferred charges	651.7	848.4
Investment in subsidiaries	0	0
Total assets	8,058.3	3,423.9
Current liabilities
Current portion of long-term debt	6.8	3.3
Accounts payable	856.4	382.3
Intercompany payables	0	0
Accrued expenses and other	421.8	265.9
Total current liabilities	1,285	651.5
Intercompany notes and accounts payable	0	0
Long-term debt, net	4,169.3	1,400.9
Investment in Subsidiaries Obligation		0
Other long-term liabilities	1,167.4	865.7
Total liabilities	6,621.7	2,918.1
Stockholders' Equity Attributable to Parent	1,432.8	505.8
Noncontrolling interests in subsidiaries	3.8	0
Total stockholders' equity	1,436.6	505.8
Total liabilities and stockholders' equity	8,058.3	3,423.9
Holdings [Member]
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Intercompany receivables	0	0
Inventories, net	0	0
Prepaid expenses and other	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Intercompany notes and accounts receivable	14.6	0
Other assets and deferred charges	0	0
Investment in subsidiaries	2,735	827.6
Total assets	2,749.6	827.6
Current liabilities
Current portion of long-term debt	0	0
Accounts payable	0	0
Intercompany payables	1,313	0
Accrued expenses and other	0	0
Total current liabilities	1,313	0
Intercompany notes and accounts payable	0	321.8
Long-term debt, net	0	0
Investment in Subsidiaries Obligation		0
Other long-term liabilities	0	0
Total liabilities	1,313	321.8
Stockholders' Equity Attributable to Parent	1,432.8
Noncontrolling interests in subsidiaries	3.8
Total stockholders' equity	1,436.6	505.8
Total liabilities and stockholders' equity	2,749.6	827.6
AAM Inc. [Member]
Current assets
Cash and cash equivalents	188.5	84.3	136.5	52
Accounts receivable, net	134.4	126.7
Intercompany receivables	3,559.1	442.6
Inventories, net	34	31.3
Prepaid expenses and other	27.4	29.4
Total current assets	3,943.4	714.3
Property, plant and equipment, net	234.1	213.7
Goodwill	0	0
Intangible assets, net	21.9	22.8
Intercompany notes and accounts receivable	0	343.9
Other assets and deferred charges	717.4	644.9
Investment in subsidiaries	1,917.2	1,544.4
Total assets	6,834	3,484
Current liabilities
Current portion of long-term debt	0	0
Accounts payable	130.2	80.6
Intercompany payables	499.7	324.8
Accrued expenses and other	183	142.2
Total current liabilities	812.9	547.6
Intercompany notes and accounts payable	76.9	14.6
Long-term debt, net	4,096.3	1,339.7
Investment in Subsidiaries Obligation		0
Other long-term liabilities	742.2	754.5
Total liabilities	5,728.3	2,656.4
Stockholders' Equity Attributable to Parent	1,105.7
Noncontrolling interests in subsidiaries	0
Total stockholders' equity	1,105.7	827.6
Total liabilities and stockholders' equity	6,834	3,484
Guarantor Subsidiaries [Member]
Current assets
Cash and cash equivalents	0.1	1.6	1.3	0
Accounts receivable, net	320.2	21.9
Intercompany receivables	465.9	326
Inventories, net	151.2	21.5
Prepaid expenses and other	12.1	0.5
Total current assets	949.5	371.5
Property, plant and equipment, net	788.5	102.9
Goodwill	1,220.2	147.8
Intangible assets, net	1,178.1	0
Intercompany notes and accounts receivable	260.9	242.2
Other assets and deferred charges	137.2	39.8
Investment in subsidiaries	708.9	0
Total assets	5,243.3	904.2
Current liabilities
Current portion of long-term debt	0	0
Accounts payable	238.2	35.8
Intercompany payables	2,010.2	153.4
Accrued expenses and other	56.3	4.3
Total current liabilities	2,304.7	193.5
Intercompany notes and accounts payable	0	7.5
Long-term debt, net	4.6	4.1
Investment in Subsidiaries Obligation		124.7
Other long-term liabilities	594	0.6
Total liabilities	2,903.3	330.4
Stockholders' Equity Attributable to Parent	2,340
Noncontrolling interests in subsidiaries	0
Total stockholders' equity	2,340	573.8
Total liabilities and stockholders' equity	5,243.3	904.2
Non-Guarantor Subsidiaries [Member]
Current assets
Cash and cash equivalents	361	395.3	296.1	230.5
Accounts receivable, net	667.4	411.4
Intercompany receivables	8	9.1
Inventories, net	211.4	129.5
Prepaid expenses and other	105	45.9
Total current assets	1,352.8	991.2
Property, plant and equipment, net	1,280.1	777.1
Goodwill	434.4	6.2
Intangible assets, net	36.6	5.7
Intercompany notes and accounts receivable	0	0
Other assets and deferred charges	129.8	163.7
Investment in subsidiaries	0	0
Total assets	3,233.7	1,943.9
Current liabilities
Current portion of long-term debt	6.8	3.3
Accounts payable	488	265.9
Intercompany payables	210.1	299.5
Accrued expenses and other	182.5	119.4
Total current liabilities	887.4	688.1
Intercompany notes and accounts payable	198.6	242.2
Long-term debt, net	68.4	57.1
Investment in Subsidiaries Obligation		0
Other long-term liabilities	163.9	110.6
Total liabilities	1,318.3	1,098
Stockholders' Equity Attributable to Parent	1,911.6
Noncontrolling interests in subsidiaries	3.8
Total stockholders' equity	1,915.4	845.9
Total liabilities and stockholders' equity	3,233.7	1,943.9
Consolidation, Eliminations [Member]
Current assets
Cash and cash equivalents	0	0	$ 0	$ 0
Accounts receivable, net	0	0
Intercompany receivables	(4,033)	(777.7)
Inventories, net	0	0
Prepaid expenses and other	0	0
Total current assets	(4,033)	(777.7)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Intercompany notes and accounts receivable	(275.5)	(586.1)
Other assets and deferred charges	(332.7)	0
Investment in subsidiaries	(5,361.1)	(2,372)
Total assets	(10,002.3)	(3,735.8)
Current liabilities
Current portion of long-term debt	0	0
Accounts payable	0	0
Intercompany payables	(4,033)	(777.7)
Accrued expenses and other	0	0
Total current liabilities	(4,033)	(777.7)
Intercompany notes and accounts payable	(275.5)	(586.1)
Long-term debt, net	0	0
Investment in Subsidiaries Obligation		(124.7)
Other long-term liabilities	(332.7)	0
Total liabilities	(4,641.2)	(1,488.5)
Stockholders' Equity Attributable to Parent	(5,357.3)
Noncontrolling interests in subsidiaries	(3.8)
Total stockholders' equity	(5,361.1)	(2,247.3)
Total liabilities and stockholders' equity	$ (10,002.3)	$ (3,735.8)

Supplemental Guarantor Conden74

Supplemental Guarantor Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net cash provided by operating activities			$ 420.7	$ 291
Investing activities
Purchases of property, plant and equipment			(278.7)	(158.7)
Proceeds from sale of property, plant and equipment			1.7	0.7
Purchase buyouts of leased equipment			(12.6)	0
Proceeds from sale of business, net			5.9	0
Acquisition of business, net of cash acquired			(895.5)	(5.6)
Proceeds from government grants			0	2.8
Final distribution of Reserve Yield Plus Fund	$ 0	$ 0	0	1
Intercompany Activity - Investing				0
Net cash used in investing activities			(1,179.2)	(159.8)
Financing activities
Net debt activity			913.5	22.6
Debt issuance costs			(90.8)	0
Employee stock option exercises			0.9	0.3
Purchase of treasury stock			(7)	(5.3)
Intercompany Activity - Financing			0	0
Net cash provided by financing activities			816.6	17.6
Effect of exchange rate changes on cash			10.3	2.6
Net increase (decrease) in cash and cash equivalents			68.4	151.4
Cash and cash equivalents at beginning of period			481.2	282.5
Cash and cash equivalents at end of period	549.6	433.9	549.6	433.9
Holdings [Member]
Net cash provided by operating activities			0	0
Investing activities
Purchases of property, plant and equipment			0	0
Proceeds from sale of property, plant and equipment			0	0
Purchase buyouts of leased equipment			0
Proceeds from sale of business, net			0
Acquisition of business, net of cash acquired			0	0
Proceeds from government grants				0
Final distribution of Reserve Yield Plus Fund				0
Intercompany Activity - Investing				0
Net cash used in investing activities			0	0
Financing activities
Net debt activity			0	0
Debt issuance costs			0
Employee stock option exercises			0	0
Purchase of treasury stock			(7)	(5.3)
Intercompany Activity - Financing			7	5.3
Net cash provided by financing activities			0	0
Effect of exchange rate changes on cash			0	0
Net increase (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	0	0
AAM Inc. [Member]
Net cash provided by operating activities			276.4	114.8
Investing activities
Purchases of property, plant and equipment			(43.1)	(25.9)
Proceeds from sale of property, plant and equipment			0.3	0
Purchase buyouts of leased equipment			(12.6)
Proceeds from sale of business, net			7.5
Acquisition of business, net of cash acquired			(953.5)	0
Proceeds from government grants				0
Final distribution of Reserve Yield Plus Fund				1
Intercompany Activity - Investing				0
Net cash used in investing activities			(1,001.4)	(24.9)
Financing activities
Net debt activity			926.1	(0.4)
Debt issuance costs			(90.8)
Employee stock option exercises			0.9	0.3
Purchase of treasury stock			0	0
Intercompany Activity - Financing			(7)	(5.3)
Net cash provided by financing activities			829.2	(5.4)
Effect of exchange rate changes on cash			0	0
Net increase (decrease) in cash and cash equivalents			104.2	84.5
Cash and cash equivalents at beginning of period			84.3	52
Cash and cash equivalents at end of period	188.5	136.5	188.5	136.5
Guarantor Subsidiaries [Member]
Net cash provided by operating activities			9	20.9
Investing activities
Purchases of property, plant and equipment			(73.3)	(12)
Proceeds from sale of property, plant and equipment			0.3	0.3
Purchase buyouts of leased equipment			0
Proceeds from sale of business, net			(1.6)
Acquisition of business, net of cash acquired			64.6	(5.6)
Proceeds from government grants				0
Final distribution of Reserve Yield Plus Fund				0
Intercompany Activity - Investing				(2)
Net cash used in investing activities			(10)	(19.3)
Financing activities
Net debt activity			(0.5)	(0.3)
Debt issuance costs			0
Employee stock option exercises			0	0
Purchase of treasury stock			0	0
Intercompany Activity - Financing			0	0
Net cash provided by financing activities			(0.5)	(0.3)
Effect of exchange rate changes on cash			0	0
Net increase (decrease) in cash and cash equivalents			(1.5)	1.3
Cash and cash equivalents at beginning of period			1.6	0
Cash and cash equivalents at end of period	0.1	1.3	0.1	1.3
Non-Guarantor Subsidiaries [Member]
Net cash provided by operating activities			135.3	155.3
Investing activities
Purchases of property, plant and equipment			(162.3)	(120.8)
Proceeds from sale of property, plant and equipment			1.1	0.4
Purchase buyouts of leased equipment			0
Proceeds from sale of business, net			0
Acquisition of business, net of cash acquired			(6.6)	0
Proceeds from government grants				2.8
Final distribution of Reserve Yield Plus Fund				0
Intercompany Activity - Investing				0
Net cash used in investing activities			(167.8)	(117.6)
Financing activities
Net debt activity			(12.1)	23.3
Debt issuance costs			0
Employee stock option exercises			0	0
Purchase of treasury stock			0	0
Intercompany Activity - Financing			0	2
Net cash provided by financing activities			(12.1)	25.3
Effect of exchange rate changes on cash			10.3	2.6
Net increase (decrease) in cash and cash equivalents			(34.3)	65.6
Cash and cash equivalents at beginning of period			395.3	230.5
Cash and cash equivalents at end of period	361	296.1	361	296.1
Consolidation, Eliminations [Member]
Net cash provided by operating activities			0	0
Investing activities
Purchases of property, plant and equipment			0	0
Proceeds from sale of property, plant and equipment			0	0
Purchase buyouts of leased equipment			0
Proceeds from sale of business, net			0
Acquisition of business, net of cash acquired			0	0
Proceeds from government grants				0
Final distribution of Reserve Yield Plus Fund				0
Intercompany Activity - Investing				2
Net cash used in investing activities			0	2
Financing activities
Net debt activity			0	0
Debt issuance costs			0
Employee stock option exercises			0	0
Purchase of treasury stock			0	0
Intercompany Activity - Financing			0	(2)
Net cash provided by financing activities			0	(2)
Effect of exchange rate changes on cash			0	0
Net increase (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	$ 0	$ 0