American Axle & Manufacturing (AXL) 10-Q 3 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2018
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	2,018
Document Fiscal Period Focus	Q2
Document Period End Date	Jun. 30, 2018
Amendment Flag	false
Document Type	10-Q
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		111,685,947
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net sales	$ 1,900.9	$ 1,757.8	$ 3,759.3	$ 2,807.7
Cost of goods sold	1,569.5	1,441.4	3,111.6	2,280.6
Gross profit	331.4	316.4	647.7	527.1
Selling, general and administrative expenses	95	105.6	192.3	186.8
Amortization of intangible assets	24.8	24.8	49.7	26.4
Restructuring and acquisition-related costs	36.8	51.7	55.1	67.7
Gain on sale of business	(15.5)	0	(15.5)	0
Operating income	190.3	134.3	366.1	246.2
Interest expense	(54.4)	(56.9)	(107.6)	(82.4)
Investment income	0.5	0.8	1	1.4
Debt refinancing and redemption costs	(4.3)	(2.7)	(14.6)	(2.7)
Gain on settlement of capital lease	15.6	0	15.6	0
Other income (expense), net	5.6	(6.8)	0.2	(7.9)
Income before income taxes	153.3	68.7	260.7	154.6
Income tax expense	2	2.4	19.9	9.9
Net income	151.3	66.3	240.8	144.7
Net income attributable to noncontrolling interests	(0.2)	(0.1)	(0.3)	(0.1)
Net income attributable to AAM	$ 151.1	$ 66.2	$ 240.5	$ 144.6
Basic earnings per share	$ 1.31	$ 0.59	$ 2.09	$ 1.52
Diluted earnings per share	$ 1.30	$ 0.59	$ 2.08	$ 1.51

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net income	$ 151.3	$ 66.3	$ 240.8	$ 144.7
Other comprehensive income (loss)
Defined benefit plans, net of tax (a)	12.2	0.9	13.5	0.6
Foreign currency translation adjustments	(81)	24.6	(43.1)	36.5
Changes in cash flow hedges, net of tax (b)	(7.9)	4.9	7.2	20.4
Other comprehensive income (loss)	(76.7)	30.4	(22.4)	57.5
Comprehensive income	74.6	96.7	218.4	202.2
Net income attributable to noncontrolling interests	(0.2)	(0.1)	(0.3)	(0.1)
Comprehensive income attributable to AAM	$ 74.4	$ 96.6	$ 218.1	$ 202.1

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other comprehensive income (loss), pension and other postretirement benefit plans, tax	$ (4.1)	$ (0.4)	$ (4.5)	$ (0.2)
Other comprehensive income (loss), derivatives qualifying as hedges, tax	$ (0.1)	$ 0.7	$ (1.2)	$ 0.7

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 353.2	$ 376.8
Accounts receivable, net	1,253.6	1,035.9
Inventories, net	426.4	392
Prepaid expenses and other	121.8	140.3
Total current assets	2,155	1,945
Property, plant and equipment, net	2,459.3	2,402.9
Deferred income taxes	30.6	37.1
Goodwill	1,631.7	1,654.3
Intangible assets, net	1,159.8	1,212.5
GM postretirement cost sharing asset	248.3	252.2
Other assets and deferred charges	405.7	378.8
Total assets	8,090.4	7,882.8
Current liabilities
Current portion of long-term debt	33.2	5.9
Accounts payable	930.9	799
Accrued compensation and benefits	161.5	200
Deferred revenue	38.1	34.1
Accrued expenses and other	168	177.4
Total current liabilities	1,331.7	1,216.4
Long-term debt, net	3,873	3,969.3
Deferred revenue	81.6	78.8
Deferred income taxes	143	101.7
Postretirement benefits and other long-term liabilities	894.9	976.6
Total liabilities	6,324.2	6,342.8
Stockholders' equity
Common stock, par value $0.01 per share; 150.0 million shares authorized; 118.8 million shares issued as of June 30, 2018 and 118.2 million shares issued as of December 31, 2017	1.2	1.2
Paid-in capital	1,278.3	1,264.6
Retained earnings	1,001.5	761
Treasury stock at cost, 7.1 million shares as of June 30, 2018 and 6.9 million shares as of December 31, 2017	(201.7)	(198.1)
Accumulated other comprehensive income (loss)
Defined benefit plans, net of tax	(238.5)	(252)
Foreign currency translation adjustments	(77.2)	(34.1)
Unrecognized income (loss) on cash flow hedges, net of tax	0.6	(6.6)
Total AAM stockholders' equity	1,764.2	1,536
Noncontrolling interests in subsidiaries	2	4
Total stockholders' equity	1,766.2	1,540
Total liabilities and stockholders' equity	$ 8,090.4	$ 7,882.8

Condensed Consolidated Balance6

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Millions	Jun. 30, 2018	Dec. 31, 2017
Common stock, par or stated value per share	$ 0.01	$ 0.01
Common stock, shares authorized	150	150
Treasury stock, shares	7.1	6.9
Common stock, shares, issued	118.8	118.2

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Net income	$ 240.8	$ 144.7
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	258	180.8
Impairment of long-lived assets	23.9
Deferred income taxes	38	(24.6)
Stock-based compensation	13.7	30.9
Pensions and other postretirement benefits, net of contributions	(0.6)	(0.5)
Gain on sale of business	(15.5)	0
Loss (Gain) on disposal of property, plant and equipment, net	(4.9)	1.1
Debt refinancing and redemption costs and (gain) on settlement of capital lease	(0.8)	2.7
Changes in operating assets and liabilities, net of amounts acquired or disposed
Accounts receivable	(225.7)	(139.8)
Inventories	(47.4)	6.2
Accounts payable and accrued expenses	83.7	45
Deferred revenue	8.1	8.4
Other assets and liabilities	(81.9)	(41.7)
Net cash provided by operating activities	289.4	213.2
Investing activities
Purchases of property, plant and equipment	(273)	(138.6)
Proceeds from sale of property, plant and equipment	0.9	1.5
Purchase buyouts of leased equipment	(0.5)	(8.4)
Proceeds from sale of business, net	47.1	5.9
Acquisition of business, net of cash acquired	(1.3)	(895.5)
Net cash used in investing activities	(226.8)	(1,035.1)
Financing activities
Payments of long-term debt and capital lease obligations	(528.7)	(1,937.5)
Proceeds from issuance of long-term debt	461.9	2,857.9
Debt issuance costs	(6.8)	(90.5)
Purchase of noncontrolling interest	(2.2)	0
Purchase of treasury stock	(3.6)	(6.9)
Employee stock option exercises	0	0.9
Net cash provided by (used in) financing activities	(79.4)	823.9
Effect of exchange rate changes on cash	(4.3)	7.4
Net increase (decrease) in cash, cash equivalents and restricted cash	(21.1)	9.4
Cash, cash equivalents and restricted cash at beginning of period	376.8	481.2
Cash, cash equivalents and restricted cash at end of period	355.7	490.6
Supplemental cash flow information
Interest paid	104.4	79.8
Income taxes paid, net of refunds	19.6	16.7
Non-cash investing activities: AAM common shares issued for acquisition of MPG	$ 0	$ 576.7

Organization and Basis of Prese

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	1. ORGANIZATION AND BASIS OF PRESENTATION Organization We are a global Tier 1 supplier to the automotive, 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, 2017 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, 2017 . Sale of Powertrain Aftermarket Business In April 2018, we completed the sale of the aftermarket business associated with our Powertrain segment for approximately $50 million , of which we received net proceeds of approximately $47 million . The difference between the selling price and the net proceeds received was primarily attributable to $2.5 million of cash that was placed into an escrow account that we expect to be distributed to us 18 months subsequent to the date of the sale. We have recorded this amount as restricted cash in Other assets and deferred charges in our Condensed Consolidated Balance Sheet as of June 30, 2018. As a result of the sale, we recorded a $15.5 million pre-tax gain, which is disclosed in the Gain on sale of business line of our Condensed Consolidated Statements of Income for the three and six months ended June 30, 2018. The impact to our Condensed Consolidated Balance Sheet was immaterial. Effect of New Accounting Standards Accounting Standards Update 2018-02 On February 14, 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2018-02 - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (Topic 220). ASU 2018-02 allows companies the option to reclassify disproportionate tax effects in accumulated other comprehensive income (AOCI) caused by the 2017 Tax Cuts and Jobs Act, also known as stranded tax effects, to retained earnings. ASU 2018-02 also requires expanded disclosures related to disproportionate income tax effects from AOCI, some of which are applicable to all companies regardless of whether the option to reclassify the stranded tax effects is exercised. This guidance becomes effective at the beginning of our 2019 fiscal year, however early adoption is permitted for financial statements which have not yet been issued. 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. This guidance becomes effective at the beginning of our 2020 fiscal year and early adoption is permitted. The guidance requires a prospective transition method. We do not expect the adoption of this guidance to have a material effect on our consolidated financial statements, however, goodwill could be more susceptible to impairment in periods subsequent to adoption. Accounting Standards Update 2016-02 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.

Revenue from Contracts with Cus

Revenue from Contracts with Customers Revenue from Contracts with Customers (Notes)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	2. REVENUE FROM CONTRACTS WITH CUSTOMERS On January 1, 2018, we adopted new accounting guidance under Accounting Standards Codification Topic 606 (ASC 606) Revenue from Contracts with Customers . ASC 606 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most existing 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. We have elected to adopt this guidance utilizing the modified retrospective transition method, which requires a one-time adjustment to opening retained earnings for the cumulative impact of adopting the new guidance. No adjustment to retained earnings was required as of January 1, 2018 as there was no impact to previously reported revenue or expenses associated with adopting ASC 606. We are obligated under our contracts with customers to manufacture and supply products for use in our customers’ operations. We satisfy these performance obligations at the point in time that the customer obtains control of the products, which is the point in time that the customer is able to direct the use of, and obtain substantially all of the remaining benefits from, the products. This typically occurs upon shipment to the customer in accordance with purchase orders and delivery releases issued by our customers. There is significant judgment involved in determining when the customer obtains control of the products and we have utilized the following indicators of control in our assessment: • We have the present right to payment for the asset; • The customer has legal title to the asset; • We have transferred physical possession of the asset; • The customer has the significant risks and rewards of ownership of the asset; and • The customer has accepted the asset. Our product offerings by segment are as follows: • Driveline products consist primarily of axles, driveshafts, power transfer units, rear drive modules, transfer cases, 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 and transmission shafts, ring and pinion gears, differential gears, transmission gears, and suspension components for Original Equipment Manufacturers 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 Original Equipment Manufacturers 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, brackets, and turbo charger housings for the global light vehicle, commercial and industrial markets. Our contracts with customers generally state the terms of the sale, including the quantity and price of each product purchased. Trade accounts receivable from our customers are generally due approximately 50 days from the date our customers receive our product. Our contracts typically do not contain variable consideration as the contracts include stated prices. We provide our customers with assurance type warranties, which are not separate performance obligations and are outside the scope of ASC 606. Refer to Note 11 - Product Warranties for further information. Disaggregation of Net Sales Net sales recognized from contracts with customers, disaggregated by segment and geographical location, are presented in the following table for the three and six months ended June 30, 2018 and 2017 . Net sales are attributed to regions based on the location of production. Intersegment sales have been excluded from the table. Three Months Ended June 30, 2018 Driveline Metal Forming Powertrain Casting Total North America $ 899.0 $ 216.3 $ 197.2 $ 209.6 $ 1,522.1 Asia 159.3 1.2 29.9 — 190.4 Europe 30.7 70.3 54.9 — 155.9 South America 31.0 — 1.5 — 32.5 Total $ 1,120.0 $ 287.8 $ 283.5 $ 209.6 $ 1,900.9 Three Months Ended June 30, 2017 Driveline Metal Forming Powertrain Casting Total North America $ 862.0 $ 201.6 $ 204.2 $ 195.4 $ 1,463.2 Asia 103.9 0.7 32.5 — 137.1 Europe 21.2 57.6 44.6 — 123.4 South America 34.0 — 0.1 — 34.1 Total $ 1,021.1 $ 259.9 $ 281.4 $ 195.4 $ 1,757.8 Six Months Ended June 30, 2018 Driveline Metal Forming Powertrain Casting Total North America $ 1,784.3 $ 432.6 $ 396.4 $ 419.4 $ 3,032.7 Asia 282.1 2.6 61.0 — 345.7 Europe 59.7 143.7 110.8 — 314.2 South America 64.3 — 2.4 — 66.7 Total $ 2,190.4 $ 578.9 $ 570.6 $ 419.4 $ 3,759.3 Six Months Ended June 30, 2017 Driveline Metal Forming Powertrain Casting Total North America $ 1,727.2 $ 252.7 $ 204.2 $ 195.4 $ 2,379.5 Asia 189.4 0.7 32.5 — 222.6 Europe 41.9 57.6 44.6 — 144.1 South America 61.4 — 0.1 — 61.5 Total $ 2,019.9 $ 311.0 $ 281.4 $ 195.4 $ 2,807.7 Contract Assets and Liabilities The following table summarizes our beginning and ending balances for accounts receivable and contract liabilities associated with our contracts with customers: Accounts Receivable, Net Contract Liabilities (Current) Contract Liabilities (Long-term) December 31, 2017 $ 1,035.9 $ 34.1 $ 78.8 June 30, 2018 1,253.6 38.1 81.6 Increase/(decrease) $ 217.7 $ 4.0 $ 2.8 Contract liabilities relate to deferred revenue associated with cash receipts from our customers for various settlements and commercial agreements for which we have a future performance obligation to the customer. We recognize this deferred revenue into revenue over the life of the associated program as we satisfy our performance obligations to the customer. We do not have contract assets as defined in ASC 606. For the three and six months ended June 30, 2018 , we recognized contract liabilities of $21.0 million and $27.7 million , respectively, all of which have been recorded in our Condensed Consolidated Balance Sheet as long-term deferred revenue. During the three and six months ended June 30, 2018 , we also amortized $12.9 million and $20.9 million , respectively, of previously recorded contract liabilities into revenue as we satisfied performance obligations with our customers. Sales and Other Taxes ASC 606 provides a practical expedient that allows companies to exclude from the transaction price any amounts collected from customers for all sales (and other similar) taxes. We do not include sales and other taxes in our transaction price and thus do not recognize these amounts as revenue.

Restructuring and Acquisition-R

Restructuring and Acquisition-Related Costs	6 Months Ended
	Jun. 30, 2018
Restructuring and Related Activities [Abstract]
Business Acquisition, Integration, Restructuring and Other Related Costs [Text Block]	3. RESTRUCTURING AND ACQUISITION-RELATED COSTS In 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. Since the inception of our global restructuring program, we have incurred severance charges totaling $2.8 million and implementation costs totaling $29.6 million . We expect minimal restructuring charges in future periods related to this global restructuring plan. A summary of our restructuring activity for the first six months of 2018 and 2017 is shown below: Severance Charges Implementation Costs Asset Impairment Charges Total (in millions) Accrual as of December 31, 2016 $ 0.6 $ 9.2 $ — $ 9.8 Charges 1.5 7.0 — 8.5 Cash utilization (2.0 ) (11.8 ) — (13.8 ) Accrual as of June 30, 2017 $ 0.1 $ 4.4 $ — $ 4.5 Accrual as of December 31, 2017 $ 0.3 $ — $ — $ 0.3 Charges 2.0 5.5 23.9 31.4 Cash utilization (0.4 ) (5.1 ) — (5.5 ) Non-cash utilization — — (23.9 ) (23.9 ) Accrual as of June 30, 2018 $ 1.9 $ 0.4 $ — $ 2.3 As part of our restructuring actions, we incurred severance charges of approximately $2.0 million and $1.5 million , as well as implementation costs, including professional expenses, of approximately $5.5 million and $7.0 million , during the six months ended June 30, 2018 and 2017 , respectively. We expect to incur up to $45 million of total restructuring charges in 2018 . The increase in estimated restructuring charges, which was previously disclosed as a range of $10 to $20 million for the full year 2018, is the result of the non-cash impairment charges described below. In the second quarter of 2018, we initiated actions to exit operations at manufacturing facilities in our Metal Forming and Powertrain segments. As a result of these actions, we were required to assess the associated long-lived assets for impairment. Based on our analysis, assets that were not to be redeployed to other AAM facilities were determined to be fully impaired resulting in a charge of $23.9 million in the second quarter of 2018. See Note 8 - Fair Value for further detail. In 2017, we completed the acquisitions of Metaldyne Performance Group, Inc. (MPG) and USM Mexico Manufacturing LLC (USM Mexico). During the six months ended June 30, 2018 , we incurred the following charges related to these acquisitions: Acquisition-Related Costs Integration Expenses Total (in millions) Charges $ 1.1 $ 22.6 $ 23.7 Total restructuring and acquisition-related charges $ 55.1 Acquisition-related costs primarily consist of advisory, legal, accounting, valuation and certain other professional or consulting fees incurred. Integration expenses reflect costs incurred for information technology systems, ongoing operational activities, and consulting fees incurred in conjunction with the acquisitions. Total restructuring charges and acquisition-related charges of $36.8 million and $55.1 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 six months ended June 30, 2018 , respectively.

Business Combinations

Business Combinations	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	4. 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 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 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 403.1 Inventories 199.0 Prepaid expenses and other long-term assets 119.9 Property, plant and equipment 971.8 Intangible assets 1,223.1 Total assets acquired $ 3,119.0 Accounts payable 287.8 Accrued expenses and other 137.7 Deferred income tax liabilities 580.2 Debt 1,918.7 Postretirement benefits and other long-term liabilities 54.1 Net assets acquired $ 140.5 Goodwill $ 1,393.3 Under the guidance in ASC 805, estimated amounts that are designated as provisional may be adjusted during a period referred to as the "measurement period." 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 are included in earnings in the period identified. We finalized the valuation of the assets and liabilities of MPG in the first quarter of 2018. In doing so, 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 $0.9 million . These adjustments related to Property, plant and equipment, as well as the corresponding impact on Deferred income tax liabilities, as a result of customary post-closing reviews. 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 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. For the six months ended June 30, 2018, net sales and net income attributable to AAM included approximately $1,470 million and $120 million , respectively, attributable to MPG. For the period April 6, 2017 through June 30, 2017, net sales and net income attributable to AAM included approximately $684 million and $28 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 six months ended June 30, 2017 were approximately $3.5 billion , excluding MPG sales to AAM during this period. Unaudited pro forma net income for the six months ended June 30, 2017 was approximately $185 million . Unaudited pro forma earnings per share for the six months ended June 30, 2017 were approximately $1.94 per share. The unaudited pro forma net income amount for the six months ended June 30, 2017 has been adjusted by approximately $45 million , net of tax, for acquisition-related costs reclassified from 2017 to 2016 as we are required to disclose the pro forma amounts as if our 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 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 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 Adjustment to contractual purchase price for working capital settlement 2.5 Adjustment 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 $ 146.6 Accounts receivable 1.1 Inventories 4.8 Prepaid expenses and other 3.6 Property, plant and equipment 38.4 Intangible assets 31.7 Total assets acquired $ 79.6 Accounts payable 10.8 Accrued expenses and other 2.7 Deferred income tax liabilities 1.2 Net assets acquired $ 64.9 Goodwill $ 81.7 The purchase agreement specified a period of time subsequent to the acquisition date for calculating the final working capital amount of USM Mexico as of the acquisition date, which was finalized in the first quarter of 2018. None of the goodwill is 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. The operating results of USM Mexico were insignificant to AAM's Condensed Consolidated Statements of Income for the six months ended June 30, 2018 and June 30, 2017. Further, we have not included pro forma revenue and earnings for the six months ended June 30, 2017 as the inclusion of USM Mexico would be insignificant to AAM's consolidated results for this period.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets Disclosure [Text Block]	5. GOODWILL AND INTANGIBLE ASSETS Goodwill The following table provides a reconciliation of changes in goodwill for the six months ended June 30, 2018 : Driveline Metal Forming Powertrain Casting Consolidated (in millions) Balance as of December 31, 2017 $ 211.1 $ 558.9 $ 478.8 $ 405.5 $ 1,654.3 Acquisition of MPG — 0.9 — — 0.9 Acquisition of USM Mexico 1.3 — — — 1.3 Sale of business — — (15.1 ) — (15.1 ) Foreign currency translation (0.5 ) (4.8 ) (4.4 ) — (9.7 ) Balance as of June 30, 2018 $ 211.9 $ 555.0 $ 459.3 $ 405.5 $ 1,631.7 In April 2018, we completed the sale of the aftermarket business associated with our Powertrain segment. We allocated $15.1 million of goodwill to the sold business, which represents the fair value of the business sold relative to the fair value of the associated reporting unit. Intangible Assets 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: June 30, December 31, 2018 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in millions) Capitalized computer software $ 37.4 $ (17.2 ) $ 20.2 $ 35.6 $ (14.3 ) $ 21.3 e-AAM in-process research and development 5.4 (0.4 ) 5.0 5.9 — 5.9 Customer platforms 952.2 (88.1 ) 864.1 952.2 (52.9 ) 899.3 Customer relationships 147.0 (12.0 ) 135.0 151.8 (7.3 ) 144.5 Technology and other 150.8 (15.3 ) 135.5 150.8 (9.3 ) 141.5 Total $ 1,292.8 $ (133.0 ) $ 1,159.8 $ 1,296.3 $ (83.8 ) $ 1,212.5 As a result of the acquisition of MPG in 2017, we recorded intangible assets related to aftermarket customer relationships that were associated with the Powertrain aftermarket business that we sold in the second quarter of 2018. As such, we have reduced the gross carrying amount of our customer relationships by $4.8 million , and reduced the associated accumulated amortization by $0.3 million as of June 30, 2018. Amortization expense for our intangible assets was $24.8 million and $49.7 million for the three and six months ended June 30, 2018 respectively, and $24.8 million and $26.4 million for the three and six months ended June 30, 2017 , respectively. Estimated amortization expense for each of the years 2018 through 2022 is approximately $100 million .

Inventories

Inventories	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Inventory Disclosure [Text Block]	6. 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: June 30, 2018 December 31, 2017 (in millions) Raw materials and work-in-progress $ 366.1 $ 319.7 Finished goods 78.6 89.6 Gross inventories 444.7 409.3 Inventory valuation reserves (18.3 ) (17.3 ) Inventories, net $ 426.4 $ 392.0

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Long-term Debt [Text Block]	7. LONG-TERM DEBT Long-term debt consists of the following: June 30, 2018 December 31, 2017 (in millions) Revolving Credit Facility $ — $ — Term Loan A Facility 92.5 92.5 Term Loan B Facility 1,526.8 1,526.8 7.75% Notes due 2019 200.0 200.0 6.625% Notes due 2022 450.0 550.0 6.50% Notes due 2027 500.0 500.0 6.25% Notes due 2026 400.0 — 6.25% Notes due 2025 700.0 700.0 6.25% Notes due 2021 — 400.0 Foreign credit facilities 94.8 53.2 Capital lease obligations 15.4 28.3 Total debt 3,979.5 4,050.8 Less: Current portion of long-term debt 33.2 5.9 Long-term debt 3,946.3 4,044.9 Less: Debt issuance costs 73.3 75.6 Long-term debt, net $ 3,873.0 $ 3,969.3 Senior Secured Credit Facilities In 2017 , Holdings and American Axle & Manufacturing, Inc. (AAM, Inc.) entered into a credit agreement (the Credit Agreement). 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. The Credit Agreement includes 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 $932 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 Senior Secured Credit Facilities). The proceeds of the Revolving Credit Facility are used for general corporate purposes. As of June 30, 2018 we have prepaid $2.5 million of the outstanding principal on our Term Loan A Facility and $7.8 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 two quarters. Approximately $11.5 million related to the Term Loan A Facility and Term Loan B Facility is presented in the Current portion of long-term debt line item in our Condensed Consolidated Balance Sheet as of June 30, 2018 . At June 30, 2018 , we had $896.5 million available under the Revolving Credit Facility. This availability reflects a reduction of $35.5 million for standby letters of credit issued against the facility. The 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 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. 6.25% Notes due 2026 In March 2018, we issued $400.0 million in aggregate principal amount of 6.25% senior notes due 2026 (the 6.25% Notes due 2026). Proceeds from the 6.25% Notes due 2026 were used primarily to fund the tender offer for the 6.25% senior notes due 2021 (the 6.25% Notes due 2021) described below. We paid debt issuance costs of $6.6 million in the first six months of 2018 related to the 6.25% Notes due 2026. Tender Offer of 6.25% Notes due 2021 Also in March 2018, we made a tender offer for our 6.25% Notes due 2021. Under this tender offer, we retired $383.1 million of the 6.25% Notes due 2021 in the first quarter of 2018. We redeemed the remaining $16.9 million of the 6.25% Notes due 2021 during the second quarter of 2018 . During the six months ended June 30, 2018 , we expensed $2.5 million for the write-off of the remaining unamortized debt issuance costs that we had been amortizing over the expected life of the borrowing and $8.0 million in tender premiums. Redemption of 6.625% Notes due 2022 In May 2018 , we voluntarily redeemed a portion of our 6.625% Notes due 2022. This resulted in a principal payment of $100.0 million , and a payment of $0.8 million in accrued interest. During the six months ended June 30, 2018 , we expensed $0.8 million for the write-off of a portion of the remaining unamortized debt issuance costs that we had been amortizing over the expected life of the borrowing and $3.3 million for an early redemption premium. Settlement of Capital Lease Obligation In the second quarter of 2018, we reached a settlement agreement related to a capital lease obligation that we had recognized as a result of the acquisition of MPG. This settlement resulted in a gain of $15.6 million , including accrued interest. As of June 30, 2018, $11.4 million is presented in Current portion of long-term debt in our Condensed Consolidated Balance Sheet related to this capital lease obligation, which we expect to pay in the second half of 2018. Foreign credit facilities We utilize local currency credit facilities to finance the operations of certain foreign subsidiaries. At June 30, 2018 , $94.8 million was outstanding under our foreign credit facilities as compared to $53.2 million at December 31, 2017. The increase in outstanding borrowings under our foreign credit facilities primarily relate to our operations in China as we prepare for program launch activity. At June 30, 2018, an additional $94.8 million was available under our foreign credit facilities. The weighted-average interest rate of our long-term debt outstanding was 5.9% at June 30, 2018 and 5.7% at December 31, 2017 .

Fair Value

Fair Value	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	8. 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: June 30, 2018 December 31, 2017 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Balance Sheet Classification Cash equivalents $ 108.4 $ 108.4 $ 72.8 $ 72.8 Level 1 Prepaid expenses and other Cash flow hedges - currency forward contracts 0.5 0.5 0.1 0.1 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 0.4 0.4 1.3 1.3 Level 2 Nondesignated - currency forward contracts 0.1 0.1 — — Level 2 Other assets and deferred charges Cash flow hedges - currency forward contracts 0.2 0.2 0.2 0.2 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 1.8 1.8 0.9 0.9 Level 2 Accrued expenses and other Cash flow hedges - currency forward contracts 3.3 3.3 6.0 6.0 Level 2 Nondesignated - currency forward contracts 1.5 1.5 2.8 2.8 Level 2 Postretirement benefits and other long-term liabilities Cash flow hedges - currency forward contracts 2.0 2.0 2.6 2.6 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 1.0 1.0 0.3 0.3 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: June 30, 2018 December 31, 2017 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Revolving Credit Facility $ — $ — $ — $ — Level 2 Term Loan A Facility 92.5 91.9 92.5 92.5 Level 2 Term Loan B Facility 1,526.8 1,517.2 1,526.8 1,528.7 Level 2 7.75% Notes due 2019 200.0 209.5 200.0 217.5 Level 2 6.625% Notes due 2022 450.0 460.7 550.0 570.2 Level 2 6.50% Notes due 2027 500.0 494.4 500.0 527.5 Level 2 6.25% Notes due 2026 400.0 389.0 — — Level 2 6.25% Notes due 2025 700.0 683.9 700.0 736.8 Level 2 6.25% Notes due 2021 — — 400.0 410.0 Level 2 Long-Lived Assets During the second quarter of 2018, we recorded asset impairment charges as a result of restructuring actions initiated during the quarter. See Note 3 - Restructuring and Acquisition-Related Costs for further detail. The following table summarizes the impairments of long-lived assets measured at fair value on a nonrecurring basis subsequent to initial recognition: Balance Sheet Classification Fair Value at June 30, 2018 Asset Impairment for the Six Months Ended June 30, 2018 (in millions) Property, plant and equipment, net $ — $ 23.6 Other assets and deferred charges — 0.3

Derivatives

Derivatives	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	9. 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. On January 1, 2018, we early adopted new accounting guidance under Accounting Standards Update (ASU) 2017-12 - Targeted Improvements 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. The early adoption of this guidance did not have any impact on the measurement of our existing hedging relationships. 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 June 30, 2018 , we have currency forward contracts outstanding with a notional amount of $213.8 million that hedge our exposure to changes in foreign currency exchange rates for certain payroll expenses into the second quarter of 2021 and other items into the fourth 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. In the second quarter of 2018 , we discontinued this variable-to-fixed interest rate swap, which was in an asset position of $5.6 million on the date that it was discontinued. Also in the second quarter of 2018 , we entered into a new 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: $900.0 million through May 2019, $750.0 million through May 2020, $500.0 million through May 2021, $400.0 million through May 2022 and $400.0 million through May 2023. The following table summarizes the reclassification of derivative gains and losses into net income from accumulated other comprehensive income (loss) for those derivative instruments designated as cash flow hedges under ASC 815 - Derivatives and Hedging : Location Gain (Loss) Reclassified During Total of Financial Gain (Loss) Expected of Gain (Loss) Three Months Ended Six Months Ended Statement to be Reclassified Reclassified into June 30, June 30, Line Item During the Net Income 2018 2017 2018 2017 2018 Next 12 Months (in millions) Currency forward contracts Cost of Goods Sold $ (0.8 ) $ (1.1 ) $ (2.8 ) $ (3.9 ) $ 3,111.6 $ (2.8 ) Variable-to-fixed interest rate swap Interest Expense 0.9 — 1.3 — 107.6 2.5 See Note 14 - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (AOCI) for amounts recognized in other comprehensive income (loss) during the three and six months ended June 30, 2018 and 2017. The following table summarizes the amount and location of gains and 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 Total of Financial Location of Gain (Loss) Three Months Ended Six Months Ended Statement Line Recognized in June 30, June 30, Item Net Income 2018 2017 2018 2017 2018 (in millions) Currency forward contracts Cost of Goods Sold $ (3.5 ) $ 2.2 $ 0.5 $ 5.7 $ 3,111.6 Currency forward contracts Other Income (Expense), net 1.8 — 1.8 — 0.2 Currency option contracts Cost of Goods Sold — 1.1 — 1.1 3,111.6

Employee Benefit Plans

Employee Benefit Plans	6 Months Ended
	Jun. 30, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Pension and Other Postretirement Benefits Disclosure [Text Block]	10. EMPLOYEE BENEFIT PLANS In 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 became effective January 1, 2018 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. Upon adoption of this guidance, we now include the components of net benefit cost other than service cost in Other income (expense) in our Condensed Consolidated Statements of Income. We have not retrospectively restated the Condensed Consolidated Statement of Income for the three or six months ended June 30, 2017 as the total of the components of net benefit cost other than service cost were immaterial for these periods. For the three and six months ended June 30, 2018 , the total of the components of net benefit cost other than service cost included in Other income (expense) was expense of $0.3 million and $0.5 million respectively, which excludes the curtailment shown in the table below. This curtailment was associated with a recent restructuring of certain benefit plans as a result of our integration of MPG and has been presented in the Restructuring and acquisition-related costs line item in our Condensed Consolidated Statement of Income for the six months ended June 30, 2018 . The components of net periodic benefit cost (credit) are as follows: Pension Benefits Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 (in millions) Service cost $ 1.0 $ 1.1 $ 2.1 $ 1.9 Interest cost 6.8 7.4 13.7 14.2 Expected asset return (11.5 ) (11.1 ) (23.0 ) (21.6 ) Amortized loss 2.2 1.8 4.4 3.5 Amortized prior service cost 0.1 — 0.1 — Curtailment — — 3.2 — Net periodic benefit cost (credit) $ (1.4 ) $ (0.8 ) $ 0.5 $ (2.0 ) Other Postretirement Benefits Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 (in millions) Service cost $ 0.1 $ 0.1 $ 0.2 $ 0.2 Interest cost 3.1 3.3 6.2 6.6 Amortized loss 0.2 0.1 0.4 0.3 Amortized prior service credit (0.6 ) (0.6 ) (1.3 ) (1.3 ) Net periodic benefit cost $ 2.8 $ 2.9 $ 5.5 $ 5.8 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 June 30, 2018 and December 31, 2017 , we have a noncurrent pension liability of $115.3 million and $134.7 million , respectively. In the second quarter of 2018, our AAM Supplemental Executive Retirement Plan (SERP) was amended and restated to freeze further benefit accruals and the vesting of benefits, as well as new eligibility to participate in the SERP. As a result, we recorded a reduction of our noncurrent pension liability, as well as a reduction of the accumulated other comprehensive loss associated with the SERP, of $11.6 million in the second quarter of 2018. As of June 30, 2018 and December 31, 2017 , we have a noncurrent other postretirement benefits liability of $579.9 million and $583.0 million , respectively. Due to the availability of our pre-funded pension balances (previous contributions in excess of prior required pension contributions) related to certain of our U.S. pension plans, we expect our regulatory pension funding requirements in 2018 to be approximately $2 million . We expect our cash payments for other postretirement benefit obligations in 2018 , net of GM cost sharing, to be approximately $17 million .

Product Warranties

Product Warranties	6 Months Ended
	Jun. 30, 2018
Product Warranties Disclosures [Abstract]
Product Warranty Disclosure [Text Block]	11. 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 Six Months Ended June 30, June 30, 2018 2017 2018 2017 (in millions) Beginning balance $ 53.6 $ 47.5 $ 49.5 $ 42.9 Accruals 6.2 4.1 10.5 9.6 Payments (0.6 ) (1.5 ) (1.1 ) (2.4 ) Adjustment to prior period accruals (0.2 ) (2.4 ) (0.2 ) (2.6 ) Foreign currency translation (0.6 ) 0.2 (0.3 ) 0.4 Ending balance $ 58.4 $ 47.9 $ 58.4 $ 47.9

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	12. INCOME TAXES Tax Provision for the Three and Six Months Ended June 30, 2018 and 2017 We are required to adjust our effective tax rate each quarter based on our estimated 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 $2.0 million for the three months ended June 30, 2018 as compared to $2.4 million for the three months ended June 30, 2017 . Our effective income tax rate was 1.3% in the second quarter of 2018 as compared to 3.6% in the second quarter of 2017 . Income tax expense was $19.9 million for the six months ended June 30, 2018 as compared to $9.9 million for the six months ended June 30, 2017 . Our effective income tax rate was 7.6% in the first six months of 2018 as compared to 6.4% in the first six months of 2017 . The changes in income tax expense and effective income tax rate for the three and six months ended June 30, 2018, as compared to the three and six months ended June 30, 2017, reflect the reduction in the U.S. statutory tax rate as a result of the 2017 Act (defined below), as well as a $20.0 million discrete tax benefit associated with the reduction of our liability for unrecognized tax benefits as described below. Our income tax expense and effective income tax rate for the three and six months ended June 30, 2018 also reflect the benefit of additional U.S. tax credits and a discrete tax expense related to the sale of the aftermarket business associated with our Powertrain segment. Our effective income tax rates for the three and six months ended June 30, 2018, as compared to the three and six months ended June 30, 2017, reflect a decreased benefit related to the proportionate share of income attributable to lower tax rate jurisdictions due primarily to the decrease in the U.S. statutory tax rate. The factors described above also impacted our effective income tax rate for the three and six months ended June 30, 2018 as compared to the U.S. statutory rate. Based on the protocol of finalizing audits and advance pricing agreements with 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 June 30, 2018 and December 31, 2017 , we have recorded a liability for unrecognized income tax benefits and related interest and penalties of $34.1 million and $55.2 million , respectively. In the second quarter of 2018, we finalized an advance pricing agreement in a foreign jurisdiction, which resulted in a reduction of our liability for unrecognized tax benefits and related interest and penalties of $20.0 million . In the second half of 2018, we may finalize another advance pricing agreement in a foreign jurisdiction, which could result in a cash payment to the relevant tax authorities and a reduction of our liability for unrecognized tax benefits and related interest and penalties. We do not expect any potential settlement to 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 other communications with tax authorities and will adjust our estimated liability as necessary. Tax Cuts and Jobs Act On December 22, 2017, the Tax Cuts and Jobs Act (the 2017 Act) was enacted in the United States. The following is a summary of the key provisions of the 2017 Act: • Reduces the U.S. federal statutory income tax rate for corporations from 35% to 21% • Requires companies to pay a one-time transition tax (Transition Tax) on certain foreign earnings for which U.S. income tax was previously deferred • Generally eliminates U.S. federal income taxes on dividends from foreign subsidiaries • Requires a current inclusion in U.S. federal taxable income of certain earnings of controlled foreign corporations (GILTI) • Eliminates the corporate alternative minimum tax (AMT) and changes how existing AMT credits can be realized • Creates a new limitation on deductible net interest expense incurred by U.S. corporations • Allows for immediate expensing of certain capital investments in the U.S. for the period September 27, 2017 through December 31, 2022 • Creates a new base erosion anti-abuse minimum tax (BEAT) • Allows for a current deduction for a portion of foreign derived intangible income (FDII) Following the enactment of the 2017 Act, the Securities and Exchange Commission issued Staff Accounting Bulletin (SAB) 118 to provide guidance on the accounting and reporting impacts of the 2017 Act. For the impact of changes resulting from the 2017 Act, under the guidance in SAB 118, we either 1) recorded an estimated provisional amount when the impact of the change could be reasonably estimated; or 2) continued to apply the accounting guidance that was in effect immediately prior to the 2017 Act when the impact of the change could not be reasonably estimated. For estimated provisional amounts recorded, there is a measurement period of no longer than one year during which we should adjust those amounts as additional information becomes available. In connection with our preliminary analysis of the impacts of the 2017 Act, we recorded estimates in 2017 related to the remeasurement of our net deferred tax liabilities as a result of the change in tax rate, a reduction of a previously recorded deferred tax liability on certain foreign earnings, and estimated expense related to the Transition Tax. These estimates were based on information available at the time and, in accordance with the guidance in SAB 118, we designated these amounts as provisional. As such, these amounts are subject to adjustment as we obtain additional information and complete our analysis. The additional information required is as follows: Reduction of U.S. federal corporate tax rate: While we were able to make a reasonable estimate in 2017 of the impact of the reduction in the corporate tax rate, the final impact may be affected by other elements related to the 2017 Act including, but not limited to, our calculation of deemed repatriation of deferred foreign income and the state tax effect of adjustments made to federal temporary differences. Transition Tax: In order to finalize the impact of the Transition Tax, we must determine, in addition to other factors, the amount of earnings of certain foreign subsidiaries, as well as the amount of non-U.S. income taxes paid on these earnings. In 2017, we were able to make a reasonable estimate, however, we are continuing to gather information to more precisely calculate the Transition Tax. For the three and six months ended June 30, 2018 , we did not record any adjustments to these provisional amounts as we did not obtain sufficient information to adjust the estimates previously recorded. GILTI Tax: Beginning in 2018, the effect of the global intangible low-taxed income (GILTI) provisions have been included in our annual effective income tax rate calculation. Under GAAP, we are required to make an accounting policy election to either 1) treat taxes due related to GILTI as a current period expense when incurred (the "period cost method") or 2) factor such amounts into our measurement of deferred taxes (the "deferred method"). We are continuing to evaluate the GILTI tax rules and have not yet adopted our policy to account for the related impacts. We determine our provision for income taxes for interim periods using an estimate of our annual effective income tax rate. We record any changes affecting the estimated annual effective income tax rate in the interim period in which the change occurs, including discrete tax items. We have included in the estimated annual effective income tax rate the reduction in the U.S. statutory tax rate, GILTI, and the FDII deduction related to current year operations and have not provided additional GILTI on deferred items.

Earnings Per Share (EPS)

Earnings Per Share (EPS)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	13. 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 Six Months Ended June 30, June 30, 2018 2017 2018 2017 (in millions, except per share data) Numerator Net income attributable to AAM $ 151.1 $ 66.2 $ 240.5 $ 144.6 Less: Net income attributable to participating securities (4.9 ) (1.4 ) (6.8 ) (3.3 ) Net income attributable to common shareholders - Basic and Dilutive $ 146.2 $ 64.8 $ 233.7 $ 141.3 Denominators Basic common shares outstanding - Weighted-average shares outstanding 115.4 111.6 114.8 95.2 Less: Participating securities (3.7 ) (2.3 ) (3.3 ) (2.2 ) Weighted-average common shares outstanding 111.7 109.3 111.5 93.0 Effect of dilutive securities - Dilutive stock-based compensation 0.6 0.4 0.6 0.4 Diluted shares outstanding - Adjusted weighted-average shares after assumed conversions 112.3 109.7 112.1 93.4 Basic EPS $ 1.31 $ 0.59 $ 2.09 $ 1.52 Diluted EPS $ 1.30 $ 0.59 $ 2.08 $ 1.51

Reclassifications out of Accumu

Reclassifications out of Accumulated Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2018
Reclassifications out of Accumulated Other Comprehensive Income (Loss) [Abstract]
Disclosure of Reclassification Amount [Text Block]	14. 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 June 30, 2018 and June 30, 2017 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Gain (Loss) on Cash Flow Hedges Total Balance at March 31, 2018 $ (250.7 ) $ 3.8 $ 8.5 $ (238.4 ) Other comprehensive income (loss) before reclassifications 14.7 (81.2 ) (7.7 ) (74.2 ) Income tax effect of other comprehensive income (loss) before reclassifications (3.6 ) — (0.4 ) (4.0 ) Amounts reclassified from accumulated other comprehensive income (loss) 1.6 (a) 0.2 (0.1 ) (b) 1.7 Income taxes reclassified into net income (0.5 ) — 0.3 (0.2 ) Net current period other comprehensive income (loss) 12.2 (81.0 ) (7.9 ) (76.7 ) Balance at June 30, 2018 $ (238.5 ) $ (77.2 ) $ 0.6 $ (315.1 ) Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Gain (Loss) on Cash Flow Hedges Total Balance at March 31, 2017 $ (243.8 ) $ (110.5 ) $ (8.2 ) $ (362.5 ) Other comprehensive income before reclassifications — 24.6 3.1 27.7 Income tax effect of other comprehensive income before reclassifications — — 0.7 0.7 Amounts reclassified from accumulated other comprehensive loss 1.3 (a) — 1.1 (b) 2.4 Income taxes reclassified into net income (0.4 ) — — (0.4 ) Net current period other comprehensive income 0.9 24.6 4.9 30.4 Balance at June 30, 2017 $ (242.9 ) $ (85.9 ) $ (3.3 ) $ (332.1 ) (a) The amount reclassified from AOCI included $1.6 million in cost of goods sold (COGS) for the three months ended June 30, 2018 and $1.4 million in COGS and $(0.1) million in SG&A for the three months ended June 30, 2017. (b) The amounts reclassified from AOCI included $0.8 million in COGS and $(0.9) million in interest expense for the three months ended June 30, 2018 and $1.1 million in COGS for the three months ended June 30, 2017. Reclassification adjustments and other activity impacting accumulated other comprehensive income (loss) during the six months ended June 30, 2018 and June 30, 2017 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at December 31, 2017 $ (252.0 ) $ (34.1 ) $ (6.6 ) $ (292.7 ) Other comprehensive income (loss) before reclassifications 14.7 (43.3 ) 6.9 (21.7 ) Income tax effect of other comprehensive income (loss) before reclassifications (3.6 ) — (1.5 ) (5.1 ) Amounts reclassified from accumulated other comprehensive loss 3.3 (a) 0.2 1.5 (b) 5.0 Income taxes reclassified into net income (0.9 ) — 0.3 (0.6 ) Net current period other comprehensive income (loss) 13.5 (43.1 ) 7.2 (22.4 ) Balance at June 30, 2018 $ (238.5 ) $ (77.2 ) $ 0.6 $ (315.1 ) 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 ) 36.5 15.8 50.6 Income tax effect of other comprehensive income before reclassifications 0.6 — 0.7 1.3 Amounts reclassified from accumulated other comprehensive loss 2.5 (a) — 3.9 (b) 6.4 Income taxes reclassified into net income (0.8 ) — — (0.8 ) Net current period other comprehensive income 0.6 36.5 20.4 57.5 Balance at June 30, 2017 $ (242.9 ) $ (85.9 ) $ (3.3 ) $ (332.1 ) (a) The amount reclassified from AOCI included $3.0 million in cost of goods sold (COGS) and $0.3 million in selling, general & administrative expenses (SG&A) for the six months ended June 30, 2018 and $2.8 million in COGS and $(0.3) million in SG&A for the six months ended June 30, 2017. (b) The amounts reclassified from AOCI included $2.8 million in COGS and $(1.3) million in interest expense for the six months ended June 30, 2018 and $3.9 million in COGS for the six months ended June 30, 2017.

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting Disclosure [Text Block]	15. SEGMENT REPORTING Our business is 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. Refer to Note 2 - Revenue from Contracts with Customers for a description of our product offerings by segment. 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 EBITDA for our reportable segments excluding the impact of restructuring and acquisition-related costs, debt refinancing and redemption costs, gain on the sale of a business, and non-recurring items. The following tables represent information by reportable segment for the three months ended June 30, 2018 and 2017 (in millions) : Three Months Ended June 30, 2018 Driveline Metal Forming Powertrain Casting Total Sales $ 1,120.2 $ 397.1 $ 288.3 $ 243.2 $ 2,048.8 Less: intersegment sales 0.2 109.3 4.8 33.6 147.9 Net external sales $ 1,120.0 $ 287.8 $ 283.5 $ 209.6 $ 1,900.9 Segment Adjusted EBITDA $ 184.9 $ 89.1 $ 47.0 $ 26.9 $ 347.9 Three Months Ended June 30, 2017 Driveline Metal Forming Powertrain Casting Total Sales $ 1,021.5 $ 369.3 $ 283.6 $ 225.6 $ 1,900.0 Less: intersegment sales 0.4 109.4 2.2 30.2 142.2 Net external sales $ 1,021.1 $ 259.9 $ 281.4 $ 195.4 $ 1,757.8 Segment Adjusted EBITDA $ 179.0 $ 69.4 $ 51.9 $ 25.5 $ 325.8 The following tables represent information by reportable segment for the six months ended June 30, 2018 and 2017 : Six Months Ended June 30, 2018 Driveline Metal Forming Powertrain Casting Total Sales $ 2,190.8 $ 794.1 $ 580.2 $ 482.2 $ 4,047.3 Less: intersegment sales 0.4 215.2 9.6 62.8 288.0 Net external sales $ 2,190.4 $ 578.9 $ 570.6 $ 419.4 $ 3,759.3 Segment Adjusted EBITDA $ 354.9 $ 164.4 $ 97.1 $ 48.5 $ 664.9 Six Months Ended June 30, 2017 Driveline Metal Forming Powertrain Casting Total Sales $ 2,020.8 $ 519.3 $ 283.6 $ 225.6 $ 3,049.3 Less: intersegment sales 0.9 208.3 2.2 30.2 241.6 Net external sales $ 2,019.9 $ 311.0 $ 281.4 $ 195.4 $ 2,807.7 Segment Adjusted EBITDA $ 332.2 $ 99.8 $ 51.9 $ 25.5 $ 509.4 The following table represents a reconciliation of Total Segment Adjusted EBITDA to consolidated income before income taxes for the three and six months ended June 30, 2018 and 2017 (in millions) : Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total Segment Adjusted EBITDA $ 347.9 $ 325.8 $ 664.9 $ 509.4 Interest expense (54.4 ) (56.9 ) (107.6 ) (82.4 ) Depreciation and amortization (130.2 ) (124.6 ) (258.0 ) (180.8 ) Restructuring and acquisition-related costs (36.8 ) (51.7 ) (55.1 ) (67.7 ) Gain on sale of business 15.5 — 15.5 — Gain on settlement of capital lease 15.6 — 15.6 — Acquisition-related fair value inventory adjustment — (24.9 ) — (24.9 ) Impact of change in accounting principle — 3.7 — 3.7 Debt refinancing and redemption costs (4.3 ) (2.7 ) (14.6 ) (2.7 ) Income before income taxes $ 153.3 $ 68.7 $ 260.7 $ 154.6

Supplemental Guarantor Condense

Supplemental Guarantor Condensed Consolidating Financial Statements	6 Months Ended
	Jun. 30, 2018
Supplemental Guarantor Condensed Consolidating Financial Statements [Abstract]
Supplemental Guarantor Disclosure [Text Block]	16. 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 2026), and 6.25% Notes (due 2025) 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 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 June 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2018 Net sales External $ — $ 302.8 $ 572.6 $ 1,025.5 $ — $ 1,900.9 Intercompany — 2.3 78.0 10.8 (91.1 ) — Total net sales — 305.1 650.6 1,036.3 (91.1 ) 1,900.9 Cost of goods sold — 305.7 542.3 812.6 (91.1 ) 1,569.5 Gross profit (loss) — (0.6 ) 108.3 223.7 — 331.4 Selling, general and administrative expenses — 60.2 19.9 14.9 — 95.0 Amortization of intangible assets — 1.4 22.5 0.9 — 24.8 Restructuring and acquisition-related costs — 9.8 26.8 0.2 — 36.8 Gain on sale of business — — (15.5 ) — — (15.5 ) Operating income (loss) — (72.0 ) 54.6 207.7 — 190.3 Non-operating income (expense), net — (63.3 ) 3.2 23.1 — (37.0 ) Income (loss) before income taxes — (135.3 ) 57.8 230.8 — 153.3 Income tax expense (benefit) — 8.0 0.1 (6.1 ) — 2.0 Earnings from equity in subsidiaries 151.1 106.3 67.3 — (324.7 ) — Net income (loss) before royalties 151.1 (37.0 ) 125.0 236.9 (324.7 ) 151.3 Royalties — 85.0 0.9 (85.9 ) — — Net income after royalties 151.1 48.0 125.9 151.0 (324.7 ) 151.3 Net income attributable to noncontrolling interests — — — (0.2 ) — (0.2 ) Net income attributable to AAM $ 151.1 $ 48.0 $ 125.9 $ 150.8 $ (324.7 ) $ 151.1 Other comprehensive loss, net of tax (76.7 ) (29.2 ) (75.3 ) (81.0 ) 185.5 (76.7 ) Comprehensive income attributable to AAM $ 74.4 $ 18.8 $ 50.6 $ 69.8 $ (139.2 ) $ 74.4 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net sales External $ — $ 260.3 $ 560.6 $ 936.9 $ — $ 1,757.8 Intercompany — 1.9 101.9 7.9 (111.7 ) — Total net sales — 262.2 662.5 944.8 (111.7 ) 1,757.8 Cost of goods sold — 245.4 580.6 727.1 (111.7 ) 1,441.4 Gross profit — 16.8 81.9 217.7 — 316.4 Selling, general and administrative expenses — 65.8 21.0 18.8 — 105.6 Amortization of intangible assets — 1.5 22.7 0.6 — 24.8 Restructuring and acquisition-related costs — 50.1 — 1.6 — 51.7 Operating income (loss) — (100.6 ) 38.2 196.7 — 134.3 Non-operating income (expense), net — (61.6 ) 7.0 (11.0 ) — (65.6 ) Income (loss) before income taxes — (162.2 ) 45.2 185.7 — 68.7 Income tax expense (benefit) — (30.4 ) 15.8 17.0 — 2.4 Earnings from equity in subsidiaries 66.2 81.3 8.2 — (155.7 ) — Net income (loss) before royalties 66.2 (50.5 ) 37.6 168.7 (155.7 ) 66.3 Royalties — 89.2 1.3 (90.5 ) — — Net income after royalties 66.2 38.7 38.9 78.2 (155.7 ) 66.3 Net income attributable to noncontrolling interests — — — (0.1 ) — (0.1 ) Net income attributable to AAM $ 66.2 $ 38.7 $ 38.9 $ 78.1 $ (155.7 ) $ 66.2 Other comprehensive income, net of tax 30.4 11.3 21.6 17.1 (50.0 ) 30.4 Comprehensive income attributable to AAM $ 96.6 $ 50.0 $ 60.5 $ 95.2 $ (205.7 ) $ 96.6 Condensed Consolidating Statements of Income Six Months Ended June 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2018 Net sales External $ — $ 604.3 $ 1,154.9 $ 2,000.1 $ — $ 3,759.3 Intercompany — 3.3 156.0 20.3 (179.6 ) — Total net sales — 607.6 1,310.9 2,020.4 (179.6 ) 3,759.3 Cost of goods sold — 583.9 1,119.1 1,588.2 (179.6 ) 3,111.6 Gross profit — 23.7 191.8 432.2 — 647.7 Selling, general and administrative expenses — 120.0 41.8 30.5 — 192.3 Amortization of intangible assets — 2.9 45.1 1.7 — 49.7 Restructuring and acquisition-related costs — 26.1 27.9 1.1 — 55.1 Gain on sale of business — — (15.5 ) — — (15.5 ) Operating income (loss) — (125.3 ) 92.5 398.9 — 366.1 Non-operating income (expense), net — (133.8 ) 8.2 20.2 — (105.4 ) Income (loss) before income taxes — (259.1 ) 100.7 419.1 — 260.7 Income tax expense — 9.1 0.5 10.3 — 19.9 Earnings from equity in subsidiaries 240.5 173.5 107.8 — (521.8 ) — Net income (loss) before royalties 240.5 (94.7 ) 208.0 408.8 (521.8 ) 240.8 Royalties — 169.2 1.9 (171.1 ) — — Net income after royalties 240.5 74.5 209.9 237.7 (521.8 ) 240.8 Net income attributable to noncontrolling interests — — — (0.3 ) — (0.3 ) Net income attributable to AAM $ 240.5 $ 74.5 $ 209.9 $ 237.4 $ (521.8 ) $ 240.5 Other comprehensive loss, net of tax (22.4 ) (3.6 ) (40.2 ) (37.3 ) 81.1 (22.4 ) Comprehensive income attributable to AAM $ 218.1 $ 70.9 $ 169.7 $ 200.1 $ (440.7 ) $ 218.1 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net sales External $ — $ 556.9 $ 610.8 $ 1,640.0 $ — $ 2,807.7 Intercompany — 2.2 134.7 12.9 (149.8 ) — Total net sales — 559.1 745.5 1,652.9 (149.8 ) 2,807.7 Cost of goods sold — 522.6 641.7 1,266.1 (149.8 ) 2,280.6 Gross profit — 36.5 103.8 386.8 — 527.1 Selling, general and administrative expenses — 138.2 21.0 27.6 — 186.8 Amortization of intangible assets — 2.8 22.7 0.9 — 26.4 Restructuring and acquisition-related costs — 65.4 — 2.3 — 67.7 Operating income (loss) — (169.9 ) 60.1 356.0 — 246.2 Non-operating income (expense), net — (87.9 ) 9.4 (13.1 ) — (91.6 ) Income (loss) before income taxes — (257.8 ) 69.5 342.9 — 154.6 Income tax expense (benefit) — (33.2 ) 24.2 18.9 — 9.9 Earnings from equity in subsidiaries 144.6 173.0 15.9 — (333.5 ) — Net income (loss) before royalties 144.6 (51.6 ) 61.2 324.0 (333.5 ) 144.7 Royalties — 168.7 1.3 (170.0 ) — — Net income after royalties 144.6 117.1 62.5 154.0 (333.5 ) 144.7 Net income attributable to noncontrolling interests — — — (0.1 ) — (0.1 ) Net income attributable to AAM $ 144.6 $ 117.1 $ 62.5 $ 153.9 $ (333.5 ) $ 144.6 Other comprehensive income, net of tax 57.5 38.6 32.1 43.5 (114.2 ) 57.5 Comprehensive income attributable to AAM $ 202.1 $ 155.7 $ 94.6 $ 197.4 $ (447.7 ) $ 202.1 Condensed Consolidating Balance Sheets (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated June 30, 2018 Assets Current assets Cash and cash equivalents $ — $ 82.3 $ 0.3 $ 270.6 $ — $ 353.2 Accounts receivable, net — 182.7 339.3 731.6 — 1,253.6 Intercompany receivables — 2,748.4 1,446.6 91.1 (4,286.1 ) — Inventories, net — 34.4 153.8 238.2 — 426.4 Prepaid expenses and other — 37.3 4.9 79.6 — 121.8 Total current assets — 3,085.1 1,944.9 1,411.1 (4,286.1 ) 2,155.0 Property, plant and equipment, net — 259.6 770.3 1,429.4 — 2,459.3 Goodwill — — 1,204.5 427.2 — 1,631.7 Intangible assets, net — 19.9 1,106.2 33.7 — 1,159.8 Intercompany notes and accounts receivable 11.7 1,319.7 133.7 — (1,465.1 ) — Other assets and deferred charges — 341.9 115.3 227.4 — 684.6 Investment in subsidiaries 3,071.1 2,146.6 1,690.1 — (6,907.8 ) — Total assets $ 3,082.8 $ 7,172.8 $ 6,965.0 $ 3,528.8 $ (12,659.0 ) $ 8,090.4 Liabilities and Stockholders’ Equity Current liabilities Current portion of long-term debt $ — $ 11.5 $ — $ 21.7 $ — $ 33.2 Accounts payable — 156.8 245.6 528.5 — 930.9 Intercompany payables — 1,404.5 2,747.6 134.0 (4,286.1 ) — Accrued expenses and other — 141.1 40.9 185.6 — 367.6 Total current liabilities — 1,713.9 3,034.1 869.8 (4,286.1 ) 1,331.7 Intercompany notes and accounts payable 1,316.6 15.2 — 133.3 (1,465.1 ) — Long-term debt, net — 3,785.0 3.5 84.5 — 3,873.0 Other long-term liabilities — 598.8 332.0 188.7 — 1,119.5 Total liabilities 1,316.6 6,112.9 3,369.6 1,276.3 (5,751.2 ) 6,324.2 Total AAM Stockholders’ equity 1,764.2 1,059.9 3,595.4 2,250.5 (6,905.8 ) 1,764.2 Noncontrolling interests in subsidiaries 2.0 — — 2.0 (2.0 ) 2.0 Total stockholders’ equity 1,766.2 1,059.9 3,595.4 2,252.5 (6,907.8 ) 1,766.2 Total liabilities and stockholders’ equity $ 3,082.8 $ 7,172.8 $ 6,965.0 $ 3,528.8 $ (12,659.0 ) $ 8,090.4 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated December 31, 2017 Assets Current assets Cash and cash equivalents $ — $ 91.9 $ 0.1 $ 284.8 $ — $ 376.8 Accounts receivable, net — 138.9 287.9 609.1 — 1,035.9 Intercompany receivables — 3,475.2 479.9 7.5 (3,962.6 ) — Inventories, net — 37.2 147.4 207.4 — 392.0 Prepaid expenses and other — 40.4 9.9 90.0 — 140.3 Total current assets — 3,783.6 925.2 1,198.8 (3,962.6 ) 1,945.0 Property, plant and equipment, net — 250.9 786.8 1,365.2 — 2,402.9 Goodwill — — 1,218.4 435.9 — 1,654.3 Intangible assets, net — 21.0 1,155.6 35.9 — 1,212.5 Intercompany notes and accounts receivable 11.7 — 243.5 — (255.2 ) — Other assets and deferred charges — 349.1 122.8 196.2 — 668.1 Investment in subsidiaries 2,841.3 1,955.2 1,280.1 — (6,076.6 ) — Total assets $ 2,853.0 $ 6,359.8 $ 5,732.4 $ 3,232.0 $ (10,294.4 ) $ 7,882.8 Liabilities and Stockholders’ Equity Current liabilities Current portion of long-term debt $ — $ — $ — $ 5.9 $ — $ 5.9 Accounts payable — 139.0 204.6 455.4 — 799.0 Intercompany payables 1,313.0 563.7 2,017.7 68.2 (3,962.6 ) — Accrued expenses and other — 181.6 52.4 177.5 — 411.5 Total current liabilities 1,313.0 884.3 2,274.7 707.0 (3,962.6 ) 1,216.4 Intercompany notes and accounts payable — 11.7 — 243.5 (255.2 ) — Long-term debt, net — 3,894.6 4.4 70.3 — 3,969.3 Other long-term liabilities — 639.1 333.2 184.8 — 1,157.1 Total liabilities 1,313.0 5,429.7 2,612.3 1,205.6 (4,217.8 ) 6,342.8 Total AAM Stockholders’ equity 1,536.0 930.1 3,120.1 2,022.4 (6,072.6 ) 1,536.0 Noncontrolling interests in subsidiaries 4.0 — — 4.0 (4.0 ) 4.0 Total stockholders’ equity 1,540.0 930.1 3,120.1 2,026.4 (6,076.6 ) 1,540.0 Total liabilities and stockholders’ equity $ 2,853.0 $ 6,359.8 $ 5,732.4 $ 3,232.0 $ (10,294.4 ) $ 7,882.8 Condensed Consolidating Statements of Cash Flows Six Months Ended June 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2018 Net cash provided by operating activities $ — $ 152.3 $ 8.6 $ 128.5 $ — $ 289.4 Investing activities Purchases of property, plant and equipment — (40.3 ) (74.5 ) (158.2 ) — (273.0 ) Proceeds from sale of property, plant and equipment — — 0.5 0.4 — 0.9 Purchase buyouts of leased equipment — — (0.5 ) — — (0.5 ) Proceeds from sale of business, net — — 42.7 4.4 — 47.1 Acquisition of business, net of cash acquired — — — (1.3 ) — (1.3 ) Net cash used in investing activities — (40.3 ) (31.8 ) (154.7 ) — (226.8 ) Financing activities Net debt activity — (111.2 ) (0.4 ) 44.8 — (66.8 ) Debt issuance costs — (6.8 ) — — — (6.8 ) Purchase of treasury stock (3.6 ) — — — — (3.6 ) Purchase of noncontrolling interest — — (2.2 ) — — (2.2 ) Intercompany activity 3.6 (3.6 ) 28.5 (28.5 ) — — Net cash provided by (used in) financing activities — (121.6 ) 25.9 16.3 — (79.4 ) Effect of exchange rate changes on cash — — — (4.3 ) — (4.3 ) Net increase (decrease) in cash, cash equivalents and restricted cash — (9.6 ) 2.7 (14.2 ) — (21.1 ) Cash, cash equivalents and restricted cash at beginning of period — 91.9 0.1 284.8 — 376.8 Cash, cash equivalents and restricted cash at end of period $ — $ 82.3 $ 2.8 $ 270.6 $ — $ 355.7 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net cash provided by (used in) operating activities $ — $ 222.8 $ (25.2 ) $ 15.6 $ — $ 213.2 Investing activities Purchases of property, plant and equipment — (28.4 ) (39.2 ) (71.0 ) — (138.6 ) Proceeds from sale of property, plant and equipment — 0.3 0.1 1.1 — 1.5 Purchase buyouts of leased equipment — (8.4 ) — — — (8.4 ) 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 — (982.5 ) 23.9 (76.5 ) — (1,035.1 ) Financing activities Net debt activity — 931.4 (0.2 ) (10.8 ) — 920.4 Debt issuance costs — (90.5 ) — — — (90.5 ) Employee stock option exercises — 0.9 — — — 0.9 Purchase of treasury stock (6.9 ) — — — — (6.9 ) Intercompany activity 6.9 (6.9 ) — — — — Net cash provided by (used in) financing activities — 834.9 (0.2 ) (10.8 ) — 823.9 Effect of exchange rate changes on cash — — — 7.4 — 7.4 Net increase (decrease) in cash, cash equivalents and restricted cash — 75.2 (1.5 ) (64.3 ) — 9.4 Cash, cash equivalents and restricted cash at beginning of period — 84.3 1.6 395.3 — 481.2 Cash, cash equivalents and restricted cash at end of period $ — $ 159.5 $ 0.1 $ 331.0 $ — $ 490.6

Organization and Basis of Pre24

Organization and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2018
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, 2017 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, 2017 .
New Accounting Pronouncements, Policy [Policy Text Block]	Effect of New Accounting Standards Accounting Standards Update 2018-02 On February 14, 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2018-02 - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (Topic 220). ASU 2018-02 allows companies the option to reclassify disproportionate tax effects in accumulated other comprehensive income (AOCI) caused by the 2017 Tax Cuts and Jobs Act, also known as stranded tax effects, to retained earnings. ASU 2018-02 also requires expanded disclosures related to disproportionate income tax effects from AOCI, some of which are applicable to all companies regardless of whether the option to reclassify the stranded tax effects is exercised. This guidance becomes effective at the beginning of our 2019 fiscal year, however early adoption is permitted for financial statements which have not yet been issued. 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. This guidance becomes effective at the beginning of our 2020 fiscal year and early adoption is permitted. The guidance requires a prospective transition method. We do not expect the adoption of this guidance to have a material effect on our consolidated financial statements, however, goodwill could be more susceptible to impairment in periods subsequent to adoption. Accounting Standards Update 2016-02 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.

Revenue from Contracts with C25

Revenue from Contracts with Customers Disaggregation of Revenue (Tables)	6 Months Ended
	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Table Text Block]	Disaggregation of Net Sales Net sales recognized from contracts with customers, disaggregated by segment and geographical location, are presented in the following table for the three and six months ended June 30, 2018 and 2017 . Net sales are attributed to regions based on the location of production. Intersegment sales have been excluded from the table. Three Months Ended June 30, 2018 Driveline Metal Forming Powertrain Casting Total North America $ 899.0 $ 216.3 $ 197.2 $ 209.6 $ 1,522.1 Asia 159.3 1.2 29.9 — 190.4 Europe 30.7 70.3 54.9 — 155.9 South America 31.0 — 1.5 — 32.5 Total $ 1,120.0 $ 287.8 $ 283.5 $ 209.6 $ 1,900.9 Three Months Ended June 30, 2017 Driveline Metal Forming Powertrain Casting Total North America $ 862.0 $ 201.6 $ 204.2 $ 195.4 $ 1,463.2 Asia 103.9 0.7 32.5 — 137.1 Europe 21.2 57.6 44.6 — 123.4 South America 34.0 — 0.1 — 34.1 Total $ 1,021.1 $ 259.9 $ 281.4 $ 195.4 $ 1,757.8 Six Months Ended June 30, 2018 Driveline Metal Forming Powertrain Casting Total North America $ 1,784.3 $ 432.6 $ 396.4 $ 419.4 $ 3,032.7 Asia 282.1 2.6 61.0 — 345.7 Europe 59.7 143.7 110.8 — 314.2 South America 64.3 — 2.4 — 66.7 Total $ 2,190.4 $ 578.9 $ 570.6 $ 419.4 $ 3,759.3 Six Months Ended June 30, 2017 Driveline Metal Forming Powertrain Casting Total North America $ 1,727.2 $ 252.7 $ 204.2 $ 195.4 $ 2,379.5 Asia 189.4 0.7 32.5 — 222.6 Europe 41.9 57.6 44.6 — 144.1 South America 61.4 — 0.1 — 61.5 Total $ 2,019.9 $ 311.0 $ 281.4 $ 195.4 $ 2,807.7

Revenue from Contracts with C26

Revenue from Contracts with Customers Contract Assets and Liabilities (Tables)	6 Months Ended
	Jun. 30, 2018
Contract with Customer, Asset and Liability [Abstract]
Contract with Customer, Asset and Liability [Table Text Block]	Contract Assets and Liabilities The following table summarizes our beginning and ending balances for accounts receivable and contract liabilities associated with our contracts with customers: Accounts Receivable, Net Contract Liabilities (Current) Contract Liabilities (Long-term) December 31, 2017 $ 1,035.9 $ 34.1 $ 78.8 June 30, 2018 1,253.6 38.1 81.6 Increase/(decrease) $ 217.7 $ 4.0 $ 2.8

Restructuring and Acquisition27

Restructuring and Acquisition-Related Costs (Tables)	6 Months Ended
	Jun. 30, 2018
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs [Table Text Block]	A summary of our restructuring activity for the first six months of 2018 and 2017 is shown below: Severance Charges Implementation Costs Asset Impairment Charges Total (in millions) Accrual as of December 31, 2016 $ 0.6 $ 9.2 $ — $ 9.8 Charges 1.5 7.0 — 8.5 Cash utilization (2.0 ) (11.8 ) — (13.8 ) Accrual as of June 30, 2017 $ 0.1 $ 4.4 $ — $ 4.5 Accrual as of December 31, 2017 $ 0.3 $ — $ — $ 0.3 Charges 2.0 5.5 23.9 31.4 Cash utilization (0.4 ) (5.1 ) — (5.5 ) Non-cash utilization — — (23.9 ) (23.9 ) Accrual as of June 30, 2018 $ 1.9 $ 0.4 $ — $ 2.3
Business Combination, Separately Recognized Transactions [Table Text Block]	In 2017, we completed the acquisitions of Metaldyne Performance Group, Inc. (MPG) and USM Mexico Manufacturing LLC (USM Mexico). During the six months ended June 30, 2018 , we incurred the following charges related to these acquisitions: Acquisition-Related Costs Integration Expenses Total (in millions) Charges $ 1.1 $ 22.6 $ 23.7 Total restructuring and acquisition-related charges $ 55.1

Business Combinations (Tables)

Business Combinations (Tables)	6 Months Ended
	Jun. 30, 2018
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 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 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 403.1 Inventories 199.0 Prepaid expenses and other long-term assets 119.9 Property, plant and equipment 971.8 Intangible assets 1,223.1 Total assets acquired $ 3,119.0 Accounts payable 287.8 Accrued expenses and other 137.7 Deferred income tax liabilities 580.2 Debt 1,918.7 Postretirement benefits and other long-term liabilities 54.1 Net assets acquired $ 140.5 Goodwill $ 1,393.3
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 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 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 Adjustment to contractual purchase price for working capital settlement 2.5 Adjustment 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 $ 146.6 Accounts receivable 1.1 Inventories 4.8 Prepaid expenses and other 3.6 Property, plant and equipment 38.4 Intangible assets 31.7 Total assets acquired $ 79.6 Accounts payable 10.8 Accrued expenses and other 2.7 Deferred income tax liabilities 1.2 Net assets acquired $ 64.9 Goodwill $ 81.7

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2018
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 six months ended June 30, 2018 : Driveline Metal Forming Powertrain Casting Consolidated (in millions) Balance as of December 31, 2017 $ 211.1 $ 558.9 $ 478.8 $ 405.5 $ 1,654.3 Acquisition of MPG — 0.9 — — 0.9 Acquisition of USM Mexico 1.3 — — — 1.3 Sale of business — — (15.1 ) — (15.1 ) Foreign currency translation (0.5 ) (4.8 ) (4.4 ) — (9.7 ) Balance as of June 30, 2018 $ 211.9 $ 555.0 $ 459.3 $ 405.5 $ 1,631.7
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: June 30, December 31, 2018 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in millions) Capitalized computer software $ 37.4 $ (17.2 ) $ 20.2 $ 35.6 $ (14.3 ) $ 21.3 e-AAM in-process research and development 5.4 (0.4 ) 5.0 5.9 — 5.9 Customer platforms 952.2 (88.1 ) 864.1 952.2 (52.9 ) 899.3 Customer relationships 147.0 (12.0 ) 135.0 151.8 (7.3 ) 144.5 Technology and other 150.8 (15.3 ) 135.5 150.8 (9.3 ) 141.5 Total $ 1,292.8 $ (133.0 ) $ 1,159.8 $ 1,296.3 $ (83.8 ) $ 1,212.5 As a result of the acquisition of MPG in 2017, we recorded intangible assets related to aftermarket customer relationships that were associated with the Powertrain aftermarket business that we sold in the second quarter of 2018. As such, we have reduced the gross carrying amount of our customer relationships by $4.8 million , and reduced the associated accumulated amortization by $0.3 million as of June 30, 2018. Amortization expense for our intangible assets was $24.8 million and $49.7 million for the three and six months ended June 30, 2018 respectively, and $24.8 million and $26.4 million for the three and six months ended June 30, 2017 , respectively. Estimated amortization expense for each of the years 2018 through 2022 is approximately $100 million .

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Schedule of Inventory, Current [Table Text Block]	Inventories consist of the following: June 30, 2018 December 31, 2017 (in millions) Raw materials and work-in-progress $ 366.1 $ 319.7 Finished goods 78.6 89.6 Gross inventories 444.7 409.3 Inventory valuation reserves (18.3 ) (17.3 ) Inventories, net $ 426.4 $ 392.0

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	Long-term debt consists of the following: June 30, 2018 December 31, 2017 (in millions) Revolving Credit Facility $ — $ — Term Loan A Facility 92.5 92.5 Term Loan B Facility 1,526.8 1,526.8 7.75% Notes due 2019 200.0 200.0 6.625% Notes due 2022 450.0 550.0 6.50% Notes due 2027 500.0 500.0 6.25% Notes due 2026 400.0 — 6.25% Notes due 2025 700.0 700.0 6.25% Notes due 2021 — 400.0 Foreign credit facilities 94.8 53.2 Capital lease obligations 15.4 28.3 Total debt 3,979.5 4,050.8 Less: Current portion of long-term debt 33.2 5.9 Long-term debt 3,946.3 4,044.9 Less: Debt issuance costs 73.3 75.6 Long-term debt, net $ 3,873.0 $ 3,969.3

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2018
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: June 30, 2018 December 31, 2017 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Balance Sheet Classification Cash equivalents $ 108.4 $ 108.4 $ 72.8 $ 72.8 Level 1 Prepaid expenses and other Cash flow hedges - currency forward contracts 0.5 0.5 0.1 0.1 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 0.4 0.4 1.3 1.3 Level 2 Nondesignated - currency forward contracts 0.1 0.1 — — Level 2 Other assets and deferred charges Cash flow hedges - currency forward contracts 0.2 0.2 0.2 0.2 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 1.8 1.8 0.9 0.9 Level 2 Accrued expenses and other Cash flow hedges - currency forward contracts 3.3 3.3 6.0 6.0 Level 2 Nondesignated - currency forward contracts 1.5 1.5 2.8 2.8 Level 2 Postretirement benefits and other long-term liabilities Cash flow hedges - currency forward contracts 2.0 2.0 2.6 2.6 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 1.0 1.0 0.3 0.3 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: June 30, 2018 December 31, 2017 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Revolving Credit Facility $ — $ — $ — $ — Level 2 Term Loan A Facility 92.5 91.9 92.5 92.5 Level 2 Term Loan B Facility 1,526.8 1,517.2 1,526.8 1,528.7 Level 2 7.75% Notes due 2019 200.0 209.5 200.0 217.5 Level 2 6.625% Notes due 2022 450.0 460.7 550.0 570.2 Level 2 6.50% Notes due 2027 500.0 494.4 500.0 527.5 Level 2 6.25% Notes due 2026 400.0 389.0 — — Level 2 6.25% Notes due 2025 700.0 683.9 700.0 736.8 Level 2 6.25% Notes due 2021 — — 400.0 410.0 Level 2
Impairments of Long-Lived Assets Measured at Fair Value [Table Text Block]	The following table summarizes the impairments of long-lived assets measured at fair value on a nonrecurring basis subsequent to initial recognition: Balance Sheet Classification Fair Value at June 30, 2018 Asset Impairment for the Six Months Ended June 30, 2018 (in millions) Property, plant and equipment, net $ — $ 23.6 Other assets and deferred charges — 0.3

Derivatives (Tables)

Derivatives (Tables)	6 Months Ended
	Jun. 30, 2018
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 reclassification of derivative gains and losses into net income from accumulated other comprehensive income (loss) for those derivative instruments designated as cash flow hedges under ASC 815 - Derivatives and Hedging : Location Gain (Loss) Reclassified During Total of Financial Gain (Loss) Expected of Gain (Loss) Three Months Ended Six Months Ended Statement to be Reclassified Reclassified into June 30, June 30, Line Item During the Net Income 2018 2017 2018 2017 2018 Next 12 Months (in millions) Currency forward contracts Cost of Goods Sold $ (0.8 ) $ (1.1 ) $ (2.8 ) $ (3.9 ) $ 3,111.6 $ (2.8 ) Variable-to-fixed interest rate swap Interest Expense 0.9 — 1.3 — 107.6 2.5 The following table summarizes the amount and location of gains and 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 Total of Financial Location of Gain (Loss) Three Months Ended Six Months Ended Statement Line Recognized in June 30, June 30, Item Net Income 2018 2017 2018 2017 2018 (in millions) Currency forward contracts Cost of Goods Sold $ (3.5 ) $ 2.2 $ 0.5 $ 5.7 $ 3,111.6 Currency forward contracts Other Income (Expense), net 1.8 — 1.8 — 0.2 Currency option contracts Cost of Goods Sold — 1.1 — 1.1 3,111.6

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2018
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 Six Months Ended June 30, June 30, 2018 2017 2018 2017 (in millions) Service cost $ 1.0 $ 1.1 $ 2.1 $ 1.9 Interest cost 6.8 7.4 13.7 14.2 Expected asset return (11.5 ) (11.1 ) (23.0 ) (21.6 ) Amortized loss 2.2 1.8 4.4 3.5 Amortized prior service cost 0.1 — 0.1 — Curtailment — — 3.2 — Net periodic benefit cost (credit) $ (1.4 ) $ (0.8 ) $ 0.5 $ (2.0 ) Other Postretirement Benefits Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 (in millions) Service cost $ 0.1 $ 0.1 $ 0.2 $ 0.2 Interest cost 3.1 3.3 6.2 6.6 Amortized loss 0.2 0.1 0.4 0.3 Amortized prior service credit (0.6 ) (0.6 ) (1.3 ) (1.3 ) Net periodic benefit cost $ 2.8 $ 2.9 $ 5.5 $ 5.8

Product Warranties (Tables)

Product Warranties (Tables)	6 Months Ended
	Jun. 30, 2018
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 Six Months Ended June 30, June 30, 2018 2017 2018 2017 (in millions) Beginning balance $ 53.6 $ 47.5 $ 49.5 $ 42.9 Accruals 6.2 4.1 10.5 9.6 Payments (0.6 ) (1.5 ) (1.1 ) (2.4 ) Adjustment to prior period accruals (0.2 ) (2.4 ) (0.2 ) (2.6 ) Foreign currency translation (0.6 ) 0.2 (0.3 ) 0.4 Ending balance $ 58.4 $ 47.9 $ 58.4 $ 47.9

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
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 Six Months Ended June 30, June 30, 2018 2017 2018 2017 (in millions, except per share data) Numerator Net income attributable to AAM $ 151.1 $ 66.2 $ 240.5 $ 144.6 Less: Net income attributable to participating securities (4.9 ) (1.4 ) (6.8 ) (3.3 ) Net income attributable to common shareholders - Basic and Dilutive $ 146.2 $ 64.8 $ 233.7 $ 141.3 Denominators Basic common shares outstanding - Weighted-average shares outstanding 115.4 111.6 114.8 95.2 Less: Participating securities (3.7 ) (2.3 ) (3.3 ) (2.2 ) Weighted-average common shares outstanding 111.7 109.3 111.5 93.0 Effect of dilutive securities - Dilutive stock-based compensation 0.6 0.4 0.6 0.4 Diluted shares outstanding - Adjusted weighted-average shares after assumed conversions 112.3 109.7 112.1 93.4 Basic EPS $ 1.31 $ 0.59 $ 2.09 $ 1.52 Diluted EPS $ 1.30 $ 0.59 $ 2.08 $ 1.51

Reclassifications out of Accu37

Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and June 30, 2017 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Gain (Loss) on Cash Flow Hedges Total Balance at March 31, 2018 $ (250.7 ) $ 3.8 $ 8.5 $ (238.4 ) Other comprehensive income (loss) before reclassifications 14.7 (81.2 ) (7.7 ) (74.2 ) Income tax effect of other comprehensive income (loss) before reclassifications (3.6 ) — (0.4 ) (4.0 ) Amounts reclassified from accumulated other comprehensive income (loss) 1.6 (a) 0.2 (0.1 ) (b) 1.7 Income taxes reclassified into net income (0.5 ) — 0.3 (0.2 ) Net current period other comprehensive income (loss) 12.2 (81.0 ) (7.9 ) (76.7 ) Balance at June 30, 2018 $ (238.5 ) $ (77.2 ) $ 0.6 $ (315.1 ) Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Gain (Loss) on Cash Flow Hedges Total Balance at March 31, 2017 $ (243.8 ) $ (110.5 ) $ (8.2 ) $ (362.5 ) Other comprehensive income before reclassifications — 24.6 3.1 27.7 Income tax effect of other comprehensive income before reclassifications — — 0.7 0.7 Amounts reclassified from accumulated other comprehensive loss 1.3 (a) — 1.1 (b) 2.4 Income taxes reclassified into net income (0.4 ) — — (0.4 ) Net current period other comprehensive income 0.9 24.6 4.9 30.4 Balance at June 30, 2017 $ (242.9 ) $ (85.9 ) $ (3.3 ) $ (332.1 ) (a) The amount reclassified from AOCI included $1.6 million in cost of goods sold (COGS) for the three months ended June 30, 2018 and $1.4 million in COGS and $(0.1) million in SG&A for the three months ended June 30, 2017. (b) The amounts reclassified from AOCI included $0.8 million in COGS and $(0.9) million in interest expense for the three months ended June 30, 2018 and $1.1 million in COGS for the three months ended June 30, 2017. Reclassification adjustments and other activity impacting accumulated other comprehensive income (loss) during the six months ended June 30, 2018 and June 30, 2017 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at December 31, 2017 $ (252.0 ) $ (34.1 ) $ (6.6 ) $ (292.7 ) Other comprehensive income (loss) before reclassifications 14.7 (43.3 ) 6.9 (21.7 ) Income tax effect of other comprehensive income (loss) before reclassifications (3.6 ) — (1.5 ) (5.1 ) Amounts reclassified from accumulated other comprehensive loss 3.3 (a) 0.2 1.5 (b) 5.0 Income taxes reclassified into net income (0.9 ) — 0.3 (0.6 ) Net current period other comprehensive income (loss) 13.5 (43.1 ) 7.2 (22.4 ) Balance at June 30, 2018 $ (238.5 ) $ (77.2 ) $ 0.6 $ (315.1 ) 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 ) 36.5 15.8 50.6 Income tax effect of other comprehensive income before reclassifications 0.6 — 0.7 1.3 Amounts reclassified from accumulated other comprehensive loss 2.5 (a) — 3.9 (b) 6.4 Income taxes reclassified into net income (0.8 ) — — (0.8 ) Net current period other comprehensive income 0.6 36.5 20.4 57.5 Balance at June 30, 2017 $ (242.9 ) $ (85.9 ) $ (3.3 ) $ (332.1 ) (a) The amount reclassified from AOCI included $3.0 million in cost of goods sold (COGS) and $0.3 million in selling, general & administrative expenses (SG&A) for the six months ended June 30, 2018 and $2.8 million in COGS and $(0.3) million in SG&A for the six months ended June 30, 2017. (b) The amounts reclassified from AOCI included $2.8 million in COGS and $(1.3) million in interest expense for the six months ended June 30, 2018 and $3.9 million in COGS for the six months ended June 30, 2017.

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and 2017 (in millions) : Three Months Ended June 30, 2018 Driveline Metal Forming Powertrain Casting Total Sales $ 1,120.2 $ 397.1 $ 288.3 $ 243.2 $ 2,048.8 Less: intersegment sales 0.2 109.3 4.8 33.6 147.9 Net external sales $ 1,120.0 $ 287.8 $ 283.5 $ 209.6 $ 1,900.9 Segment Adjusted EBITDA $ 184.9 $ 89.1 $ 47.0 $ 26.9 $ 347.9 Three Months Ended June 30, 2017 Driveline Metal Forming Powertrain Casting Total Sales $ 1,021.5 $ 369.3 $ 283.6 $ 225.6 $ 1,900.0 Less: intersegment sales 0.4 109.4 2.2 30.2 142.2 Net external sales $ 1,021.1 $ 259.9 $ 281.4 $ 195.4 $ 1,757.8 Segment Adjusted EBITDA $ 179.0 $ 69.4 $ 51.9 $ 25.5 $ 325.8 The following tables represent information by reportable segment for the six months ended June 30, 2018 and 2017 : Six Months Ended June 30, 2018 Driveline Metal Forming Powertrain Casting Total Sales $ 2,190.8 $ 794.1 $ 580.2 $ 482.2 $ 4,047.3 Less: intersegment sales 0.4 215.2 9.6 62.8 288.0 Net external sales $ 2,190.4 $ 578.9 $ 570.6 $ 419.4 $ 3,759.3 Segment Adjusted EBITDA $ 354.9 $ 164.4 $ 97.1 $ 48.5 $ 664.9 Six Months Ended June 30, 2017 Driveline Metal Forming Powertrain Casting Total Sales $ 2,020.8 $ 519.3 $ 283.6 $ 225.6 $ 3,049.3 Less: intersegment sales 0.9 208.3 2.2 30.2 241.6 Net external sales $ 2,019.9 $ 311.0 $ 281.4 $ 195.4 $ 2,807.7 Segment Adjusted EBITDA $ 332.2 $ 99.8 $ 51.9 $ 25.5 $ 509.4
Reconciliation of Total Segment Adjusted EBITDA to Income Before Income Taxes [Table Text Block]	The following table represents a reconciliation of Total Segment Adjusted EBITDA to consolidated income before income taxes for the three and six months ended June 30, 2018 and 2017 (in millions) : Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total Segment Adjusted EBITDA $ 347.9 $ 325.8 $ 664.9 $ 509.4 Interest expense (54.4 ) (56.9 ) (107.6 ) (82.4 ) Depreciation and amortization (130.2 ) (124.6 ) (258.0 ) (180.8 ) Restructuring and acquisition-related costs (36.8 ) (51.7 ) (55.1 ) (67.7 ) Gain on sale of business 15.5 — 15.5 — Gain on settlement of capital lease 15.6 — 15.6 — Acquisition-related fair value inventory adjustment — (24.9 ) — (24.9 ) Impact of change in accounting principle — 3.7 — 3.7 Debt refinancing and redemption costs (4.3 ) (2.7 ) (14.6 ) (2.7 ) Income before income taxes $ 153.3 $ 68.7 $ 260.7 $ 154.6

Supplemental Guarantor Conden39

Supplemental Guarantor Condensed Consolidating Financial Statements (Tables)	6 Months Ended
	Jun. 30, 2018
Supplemental Guarantor Condensed Consolidating Financial Statements [Abstract]
Supplemental Guarantor Consolidating Income Statement [Table Text Block]	Condensed Consolidating Statements of Income Three Months Ended June 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2018 Net sales External $ — $ 302.8 $ 572.6 $ 1,025.5 $ — $ 1,900.9 Intercompany — 2.3 78.0 10.8 (91.1 ) — Total net sales — 305.1 650.6 1,036.3 (91.1 ) 1,900.9 Cost of goods sold — 305.7 542.3 812.6 (91.1 ) 1,569.5 Gross profit (loss) — (0.6 ) 108.3 223.7 — 331.4 Selling, general and administrative expenses — 60.2 19.9 14.9 — 95.0 Amortization of intangible assets — 1.4 22.5 0.9 — 24.8 Restructuring and acquisition-related costs — 9.8 26.8 0.2 — 36.8 Gain on sale of business — — (15.5 ) — — (15.5 ) Operating income (loss) — (72.0 ) 54.6 207.7 — 190.3 Non-operating income (expense), net — (63.3 ) 3.2 23.1 — (37.0 ) Income (loss) before income taxes — (135.3 ) 57.8 230.8 — 153.3 Income tax expense (benefit) — 8.0 0.1 (6.1 ) — 2.0 Earnings from equity in subsidiaries 151.1 106.3 67.3 — (324.7 ) — Net income (loss) before royalties 151.1 (37.0 ) 125.0 236.9 (324.7 ) 151.3 Royalties — 85.0 0.9 (85.9 ) — — Net income after royalties 151.1 48.0 125.9 151.0 (324.7 ) 151.3 Net income attributable to noncontrolling interests — — — (0.2 ) — (0.2 ) Net income attributable to AAM $ 151.1 $ 48.0 $ 125.9 $ 150.8 $ (324.7 ) $ 151.1 Other comprehensive loss, net of tax (76.7 ) (29.2 ) (75.3 ) (81.0 ) 185.5 (76.7 ) Comprehensive income attributable to AAM $ 74.4 $ 18.8 $ 50.6 $ 69.8 $ (139.2 ) $ 74.4 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net sales External $ — $ 260.3 $ 560.6 $ 936.9 $ — $ 1,757.8 Intercompany — 1.9 101.9 7.9 (111.7 ) — Total net sales — 262.2 662.5 944.8 (111.7 ) 1,757.8 Cost of goods sold — 245.4 580.6 727.1 (111.7 ) 1,441.4 Gross profit — 16.8 81.9 217.7 — 316.4 Selling, general and administrative expenses — 65.8 21.0 18.8 — 105.6 Amortization of intangible assets — 1.5 22.7 0.6 — 24.8 Restructuring and acquisition-related costs — 50.1 — 1.6 — 51.7 Operating income (loss) — (100.6 ) 38.2 196.7 — 134.3 Non-operating income (expense), net — (61.6 ) 7.0 (11.0 ) — (65.6 ) Income (loss) before income taxes — (162.2 ) 45.2 185.7 — 68.7 Income tax expense (benefit) — (30.4 ) 15.8 17.0 — 2.4 Earnings from equity in subsidiaries 66.2 81.3 8.2 — (155.7 ) — Net income (loss) before royalties 66.2 (50.5 ) 37.6 168.7 (155.7 ) 66.3 Royalties — 89.2 1.3 (90.5 ) — — Net income after royalties 66.2 38.7 38.9 78.2 (155.7 ) 66.3 Net income attributable to noncontrolling interests — — — (0.1 ) — (0.1 ) Net income attributable to AAM $ 66.2 $ 38.7 $ 38.9 $ 78.1 $ (155.7 ) $ 66.2 Other comprehensive income, net of tax 30.4 11.3 21.6 17.1 (50.0 ) 30.4 Comprehensive income attributable to AAM $ 96.6 $ 50.0 $ 60.5 $ 95.2 $ (205.7 ) $ 96.6 Condensed Consolidating Statements of Income Six Months Ended June 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2018 Net sales External $ — $ 604.3 $ 1,154.9 $ 2,000.1 $ — $ 3,759.3 Intercompany — 3.3 156.0 20.3 (179.6 ) — Total net sales — 607.6 1,310.9 2,020.4 (179.6 ) 3,759.3 Cost of goods sold — 583.9 1,119.1 1,588.2 (179.6 ) 3,111.6 Gross profit — 23.7 191.8 432.2 — 647.7 Selling, general and administrative expenses — 120.0 41.8 30.5 — 192.3 Amortization of intangible assets — 2.9 45.1 1.7 — 49.7 Restructuring and acquisition-related costs — 26.1 27.9 1.1 — 55.1 Gain on sale of business — — (15.5 ) — — (15.5 ) Operating income (loss) — (125.3 ) 92.5 398.9 — 366.1 Non-operating income (expense), net — (133.8 ) 8.2 20.2 — (105.4 ) Income (loss) before income taxes — (259.1 ) 100.7 419.1 — 260.7 Income tax expense — 9.1 0.5 10.3 — 19.9 Earnings from equity in subsidiaries 240.5 173.5 107.8 — (521.8 ) — Net income (loss) before royalties 240.5 (94.7 ) 208.0 408.8 (521.8 ) 240.8 Royalties — 169.2 1.9 (171.1 ) — — Net income after royalties 240.5 74.5 209.9 237.7 (521.8 ) 240.8 Net income attributable to noncontrolling interests — — — (0.3 ) — (0.3 ) Net income attributable to AAM $ 240.5 $ 74.5 $ 209.9 $ 237.4 $ (521.8 ) $ 240.5 Other comprehensive loss, net of tax (22.4 ) (3.6 ) (40.2 ) (37.3 ) 81.1 (22.4 ) Comprehensive income attributable to AAM $ 218.1 $ 70.9 $ 169.7 $ 200.1 $ (440.7 ) $ 218.1 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net sales External $ — $ 556.9 $ 610.8 $ 1,640.0 $ — $ 2,807.7 Intercompany — 2.2 134.7 12.9 (149.8 ) — Total net sales — 559.1 745.5 1,652.9 (149.8 ) 2,807.7 Cost of goods sold — 522.6 641.7 1,266.1 (149.8 ) 2,280.6 Gross profit — 36.5 103.8 386.8 — 527.1 Selling, general and administrative expenses — 138.2 21.0 27.6 — 186.8 Amortization of intangible assets — 2.8 22.7 0.9 — 26.4 Restructuring and acquisition-related costs — 65.4 — 2.3 — 67.7 Operating income (loss) — (169.9 ) 60.1 356.0 — 246.2 Non-operating income (expense), net — (87.9 ) 9.4 (13.1 ) — (91.6 ) Income (loss) before income taxes — (257.8 ) 69.5 342.9 — 154.6 Income tax expense (benefit) — (33.2 ) 24.2 18.9 — 9.9 Earnings from equity in subsidiaries 144.6 173.0 15.9 — (333.5 ) — Net income (loss) before royalties 144.6 (51.6 ) 61.2 324.0 (333.5 ) 144.7 Royalties — 168.7 1.3 (170.0 ) — — Net income after royalties 144.6 117.1 62.5 154.0 (333.5 ) 144.7 Net income attributable to noncontrolling interests — — — (0.1 ) — (0.1 ) Net income attributable to AAM $ 144.6 $ 117.1 $ 62.5 $ 153.9 $ (333.5 ) $ 144.6 Other comprehensive income, net of tax 57.5 38.6 32.1 43.5 (114.2 ) 57.5 Comprehensive income attributable to AAM $ 202.1 $ 155.7 $ 94.6 $ 197.4 $ (447.7 ) $ 202.1
Supplemental Guarantor Consolidating Balance Sheet [Table Text Block]	Condensed Consolidating Balance Sheets (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated June 30, 2018 Assets Current assets Cash and cash equivalents $ — $ 82.3 $ 0.3 $ 270.6 $ — $ 353.2 Accounts receivable, net — 182.7 339.3 731.6 — 1,253.6 Intercompany receivables — 2,748.4 1,446.6 91.1 (4,286.1 ) — Inventories, net — 34.4 153.8 238.2 — 426.4 Prepaid expenses and other — 37.3 4.9 79.6 — 121.8 Total current assets — 3,085.1 1,944.9 1,411.1 (4,286.1 ) 2,155.0 Property, plant and equipment, net — 259.6 770.3 1,429.4 — 2,459.3 Goodwill — — 1,204.5 427.2 — 1,631.7 Intangible assets, net — 19.9 1,106.2 33.7 — 1,159.8 Intercompany notes and accounts receivable 11.7 1,319.7 133.7 — (1,465.1 ) — Other assets and deferred charges — 341.9 115.3 227.4 — 684.6 Investment in subsidiaries 3,071.1 2,146.6 1,690.1 — (6,907.8 ) — Total assets $ 3,082.8 $ 7,172.8 $ 6,965.0 $ 3,528.8 $ (12,659.0 ) $ 8,090.4 Liabilities and Stockholders’ Equity Current liabilities Current portion of long-term debt $ — $ 11.5 $ — $ 21.7 $ — $ 33.2 Accounts payable — 156.8 245.6 528.5 — 930.9 Intercompany payables — 1,404.5 2,747.6 134.0 (4,286.1 ) — Accrued expenses and other — 141.1 40.9 185.6 — 367.6 Total current liabilities — 1,713.9 3,034.1 869.8 (4,286.1 ) 1,331.7 Intercompany notes and accounts payable 1,316.6 15.2 — 133.3 (1,465.1 ) — Long-term debt, net — 3,785.0 3.5 84.5 — 3,873.0 Other long-term liabilities — 598.8 332.0 188.7 — 1,119.5 Total liabilities 1,316.6 6,112.9 3,369.6 1,276.3 (5,751.2 ) 6,324.2 Total AAM Stockholders’ equity 1,764.2 1,059.9 3,595.4 2,250.5 (6,905.8 ) 1,764.2 Noncontrolling interests in subsidiaries 2.0 — — 2.0 (2.0 ) 2.0 Total stockholders’ equity 1,766.2 1,059.9 3,595.4 2,252.5 (6,907.8 ) 1,766.2 Total liabilities and stockholders’ equity $ 3,082.8 $ 7,172.8 $ 6,965.0 $ 3,528.8 $ (12,659.0 ) $ 8,090.4 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated December 31, 2017 Assets Current assets Cash and cash equivalents $ — $ 91.9 $ 0.1 $ 284.8 $ — $ 376.8 Accounts receivable, net — 138.9 287.9 609.1 — 1,035.9 Intercompany receivables — 3,475.2 479.9 7.5 (3,962.6 ) — Inventories, net — 37.2 147.4 207.4 — 392.0 Prepaid expenses and other — 40.4 9.9 90.0 — 140.3 Total current assets — 3,783.6 925.2 1,198.8 (3,962.6 ) 1,945.0 Property, plant and equipment, net — 250.9 786.8 1,365.2 — 2,402.9 Goodwill — — 1,218.4 435.9 — 1,654.3 Intangible assets, net — 21.0 1,155.6 35.9 — 1,212.5 Intercompany notes and accounts receivable 11.7 — 243.5 — (255.2 ) — Other assets and deferred charges — 349.1 122.8 196.2 — 668.1 Investment in subsidiaries 2,841.3 1,955.2 1,280.1 — (6,076.6 ) — Total assets $ 2,853.0 $ 6,359.8 $ 5,732.4 $ 3,232.0 $ (10,294.4 ) $ 7,882.8 Liabilities and Stockholders’ Equity Current liabilities Current portion of long-term debt $ — $ — $ — $ 5.9 $ — $ 5.9 Accounts payable — 139.0 204.6 455.4 — 799.0 Intercompany payables 1,313.0 563.7 2,017.7 68.2 (3,962.6 ) — Accrued expenses and other — 181.6 52.4 177.5 — 411.5 Total current liabilities 1,313.0 884.3 2,274.7 707.0 (3,962.6 ) 1,216.4 Intercompany notes and accounts payable — 11.7 — 243.5 (255.2 ) — Long-term debt, net — 3,894.6 4.4 70.3 — 3,969.3 Other long-term liabilities — 639.1 333.2 184.8 — 1,157.1 Total liabilities 1,313.0 5,429.7 2,612.3 1,205.6 (4,217.8 ) 6,342.8 Total AAM Stockholders’ equity 1,536.0 930.1 3,120.1 2,022.4 (6,072.6 ) 1,536.0 Noncontrolling interests in subsidiaries 4.0 — — 4.0 (4.0 ) 4.0 Total stockholders’ equity 1,540.0 930.1 3,120.1 2,026.4 (6,076.6 ) 1,540.0 Total liabilities and stockholders’ equity $ 2,853.0 $ 6,359.8 $ 5,732.4 $ 3,232.0 $ (10,294.4 ) $ 7,882.8
Supplemental Guarantor Consolidating Statement of Cash Flows [Table Text Block]	Condensed Consolidating Statements of Cash Flows Six Months Ended June 30, (in millions) Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2018 Net cash provided by operating activities $ — $ 152.3 $ 8.6 $ 128.5 $ — $ 289.4 Investing activities Purchases of property, plant and equipment — (40.3 ) (74.5 ) (158.2 ) — (273.0 ) Proceeds from sale of property, plant and equipment — — 0.5 0.4 — 0.9 Purchase buyouts of leased equipment — — (0.5 ) — — (0.5 ) Proceeds from sale of business, net — — 42.7 4.4 — 47.1 Acquisition of business, net of cash acquired — — — (1.3 ) — (1.3 ) Net cash used in investing activities — (40.3 ) (31.8 ) (154.7 ) — (226.8 ) Financing activities Net debt activity — (111.2 ) (0.4 ) 44.8 — (66.8 ) Debt issuance costs — (6.8 ) — — — (6.8 ) Purchase of treasury stock (3.6 ) — — — — (3.6 ) Purchase of noncontrolling interest — — (2.2 ) — — (2.2 ) Intercompany activity 3.6 (3.6 ) 28.5 (28.5 ) — — Net cash provided by (used in) financing activities — (121.6 ) 25.9 16.3 — (79.4 ) Effect of exchange rate changes on cash — — — (4.3 ) — (4.3 ) Net increase (decrease) in cash, cash equivalents and restricted cash — (9.6 ) 2.7 (14.2 ) — (21.1 ) Cash, cash equivalents and restricted cash at beginning of period — 91.9 0.1 284.8 — 376.8 Cash, cash equivalents and restricted cash at end of period $ — $ 82.3 $ 2.8 $ 270.6 $ — $ 355.7 Holdings AAM Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Elims Consolidated 2017 Net cash provided by (used in) operating activities $ — $ 222.8 $ (25.2 ) $ 15.6 $ — $ 213.2 Investing activities Purchases of property, plant and equipment — (28.4 ) (39.2 ) (71.0 ) — (138.6 ) Proceeds from sale of property, plant and equipment — 0.3 0.1 1.1 — 1.5 Purchase buyouts of leased equipment — (8.4 ) — — — (8.4 ) 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 — (982.5 ) 23.9 (76.5 ) — (1,035.1 ) Financing activities Net debt activity — 931.4 (0.2 ) (10.8 ) — 920.4 Debt issuance costs — (90.5 ) — — — (90.5 ) Employee stock option exercises — 0.9 — — — 0.9 Purchase of treasury stock (6.9 ) — — — — (6.9 ) Intercompany activity 6.9 (6.9 ) — — — — Net cash provided by (used in) financing activities — 834.9 (0.2 ) (10.8 ) — 823.9 Effect of exchange rate changes on cash — — — 7.4 — 7.4 Net increase (decrease) in cash, cash equivalents and restricted cash — 75.2 (1.5 ) (64.3 ) — 9.4 Cash, cash equivalents and restricted cash at beginning of period — 84.3 1.6 395.3 — 481.2 Cash, cash equivalents and restricted cash at end of period $ — $ 159.5 $ 0.1 $ 331.0 $ — $ 490.6

Organization and Basis of Pre40

Organization and Basis of Presentation Company Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)EmployeesCountriesFacilities	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)EmployeesCountriesFacilities	Jun. 30, 2017USD ($)
Franchisor Disclosure [Line Items]
Entity Number of Employees | Employees	25,000		25,000
Number of Facilities | Facilities	90		90
Number of Countries in which Entity Operates | Countries	17		17
Divestiture of Business - Selling Price	$ 50
Proceeds from Divestiture of Businesses	47
Restricted Cash	2.5		$ 2.5
Gain on sale of business	$ 15.5	$ 0	$ 15.5	$ 0

Revenue from Contracts with C41

Revenue from Contracts with Customers Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue, Performance Obligation, Description of Payment Terms			50 days
Net sales	$ 1,900.9	$ 1,757.8	$ 3,759.3	$ 2,807.7
North America [Member]
Disaggregation of Revenue [Line Items]
Net sales	1,522.1	1,463.2	3,032.7	2,379.5
Asia [Member]
Disaggregation of Revenue [Line Items]
Net sales	190.4	137.1	345.7	222.6
Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	155.9	123.4	314.2	144.1
South America [Member]
Disaggregation of Revenue [Line Items]
Net sales	32.5	34.1	66.7	61.5
Driveline [Member]
Disaggregation of Revenue [Line Items]
Net sales	1,120	1,021.1	2,190.4	2,019.9
Driveline [Member] | North America [Member]
Disaggregation of Revenue [Line Items]
Net sales	899	862	1,784.3	1,727.2
Driveline [Member] | Asia [Member]
Disaggregation of Revenue [Line Items]
Net sales	159.3	103.9	282.1	189.4
Driveline [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	30.7	21.2	59.7	41.9
Driveline [Member] | South America [Member]
Disaggregation of Revenue [Line Items]
Net sales	31	34	64.3	61.4
Metal Forming [Member]
Disaggregation of Revenue [Line Items]
Net sales	287.8	259.9	578.9	311
Metal Forming [Member] | North America [Member]
Disaggregation of Revenue [Line Items]
Net sales	216.3	201.6	432.6	252.7
Metal Forming [Member] | Asia [Member]
Disaggregation of Revenue [Line Items]
Net sales	1.2	0.7	2.6	0.7
Metal Forming [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	70.3	57.6	143.7	57.6
Metal Forming [Member] | South America [Member]
Disaggregation of Revenue [Line Items]
Net sales	0	0	0	0
Powertrain [Member]
Disaggregation of Revenue [Line Items]
Net sales	283.5	281.4	570.6	281.4
Powertrain [Member] | North America [Member]
Disaggregation of Revenue [Line Items]
Net sales	197.2	204.2	396.4	204.2
Powertrain [Member] | Asia [Member]
Disaggregation of Revenue [Line Items]
Net sales	29.9	32.5	61	32.5
Powertrain [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	54.9	44.6	110.8	44.6
Powertrain [Member] | South America [Member]
Disaggregation of Revenue [Line Items]
Net sales	1.5	0.1	2.4	0.1
Casting [Member]
Disaggregation of Revenue [Line Items]
Net sales	209.6	195.4	419.4	195.4
Casting [Member] | North America [Member]
Disaggregation of Revenue [Line Items]
Net sales	209.6	195.4	419.4	195.4
Casting [Member] | Asia [Member]
Disaggregation of Revenue [Line Items]
Net sales	0	0	0	0
Casting [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	0	0	0	0
Casting [Member] | South America [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 0

Revenue from Contracts with C42

Revenue from Contracts with Customers Contract Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Accounts receivable, net	$ 1,253.6	$ 1,253.6	$ 1,035.9
Deferred revenue, current	38.1	38.1	34.1
Deferred revenue, noncurrent	81.6	81.6	$ 78.8
Increase (decrease) in accounts receivable		217.7
Contract liability, current, increase (decrease)		4
Contract liability, noncurrent, increase (decrease)		2.8
Contract liability, additions	21	27.7
Contract with customer, liability, revenue recognized	$ 12.9	$ 20.9

Restructuring and Acquisition43

Restructuring and Acquisition-Related Costs (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Restructuring Reserve [Roll Forward]
Restructuring reserve	$ 0.3	$ 9.8
Charges	31.4	8.5
Cash utilization	(5.5)	(13.8)
Non-cash utilization	(23.9)
Restructuring reserve	2.3	4.5
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring reserve	0	9.2
Charges	5.5	7
Cash utilization	(5.1)	(11.8)
Non-cash utilization	0
Restructuring reserve	0.4	4.4
Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Restructuring reserve	0	0
Charges	23.9	0
Cash utilization	0	0
Non-cash utilization	(23.9)
Restructuring reserve	0	0
Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring reserve	0.3	0.6
Charges	2	1.5
Cash utilization	(0.4)	(2)
Non-cash utilization	0
Restructuring reserve	$ 1.9	$ 0.1

Restructuring Reserve Narrative

Restructuring Reserve Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		21 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 31.4	$ 8.5
Restructuring and acquisition-related costs	$ 36.8	$ 51.7	55.1	67.7
Restructuring and Related Cost, Total Expected Cost to be Incurred Current Year	$ 45		45		$ 45
2016 Restructuring Plan - Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges					2.8
2016 Restructuring Plan - Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges					$ 29.6
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			2	1.5
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			5.5	7
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 23.9	$ 0
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining						$ 10
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining						$ 20

Business Combinations, Separate

Business Combinations, Separately Recognized Transactions Table (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring and Related Activities [Abstract]
Acquisition-related costs			$ 1.1
Integration expenses			22.6
Acquisition-related costs and integration expenses			23.7
Restructuring and acquisition-related costs	$ 36.8	$ 51.7	$ 55.1	$ 67.7

Acquisition of MPG Narrative (D

Acquisition of MPG Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 06, 2017	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017
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						$ 461.9	$ 2,857.9
Business Acquisition, Pro Forma Earnings Per Share, Diluted						$ 1.94
Metaldyne Performance Group, Inc. [Member]
Business Acquisition [Line Items]
Total consideration transferred				$ 1,530.2
Net debt acquired				$ 1,700
Debt acquired	$ 1,918.7
Cash acquired	(202.1)
Proceeds from Notes Payable					$ 1,200
Goodwill, purchase accounting adjustments		$ 0.9
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			$ 684			$ 1,470
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual			$ 28			120
Business Acquisition, Pro Forma Revenue						3,500
Business Acquisition, Pro Forma Net Income (Loss)						185
MPG Pro Forma Net Income Adjustment						$ 45
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 [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	Jun. 30, 2018	Dec. 31, 2017	Apr. 06, 2017
Business Acquisition [Line Items]
Goodwill		$ 1,631.7	$ 1,654.3
Metaldyne Performance Group, Inc. [Member]
Business Acquisition [Line Items]
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 acquired				202.1
Accounts receivable				403.1
Inventories				199
Prepaid expenses and other				119.9
Property, plant and equipment				971.8
Intangible assets				1,223.1
Total assets acquired				3,119
Accounts payable				287.8
Accrued expenses and other				137.7
Deferred income tax liabilities				580.2
Debt acquired				1,918.7
Postretirement benefits and other long-term liabilities				54.1
Net assets acquired				140.5
Goodwill				$ 1,393.3

USM Acquisition Table (Details)

USM Acquisition Table (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Mar. 01, 2017
Business Acquisition [Line Items]
Adjusted purchase price, net of cash acquired		$ 1.3	$ 895.5
Goodwill		$ 1,631.7		$ 1,654.3
USM Mexico Manufacturing LLC [Member]
Business Acquisition [Line Items]
Contractual purchase price	$ 162.5
Adjustment to contractual purchase price for working capital settlement					$ 2.5
Adjustment 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	$ 146.6
Accounts receivable					1.1
Inventories					4.8
Prepaid expenses and other					3.6
Property, plant and equipment					38.4
Intangible assets					31.7
Total assets acquired					79.6
Accounts payable					10.8
Accrued expenses and other					2.7
Deferred income tax liabilities					1.2
Net assets acquired					64.9
Goodwill					$ 81.7

Goodwill Rollforward (Details)

Goodwill Rollforward (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Goodwill [Roll Forward]
Goodwill		$ 1,654.3
Goodwill, Written off Related to Sale of Business Unit		(15.1)
Goodwill, Foreign Currency Translation Gain (Loss)		(9.7)
Goodwill	$ 1,631.7	1,631.7
Driveline [Member]
Goodwill [Roll Forward]
Goodwill		211.1
Goodwill, Written off Related to Sale of Business Unit		0
Goodwill, Foreign Currency Translation Gain (Loss)		(0.5)
Goodwill	211.9	211.9
Metal Forming [Member]
Goodwill [Roll Forward]
Goodwill		558.9
Goodwill, Written off Related to Sale of Business Unit		0
Goodwill, Foreign Currency Translation Gain (Loss)		(4.8)
Goodwill	555	555
Powertrain [Member]
Goodwill [Roll Forward]
Goodwill		478.8
Goodwill, Written off Related to Sale of Business Unit	(15.1)	(15.1)
Goodwill, Foreign Currency Translation Gain (Loss)		(4.4)
Goodwill	459.3	459.3
Casting [Member]
Goodwill [Roll Forward]
Goodwill		405.5
Goodwill, Written off Related to Sale of Business Unit		0
Goodwill, Foreign Currency Translation Gain (Loss)		0
Goodwill	$ 405.5	405.5
Metaldyne Performance Group, Inc. [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		0.9
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		0.9
Metaldyne Performance Group, Inc. [Member] | Powertrain [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		0
Metaldyne Performance Group, Inc. [Member] | Casting [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		0
USM Mexico Manufacturing LLC [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		1.3
USM Mexico Manufacturing LLC [Member] | Driveline [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		1.3
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 Table (Detail

Intangible Assets Table (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 1,292.8		$ 1,292.8		$ 1,296.3
Finite-Lived Intangible Assets, Accumulated Amortization	(133)		(133)		(83.8)
Finite-Lived Intangible Assets, Net	1,159.8		1,159.8		1,212.5
Amortization of Intangible Assets	24.8	$ 24.8	49.7	$ 26.4
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	100		100
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
Powertrain [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets, Written off Related to Sale of Business Unit	4.8
Intangible Assets, Written off Related to Sale of Business Unit, Accumulated Amortization	0.3
Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	37.4		37.4		35.6
Finite-Lived Intangible Assets, Accumulated Amortization	(17.2)		(17.2)		(14.3)
Finite-Lived Intangible Assets, Net	20.2		20.2		21.3
In Process Research and Development [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	5.4		5.4		5.9
Finite-Lived Intangible Assets, Accumulated Amortization	(0.4)		(0.4)		0
Finite-Lived Intangible Assets, Net	5		5		5.9
Customer Platforms - Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	952.2		952.2		952.2
Finite-Lived Intangible Assets, Accumulated Amortization	(88.1)		(88.1)		(52.9)
Finite-Lived Intangible Assets, Net	864.1		864.1		899.3
Customer Relationships - Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	147		147		151.8
Finite-Lived Intangible Assets, Accumulated Amortization	(12)		(12)		(7.3)
Finite-Lived Intangible Assets, Net	135		135		144.5
Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	150.8		150.8		150.8
Finite-Lived Intangible Assets, Accumulated Amortization	(15.3)		(15.3)		(9.3)
Finite-Lived Intangible Assets, Net	$ 135.5		$ 135.5		$ 141.5

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Inventory [Line Items]
Raw materials and work-in-progress	$ 366.1	$ 319.7
Finished goods	78.6	89.6
Gross inventories	444.7	409.3
Inventory valuation reserves	(18.3)	(17.3)
Inventories, net	$ 426.4	$ 392

Schedule of Long-Term Debt (Det

Schedule of Long-Term Debt (Details) - USD ($) $ in Millions	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Debt, Long-term and Short-term, Combined Amount	$ 3,979.5		$ 4,050.8
Current portion of long-term debt	33.2		5.9
Long-term debt	3,946.3		4,044.9
Long-term debt, net	3,873		3,969.3
Total Debt Instruments excluding Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense	73.3		75.6
Secured Debt [Member] | Term Loan A [Member]
Debt Instrument [Line Items]
Long-term Debt	92.5		92.5
Secured Debt [Member] | Term Loan B [Member]
Debt Instrument [Line Items]
Long-term Debt	1,526.8		1,526.8
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]
Long-term Debt	200		200
Unsecured Debt [Member] | 6.625% Notes [Member]
Debt Instrument [Line Items]
Long-term Debt	450		550
Unsecured Debt [Member] | 6.50% Notes [Member]
Debt Instrument [Line Items]
Long-term Debt	500		500
Unsecured Debt [Member] | 6.25% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Long-term Debt	400	$ 400	0
Unsecured Debt [Member] | 6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt	700		700
Unsecured Debt [Member] | 6.25% Notes Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt	0		400
Foreign Credit Facilities [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	94.8		53.2
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Capital lease obligations	15.4		$ 28.3
Current portion of long-term debt	$ 11.4

New Senior Secured Credit Facil

New Senior Secured Credit Facilities Narrative (Details) - USD ($) $ in Millions	Apr. 06, 2017	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt			$ 461.9	$ 2,857.9
Long-term Debt, Current Maturities		$ 33.2	33.2		$ 5.9
Term Loan A [Member]
Debt Instrument [Line Items]
Payment for Debt Extinguishment or Debt Prepayment Cost		2.5
Term Loan B [Member]
Debt Instrument [Line Items]
Payment for Debt Extinguishment or Debt Prepayment Cost		7.8
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	$ 932
Secured Debt [Member] | Term Loan A & Term Loan B [Domain]
Debt Instrument [Line Items]
Long-term Debt, Current Maturities		11.5	11.5
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Line of Credit		0	0		$ 0
Line of Credit Facility, Remaining Borrowing Capacity		896.5	896.5
Line of Credit Facility, Standby Letters of Credit Issued Against the Facility		$ 35.5	$ 35.5

Issuance of New Notes Narrative

Issuance of New Notes Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Mar. 31, 2017
Debt Instrument [Line Items]
Payments of Debt Issuance Costs		$ 6.8	$ 90.5
6.25% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Payments of Debt Issuance Costs	$ 6.6
6.25% Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%	6.25%
Metaldyne Performance Group, Inc. [Member] | 6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.25%
Metaldyne Performance Group, Inc. [Member] | 6.50% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.50%
Unsecured Debt [Member] | 6.25% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 400	$ 400		$ 0
Debt Instrument, Interest Rate, Stated Percentage		6.25%
Unsecured Debt [Member] | 6.25% Notes Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 0		400
Unsecured Debt [Member] | 6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 700		700
Debt Instrument, Interest Rate, Stated Percentage		6.25%
Unsecured Debt [Member] | 6.50% Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 500		$ 500
Debt Instrument, Interest Rate, Stated Percentage		6.50%

Other Debt Disclosures Narrativ

Other Debt Disclosures Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Write off of Deferred Debt Issuance Cost	$ 4.3	$ 2.7	$ 14.6	$ 2.7
Debt refinancing and redemption costs	15.6	$ 0	15.6	$ 0
Long-term Debt, Current Maturities	$ 33.2		$ 33.2			$ 5.9
Long-term Debt, Weighted Average Interest Rate, at Point in Time	5.90%		5.90%			5.70%
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Long-term Debt, Current Maturities	$ 11.4		$ 11.4
Foreign Credit Facilities [Member]
Debt Instrument [Line Items]
Long-term Line of Credit	94.8		94.8			$ 53.2
Debt Instrument, Unused Borrowing Capacity, Amount	$ 94.8		$ 94.8
6.25% Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%		6.25%		6.25%
6.25% Notes Due 2021 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchase Amount	$ 16.9		$ 16.9		$ 383.1
Write off of Deferred Debt Issuance Cost			2.5
Debt Instrument, Tender Premiums			$ 8
6.625% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.625%		6.625%
6.625% Notes [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.625%		6.625%
Debt Instrument, Repurchase Amount	$ 100		$ 100
Interest Paid, Including Capitalized Interest, Operating and Investing Activities			0.8
Write off of Deferred Debt Issuance Cost			0.8
Redemption Premium			$ 3.3

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
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	$ 108.4	$ 72.8
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	108.4	72.8
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]
Foreign Currency Contract, Asset, Fair Value Disclosure	0.5	0.1
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]
Foreign Currency Contract, Asset, Fair Value Disclosure	0.5	0.1
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]
Foreign Currency Contract, Asset, Fair Value Disclosure	0.2	0.2
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]
Foreign Currency Contract, Asset, Fair Value Disclosure	0.2	0.2
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]
Foreign Currency Contract, Liabilities, Fair Value Disclosure	3.3	6
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]
Foreign Currency Contract, Liabilities, Fair Value Disclosure	3.3	6
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]
Foreign Currency Contract, Liabilities, Fair Value Disclosure	2	2.6
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]
Foreign Currency Contract, Liabilities, Fair Value Disclosure	2	2.6
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]
Foreign Currency Contract, Asset, Fair Value Disclosure	0.1	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]
Foreign Currency Contract, Asset, Fair Value Disclosure	0.1	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]
Foreign Currency Contract, Liabilities, Fair Value Disclosure	1.5	2.8
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]
Foreign Currency Contract, Liabilities, Fair Value Disclosure	1.5	2.8
Interest Rate Swap [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]
Interest Rate Derivative Assets, at Fair Value	0.4	0
Interest Rate Swap [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]
Interest Rate Derivative Assets, at Fair Value	0.4	1.3
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	1.8	0.9
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	1.8	0.9
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	1	0.3
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	$ 1	$ 0.3

Fair Value of Debt (Details)

Fair Value of Debt (Details) - Fair Value, Inputs, Level 2 [Member] - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
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]
Long-term Debt	92.5	92.5
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]
Long-term Debt	91.9	92.5
Term Loan B [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	1,526.8	1,526.8
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]
Long-term Debt	1,517.2	1,528.7
7.75% Notes [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	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]
Long-term Debt	209.5	217.5
6.625% Notes [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	450	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]
Long-term Debt	460.7	570.2
6.50% Notes [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	500	500
6.50% Notes [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	494.4	527.5
6.25% Notes Due 2026 [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	400	0
6.25% Notes Due 2026 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	389	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]
Long-term Debt	700	700
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]
Long-term Debt	683.9	736.8
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]
Long-term Debt	0	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]
Long-term Debt	$ 0	$ 410

Fair Value Fair Value of Impair

Fair Value Fair Value of Impaired Assets (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Property, Plant and Equipment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Long Lived Assets, Fair Value	$ 0
Impairment of Long-Lived Assets to be Disposed of	23.6
Other Assets and Deferred Charges [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Long Lived Assets, Fair Value	0
Impairment of Long-Lived Assets to be Disposed of	$ 0.3

Derivatives Narrative (Details)

Derivatives Narrative (Details) $ in Millions	3 Months Ended
	Jun. 30, 2018USD ($)
Foreign Currency Forward & Foreign Currency Option Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	$ 213.8
Debt [Member] | Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Gain on Derivative	5.6
Derivative, Amount of Hedged Item, Through May 2019	900
Derivative, Amount of Hedged Item, Through May 2020	750
Derivative, Amount of Hedged Item, Through May 2021	500
Derivative, Amount of Hedged Item, Through May 2022	400
Derivative, Amount of Hedged Item, Through May 2023	$ 400

Schedule of Derivatives (Detail

Schedule of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Cost of goods sold	$ 1,569.5	$ 1,441.4	$ 3,111.6	$ 2,280.6
Interest expense	54.4	56.9	107.6	82.4
Other income (expense), net	5.6	(6.8)	$ 0.2	(7.9)
Foreign Exchange Forward [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Description of Location of Gain (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	(3.5)	2.2	$ 0.5	5.7
Foreign Exchange Forward [Member] | Cost of Sales [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Income Statement Location Gain (Loss) Reclassified from Accumulated OCI			Cost of Goods Sold
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(0.8)	(1.1)	$ (2.8)	(3.9)
Foreign Exchange Forward [Member] | Cost of Sales [Member] | Cash Flow Hedging [Member] | Scenario, Forecast [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months					$ (2.8)
Foreign Exchange Forward [Member] | Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Description of Location of Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments in Financial Statements			Other Income (Expense), net
Derivative Instruments Not Designated as Hedging Instruments, Gain	1.8	0	$ 1.8	0
Foreign Exchange Option [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Description of Location of Gain (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	0	1.1	$ 0	1.1
Interest Rate Swap [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Income Statement Location Gain (Loss) Reclassified from Accumulated OCI			Interest Expense
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 0.9	$ 0	$ 1.3	$ 0
Interest Rate Swap [Member] | Interest Expense [Member] | Cash Flow Hedging [Member] | Scenario, Forecast [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months					$ 2.5

Schedule of Employee Benefit Pl

Schedule of Employee Benefit Plans Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	$ 11.6
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	1	$ 1.1		$ 2.1	$ 1.9
Interest cost	6.8	7.4		13.7	14.2
Expected asset return	(11.5)	(11.1)		(23)	(21.6)
Amortized loss	2.2	1.8		4.4	3.5
Curtailment	0	0		3.2	0
Amortized prior service credit	0.1	0		0.1	0
Net periodic benefit cost (credit)	(1.4)	$ (0.8)		0.5	(2)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.1		$ 0.1	0.2	0.2
Interest cost	3.1		3.3	6.2	6.6
Amortized loss	0.2		0.1	0.4	0.3
Amortized prior service credit	(0.6)		(0.6)	(1.3)	(1.3)
Net periodic benefit cost	2.8		$ 2.9	5.5	$ 5.8
Other Operating Income (Expense) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Components of net periodic benefit cost other than service cost	$ 0.3			$ 0.5

Employee Benefit Plans and Othe

Employee Benefit Plans and Other Postretirement Benefit Plans Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Liability, Defined Benefit Pension Plan, Noncurrent	$ 115.3	$ 134.7
Liability, Other Postretirement Defined Benefit Plan, Noncurrent	579.9	$ 583
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	2
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	$ 17

Product Warranties (Details)

Product Warranties (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Product Warranty Rollforward
Beginning balance	$ 53.6	$ 47.5	$ 49.5	$ 42.9
Accruals	6.2	4.1	10.5	9.6
Payments	(0.6)	(1.5)	(1.1)	(2.4)
Adjustment to prior period accruals	(0.2)	(2.4)	(0.2)	(2.6)
Foreign currency translation	(0.6)	0.2	(0.3)	0.4
Ending balance	$ 58.4	$ 47.9	$ 58.4	$ 47.9

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income tax expense	$ 2	$ 2.4	$ 19.9	$ 9.9
Effective income tax rate, continuing operations	1.30%	3.60%	7.60%	6.40%
Unrecognized tax benefit liability, including penalties and accrued interest	$ 34.1		$ 34.1		$ 55.2
Foreign Tax Authority [Member]
Change in Liability for Unrecognized Tax Benefits and Related Interest and Penalties	$ 20

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator
Net income attributable to AAM	$ 151.1	$ 66.2	$ 240.5	$ 144.6
Less: Net income attributable to participating securities	(4.9)	(1.4)	(6.8)	(3.3)
Net income attributable to common shareholders - Basic and Dilutive	$ 146.2	$ 64.8	$ 233.7	$ 141.3
Denominators
Basic - Weighted-average shares outstanding	115.4	111.6	114.8	95.2
Basic - Less: Participating securities	(3.7)	(2.3)	(3.3)	(2.2)
Basic - Weighted-average common shares outstanding	111.7	109.3	111.5	93
Effect of dilutive securities - dilutive stock-based compensation	0.6	0.4	0.6	0.4
Diluted - Adjusted weighted-average shares after assumed conversions	112.3	109.7	112.1	93.4
Basic EPS	$ 1.31	$ 0.59	$ 2.09	$ 1.52
Diluted EPS	$ 1.30	$ 0.59	$ 2.08	$ 1.51

Reclassifications out of Accu66

Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined benefit plans - Beginning balance			$ (252)
Defined benefit plans, net current period other comprehensive income (loss)	$ (12.2)	$ (0.9)	(13.5)	$ (0.6)
Defined benefit plans - Ending balance	(238.5)		(238.5)
Foreign currency translation adjustments - Beginning balance			(34.1)
Foreign currency translation adjustments, net current period other comprehensive income (loss)	(81)	24.6	(43.1)	36.5
Foreign currency translation adjustments - Ending balance	(77.2)		(77.2)
Unrecognized gain (loss) on cash flow hedges - Beginning balance			(6.6)
Other comprehensive income (loss), derivatives qualifying as hedges, tax	0.1	(0.7)	1.2	(0.7)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(7.9)	4.9	7.2	20.4
Unrecognized loss on cash flow hedges - Ending balance	0.6		0.6
Other comprehensive income (loss)	(76.7)	30.4	(22.4)	57.5
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Defined benefit plans - Beginning balance	(250.7)	(243.8)	(252)	(243.5)
Defined benefit plans, other comprehensive income (loss), before reclassifications	14.7	0	14.7	(1.7)
Income tax effect of other comprehensive income (loss) before reclassifications	(3.6)	0	(3.6)	0.6
Defined benefit plans, amounts reclassified from accumulated other comprehensive income (loss)	1.6	1.3	3.3	2.5
Income taxes reclassified into net income	(0.5)	(0.4)	(0.9)	(0.8)
Defined benefit plans, net current period other comprehensive income (loss)	12.2	0.9	13.5	0.6
Defined benefit plans - Ending balance	(238.5)	(242.9)	(238.5)	(242.9)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Foreign currency translation adjustments - Beginning balance	3.8	(110.5)	(34.1)	(122.4)
Foreign currency translation adjustments, other comprehensive income (loss) arising during period	(81.2)	24.6	(43.3)	36.5
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	0	0	0	0
Foreign currency translation adjustments, amounts reclassified from accumulated other comprehensive income (loss)	0.2	0	0.2	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Tax	0	0	0	0
Foreign currency translation adjustments, net current period other comprehensive income (loss)	(81)	24.6	(43.1)	36.5
Foreign currency translation adjustments - Ending balance	(77.2)	(85.9)	(77.2)	(85.9)
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Unrecognized gain (loss) on cash flow hedges - Beginning balance	8.5	(8.2)	(6.6)	(23.7)
Unrecognized gain (loss) on cash flow hedges, other comprehensive income (loss) arising during period	(7.7)	3.1	6.9	15.8
Other comprehensive income (loss), derivatives qualifying as hedges, tax	(0.4)	0.7	(1.5)	0.7
Unrecognized gain (loss) on cash flow hedges, amounts reclassified from accumulated other comprehensive income (loss)	(0.1)	1.1	1.5	3.9
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	0.3	0	0.3	0
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(7.9)	4.9	7.2	20.4
Unrecognized loss on cash flow hedges - Ending balance	0.6	(3.3)	0.6	(3.3)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated other comprehensive income (loss), net of tax - Beginning balance	(238.4)	(362.5)	(292.7)	(389.6)
Other comprehensive income (loss) arising during period, total	(74.2)	27.7	(21.7)	50.6
Other Comprehensive Income (Loss) before Reclassifications, Tax	(4)	0.7	(5.1)	1.3
Other comprehensive income (loss), reclassification before tax	1.7	2.4	5	6.4
Reclassification from AOCI, Current Period, Tax	(0.2)	(0.4)	(0.6)	(0.8)
Other comprehensive income (loss)	(76.7)	30.4	(22.4)	57.5
Accumulated other comprehensive income (loss), net of tax - Ending balance	$ (315.1)	$ (332.1)	$ (315.1)	$ (332.1)

Reclassifications out of Accu67

Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
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)	$ 1.6	$ 1.4	$ 3	$ 2.8
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	0.8	1.1	2.8	3.9
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	(0.1)	0.3	(0.3)
Interest Expense [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	$ (0.9)	$ 0	$ (1.3)	$ 0

Segment Reporting Sales and Seg

Segment Reporting Sales and Segment Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	$ 2,048.8	$ 1,900	$ 4,047.3	$ 3,049.3
Sales Revenue, Goods, Net, Intersegment Sales	147.9	142.2	288	241.6
Revenues	1,900.9	1,757.8	3,759.3	2,807.7
Total Segment Adjusted EBITDA	347.9	325.8	664.9	509.4
Driveline [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	1,120.2	1,021.5	2,190.8	2,020.8
Sales Revenue, Goods, Net, Intersegment Sales	0.2	0.4	0.4	0.9
Revenues	1,120	1,021.1	2,190.4	2,019.9
Total Segment Adjusted EBITDA	184.9	179	354.9	332.2
Metal Forming [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	397.1	369.3	794.1	519.3
Sales Revenue, Goods, Net, Intersegment Sales	109.3	109.4	215.2	208.3
Revenues	287.8	259.9	578.9	311
Total Segment Adjusted EBITDA	89.1	69.4	164.4	99.8
Powertrain [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	288.3	283.6	580.2	283.6
Sales Revenue, Goods, Net, Intersegment Sales	4.8	2.2	9.6	2.2
Revenues	283.5	281.4	570.6	281.4
Total Segment Adjusted EBITDA	47	51.9	97.1	51.9
Casting [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net, Inclusive of Intersegment Sales	243.2	225.6	482.2	225.6
Sales Revenue, Goods, Net, Intersegment Sales	33.6	30.2	62.8	30.2
Revenues	209.6	195.4	419.4	195.4
Total Segment Adjusted EBITDA	$ 26.9	$ 25.5	$ 48.5	$ 25.5

Reconciliation of Total Segment

Reconciliation of Total Segment Adjusted EBITDA to Income Before Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA	$ 347.9	$ 325.8	$ 664.9	$ 509.4
Interest expense	(54.4)	(56.9)	(107.6)	(82.4)
Depreciation and amortization	(130.2)	(124.6)	(258)	(180.8)
Restructuring and acquisition-related costs	(36.8)	(51.7)	(55.1)	(67.7)
Gain on sale of business	15.5	0	15.5	0
Gain (Loss) on Sale of Capital Leases, Net	15.6	0	15.6	0
Acquisition-related fair value inventory adjustment	0	(24.9)	0	(24.9)
Impact of change in accounting principle	0	3.7	0	3.7
Debt refinancing and redemption costs	(4.3)	(2.7)	(14.6)	(2.7)
Income before income taxes	$ 153.3	$ 68.7	$ 260.7	$ 154.6

Supplemental Guarantor Conden70

Supplemental Guarantor Condensed Consolidating Financial Statements Narrative (Details)	Jun. 30, 2018	Mar. 31, 2018
Debt Instrument [Line Items]
Ownership in Subsidiary, Percentage	100.00%
6.625% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.625%
6.25% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.25%
6.25% Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%	6.25%
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 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Unsecured Debt [Member] | 6.25% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Unsecured Debt [Member] | 6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%

Supplemental Guarantor Conden71

Supplemental Guarantor Condensed Consolidating Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net sales
External	$ 1,900.9	$ 1,757.8	$ 3,759.3	$ 2,807.7
Intercompany	0	0	0	0
Revenues	1,900.9	1,757.8	3,759.3	2,807.7
Cost of goods sold	1,569.5	1,441.4	3,111.6	2,280.6
Gross profit	331.4	316.4	647.7	527.1
Selling, general and administrative expenses	95	105.6	192.3	186.8
Amortization of intangible assets	24.8	24.8	49.7	26.4
Restructuring and acquisition-related costs	36.8	51.7	55.1	67.7
Gain on sale of business	(15.5)	0	(15.5)	0
Operating income	190.3	134.3	366.1	246.2
Nonoperating Income (Expense)	(37)	(65.6)	(105.4)	(91.6)
Income (loss) before income taxes	153.3	68.7	260.7	154.6
Income tax expense (benefit)	2	2.4	19.9	9.9
Earnings from equity in subsidiaries	0	0	0	0
Net income (loss) before royalties	151.3	66.3	240.8	144.7
Royalties	0	0	0	0
Net income after royalties	151.3	66.3	240.8	144.7
Net income attributable to noncontrolling interests	(0.2)	(0.1)	(0.3)	(0.1)
Net income attributable to AAM	151.1	66.2	240.5	144.6
Other comprehensive income, net of tax	(76.7)	30.4	(22.4)	57.5
Comprehensive income attributable to AAM	74.4	96.6	218.1	202.1
Holdings [Member]
Net sales
External	0	0	0	0
Intercompany	0	0	0	0
Revenues	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	0	0
Gain on sale of business	0		0
Operating income	0	0	0	0
Nonoperating Income (Expense)	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	151.1	66.2	240.5	144.6
Net income (loss) before royalties	151.1	66.2	240.5	144.6
Royalties	0	0	0	0
Net income after royalties	151.1	66.2	240.5	144.6
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to AAM	151.1	66.2	240.5	144.6
Other comprehensive income, net of tax	(76.7)	30.4	(22.4)	57.5
Comprehensive income attributable to AAM	74.4	96.6	218.1	202.1
AAM Inc. [Member]
Net sales
External	302.8	260.3	604.3	556.9
Intercompany	2.3	1.9	3.3	2.2
Revenues	305.1	262.2	607.6	559.1
Cost of goods sold	305.7	245.4	583.9	522.6
Gross profit	(0.6)	16.8	23.7	36.5
Selling, general and administrative expenses	60.2	65.8	120	138.2
Amortization of intangible assets	1.4	1.5	2.9	2.8
Restructuring and acquisition-related costs	9.8	50.1	26.1	65.4
Gain on sale of business	0		0
Operating income	(72)	(100.6)	(125.3)	(169.9)
Nonoperating Income (Expense)	(63.3)	(61.6)	(133.8)	(87.9)
Income (loss) before income taxes	(135.3)	(162.2)	(259.1)	(257.8)
Income tax expense (benefit)	8	(30.4)	9.1	(33.2)
Earnings from equity in subsidiaries	106.3	81.3	173.5	173
Net income (loss) before royalties	(37)	(50.5)	(94.7)	(51.6)
Royalties	85	89.2	169.2	168.7
Net income after royalties	48	38.7	74.5	117.1
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to AAM	48	38.7	74.5	117.1
Other comprehensive income, net of tax	(29.2)	11.3	(3.6)	38.6
Comprehensive income attributable to AAM	18.8	50	70.9	155.7
Guarantor Subsidiaries [Member]
Net sales
External	572.6	560.6	1,154.9	610.8
Intercompany	78	101.9	156	134.7
Revenues	650.6	662.5	1,310.9	745.5
Cost of goods sold	542.3	580.6	1,119.1	641.7
Gross profit	108.3	81.9	191.8	103.8
Selling, general and administrative expenses	19.9	21	41.8	21
Amortization of intangible assets	22.5	22.7	45.1	22.7
Restructuring and acquisition-related costs	26.8	0	27.9	0
Gain on sale of business	(15.5)		(15.5)
Operating income	54.6	38.2	92.5	60.1
Nonoperating Income (Expense)	3.2	7	8.2	9.4
Income (loss) before income taxes	57.8	45.2	100.7	69.5
Income tax expense (benefit)	0.1	15.8	0.5	24.2
Earnings from equity in subsidiaries	67.3	8.2	107.8	15.9
Net income (loss) before royalties	125	37.6	208	61.2
Royalties	0.9	1.3	1.9	1.3
Net income after royalties	125.9	38.9	209.9	62.5
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to AAM	125.9	38.9	209.9	62.5
Other comprehensive income, net of tax	(75.3)	21.6	(40.2)	32.1
Comprehensive income attributable to AAM	50.6	60.5	169.7	94.6
Non-Guarantor Subsidiaries [Member]
Net sales
External	1,025.5	936.9	2,000.1	1,640
Intercompany	10.8	7.9	20.3	12.9
Revenues	1,036.3	944.8	2,020.4	1,652.9
Cost of goods sold	812.6	727.1	1,588.2	1,266.1
Gross profit	223.7	217.7	432.2	386.8
Selling, general and administrative expenses	14.9	18.8	30.5	27.6
Amortization of intangible assets	0.9	0.6	1.7	0.9
Restructuring and acquisition-related costs	0.2	1.6	1.1	2.3
Gain on sale of business	0		0
Operating income	207.7	196.7	398.9	356
Nonoperating Income (Expense)	23.1	(11)	20.2	(13.1)
Income (loss) before income taxes	230.8	185.7	419.1	342.9
Income tax expense (benefit)	(6.1)	17	10.3	18.9
Earnings from equity in subsidiaries	0	0	0	0
Net income (loss) before royalties	236.9	168.7	408.8	324
Royalties	(85.9)	(90.5)	(171.1)	(170)
Net income after royalties	151	78.2	237.7	154
Net income attributable to noncontrolling interests	(0.2)	(0.1)	(0.3)	(0.1)
Net income attributable to AAM	150.8	78.1	237.4	153.9
Other comprehensive income, net of tax	(81)	17.1	(37.3)	43.5
Comprehensive income attributable to AAM	69.8	95.2	200.1	197.4
Consolidation, Eliminations [Member]
Net sales
External	0	0	0	0
Intercompany	(91.1)	(111.7)	(179.6)	(149.8)
Revenues	(91.1)	(111.7)	(179.6)	(149.8)
Cost of goods sold	(91.1)	(111.7)	(179.6)	(149.8)
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	0	0
Gain on sale of business	0		0
Operating income	0	0	0	0
Nonoperating Income (Expense)	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	(324.7)	(155.7)	(521.8)	(333.5)
Net income (loss) before royalties	(324.7)	(155.7)	(521.8)	(333.5)
Royalties	0	0	0	0
Net income after royalties	(324.7)	(155.7)	(521.8)	(333.5)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to AAM	(324.7)	(155.7)	(521.8)	(333.5)
Other comprehensive income, net of tax	185.5	(50)	81.1	(114.2)
Comprehensive income attributable to AAM	$ (139.2)	$ (205.7)	$ (440.7)	$ (447.7)

Supplemental Guarantor Conden72

Supplemental Guarantor Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 353.2	$ 376.8
Accounts receivable, net	1,253.6	1,035.9
Intercompany receivables	0	0
Inventories, net	426.4	392
Prepaid expenses and other	121.8	140.3
Total current assets	2,155	1,945
Property, plant and equipment, net	2,459.3	2,402.9
Goodwill	1,631.7	1,654.3
Intangible assets, net	1,159.8	1,212.5
Intercompany notes and accounts receivable	0	0
Other assets and deferred charges	684.6	668.1
Investment in subsidiaries	0	0
Total assets	8,090.4	7,882.8
Current liabilities
Current portion of long-term debt	33.2	5.9
Accounts payable	930.9	799
Intercompany payables	0	0
Accrued expenses and other	367.6	411.5
Total current liabilities	1,331.7	1,216.4
Intercompany notes and accounts payable	0	0
Long-term debt, net	3,873	3,969.3
Other long-term liabilities	1,119.5	1,157.1
Total liabilities	6,324.2	6,342.8
Stockholders' Equity Attributable to Parent	1,764.2	1,536
Noncontrolling interests in subsidiaries	2	4
Total stockholders' equity	1,766.2	1,540
Total liabilities and stockholders' equity	8,090.4	7,882.8
Holdings [Member]
Current assets
Cash and cash equivalents	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	11.7	11.7
Other assets and deferred charges	0	0
Investment in subsidiaries	3,071.1	2,841.3
Total assets	3,082.8	2,853
Current liabilities
Current portion of long-term debt	0	0
Accounts payable	0	0
Intercompany payables	0	1,313
Accrued expenses and other	0	0
Total current liabilities	0	1,313
Intercompany notes and accounts payable	1,316.6	0
Long-term debt, net	0	0
Other long-term liabilities	0	0
Total liabilities	1,316.6	1,313
Stockholders' Equity Attributable to Parent	1,764.2	1,536
Noncontrolling interests in subsidiaries	2	4
Total stockholders' equity	1,766.2	1,540
Total liabilities and stockholders' equity	3,082.8	2,853
AAM Inc. [Member]
Current assets
Cash and cash equivalents	82.3	91.9
Accounts receivable, net	182.7	138.9
Intercompany receivables	2,748.4	3,475.2
Inventories, net	34.4	37.2
Prepaid expenses and other	37.3	40.4
Total current assets	3,085.1	3,783.6
Property, plant and equipment, net	259.6	250.9
Goodwill	0	0
Intangible assets, net	19.9	21
Intercompany notes and accounts receivable	1,319.7	0
Other assets and deferred charges	341.9	349.1
Investment in subsidiaries	2,146.6	1,955.2
Total assets	7,172.8	6,359.8
Current liabilities
Current portion of long-term debt	11.5	0
Accounts payable	156.8	139
Intercompany payables	1,404.5	563.7
Accrued expenses and other	141.1	181.6
Total current liabilities	1,713.9	884.3
Intercompany notes and accounts payable	15.2	11.7
Long-term debt, net	3,785	3,894.6
Other long-term liabilities	598.8	639.1
Total liabilities	6,112.9	5,429.7
Stockholders' Equity Attributable to Parent	1,059.9	930.1
Noncontrolling interests in subsidiaries	0	0
Total stockholders' equity	1,059.9	930.1
Total liabilities and stockholders' equity	7,172.8	6,359.8
Guarantor Subsidiaries [Member]
Current assets
Cash and cash equivalents	0.3	0.1
Accounts receivable, net	339.3	287.9
Intercompany receivables	1,446.6	479.9
Inventories, net	153.8	147.4
Prepaid expenses and other	4.9	9.9
Total current assets	1,944.9	925.2
Property, plant and equipment, net	770.3	786.8
Goodwill	1,204.5	1,218.4
Intangible assets, net	1,106.2	1,155.6
Intercompany notes and accounts receivable	133.7	243.5
Other assets and deferred charges	115.3	122.8
Investment in subsidiaries	1,690.1	1,280.1
Total assets	6,965	5,732.4
Current liabilities
Current portion of long-term debt	0	0
Accounts payable	245.6	204.6
Intercompany payables	2,747.6	2,017.7
Accrued expenses and other	40.9	52.4
Total current liabilities	3,034.1	2,274.7
Intercompany notes and accounts payable	0	0
Long-term debt, net	3.5	4.4
Other long-term liabilities	332	333.2
Total liabilities	3,369.6	2,612.3
Stockholders' Equity Attributable to Parent	3,595.4	3,120.1
Noncontrolling interests in subsidiaries	0	0
Total stockholders' equity	3,595.4	3,120.1
Total liabilities and stockholders' equity	6,965	5,732.4
Non-Guarantor Subsidiaries [Member]
Current assets
Cash and cash equivalents	270.6	284.8
Accounts receivable, net	731.6	609.1
Intercompany receivables	91.1	7.5
Inventories, net	238.2	207.4
Prepaid expenses and other	79.6	90
Total current assets	1,411.1	1,198.8
Property, plant and equipment, net	1,429.4	1,365.2
Goodwill	427.2	435.9
Intangible assets, net	33.7	35.9
Intercompany notes and accounts receivable	0	0
Other assets and deferred charges	227.4	196.2
Investment in subsidiaries	0	0
Total assets	3,528.8	3,232
Current liabilities
Current portion of long-term debt	21.7	5.9
Accounts payable	528.5	455.4
Intercompany payables	134	68.2
Accrued expenses and other	185.6	177.5
Total current liabilities	869.8	707
Intercompany notes and accounts payable	133.3	243.5
Long-term debt, net	84.5	70.3
Other long-term liabilities	188.7	184.8
Total liabilities	1,276.3	1,205.6
Stockholders' Equity Attributable to Parent	2,250.5	2,022.4
Noncontrolling interests in subsidiaries	2	4
Total stockholders' equity	2,252.5	2,026.4
Total liabilities and stockholders' equity	3,528.8	3,232
Consolidation, Eliminations [Member]
Current assets
Cash and cash equivalents	0	0
Accounts receivable, net	0	0
Intercompany receivables	(4,286.1)	(3,962.6)
Inventories, net	0	0
Prepaid expenses and other	0	0
Total current assets	(4,286.1)	(3,962.6)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Intercompany notes and accounts receivable	(1,465.1)	(255.2)
Other assets and deferred charges	0	0
Investment in subsidiaries	(6,907.8)	(6,076.6)
Total assets	(12,659)	(10,294.4)
Current liabilities
Current portion of long-term debt	0	0
Accounts payable	0	0
Intercompany payables	(4,286.1)	(3,962.6)
Accrued expenses and other	0	0
Total current liabilities	(4,286.1)	(3,962.6)
Intercompany notes and accounts payable	(1,465.1)	(255.2)
Long-term debt, net	0	0
Other long-term liabilities	0	0
Total liabilities	(5,751.2)	(4,217.8)
Stockholders' Equity Attributable to Parent	(6,905.8)	(6,072.6)
Noncontrolling interests in subsidiaries	(2)	(4)
Total stockholders' equity	(6,907.8)	(6,076.6)
Total liabilities and stockholders' equity	$ (12,659)	$ (10,294.4)

Supplemental Guarantor Conden73

Supplemental Guarantor Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Cash, cash equivalents and restricted cash	$ 355.7	$ 490.6	$ 376.8	$ 481.2
Net cash provided by (used in) operating activities	289.4	213.2
Investing activities
Purchases of property, plant and equipment	(273)	(138.6)
Proceeds from sale of property, plant and equipment	0.9	1.5
Purchase buyouts of leased equipment	(0.5)	(8.4)
Acquisition of business, net of cash acquired	(1.3)	(895.5)
Intercompany Activity - Investing	0
Proceeds from sale of business, net	47.1	5.9
Net cash used in investing activities	(226.8)	(1,035.1)
Financing activities
Net debt activity	(66.8)	920.4
Debt issuance costs	(6.8)	(90.5)
Employee stock option exercises	0	0.9
Purchase of treasury stock	(3.6)	(6.9)
Purchase of noncontrolling interest	(2.2)	0
Intercompany Activity - Financing	0	0
Net cash provided by (used in) financing activities	(79.4)	823.9
Effect of exchange rate changes on cash	(4.3)	7.4
Net increase (decrease) in cash, cash equivalents and restricted cash	(21.1)	9.4
Holdings [Member]
Cash, cash equivalents and restricted cash	0	0	0	0
Net cash provided by (used in) 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	0
Acquisition of business, net of cash acquired	0	0
Intercompany Activity - Investing	0
Proceeds from sale of business, net	0	0
Net cash used in investing activities	0	0
Financing activities
Net debt activity	0	0
Debt issuance costs	0	0
Employee stock option exercises		0
Purchase of treasury stock	(3.6)	(6.9)
Purchase of noncontrolling interest	0
Intercompany Activity - Financing	3.6	6.9
Net cash provided by (used in) financing activities	0	0
Effect of exchange rate changes on cash	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash	0	0
AAM Inc. [Member]
Cash, cash equivalents and restricted cash	82.3	159.5	91.9	84.3
Net cash provided by (used in) operating activities	152.3	222.8
Investing activities
Purchases of property, plant and equipment	(40.3)	(28.4)
Proceeds from sale of property, plant and equipment	0	0.3
Purchase buyouts of leased equipment	0	(8.4)
Acquisition of business, net of cash acquired	0	(953.5)
Intercompany Activity - Investing	0
Proceeds from sale of business, net	0	7.5
Net cash used in investing activities	(40.3)	(982.5)
Financing activities
Net debt activity	(111.2)	931.4
Debt issuance costs	(6.8)	(90.5)
Employee stock option exercises		0.9
Purchase of treasury stock	0	0
Purchase of noncontrolling interest	0
Intercompany Activity - Financing	(3.6)	(6.9)
Net cash provided by (used in) financing activities	(121.6)	834.9
Effect of exchange rate changes on cash	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash	(9.6)	75.2
Guarantor Subsidiaries [Member]
Cash, cash equivalents and restricted cash	2.8	0.1	0.1	1.6
Net cash provided by (used in) operating activities	8.6	(25.2)
Investing activities
Purchases of property, plant and equipment	(74.5)	(39.2)
Proceeds from sale of property, plant and equipment	0.5	0.1
Purchase buyouts of leased equipment	(0.5)	0
Acquisition of business, net of cash acquired	0	64.6
Intercompany Activity - Investing	0
Proceeds from sale of business, net	42.7	(1.6)
Net cash used in investing activities	(31.8)	23.9
Financing activities
Net debt activity	(0.4)	(0.2)
Debt issuance costs	0	0
Employee stock option exercises		0
Purchase of treasury stock	0	0
Purchase of noncontrolling interest	(2.2)
Intercompany Activity - Financing	28.5	0
Net cash provided by (used in) financing activities	25.9	(0.2)
Effect of exchange rate changes on cash	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash	2.7	(1.5)
Non-Guarantor Subsidiaries [Member]
Cash, cash equivalents and restricted cash	270.6	331	284.8	395.3
Net cash provided by (used in) operating activities	128.5	15.6
Investing activities
Purchases of property, plant and equipment	(158.2)	(71)
Proceeds from sale of property, plant and equipment	0.4	1.1
Purchase buyouts of leased equipment	0	0
Acquisition of business, net of cash acquired	(1.3)	(6.6)
Intercompany Activity - Investing	0
Proceeds from sale of business, net	4.4	0
Net cash used in investing activities	(154.7)	(76.5)
Financing activities
Net debt activity	44.8	(10.8)
Debt issuance costs	0	0
Employee stock option exercises		0
Purchase of treasury stock	0	0
Purchase of noncontrolling interest	0
Intercompany Activity - Financing	(28.5)	0
Net cash provided by (used in) financing activities	16.3	(10.8)
Effect of exchange rate changes on cash	(4.3)	7.4
Net increase (decrease) in cash, cash equivalents and restricted cash	(14.2)	(64.3)
Consolidation, Eliminations [Member]
Investing activities
Purchase buyouts of leased equipment		0
Acquisition of business, net of cash acquired		0
Proceeds from sale of business, net		0
Consolidation, Eliminations [Member]
Cash, cash equivalents and restricted cash	0	0	$ 0	$ 0
Net cash provided by (used in) 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
Acquisition of business, net of cash acquired	0
Intercompany Activity - Investing	0
Proceeds from sale of business, net	0
Net cash used in investing activities	0	0
Financing activities
Net debt activity	0	0
Debt issuance costs	0	0
Employee stock option exercises		0
Purchase of treasury stock	0	0
Purchase of noncontrolling interest	0
Intercompany Activity - Financing	0	0
Net cash provided by (used in) financing activities	0	0
Effect of exchange rate changes on cash	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash	$ 0	$ 0

Uncategorized Items - axl-20180

Label	Element	Value
Asset Impairment Charges	us-gaap_AssetImpairmentCharges	$ 0