American Axle & Manufacturing (AXL) 10-K 16 Feb 24 2023 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Feb. 13, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-14303
Entity Registrant Name	AMERICAN AXLE & MANUFACTURING HOLDINGS, INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	38-3161171
Entity Address, Address Line One	One Dauch Drive
Entity Address, City or Town	Detroit
Entity Address, State or Province	MI
Entity Address, Postal Zip Code	48211-1198
City Area Code	313
Local Phone Number	758-2000
Title of 12(b) Security	Common Stock, Par Value $0.01 Per Share
Trading Symbol	AXL
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 948.7
Entity Common Stock, Shares Outstanding		117,070,442
Documents Incorporated by Reference	Portions of the registrant's Annual Report to Stockholders for the year ended December 31, 2023 and Proxy Statement for use in connection with its Annual Meeting of Stockholders to be held on May 2, 2024, to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after December 31, 2023, are incorporated by reference in Part I (Items 1, 1A, 1B, 1C, 2, 3 and 4), Part II (Items 5, 6, 7, 7A, 8, 9, 9A, 9B and 9C), Part III (Items 10, 11, 12, 13 and 14) and Part IV (Item 15) of this Report.
Entity Central Index Key	0001062231
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Auditor Information [Line Items]
Auditor Name	Deloitte & Touche LLP
Auditor Location	Detroit, Michigan
Auditor Firm ID	34

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net sales	$ 6,079.5	$ 5,802.4	$ 5,156.6
Cost of goods sold	5,455.2	5,097.5	4,433.9
Gross profit	624.3	704.9	722.7
Selling, general and administrative expenses	366.9	345.1	344.2
Amortization of intangible assets	85.6	85.7	85.8
Restructuring and acquisition-related costs	25.2	30.2	49.4
Loss on sale of business	0	0	2.7
Operating income	146.6	243.9	240.6
Interest expense	(201.7)	(174.5)	(195.2)
Interest income	26.2	17	10.9
Other income (expense)
Debt refinancing and redemption costs	(1.3)	(6.4)	(34)
Gain on bargain purchase of business	0	13.6	0
Pension curtailment and settlement charges	(1.3)	0	(42.3)
Unrealized gain (loss) on equity securities	(1.1)	(25.5)	24.4
Other income (expense), net	8.1	(1.8)	(3.2)
Income (loss) before income taxes	(24.5)	66.3	1.2
Income tax expense (benefit)	9.1	2	(4.7)
Net income (loss)	$ (33.6)	$ 64.3	$ 5.9
Basic earnings (loss) per share	$ (0.29)	$ 0.54	$ 0.05
Diluted earnings (loss) per share	$ (0.29)	$ 0.53	$ 0.05

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net income (loss)	$ (33.6)	$ 64.3	$ 5.9
Other comprehensive income (loss)
Defined benefit plans, net of tax of $(0.4) million, $(31.8) million and $(18.2) million in 2023, 2022 and 2021, respectively	1.6	95	69.1
Foreign currency translation adjustments	7.4	(38.4)	(10.2)
Changes in cash flow hedges, net of tax of $1.9 million, $(6.5) million and $(3.9) million in 2023, 2022 and 2021, respectively	3.5	32.8	8.5
Other comprehensive income	12.5	89.4	67.4
Comprehensive income (loss)	$ (21.1)	$ 153.7	$ 73.3

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other Comprehensive Income (Loss), Tax, Parenthetical Disclosure [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	$ (0.4)	$ (31.8)	$ (18.2)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax	$ 1.9	$ (6.5)	$ (3.9)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 519.9	$ 511.5
Accounts receivable, net	818.5	820.2
Inventories, net	482.9	463.9
Prepaid expenses and other	185.3	197.8
Total current assets	2,006.6	1,993.4
Property, plant and equipment, net	1,760.9	1,903
Deferred income taxes	169.4	119
Goodwill	182.1	181.6
Other intangible assets, net	532.8	616.2
GM postretirement cost sharing asset	111.9	127.6
Operating lease right-of-use assets	115.6	107.2
Other assets and deferred charges	477	421.4
Total assets	5,356.3	5,469.4
Current liabilities
Current portion of long-term debt	17	75.9
Accounts payable	773.9	734
Accrued compensation and benefits	200.1	186.6
Deferred revenue	16.6	28.1
Current portion of operating lease liabilities	21.9	21.1
Accrued expenses and other	172.1	153.6
Total current liabilities	1,201.6	1,199.3
Long-term debt, net	2,751.9	2,845.1
Deferred revenue	70.4	73.4
Deferred income taxes	16.5	10.7
Long-term portion of operating lease liabilities	95.5	87.2
Postretirement benefits and other long-term liabilities	615.5	626.4
Total liabilities	4,751.4	4,842.1
Stockholders' equity
Preferred stock, par value $0.01 per share; 10.0 million shares authorized; no shares outstanding in 2023 or 2022	0	0
Series common stock, par value $0.01 per share; 40.0 million shares authorized; no shares outstanding in 2023 or 2022	0	0
Common stock, par value $0.01 per share; 150.0 million shares authorized; 127.4 million and 123.3 million shares issued as of December 31, 2023 and December 31, 2022, respectively	1.3	1.3
Paid-in capital	1,382.6	1,369.2
Accumulated deficit	(283.2)	(249.6)
Treasury stock at cost, 10.3 million shares in 2023 and 8.7 million shares in 2022	(232.9)	(218.2)
Accumulated other comprehensive income (loss)
Defined benefit plans, net of tax	(145.3)	(146.9)
Foreign currency translation adjustments	(142.3)	(149.7)
Unrecognized gain on cash flow hedges, net of tax	24.7	21.2
Total stockholders' equity	604.9	627.3
Total liabilities and stockholders' equity	$ 5,356.3	$ 5,469.4

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Millions	Dec. 31, 2023	Dec. 31, 2022
Common stock, shares, outstanding	117.1	114.6
Preferred Stock [Member]
Preferred stock, par or stated value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	10	10
Preferred stock, shares outstanding	0	0
Series Common Stock [Member]
Common stock, par or stated value per share	$ 0.01	$ 0.01
Common stock, shares authorized	40	40
Common stock, shares, outstanding	0	0
Common Stock [Member]
Common stock, par or stated value per share	$ 0.01	$ 0.01
Common stock, shares authorized	150	150
Common stock, shares issued	127.4	123.3
Treasury Stock, Common, Shares	10.3	8.7

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net income (loss)	$ (33.6)	$ 64.3	$ 5.9
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization	487.2	492.1	544.3
Deferred income taxes	(45.7)	(29.5)	(27.2)
Stock-based compensation	13.4	17.7	18.2
Pensions and other postretirement benefits, net of contributions	(19.1)	(11.8)	19.9
Loss on sale of business, net	0	0	2.7
Loss (gain) on disposal of property, plant and equipment, net	5.8	(0.5)	5.8
Unrealized loss (gain) on equity securities	1.1	25.5	(24.4)
Gain on bargain purchase of business	0	(13.6)	0
Debt refinancing and redemption costs	1.3	6.4	34
Changes in operating assets and liabilities, net of amounts acquired or disposed
Accounts receivable	7.2	(38.7)	23.1
Inventories	(13.2)	(16.2)	(87.7)
Accounts payable and accrued expenses	58.6	61.1	62.7
Deferred revenue	(16.1)	(16.8)	13.3
Other assets and liabilities	(50.8)	(91.1)	(52.2)
Net cash provided by operating activities	396.1	448.9	538.4
Investing activities
Purchases of property, plant and equipment	(194.6)	(171.4)	(181.2)
Proceeds from sale of property, plant and equipment	0.9	4.7	2
Purchase buyouts of leases	(2.1)	(4)	0
Proceeds from sale of business, net	0	0	1
Acquisition of business, net of cash acquired	(2.5)	(88.9)	(4.9)
Investment in affiliates	(3.2)	(0.4)	(1.1)
Proceeds from insurance claim	17	17	23.1
Net cash used in investing activities	(184.5)	(243)	(161.1)
Financing activities
Proceeds from Revolving Credit Facility	0	25	0
Payments of Revolving Credit Facility	(25)	0	0
Proceeds from issuance of long-term debt	35.8	247.9	634.7
Payments of long-term debt	(184.8)	(458.3)	(1,017.6)
Debt issuance costs	(3.2)	(31.4)	(9.2)
Purchase of treasury stock	(14.7)	(1.9)	(4.3)
Finance lease obligations and other	(13.6)	1.5	(5)
Net cash used in financing activities	(205.5)	(217.2)	(401.4)
Effect of exchange rate changes on cash	2.3	(7.4)	(2.7)
Net increase (decrease) in cash and cash equivalents	8.4	(18.7)	(26.8)
Cash and cash equivalents at beginning of year	511.5	530.2	557
Cash and cash equivalents at end of year	519.9	511.5	530.2
Supplemental cash flow information
Interest paid	186.4	172.6	184.9
Income taxes paid, net	54.9	40.4	26.6
Non-cash investing activities: Deferred consideration for acquisition of business	$ 0	$ 0	$ 10

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Treasury Stock, Common	AOCI Attributable to Parent	Noncontrolling Interest in Subsidiaries
Common stock, shares, outstanding at Dec. 31, 2020	113.3
Total AAM stockholders' equity at Dec. 31, 2020		$ 1.2	$ 1,333.3	$ (319.8)	$ (212)	$ (432.2)	$ 2.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 5.9			5.9
Net income attributable to noncontrolling interests							0
Changes in cash flow hedges	$ 8.5					8.5
Foreign currency translation adjustments						(10.2)
Foreign currency translation adjustments attributable to noncontrolling interests							0
Defined benefit plans, net						69.1
Stock issued during period, shares, share-based compensation, net of forfeitures	1.2
Stock issued during period, value, share-based compensation, net of forfeitures		0.1
Stock-based compensation			18.2
Treasury stock, shares, acquired	(0.5)
Purchase of treasury stock	$ 4.3				(4.3)
Noncontrolling Interest, Decrease from Deconsolidation							(2.7)
Common stock, shares, outstanding at Dec. 31, 2021	114
Total AAM stockholders' equity at Dec. 31, 2021		1.3	1,351.5	(313.9)	(216.3)	(364.8)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 64.3			64.3
Net income attributable to noncontrolling interests							0
Changes in cash flow hedges	$ 32.8					32.8
Foreign currency translation adjustments						(38.4)
Foreign currency translation adjustments attributable to noncontrolling interests							0
Defined benefit plans, net						95
Stock issued during period, shares, share-based compensation, net of forfeitures	0.8
Stock issued during period, value, share-based compensation, net of forfeitures		0
Stock-based compensation			17.7
Treasury stock, shares, acquired	(0.2)
Purchase of treasury stock	$ 1.9				(1.9)
Common stock, shares, outstanding at Dec. 31, 2022	114.6
Total AAM stockholders' equity at Dec. 31, 2022	$ 627.3	1.3	1,369.2	(249.6)	(218.2)	(275.4)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(33.6)			(33.6)
Net income attributable to noncontrolling interests							0
Changes in cash flow hedges	$ 3.5					3.5
Foreign currency translation adjustments						7.4
Foreign currency translation adjustments attributable to noncontrolling interests							0
Defined benefit plans, net						1.6
Stock issued during period, shares, share-based compensation, net of forfeitures	4.1
Stock issued during period, value, share-based compensation, net of forfeitures		0
Stock-based compensation			13.4
Treasury stock, shares, acquired	(1.6)
Purchase of treasury stock	$ 14.7				(14.7)
Common stock, shares, outstanding at Dec. 31, 2023	117.1
Total AAM stockholders' equity at Dec. 31, 2023	$ 604.9	$ 1.3	$ 1,382.6	$ (283.2)	$ (232.9)	$ (262.9)	$ 0

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]	1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES ORGANIZATION As a leading global tier 1 automotive and mobility supplier, AAM designs, engineers and manufactures Driveline and Metal Forming technologies to support electric, hybrid and internal combustion vehicles. Headquartered in Detroit with over 80 facilities in 18 countries, AAM is bringing the future faster for a safer and more sustainable tomorrow. PRINCIPLES OF CONSOLIDATION We include the accounts of American Axle & Manufacturing Holdings, Inc. (Holdings) and its subsidiaries in our consolidated financial statements. We eliminate the effects of all intercompany transactions, balances and profits in our consolidation. CASH AND CASH EQUIVALENTS Cash and cash equivalents include all cash balances, savings accounts, sweep accounts, and highly liquid investments in money market funds and certificates of deposit with maturities of 90 days or less at the time of purchase. REVENUE RECOGNITION 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. See Note 13 - Revenue from Contracts with Customers for more detail on our revenue. ACCOUNTS RECEIVABLE The majority of our accounts receivable are due from original equipment manufacturers (OEMs) in the automotive industry and are considered past due when payment is not received within the terms stated within the contract. Trade accounts receivable for our customers are generally due within approximately 50 days from the date our customers receive our product. Amounts due from customers are stated net of allowances for credit losses. We determine our allowances by considering our expected credit losses, in addition to factors such as our previous loss history, customers' ability to pay their obligations to us, and the condition of the general economy and industry as a whole. The allowance for credit losses was $5.3 million and $9.3 million as of December 31, 2023 and 2022, respectively. We write-off accounts receivable when they become uncollectible. We have agreements in place with factoring companies to sell customer receivables on a nonrecourse basis from certain of our locations in Europe. The factoring companies collect payment for the sold receivables and AAM has no continuing involvement with such receivables. We also participate in an early payment program offered by our largest customer, which allows us to sell certain of our North American receivables from this customer to a third party at our discretion. AAM has no continuing involvement with the sold receivables. CUSTOMER TOOLING AND PRE-PRODUCTION COSTS RELATED TO LONG-TERM SUPPLY AGREEMENTS Engineering, research and development (R&D), and other pre-production design and development costs for products sold on long-term supply arrangements are expensed as incurred unless we have a contractual guarantee for reimbursement from the customer. Reimbursements received for pre-production costs relating to awarded programs are deferred and recognized into revenue over the life of the associated program. Reimbursements received for pre-production costs relating to future programs that have not been awarded, or amounts received for programs that become discontinued prior to production, are recorded as a reduction of expense. Costs for tooling used to make products sold on long-term supply arrangements for which we have either title to the assets or the noncancelable right to use the assets during the term of the supply arrangement are capitalized in property, plant and equipment. Reimbursable costs for tooling assets for which our customer has title and we do not have a noncancelable right to use during the term of the supply arrangement, are recorded in accounts receivable in our consolidated balance sheets. The reimbursement for the customer-owned tooling is recorded as a reduction of accounts receivable upon collection. Capitalized items and customer receipts in excess of tooling costs specifically related to a supply arrangement are amortized over the shorter of the term of the arrangement or over the estimated useful lives of the related assets. 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 salable, we record a provision for such loss as a component of our inventory accounts. Inventories consist of the following: December 31, 2023 2022 (in millions) Raw materials and work-in-progress $ 411.5 $ 398.9 Finished goods 103.5 92.5 Gross inventories 515.0 491.4 Inventory valuation reserves (32.1) (27.5) Inventories, net $ 482.9 $ 463.9 MAINTENANCE, REPAIR AND OPERATIONS (MRO) MATERIALS We include all spare parts and other durable materials for machinery and equipment that are consumed in the manufacturing process in MRO, which is included in Other assets and deferred charges in our Consolidated Balance Sheets. MRO assets are capitalized at actual cost and amortized on a straight-line basis over a useful life of six years, beginning from their purchase date. Repair costs for MRO assets are expensed in the period incurred. Amortization expense related to MRO was $55.6 million, $56.0 million and $61.6 million for 2023, 2022 and 2021, respectively. PROPERTY, PLANT AND EQUIPMENT (PP&E) We state property, plant and equipment, including amortizable tooling, at historical cost, as adjusted for impairments. Construction in progress includes costs incurred for the construction of buildings and building improvements, and machinery and equipment in process. Repair and maintenance costs that do not extend the useful life or otherwise improve the utility of the asset beyond its existing useful state are expensed in the period incurred. We record depreciation and tooling amortization using the straight-line method over the estimated useful lives of the depreciable assets. Depreciation and tooling amortization amounted to $346.0 million, $350.4 million and $396.9 million in 2023, 2022 and 2021, respectively. Property, plant and equipment consists of the following: Estimated December 31, Useful Lives 2023 2022 (years) (in millions) Land Indefinite $ 55.4 $ 57.8 Land improvements 10 - 15 26.9 26.5 Buildings and building improvements 15 - 40 694.9 682.0 Machinery and equipment 3 - 12 3,771.1 3,739.7 Construction in progress 151.5 140.2 4,699.8 4,646.2 Accumulated depreciation and amortization (2,938.9) (2,743.2) Property, plant and equipment, net $ 1,760.9 $ 1,903.0 As of December 31, 2023, 2022 and 2021, we had unpaid purchases of plant and equipment in our accounts payable of $43.1 million, $34.2 million and $20.1 million, respectively. IMPAIRMENT OF LONG-LIVED ASSETS When impairment indicators exist, we evaluate the carrying value of long-lived assets for potential impairment. We consider projected future undiscounted cash flows, trends and other circumstances in making such estimates and evaluations. If impairment is deemed to exist, the carrying amount of the asset is adjusted based on its fair value. Recoverability of assets “held for use” is determined by comparing the forecasted undiscounted cash flows of the operations to which the assets relate to their carrying amount. When the carrying value of an asset group exceeds its fair value and is therefore nonrecoverable, those assets are written down to fair value. Fair value is determined based on market prices, when available, or a discounted cash flow analysis is performed using management estimates. GOODWILL We record goodwill when the purchase price of acquired businesses exceeds the value of their identifiable net tangible and intangible assets acquired. We test our goodwill annually as of October 1, or more frequently if necessary, for impairment in accordance with the accounting guidance for goodwill and other indefinite-lived intangibles. See Note 3 - Goodwill and Other Intangible Assets, for more detail on our goodwill. OTHER INTANGIBLE ASSETS Intangible assets are valued using primarily the relief from royalty method or the multi-period excess earnings method, both of which utilize significant unobservable inputs. These inputs are defined in the fair value hierarchy as Level 3 inputs, which require management to make estimates and assumptions regarding certain financial measures using forecasted or projected information. See Note 3 - Goodwill and Other Intangible Assets, for more detail on our intangible assets. LEASING We record a right of use asset and lease liability when an agreement grants us the right to substantially all of the economic benefits associated with an identified asset, and we are able to direct the use of that asset throughout the term of the agreement, if such term exceeds 12 months. We exclude balance sheet recognition of right-of-use assets and associated liabilities for lease terms of 12 months or less for all classes of underlying assets. Options to extend or terminate the agreements have been included in the relevant lease term to the extent that they are reasonably certain to be exercised. For agreements that contain both lease and non-lease components, we account for these agreements as a single lease component for all classes of underlying assets. See Note 14 - Leasing, for more detail on our leases. DEBT ISSUANCE COSTS The costs related to the issuance or modification of long-term debt are deferred and amortized into interest expense over the expected life of the borrowings. As of December 31, 2023 and December 31, 2022, our unamortized debt issuance costs were $51.6 million and $60.9 million, respectively. Debt issuance costs associated with our senior unsecured notes, as well as our Term Loan A Facility and Term Loan B Facility (as defined in Note 4 - Long-Term Debt), are recorded as a reduction to the related debt liability. Debt issuance costs of $8.8 million and $9.2 million related to our Revolving Credit Facility (also as defined in Note 4 - Long-Term Debt), are classified as Other assets and deferred charges on our Consolidated Balance Sheets as of December 31, 2023 and December 31, 2022, respectively. Unamortized debt issuance costs that exist upon the extinguishment of debt are expensed proportionally to the amount of debt extinguished and classified as Debt refinancing and redemption costs on our Consolidated Statements of Operations. DERIVATIVES We recognize all derivatives on the balance sheet at fair value and we are not subject to master netting agreements. If a derivative qualifies under the accounting guidance as a hedge, depending on the nature of the hedge, changes in the fair value of the derivative are either offset against the change in fair value of the hedged asset, liability or firm commitment through earnings or recognized in other comprehensive income until the hedged item is recognized in earnings. Changes in the fair value of derivatives that do not qualify as hedges, are immediately recognized in earnings. See Note 5 - Derivatives and Risk Management, for more detail on our derivatives. CURRENCY TRANSLATION AND REMEASUREMENT We translate the assets and liabilities of our foreign subsidiaries to United States (U.S.) dollars at end-of-period exchange rates. We translate the income statement elements of our foreign subsidiaries to U.S. dollars at average-period exchange rates. We report the effect of translation for our foreign subsidiaries that use the local currency as their functional currency as a separate component of stockholders' equity. Gains and losses resulting from the remeasurement of assets and liabilities in a currency other than the functional currency of a subsidiary are reported in current period income. We also report any gains and losses arising from transactions denominated in a currency other than the functional currency of a subsidiary in current period income. These foreign currency gains and losses resulted in net gains of $12.8 million and $1.9 million for the years 2023 and 2022, respectively and a net loss of $1.7 million for the year 2021 in Other income (expense), net. PENSION AND OTHER POSTRETIREMENT DEFINED BENEFIT PLANS Net pension and postretirement benefit expenses and the related liabilities are determined on an actuarial basis. These plan expenses and obligations are dependent on management's assumptions developed in consultation with our actuaries. We review these actuarial assumptions at least annually and make modifications when appropriate. See Note 7 - Employee Benefit Plans, for more detail on our pension and other postretirement defined benefit plans. STOCK-BASED COMPENSATION AND OTHER INCENTIVE COMPENSATION We award stock-based compensation in the form of restricted stock units (RSUs) and performance shares. For the RSUs, the grant date fair value is measured as the stock price at the date of grant. For certain performance based awards, fair value is estimated using valuation techniques that require management to use estimates and assumptions. Certain awards require that management's estimates and assumptions be evaluated at each reporting date to determine if compensation expense related to the award should be adjusted, both on a catch-up and go-forward basis. We also award incentive compensation in the form of long-term cash awards (LTCAs) and performance units (PUs). We grant the LTCAs payable in cash to certain associates which vest in full over a three-year period. We also grant PUs payable in cash to officers and certain other associates which vest in full over a three-year performance period and are based primarily on AAM's three-year cumulative free cash flow. Compensation expense is recognized over the period during which the requisite service is provided, referred to as the vesting period. See Note 8 - Stock-Based Compensation and Other Incentive Compensation, for more detail on our accounting for stock-based compensation and other incentive compensation. RESEARCH AND DEVELOPMENT COSTS We expense R&D, as incurred, in selling, general and administrative expenses on our Consolidated Statements of Operations. R&D spending was $155.4 million, $144.0 million and $116.8 million in 2023, 2022 and 2021, respectively. In 2023, 2022 and 2021, our R&D expense is net of approximately $37.0 million, $20.0 million and $15.0 million, respectively, of costs capitalized as a result of contractual guarantees with customers to recover engineering, design and development costs. DEFERRED INCOME TAX ASSETS AND LIABILITIES AND VALUATION ALLOWANCES Our deferred income tax assets and liabilities reflect the impact of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the basis of such assets and liabilities for income tax purposes. In accordance with the accounting guidance for income taxes, we review the likelihood that we will realize the benefit of deferred tax assets and estimate whether recoverability of our deferred tax assets is “more likely than not,” based on forecasts of taxable income in the related tax jurisdictions. In determining the requirement for a valuation allowance, the historical results, projected future operating results based upon approved business plans, eligible carry forward periods, and tax planning opportunities are considered, along with other relevant positive and negative evidence. If, based upon available evidence, it is more likely than not the deferred tax assets will not be realized, a valuation allowance is recorded. We record uncertain tax positions on the basis of a two-step process whereby: 1) we determine whether it is "more likely than not" that the tax positions will be sustained based on the technical merits of the position: and 2) for those positions that meet the "more likely than not" recognition threshold, we recognize the largest amount of tax benefit that is greater than 50% likely to be realized upon ultimate settlement with the related tax authority. We record interest and penalties on uncertain tax positions in income tax expense (benefit). See Note 9 - Income Taxes, for more detail on our accounting for income taxes. EARNINGS (LOSS) PER SHARE (EPS) We present EPS using the two-class method. This method allocates undistributed earnings between common shares and non-vested share based payment awards that entitle the holder to non-forfeitable dividend rights. Our participating securities are our non-vested restricted stock units. See Note 10 - Earnings (Loss) Per Share (EPS), for more detail on our accounting for EPS. PRODUCT WARRANTY We record estimated warranty obligation liabilities at the dates our products are sold, 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. See Note 11 - Commitments and Contingencies, for detail on our accounting for product warranties. USE OF ESTIMATES In order to prepare consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP), we are required to make estimates and assumptions that affect the reported amounts and disclosures in our consolidated financial statements. Actual results could differ from those estimates. EFFECT OF NEW ACCOUNTING STANDARDS Standards Not Yet Adopted Accounting Standards Update 2023-07 On November 27, 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2023-07 - Improvements to Reportable Segment Disclosures (Topic 280). ASU 2023-07 enhances existing annual segment requirements to include disclosure of significant segment expenses and other segment items by reportable segment that are regularly used by the Chief Operating Decision Maker (CODM) to evaluate segment performance. This guidance also requires annual disclosure of the title and position of the CODM. ASU 2023-07 also expands interim segment disclosure requirements to include all existing annual segment disclosures in addition to the new disclosure requirements for significant segment expenses and other segment items. This guidance becomes effective at the beginning of our 2024 fiscal year for annual requirements, and at the beginning of our 2025 fiscal year for interim requirements, using a retrospective transition method. We will adopt this guidance retrospectively on January 1, 2024 for the annual requirements and will adopt the interim requirements on January 1, 2025. We are currently assessing the impact that this standard will have on our consolidated financial statements. Accounting Standards Update 2023-09 On December 14, 2023, the FASB issued ASU 2023-09 - Improvements to Income Tax Disclosures (Topic 740).

Restructuring and Acquisition-R

Restructuring and Acquisition-Related Costs	12 Months Ended
	Dec. 31, 2023
Restructuring and Related Activities [Abstract]
Business Acquisition, Integration, Restructuring and Other Related Costs [Text Block]	2. RESTRUCTURING AND ACQUISITION-RELATED COSTS In the first quarter of 2020, we initiated a global restructuring program (the 2020 Program). The primary objectives of the 2020 Program were to achieve efficiencies within our corporate and business unit support teams to reduce cost in our business, and to structurally adjust our operations to a new level of market demand based on the impact of COVID-19. From inception of the 2020 Program, we incurred restructuring costs totaling $112.4 million. The 2020 Program has concluded and we do not expect to incur any additional charges under this program. In 2021, we completed our acquisition of a manufacturing facility in Emporium, Pennsylvania (Emporium), and subsequently ceased production at the facility and relocated the production capacity to other AAM manufacturing facilities. As a result, we incurred a total of $16.5 million of restructuring charges related to the closure of the facility. As of December 31, 2023, we had completed our exit of Emporium and we do not expect to incur any additional charges related to Emporium. In 2022, we completed our acquisition of Tekfor Group (Tekfor) and in 2023 initiated certain restructuring actions associated with the acquired entities. In the first quarter of 2024, we initiated a new global restructuring program (the 2024 Program) focused on optimizing our cost structure. We expect to incur costs under the 2024 Program into 2026. A summary of our restructuring activity for the years 2023, 2022 and 2021 is shown below: Severance Charges Implementation Costs Total (in millions) Accrual at January 1, 2021 $ 1.7 $ 9.8 $ 11.5 Charges 2.9 40.3 43.2 Cash utilization (3.9) (47.4) (51.3) Accrual at December 31, 2021 0.7 2.7 3.4 Charges 3.5 18.2 21.7 Cash utilization (1.8) (19.5) (21.3) Accrual at December 31, 2022 2.4 1.4 3.8 Charges 7.2 11.1 18.3 Cash utilization (6.6) (10.8) (17.4) Accrual at December 31, 2023 $ 3.0 $ 1.7 $ 4.7 As part of our restructuring actions during 2023, we incurred severance charges of approximately $7.2 million, as well as implementation costs, consisting primarily of plant exit costs and professional fees, of approximately $11.1 million. In 2023, we incurred $11.8 million of restructuring costs under the 2020 Program, incurred $4.4 million of costs associated with the closure of Emporium, and $2.1 million of costs related to restructuring actions associated with Tekfor. Approximately $4.9 million and $11.3 million of our total restructuring costs in 2023 related to our Driveline and Metal Forming segments, respectively, while the remainder were corporate costs. In 2022, we incurred severance charges of approximately $3.5 million, as well as implementation costs, consisting primarily of plant exit costs and professional fees, of approximately $18.2 million. Approximately $1.6 million and $14.3 million of our total restructuring costs in 2022 related to our Driveline and Metal Forming segments, respectively, while the remainder were corporate costs. In 2021, we incurred severance charges of approximately $2.9 million, as well as implementation costs, consisting primarily of plant exit costs and professional fees, of approximately $40.3 million. Approximately $4.7 million and $6.5 million of our total restructuring costs in 2021 related to our Driveline and Metal Forming segments, respectively, while the remainder were corporate costs. We expect to incur approximately $10 million to $20 million of total restructuring charges in 2024 as we begin restructuring actions associated with the 2024 Program and continue our restructuring actions associated with Tekfor. In 2023 and 2022, we incurred acquisition and integration costs associated with our acquisition of Tekfor, and in 2022 and 2021, we incurred acquisition and integration costs associated with our acquisition of Emporium. In 2021, we also incurred the remaining integration costs associated with our 2017 acquisition of MPG. The following table represents a summary of charges incurred in 2023, 2022 and 2021 associated with acquisition and integration costs: Acquisition-Related Costs Integration Expenses Total (in millions) 2023 Charges $ — $ 6.9 $ 6.9 2022 Charges 6.0 2.5 8.5 2021 Charges 0.4 5.8 6.2 Acquisition-related costs primarily consist of advisory, legal, accounting, valuation and certain other professional or consulting fees incurred. Integration expenses primarily reflect costs incurred for information technology infrastructure and enterprise resource planning systems, and consulting fees incurred in conjunction with integration activities. Total restructuring charges and acquisition-related charges of $25.2 million, $30.2 million and $49.4 million are shown on a separate line item titled "Restructuring and Acquisition-Related Costs" in our Consolidated Statements of Operations for 2023, 2022 and 2021, respectively.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets [Abstract]
Goodwill and Intangible Assets Disclosure [Text Block]	3. GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill The following table provides a reconciliation of changes in goodwill for the year ended December 31, 2023 and the year ended December 31, 2022: Consolidated (in millions) Balance as of January 1, 2022 $ 183.8 Foreign currency translation (2.2) Balance as of December 31, 2022 $ 181.6 Foreign currency translation 0.5 Balance as of December 31, 2023 $ 182.1 We conduct our annual goodwill impairment test in the fourth quarter of each year, as well as whenever adverse events or changes in circumstances indicate a possible impairment. In performing this test, we utilize a third-party valuation specialist to assist management in determining the fair value of our reporting units. Fair value of each reporting unit is estimated based on a combination of discounted cash flows and the use of pricing multiples derived from an analysis of comparable public companies multiplied against historical and/or anticipated financial metrics of each reporting unit. These calculations contain uncertainties as they require management to make assumptions including, but not limited to, market comparables, future cash flows of the reporting units, and appropriate discount and long-term growth rates. This fair value determination is categorized as Level 3 within the fair value hierarchy. We completed our annual goodwill impairment test for our Driveline reporting unit in the fourth quarter of 2023 and no impairment was identified. At December 31, 2023, accumulated goodwill impairment losses were $1,435.5 million. Other Intangible Assets The following table provides a reconciliation of the gross carrying amount and associated accumulated amortization for AAM's other intangible assets, which are all subject to amortization, as of December 31, 2023 and December 31, 2022: December 31, December 31, 2023 2022 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in millions) Capitalized computer software $ 54.2 $ (49.2) $ 5.0 $ 52.2 $ (43.2) $ 9.0 Customer platforms 856.2 (428.2) 428.0 856.2 (364.7) 491.5 Customer relationships 53.0 (23.1) 29.9 53.0 (19.7) 33.3 Technology and other 154.3 (84.4) 69.9 154.1 (71.7) 82.4 Total $ 1,117.7 $ (584.9) $ 532.8 $ 1,115.5 $ (499.3) $ 616.2 Amortization expense for our intangible assets was $85.6 million for the year ended December 31, 2023, $85.7 million for the year ended December 31, 2022, and $85.8 million for the year ended December 31, 2021. Amortization expense for the years 2024 through 2028 is expected to be in the range of approximately $80 million to $85 million per year.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Long-term Debt [Text Block]	4. LONG-TERM DEBT Long-term debt, net consists of the following: December 31, 2023 2022 (in millions) Revolving credit facility $ — $ 25.0 Term Loan A Facility 484.3 520.0 Term Loan B Facility 648.0 675.0 6.875% Notes due 2028 400.0 400.0 6.50% Notes due 2027 500.0 500.0 6.25% Notes due 2026 127.6 180.0 5.00% Notes due 2029 600.0 600.0 Foreign credit facilities 51.8 72.7 Total debt 2,811.7 2,972.7 Less: Current portion of long-term debt 17.0 75.9 Long-term debt 2,794.7 2,896.8 Less: Debt issuance costs 42.8 51.7 Long-term debt, net $ 2,751.9 $ 2,845.1 SENIOR SECURED CREDIT FACILITIES Holdings and American Axle & Manufacturing, Inc. (AAM, Inc.) are parties to an amended and restated credit agreement including a term loan A facility (the Term Loan A Facility), term loan B facility (the Term Loan B Facility) and a multi-currency revolving credit facility (the Revolving Credit Facility), which was entered into on March 11, 2022 and was amended on December 13, 2022 and June 28, 2023 (the Amended and Restated Credit Agreement). In connection with the Amended and Restated Credit Agreement, Holdings, AAM, Inc. and certain of their restricted subsidiaries are parties to a collateral agreement and guarantee agreement with the financial institutions party thereto. The Amended and Restated Credit Agreement includes customary covenants, including a total net leverage ratio covenant, a cash interest expense coverage ratio covenant, and certain covenants restricting the ability of Holdings, AAM, Inc. and certain subsidiaries of Holdings to create, incur, assume or permit to exist certain additional indebtedness and liens, to make investments and to make or agree to pay or make certain restricted payments, voluntary payments and distributions. On June 28, 2023, Holdings and AAM, Inc. entered into the First Amendment to the Amended and Restated Credit Agreement (the First Amendment), which covers the period from June 28, 2023 through the filing of our second quarter 2024 results, or earlier at AAM's option, subject to certain conditions (the Amendment Period). The First Amendment, among other things, increased the maximum levels of the total net leverage ratio covenant and reduced the minimum levels of the cash interest expense coverage ratio covenant during the Amendment Period, modified certain categories of the applicable margin (determined based on the total net leverage ratio of Holdings) for the duration of the Amendment Period with respect to interest rates under the Term Loan A Facility and the Revolving Credit Facility, and modified certain covenants restricting the ability of Holdings, AAM, Inc. and certain subsidiaries of Holdings to create, incur, assume, or permit to exist certain additional indebtedness and liens and to make or agree to pay or make certain restricted payments, voluntary payments and distributions. The terms of the Term Loan B Facility under the Amended and Restated Credit Agreement, including maturity dates, interest rates and their applicable margins, remain unchanged. We paid debt issuance costs of $3.2 million in the year ended December 31, 2023 related to the First Amendment and in 2022, we expensed $0.6 million of debt refinancing costs, paid accrued interest of $3.4 million, and paid debt issuance costs of $31.4 million related to the Amended and Restated Credit Agreement. In 2023, we made voluntary prepayments totaling $26.0 million on our Term Loan A Facility and $20.2 million on our Term Loan B Facility. As a result, we expensed approximately $1.1 million for the write-off of a portion of the unamortized debt issuance costs that we had been amortizing over the expected life of these borrowings. In 2022, prior to amending the Amended and Restated Credit Agreement in the fourth quarter, we made voluntary prepayments totaling $100.0 million on our then outstanding term loan B facility. As a result, we expensed approximately $0.6 million for the write-off of a portion of the unamortized debt issuance costs that we had been amortizing over the expected life of this borrowing. In 2021, we made voluntary prepayments totaling $21.2 million on our Term Loan A Facility and $238.8 million on our Term Loan B Facility. As a result, we expensed approximately $2.5 million for the write-off of a portion of the unamortized debt issuance costs that we had been amortizing over the expected life of these borrowings. At December 31, 2023, $892.3 million was available under the Revolving Credit Facility. This availability reflects a reduction of $32.7 million for standby letters of credit issued against the facility. The proceeds of the Revolving Credit Facility are used for general corporate purposes. In the first quarter of 2023, we paid $25.0 million on our Revolving Credit Facility that had been drawn in the fourth quarter of 2022. The Revolving Credit Facility, the Term Loan A Facility and the Term Loan B Facility (collectively, 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 Consolidated Balance Sheet. REDEMPTION OF 6.25% NOTES DUE 2026 In the fourth quarter of 2023, we voluntarily redeemed a portion of our 6.25% Notes due 2026. This resulted in a principal payment of $50.0 million and $0.9 million in accrued interest. We also expensed approximately $0.2 million for the write-off of a portion of the unamortized debt issuance costs that we had been amortizing over the expected life of the borrowing. In the fourth quarter of 2023, we also completed an open market repurchase of our 6.25% Notes due 2026 of $2.4 million. In the first quarter of 2022, we also voluntarily redeemed a portion of our 6.25% Notes due 2026. This resulted in a principal payment of $220.0 million and $0.2 million in accrued interest. We also expensed approximately $1.8 million for the write-off of a portion of the unamortized debt issuance costs that we had been amortizing over the expected life of the borrowing, and approximately $3.4 million for the payment of an early redemption premium. 5.00% NOTES DUE 2029 In the third quarter of 2021, we issued $600.0 million in aggregate principal amount of 5.00% Notes due 2029 (the 5.00% Notes). Proceeds from the 5.00% Notes were used to fund a portion of the redemption of the 6.25% Notes due 2025 described below. We paid debt issuance costs of $9.2 million in the twelve months ended December 31, 2021 related to the 5.00% Notes. REDEMPTION OF 6.25% NOTES DUE 2025 In 2021, we voluntarily redeemed our 6.25% Notes due 2025. This resulted in principal payments totaling $700.0 million and $19.4 million in accrued interest. We also expensed approximately $9.6 million for the write-off of the unamortized debt issuance costs that we had been amortizing over the expected life of the borrowing, and approximately $21.9 million for the payment of an early redemption premium. REPAYMENT OF TEKFOR GROUP INDEBTEDNESS Upon the acquisition of Tekfor, we assumed $23.4 million of existing Tekfor indebtedness, of which we repaid $10.7 million in 2022. FOREIGN CREDIT FACILITIES We utilize local currency credit facilities to finance the operations of certain foreign subsidiaries. These credit facilities, some of which are guaranteed by Holdings and/or AAM, Inc., expire at various dates through September 2028. At December 31, 2023, $51.8 million was outstanding under our foreign credit facilities and an additional $84.7 million was available. At December 31, 2022, $72.7 million was outstanding under these facilities and an additional $57.8 million was available. DEBT MATURITIES Aggregate maturities of long-term debt are as follows (in millions) : 2024 $ 29.1 2025 46.3 2026 190.2 2027 900.0 2028 411.7 Thereafter 1,234.4 Total $ 2,811.7 INTEREST EXPENSE AND INTEREST INCOME Interest expense was $201.7 million in 2023, $174.5 million in 2022 and $195.2 million in 2021. We capitalized interest of $8.0 million in 2023, $6.6 million in 2022 and $6.2 million in 2021. The weighted-average interest rate of our long-term debt outstanding at December 31, 2023 was 7.1%, as compared to 6.6% and 5.6% at December 31, 2022 and December 31, 2021, respectively. Interest income was $26.2 million in 2023, $17.0 million in 2022 and $10.9 million in 2021. Interest income primarily includes interest earned on cash and cash equivalents, the deferred payment obligation associated with the sale of our former Casting segment, as well as the impact of the interest rate differential on our fixed-to-fixed cross-currency swap.

Derivatives and Risk Management

Derivatives and Risk Management	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	5. DERIVATIVES AND RISK MANAGEMENT DERIVATIVE FINANCIAL INSTRUMENTS In the normal course of business, we are exposed to market risk associated with changes in foreign currency exchange rates and interest rates. To manage a portion of these inherent risks, we may purchase certain types of derivative financial instruments based on management's judgment of the trade-off between risk, opportunity and cost. We do not hold or issue derivative financial instruments for trading or speculative purposes. The impact of hedge ineffectiveness was not significant in any of the periods presented. CURRENCY DERIVATIVE CONTRACTS From time to time, we use foreign currency forward contracts to reduce the effects of fluctuations in exchange rates relating to certain foreign currencies. As of December 31, 2023 and December 31, 2022, we had currency forward contracts outstanding with a total notional amount of $206.9 million and $179.9 million, respectively, that hedge our exposure to changes in foreign currency exchange rates for certain payroll expenses into the second quarter of 2026 and the purchase of certain direct and indirect inventory and other working capital items into the fourth quarter of 2024. FIXED-TO-FIXED CROSS-CURRENCY SWAP In 2022, we discontinued an existing fixed-to-fixed cross-currency swap, which was in an asset position of $9.7 million on the date that it was discontinued. Also in 2022, we entered into a new fixed-to-fixed cross-currency swap to reduce the variability of functional currency equivalent cash flows associated with changes in exchange rates on certain Euro-based intercompany loans. We had notional amounts outstanding under the fixed-to fixed cross-currency swap of €200.0 million at both December 31, 2023 and December 31, 2022, which was equivalent to $220.7 million and $213.9 million, respectively. The fixed-to-fixed cross-currency swap hedges our exposure to changes in exchange rates on the intercompany loans into the second quarter of 2024. VARIABLE-TO-FIXED INTEREST RATE SWAP In 2022, we discontinued an existing variable-to-fixed interest rate swap, which was in an asset position of $6.1 million on the date that it was discontinued. In 2022, and in the first quarter of 2023, we entered into new variable-to-fixed interest rate swaps to reduce the variability of cash flows associated with interest payments on our variable rate debt. In the third quarter of 2023, we discontinued these variable-to-fixed interest rate swaps, which were in an asset position of $27.2 million on the date that they were discontinued. Also in the third quarter of 2023, we entered into new variable-to-fixed interest rate swaps to reduce the variability of cash flows associated with interest payments on our variable rate debt. As of December 31, 2023, we have $700.0 million notional amount hedged in relation to our variable-to-fixed interest rate swap into the third quarter of 2027, $200.0 million of which continues into the fourth quarter of 2029. The following table summarizes the reclassification of pre-tax derivative gains and losses into net income (loss) from accumulated other comprehensive income (loss) for those derivative instruments designated as cash flow hedges under Accounting Standards Codification (ASC) 815 - Derivatives and Hedging: Location of Gain (Loss) Reclassified into Net Income (Loss) Gain (Loss) Reclassified During the Twelve Months Ended December 31, Total of Financial Statement Line Item Gain Expected to be Reclassified During the Next 12 Months 2023 2022 2021 2023 (in millions) Currency forward contracts Cost of Goods Sold $ 19.9 $ 6.5 $ 5.6 $ 5,455.2 $ 15.9 Fixed-to-fixed cross-currency swap Other Income (Expense), net (6.6) 13.7 19.0 8.1 0.6 Variable-to-fixed interest rate swap Interest Expense 3.6 2.7 (14.8) (201.7) 1.2 See Note 12 - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) for amounts recognized in Accumulated other comprehensive income (loss) during the years ended December 31, 2023, December 31, 2022 and December 31, 2021. The following table summarizes the amount and location of gains recognized in the Consolidated Statements of Operations for those derivative instruments not designated as hedging instruments under ASC 815: Location of Gain (Loss) Recognized in Net Income (Loss) Gain Recognized During the Twelve Months Ended December 31, Total of Financial Statement Line Item 2023 2022 2021 2023 (in millions) Currency forward contracts Other Income (Expense), Net $ 4.7 $ 2.5 $ 0.2 $ 8.1 CONCENTRATIONS OF CREDIT RISK In the normal course of business, we provide credit to customers. We periodically evaluate the creditworthiness of our customers and we maintain reserves for potential credit losses. Sales to General Motors Company (GM) were approximately 39% of our consolidated net sales in 2023, 40% in 2022, and 37% in 2021. Accounts and other receivables due from GM were $305.7 million at year-end 2023 and $334.4 million at year-end 2022. Sales to Stellantis N.V. (Stellantis), were approximately 16% of our consolidated net sales in 2023, 18% in 2022 and 19% in 2021. Accounts and other receivables due from Stellantis were $108.1 million at year-end 2023 and $115.3 million at year-end 2022. Sales to Ford Motor Company (Ford) were approximately 12% of our consolidated net sales in 2023, 2022 and 2021. Accounts and other receivables due from Ford were $118.1 million at year-end 2023 and $101.7 million at year end 2022. No other single customer accounted for more than 10% of our consolidated net sales in any year presented. In addition, our total GM postretirement cost sharing asset was $120.0 million as of December 31, 2023 and $138.2 million as of December 31, 2022. See Note 7 - Employee Benefit Plans for more detail on this cost sharing asset. We diversify the concentration of invested cash and cash equivalents among different financial institutions and we monitor the selection of counterparties to other financial instruments to avoid unnecessary concentrations of credit risk.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	6. FAIR VALUE ASC 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 values 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: Fair Value December 31, 2023 December 31, 2022 Input (in millions) Balance Sheet Classification Cash equivalents $ 328.3 $ 363.6 Level 1 Prepaid expenses and other Cash flow hedges - currency forward contracts 15.9 8.2 Level 2 Cash flow hedges - variable-to-fixed interest rate swap — 2.4 Level 2 Nondesignated - currency forward contracts 0.8 0.5 Level 2 Other assets and deferred charges Cash flow hedges - currency forward contracts 5.4 3.0 Level 2 Cash flow hedges - variable-to-fixed interest rate swap — 8.5 Level 2 Investment in equity securities 0.8 1.9 Level 1 Accrued expenses and other Cash flow hedges - fixed-to-fixed cross-currency swap 9.4 — Level 2 Cash flow hedges - variable-to-fixed interest rate swap 5.0 — Level 2 Postretirement benefits and other long-term liabilities Cash flow hedges - fixed-to-fixed cross-currency swap — 1.5 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 16.5 — 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 values due to the frequent resetting of the interest rates. We have an investment in the equity securities of REE Automotive, an e-mobility company. These equity securities are measured at fair value each reporting period with changes in fair value reported through an unrealized gain or loss within Other income (expense), net in our Consolidated Statements of Operations. In the fourth quarter of 2023, REE Automotive executed a one-for-thirty reverse stock split of its common shares, resulting in a proportional increase to its share price. As of December 31, 2023, our investment in REE shares was valued at $0.8 million based on a closing price on that date of $5.14 per share. We estimated the fair value of our outstanding debt using available market information and other observable data to be as follows: December 31, 2023 December 31, 2022 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Revolving Credit Facility $ — $ — $ 25.0 $ 25.0 Level 2 Term Loan A Facility 484.3 483.6 520.0 510.3 Level 2 Term Loan B Facility 648.0 649.6 675.0 658.1 Level 2 6.875% Notes due 2028 400.0 387.0 400.0 355.4 Level 2 6.50% Notes due 2027 500.0 501.9 500.0 452.5 Level 2 6.25% Notes due 2026 127.6 126.3 180.0 165.7 Level 2 5.00% Notes due 2029 600.0 529.5 600.0 474.9 Level 2

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Compensation and Employee Benefit Plans [Text Block]	7. EMPLOYEE BENEFIT PLANS PENSION AND OTHER POSTRETIREMENT DEFINED BENEFIT PLANS We sponsor various qualified and non-qualified defined benefit pension plans for our eligible associates. We also maintain hourly and salaried benefit plans that provide postretirement medical, dental, vision and life insurance benefits (OPEB) to our eligible retirees and their dependents in the U.S. Actuarial valuations of our benefit plans were made as of December 31, 2023 and 2022. The primary weighted-average assumptions used in the year-end valuation of our principal plans appear in the following table. The U.S. discount rates are based on an actuarial review of a hypothetical portfolio of long-term, high quality corporate bonds matched against the expected payment stream for each of our plans. The discount rates for the non-U.S. plans are based on hypothetical yield curves developed from corporate bond yield information within each regional market. The assumptions for expected return on plan assets are based on future capital market expectations for the asset classes represented within our portfolios and a review of long-term historical returns. The rates of increase in compensation and health care costs are based on current market conditions, inflationary expectations and historical information. Pension Benefits OPEB 2023 2022 2021 2023 2022 2021 U.S. Non-U.S. U.S. Non-U.S. U.S. Non-U.S. Discount rate 5.15 % 4.50 % 5.50 % 4.40 % 2.90 % 1.85 % 5.15 % 5.50 % 2.90 % Expected return on plan assets 6.75 % 4.90 % 6.75 % 4.00 % 7.00 % 4.00 % N/A N/A N/A Rate of compensation increase N/A 3.30 % N/A 3.25 % N/A 3.70 % 4.00 % 4.00 % 4.00 % The accumulated benefit obligation for all defined benefit pension plans was $486.9 million and $481.8 million at December 31, 2023 and December 31, 2022, respectively. As of December 31, 2023, the accumulated benefit obligation for our underfunded defined benefit pension plans was $399.0 million, the projected benefit obligation was $399.0 million and the fair value of assets for these plans was $318.5 million. Certain eligible retirees under our OPEB plans have past service with both AAM and GM. AAM and GM share proportionally in the cost of OPEB for these retirees based on the length of service an employee had with AAM and GM. We have included in our OPEB obligation the amounts expected to be received from GM pursuant to this agreement of $120.0 million and $138.2 million at December 31, 2023 and December 31, 2022, respectively. We have also recorded a corresponding asset for these amounts on our Consolidated Balance Sheets, $8.1 million that is classified as a current asset and $111.9 million that is classified as a noncurrent asset as of December 31, 2023. The following table summarizes the changes in projected benefit obligations and plan assets and reconciles the funded status of the benefit plans, which is the net benefit plan liability: Pension Benefits OPEB December 31, December 31, 2023 2022 2023 2022 (in millions) Change in benefit obligation Benefit obligation at beginning of year $ 482.4 $ 674.1 $ 329.6 $ 509.6 Service cost 1.1 1.7 0.2 0.3 Interest cost 24.4 16.5 10.1 8.4 Plan amendments (0.6) — — (0.5) Actuarial loss (gain) 6.7 (175.9) (21.4) (101.3) Change in GM portion of OPEB obligation — — (18.2) (75.0) Participant contributions 0.2 0.2 — — Curtailments (0.5) — — — Settlements (6.1) — — — Benefit payments (27.5) (27.4) (12.5) (11.9) Tekfor acquisition — 14.3 — — Currency fluctuations 6.8 (21.1) — — Net change 4.5 (191.7) (41.8) (180.0) Benefit obligation at end of year $ 486.9 $ 482.4 $ 287.8 $ 329.6 Change in plan assets Fair value of plan assets at beginning of year $ 406.9 $ 573.8 $ — $ — Actual return on plan assets 19.0 (127.1) — — Employer contributions 9.2 2.5 12.5 11.9 Participant contributions 0.2 0.2 — — Benefit payments (27.5) (27.4) (12.5) (11.9) Settlements (6.1) — — — Tekfor acquisition — 7.5 — — Currency fluctuations 6.4 (22.6) — — Net change 1.2 (166.9) — — Fair value of plan assets at end of year $ 408.1 $ 406.9 $ — $ — Amounts recognized in our Consolidated Balance Sheets are as follows: Pension Benefits OPEB December 31, December 31, 2023 2022 2023 2022 (in millions) Noncurrent assets $ 1.7 $ 5.1 $ — $ — Current liabilities (5.8) (7.1) (18.9) (24.8) Noncurrent liabilities (74.7) (73.5) (268.9) (304.8) Net liability $ (78.8) $ (75.5) $ (287.8) $ (329.6) Pre-tax amounts recorded in accumulated other comprehensive income (loss) (AOCI), not yet recognized in net periodic benefit cost (credit) as of December 31, 2023 and 2022, consists of: Pension Benefits OPEB December 31, December 31, 2023 2022 2023 2022 (in millions) Net actuarial gain (loss) $ (212.2) $ (200.0) $ 146.0 $ 133.1 Net prior service credit (cost) 0.3 (1.5) 0.7 1.2 Total amounts recorded $ (211.9) $ (201.5) $ 146.7 $ 134.3 The increase in net actuarial loss for pension benefits was primarily attributable to the impact of the actual return on pension assets in 2023 as compared to our assumption for expected return on pension assets, as well as decreased discount rates used in the valuation at December 31, 2023, as compared to prior year, partially offset by the impact of amortization of prior actuarial losses. The increase in net actuarial gain for OPEB benefits was primarily attributable to favorable per capita cost and healthcare plan subsidy assumptions as compared to prior year, partially offset by a decrease in the discount rate and the impact of amortization of prior actuarial gains. The components of net periodic benefit cost (credit) are as follows: Pension Benefits OPEB 2023 2022 2021 2023 2022 2021 (in millions) Service cost $ 1.1 $ 1.7 $ 2.0 $ 0.2 $ 0.3 $ 0.3 Interest cost 24.4 16.5 17.3 10.1 8.4 8.4 Expected asset return (29.3) (31.0) (39.0) — — — Amortized actuarial loss (gain) 4.1 7.6 10.8 (8.5) 0.5 1.7 Amortized prior service cost (credit) 0.1 0.1 0.1 (0.5) (0.9) (1.5) Curtailment charge 1.2 — — — — — Settlement charge 0.1 — 42.3 — — — Net periodic benefit cost (credit) $ 1.7 $ (5.1) $ 33.5 $ 1.3 $ 8.3 $ 8.9 Our postretirement cost sharing asset from GM is measured on the same basis as the portion of the obligation to which it relates. The actuarial gains and losses related to the GM portion of the OPEB obligation are recognized immediately in the Consolidated Statements of Operations as an offset against the gains and losses related to the change in the corresponding GM postretirement cost sharing asset. These items are presented net in the change in benefit obligation and net periodic benefit cost components disclosed above. Remaining actuarial gains and losses are deferred and amortized over the expected future service periods of the active participants or the remaining life expectancy of the inactive participants. For measurement purposes, a weighted average annual increase in the per-capita cost of covered health care benefits of 7.00% was assumed for 2024. The rate was assumed to decrease gradually to 5.00% by 2034 and to remain at that level thereafter. The expected future pension and other postretirement benefits to be paid, net of GM cost sharing, for each of the next five years and in the aggregate for the succeeding five years thereafter are as follows: $51.5 million in 2024; $50.3 million in 2025; $52.9 million in 2026; $50.7 million in 2027; $50.6 million in 2028 and $238.7 million for 2029 through 2033. These amounts were estimated using the same assumptions that were used to measure our 2023 year-end pension and OPEB obligations and include an estimate of future employee service. Contributions We contributed $0.6 million to our pension trusts in 2023. Due to the availability of our pre-funded pension balances (previous contributions in excess of prior required pension contributions), we expect our regulatory pension funding requirements in 2024 to be less than $1.0 million. We expect our cash payments, net of GM cost sharing, for OPEB to be approximately $11.0 million in 2024. U.S. pension annuity purchase In 2021, we purchased group annuity contracts from an insurance company to settle pension obligations for certain U.S. plan participants (Pension Annuity Purchase). The purchase of the group annuity contracts, which was paid from plan assets, irrevocably transferred the remaining future pension benefit obligations for these U.S. plan participants to the insurance company and reduced our liabilities and administrative costs going forward. The Pension Annuity Purchase included approximately 3,400 of our U.S. pension plan participants. As a result of this settlement, we remeasured the assets and liabilities of our U.S. pension plans, which reduced our projected benefit obligation by $97.3 million and resulted in a non-cash pre-tax settlement charge of $42.3 million in the fourth quarter of 2021 related to the accelerated recognition of certain deferred losses. Pension plan assets The weighted-average asset allocations of our pension plan assets at December 31, 2023 and 2022 appear in the following table. The asset allocation for our plans is developed in consideration of the demographics of the plan participants and expected payment stream of the benefit obligation. U.S. Non-U.S. Target Target 2023 2022 Allocation 2023 2022 Allocation Equity securities 23.8 % 28.0 % 25% - 35% 17.8 % 13.5 % 15% - 25% Fixed income securities 69.3 64.8 60% - 70% 61.7 64.7 60% - 70% Alternative assets 5.6 6.1 0% - 10% 15.4 15.6 5% - 15% Cash 1.3 1.1 0% - 5% 5.1 6.2 0% - 5% Total 100.0 % 100.0 % 100.0 % 100.0 % The primary objective of our pension plan assets is to provide a source of retirement income for participants and beneficiaries. Our primary financial objectives for the pension plan assets have been established in conjunction with a comprehensive review of our current and projected financial requirements. These objectives include having the ability to pay all future benefits and expenses when due, maintaining flexibility and minimizing volatility. These objectives are based on a long-term investment horizon. Defined Benefit Pension Plan Assets Investments in our defined benefit plans are stated at fair value. Level 1 assets are valued using quoted market prices that represent the asset value of the shares held by the trusts. The level 2 assets are investments in pooled funds, which are valued using a model to reflect the valuation of their underlying assets that are publicly traded with observable values. The fair values of our pension plan assets are as follows: December 31, 2023 Asset Categories Level 1 Level 2 Level 3 Total (in millions) Cash and Cash Equivalents $ 8.5 $ 1.3 $ — $ 9.8 Equity U.S. Large Cap 37.2 2.2 — 39.4 U.S. Small/Mid Cap 11.5 — — 11.5 World Equity 36.2 3.0 — 39.2 Fixed Income Securities Government & Agencies 60.3 37.6 — 97.9 Corporate Bonds - Investment Grade 150.2 0.9 — 151.1 Corporate Bonds - Non-investment Grade 10.3 0.4 — 10.7 Emerging Market Debt 10.6 — — 10.6 Other 2.5 1.0 — 3.5 Other Property Funds (a) — — — 22.6 Other (a) — — — 11.8 Total Plan Assets $ 327.3 $ 46.4 $ — $ 408.1 December 31, 2022 Asset Categories Level 1 Level 2 Level 3 Total (in millions) Cash and Cash Equivalents $ 8.6 $ 1.8 $ — $ 10.4 Equity U.S. Large Cap 40.2 0.1 — 40.3 U.S. Small/Mid Cap 12.8 — — 12.8 World Equity 40.7 3.4 — 44.1 Fixed Income Securities Government & Agencies 57.9 60.0 — 117.9 Corporate Bonds - Investment Grade 123.5 0.5 — 124.0 Corporate Bonds - Non-investment Grade 9.0 0.4 — 9.4 Emerging Market Debt 8.2 — — 8.2 Other 1.7 2.3 — 4.0 Other Property Funds (a) — — — 24.9 Other (a) — — — 10.9 Total Plan Assets $ 302.6 $ 68.5 $ — $ 406.9 (a) In accordance with ASC 820 - Fair Value Measurement certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets. DEFINED CONTRIBUTION PLANS Most of our salaried and hourly U.S. associates, including certain UAW represented associates at our U.S. locations, are eligible to participate in voluntary savings plans. Our maximum match is 50% of eligible associates' contribution up to 10% of their eligible salary. Matching contributions amounted to $9.4 million in 2023, $8.6 million in 2022 and $8.0 million in 2021. Certain U.S. associates are eligible annually to receive an additional AAM Retirement Contribution (ARC) benefit between 3% to 5% of eligible salary, depending on years of service. We made ARC contributions of $9.9 million, $9.0 million and $8.3 million in 2023, 2022 and 2021, respectively.

Stock Based Compensation and Ot

Stock Based Compensation and Other Incentive Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Share-based Payment and Other Incentive Payment Arrangements [Text Block]	8. STOCK-BASED COMPENSATION AND OTHER INCENTIVE COMPENSATION STOCK-BASED COMPENSATION At December 31, 2023, we had stock-based awards outstanding under stock compensation plans approved by our stockholders. Under these plans, shares have been authorized for issuance to our directors, officers and certain other associates in the form of unvested restricted stock units, performance shares or other awards that are based on the value of our common stock. Shares available for future grants at December 31, 2023 were 5.4 million. The current stock plan will expire in May 2028. RESTRICTED STOCK UNITS We have awarded restricted stock units (RSUs). Compensation expense associated with RSUs settled in stock is recorded to paid-in-capital ratably over the three-year vesting period. The following table summarizes activity relating to our RSUs: Weighted Average Number of Grant Date Fair Shares/Units Value per Share/Unit (in millions, except per share data) Outstanding at January 1, 2021 4.9 $ 9.20 Granted 0.9 10.29 Vested (1.0) 13.65 Canceled (0.4) 8.40 Outstanding at December 31, 2021 4.4 $ 8.43 Granted 1.4 8.98 Vested (0.8) 14.73 Canceled (0.1) 6.47 Outstanding at December 31, 2022 4.9 $ 7.66 Granted 1.3 8.36 Vested (2.6) 5.62 Canceled (0.2) 9.53 Outstanding at December 31, 2023 3.4 $ 9.34 As of December 31, 2023, unrecognized compensation cost related to unvested RSUs totaled $11.2 million. The weighted average period over which this cost is expected to be recognized is approximately two years. In 2023 and 2022, the total fair market value of RSUs vested was $23.2 million and $6.0 million, respectively. PERFORMANCE SHARES As of December 31, 2023, we have performance shares (PS) outstanding under our 2018 Amended and Restated Omnibus Incentive Plan. We grant performance shares payable in stock to officers and certain other associates which vest in full over a three-year performance period. In 2023, 2022 and 2021, grants to officers were based on AAM's free cash flow in each of the three years of the performance period, as well as the cumulative free cash flow over the same period, adjusted based on a total shareholder return (TSR) measure. The TSR metric compares our TSR over the three-year performance period relative to the TSR of our pre-defined competitor peer group. Additionally, during 2023 and 2022, grants to certain other associates were based on AAM's three-year cumulative free cash flow. Based on these free cash flow and relative TSR performance metrics, the number of performance shares that become exercisable for officers will be between 0% and 230% of the grant date amount and for other associates between 0% and 150% of the grant date amount. Share price appreciation and dividends paid are measured over the performance period to determine TSR. As these awards are settled in stock, the compensation expense is recorded ratably over the vesting period to paid-in-capital. The following table summarizes activity relating to our performance shares: Weighted Average Number of Grant Date Fair Shares Value per Share TSR Awards (in millions, except per share data) Outstanding at January 1, 2021 0.6 $ 18.86 Granted — — Vested (0.3) 13.91 Canceled — — Outstanding at December 31, 2021 0.3 $ 24.36 Granted — — Vested (0.3) 24.36 Canceled — — Outstanding at December 31, 2022 — $ — Granted — — Vested — — Canceled — — Outstanding at December 31, 2023 — $ — Free Cash Flow Awards Outstanding at January 1, 2021 1.2 $ 7.50 Granted 0.4 11.26 Vested (0.3) 14.28 Canceled (0.1) 6.96 Outstanding at December 31, 2021 1.2 $ 6.96 Granted 0.5 9.83 Vested — — Canceled (0.1) 9.26 Outstanding at December 31, 2022 1.6 $ 7.81 Granted 0.6 9.19 Vested (0.9) 5.93 Canceled (0.1) 10.20 Outstanding at December 31, 2023 1.2 $ 9.80 We estimate the fair value of our free cash flow performance shares on the date of grant using our estimated three-year cumulative free cash flow, based on AAM's budget and long-range plan assumptions at the time, and adjust quarterly as necessary. We estimate the fair value of our TSR metric on the date of grant using the Monte Carlo simulation approach. The Monte Carlo simulation approach utilizes inputs on volatility assumptions, risk free rates, the price of the Company’s and our competitor peer group's common stock and their correlation as of each valuation date. Volatility assumptions are based on historical and implied volatility measurements. Based on the current fair value, the estimated unrecognized compensation cost related to unvested PS totaled $5.4 million, as of December 31, 2023. The weighted-average period over which this cost is expected to be recognized is approximately two years. OTHER INCENTIVE COMPENSATION LONG-TERM CASH AWARDS As of December 31, 2023, we have long-term cash awards (LTCAs) outstanding under our 2018 Amended and Restated Omnibus Incentive Plan. The $5.2 million, $4.6 million and $7.8 million of LTCAs granted during 2023, 2022 and 2021 respectively, are payable in cash to certain associates which vest in full over a three-year period. Compensation expense associated with LTCAs paid in cash is recorded ratably over the three-year vesting period. As of December 31, 2023, unrecognized compensation cost related to unvested LTCAs totaled $5.2 million. The weighted average period over which this cost is expected to be recognized is approximately two years. PERFORMANCE UNITS

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	9. INCOME TAXES The components of income (loss) before income taxes are as follows: 2023 2022 2021 (in millions) U.S. loss $ (212.5) $ (57.0) $ (186.8) Non - U.S. income 188.0 123.3 188.0 Total income (loss) before income taxes $ (24.5) $ 66.3 $ 1.2 The following is a summary of the components of our provision for income taxes: 2023 2022 2021 (in millions) Current Federal $ 8.5 $ 11.7 $ 3.5 State and local 0.9 1.3 0.3 Foreign 38.0 21.8 34.0 Total current $ 47.4 $ 34.8 $ 37.8 Deferred Federal $ (38.5) $ (23.2) $ (40.7) State and local (0.5) 0.1 (0.9) Foreign 0.7 (9.7) (0.9) Total deferred (38.3) (32.8) (42.5) Total income tax expense (benefit) $ 9.1 $ 2.0 $ (4.7) The following is a reconciliation of income taxes calculated at the U.S. federal statutory income tax rate of 21% in 2023, 2022 and 2021 to our provision for income taxes: 2023 2022 2021 (in millions) Federal statutory $ (5.1) $ 13.9 $ 0.3 Foreign income taxes (14.9) (14.7) (14.0) Change in enacted tax rate 0.2 — 0.1 State and local (7.5) 2.4 3.0 Tax credits (14.2) (9.6) (11.0) Valuation allowance 45.0 9.5 2.7 Withholding taxes 7.3 4.4 3.2 U.S. tax on unremitted foreign earnings 0.5 1.6 2.2 Tax benefit on loss carryback — — (5.2) Global intangible low-taxed income (GILTI) 15.3 6.4 6.5 Foreign derived intangible income deduction (0.1) (13.9) — Uncertain tax positions 1.3 3.8 1.2 Reorganization and restructuring actions (26.1) — — Other 7.4 (1.8) 6.3 Effective income tax expense (benefit) $ 9.1 $ 2.0 $ (4.7) In 2023, our effective income tax rate varied from the U.S. federal statutory rate primarily as a result of approximately $36.1 million attributable to both increased valuation allowances on disallowed interest expense in the United States, as well as net income tax expense resulting from various changes in determinations related to the potential realization of deferred tax assets and the resulting establishment of, and release of, valuation allowances in certain foreign jurisdictions. These income tax expenses were partially offset by a net income tax benefit of approximately $26.1 million resulting from various internal reorganization and restructuring actions during the year, which in turn was partially offset by the associated impact on our foreign derived intangible income and disallowed interest deductions in the U.S., as well as the impact of favorable foreign tax rates and tax credits. In 2022, our effective income tax rate varied from the U.S. federal statutory rate primarily as a result of recognizing a net income tax benefit of approximately $7.5 million due to changes in our determination related to the potential realization of deferred tax assets and the resulting release of a valuation allowance in a foreign jurisdiction, as well as the benefit from foreign derived intangible income deductions in the U.S. In addition, our effective tax rate varies from the U.S. federal statutory rate as a result of the $13.6 million gain on bargain purchase of Tekfor, which was not subject to income tax. In 2021, our effective income tax rate varied from the U.S. federal statutory rate primarily as a result of recognizing a net income tax benefit of approximately $5.2 million related to our ability to carry back prior year losses to tax years with the higher 35% corporate income tax rate. As of December 31, 2023, we have refundable income taxes of approximately $31.8 million, $20.0 million of which is classified as Prepaid expenses and other and $11.8 million classified as Other assets and deferred charges on our Consolidated Balance Sheet, as compared to approximately $17.1 million classified as Prepaid expenses and other and $1.7 million classified as Other assets and deferred charges as of December 31, 2022. We also have income taxes payable of approximately $10.6 million and $7.5 million classified as Accrued expenses and other on our Consolidated Balance Sheets as of December 31, 2023 and 2022, respectively. The approximate tax effect of each significant type of temporary difference and carryforward that results in a deferred tax asset or liability is as follows: December 31, 2023 2022 (in millions) Deferred tax assets Employee benefits $ 112.1 $ 109.0 Inventory 39.3 38.9 Net operating loss (NOL) carryforwards 173.1 203.7 Tax credit carryforwards 36.6 64.5 Capital allowance carryforwards 12.9 11.5 Capitalized expenditures 86.1 63.1 Interest carryforward 87.0 42.4 Operating lease liabilities 27.5 24.4 Other 71.3 33.3 Valuation allowances (267.1) (217.5) Deferred tax assets $ 378.8 $ 373.3 Deferred tax liabilities Other intangible assets $ (127.4) $ (136.8) Fixed assets (48.1) (88.7) Operating lease right-of-use assets (27.1) (24.2) Other (23.3) (15.3) Deferred tax liabilities $ (225.9) $ (265.0) Deferred tax assets, net $ 152.9 $ 108.3 Deferred tax assets and liabilities recognized in our Consolidated Balance Sheets are as follows: December 31, 2023 2022 (in millions) U.S. federal and state deferred tax asset, net $ 88.2 $ 47.6 Other foreign deferred tax asset, net 64.7 60.7 Deferred tax asset, net $ 152.9 $ 108.3 DEFERRED INCOME TAX ASSETS AND LIABILITIES AND VALUATION ALLOWANCES The deferred income tax assets and liabilities summarized above reflect the impact of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the basis of such assets and liabilities for income tax purposes. ASC 740 - Income Taxes states that companies must measure deferred tax amounts at the rate at which they are expected to be realized. As of December 31, 2023 and December 31, 2022, we had deferred tax assets from domestic and foreign net operating loss and tax credit carryforwards of $222.6 million and $279.7 million, respectively. Approximately $110.8 million of the deferred tax assets at December 31, 2023 relate to NOL and tax credits that can be carried forward indefinitely with the remainder expiring between 2024 and 2043. Accounting guidance for income taxes requires a deferred tax liability to be established for the U.S. tax impact of undistributed earnings of foreign subsidiaries unless it can be shown that these earnings will be permanently reinvested outside the U.S. The undistributed earnings of our foreign subsidiaries will generally not be taxed upon repatriation to the U.S. as these earnings will be treated as previously taxed income from either the one-time transition tax or GILTI, or they will be offset with a full dividends received deduction. We have provided deferred income taxes for the estimated foreign income tax and applicable withholding taxes on earnings of subsidiaries expected to be distributed. In accordance with the accounting guidance for income taxes, we review the likelihood that we will realize the benefit of deferred tax assets and estimate whether recoverability of our deferred tax assets is “more likely than not,” based on forecasts of taxable income in the related tax jurisdictions. In determining the requirement for a valuation allowance, the historical results, projected future operating results based upon approved business plans, eligible carry forward periods, and tax planning opportunities are considered, along with other relevant positive and negative evidence. If, based upon available evidence, it is more likely than not the deferred tax assets will not be realized, a valuation allowance is recorded. During 2021, we increased the valuation allowance related to certain U.S. federal income tax attributes to approximately $7.0 million. During 2022 and 2023, we recorded a full valuation allowance against the deferred tax asset established for the current year estimated increase in disallowed interest expense deductions in the U.S., resulting in an increase in tax expense of approximately $15.7 million and $31.0 million, respectively. Further, due to the uncertainty associated with the extent and ultimate impact of the significant supply chain constraints affecting the automotive industry, as well as the potential impact of geopolitical conflicts or events and macroeconomic factors, including sustained or increased inflation, we may experience lower than projected earnings in certain jurisdictions in future periods and, as a result, it is reasonably possible that changes in valuation allowances could be recognized in future periods and such changes could be material to our financial statements. During 2023, 2022 and 2021, we recorded a net tax expense of $8.9 million, $0.6 million and $0.8 million, respectively, resulting from net losses in certain jurisdictions with no corresponding tax benefit due to increases in our valuation allowance. These income tax expenses were increased in 2023, 2022 and 2021 by a net tax expense of $36.1 million, $8.9 million, and $1.9 million, respectively, resulting from changes in determinations relating to the potential realization of deferred tax assets and the resulting establishment of, or release of, valuation allowances, as well as the increase in valuation allowances related to the disallowed U.S. interest expense deductions. On June 1, 2022, our acquisition of Tekfor became effective and we recorded a valuation allowance against certain U.S. and foreign deferred tax assets of $7.8 million as of June 1, 2022 associated with the acquired entities. As of December 31, 2023 and December 31, 2022, we have a valuation allowance of $267.1 million and $217.5 million, respectively, related to net deferred tax assets in several foreign jurisdictions and U.S. federal, state and local jurisdictions. UNRECOGNIZED INCOME TAX BENEFITS To the extent that we have uncertain tax positions, a determination is made as to whether such positions meet the “more likely than not” threshold. This threshold must be met in order to record any tax benefit and, to the extent that an uncertain tax position meets the "more likely than not" threshold, we have measured and recorded the highest probable benefit, and have established appropriate reserves for benefits that exceed the amount likely to be sustained upon examination. A reconciliation of the beginning and ending amounts of unrecognized income tax benefits is as follows: Unrecognized Income Tax Interest and Benefits Penalties (in millions) Balance at January 1, 2021 $ 20.2 $ 2.0 Increase in prior year tax positions — — Decrease in prior year tax positions (1.0) (0.1) Increase in current year tax positions 2.0 0.3 Foreign currency remeasurement adjustment — — Balance at December 31, 2021 $ 21.2 $ 2.2 Increase in prior year tax positions 3.6 1.1 Decrease in prior year tax positions (0.8) — Increase in current year tax positions 0.5 — Tekfor acquisition 12.6 — Foreign currency remeasurement adjustment 0.1 — Balance at December 31, 2022 $ 37.2 $ 3.3 Increase in prior year tax positions 1.7 0.5 Decrease in prior year tax positions (9.3) (0.6) Increase in current year tax positions 11.8 — Settlement (6.9) (0.3) Foreign currency remeasurement adjustment 0.7 — Balance at December 31, 2023 $ 35.2 $ 2.9 At December 31, 2023 and December 31, 2022, we had $35.2 million and $37.2 million of gross unrecognized income tax benefits, respectively. In 2023, we reduced our liability for unrecognized income tax benefits and related interest and penalties as a result of a change in estimate on previously recorded unrecognized tax benefits in certain jurisdictions. On June 1, 2022, our acquisition of Tekfor became effective and we recorded a liability for unrecognized income tax benefits of $12.6 million as of June 1, 2022 associated with the acquired entities. In 2023, 2022, and 2021, we recognized a tax expense/(benefit) of $(0.1) million, $1.1 million and $0.2 million, respectively, related to interest and penalties in Income tax expense (benefit) on our Consolidated Statements of Operations. We have a liability of $2.9 million and $3.3 million related to the estimated future payment of interest and penalties at December 31, 2023 and 2022, respectively. The amount of the unrecognized income tax benefits, including interest and penalties, as of December 31, 2023 that, if recognized, would affect the effective tax rate is $33.8 million. We operate in multiple jurisdictions throughout the world and the income tax returns of several subsidiaries in various tax jurisdictions are currently under examination. We are currently under a U.S. federal income tax examination for years 2015 through 2020. Generally, we are no longer subject to U.S. federal, state and local, or non-U.S. income tax examinations by tax authorities prior to 2015. Based on the status of ongoing tax audits and the protocol of finalizing audits by the relevant tax authorities, it is not possible to estimate the impact of changes, if any, to previously recorded uncertain tax positions. Negative or unexpected outcomes of tax examinations and audits, and any related litigation, could have a material adverse impact on our results of operations, financial condition and cash flows. We will continue to monitor the progress and conclusions of all ongoing audits and other communications with tax authorities and will adjust our estimated liability as necessary. Other Income Tax Matters Pending Tax Litigation During their examination of our 2015 U.S. federal income tax return, the Internal Revenue Service (IRS) asserted that income earned by a Luxembourg subsidiary from its Mexican branch operations should be categorized as foreign base company sales income (FBCSI) under Section 954(d) of the Internal Revenue Code and recognized currently as taxable income on our 2015 U.S. federal income tax return. As a result of this assertion, the IRS issued a Notice of Proposed Adjustment (NOPA). AAM disagreed with the NOPA, believes that the proposed adjustment is without merit and contested the matter through the IRS's administrative appeals process. No resolution was reached in the appeals process and, in September 2022, the IRS issued a Notice of Deficiency. The IRS subsequently issued a Notice of Tax Due in December 2022 and AAM paid the assessed tax and interest of $10.1 million in January 2023. We filed a claim for refund for the amount of tax and interest paid related to this matter for the 2015 tax year and, in December 2023, we filed suit in the U.S. Court of Federal Claims. We believe, after consultation with tax and legal counsel, that it is more likely than not that our structure did not give rise to FBCSI, and it's likely that we will be successful in ultimately defending our position. As such, we have not recorded any impact of the IRS’s proposed adjustment in our consolidated financial statements as of, and for the year ended, December 31, 2023, with the exception of the cash payment and associated income tax receivable of $10.1 million paid by AAM to the IRS in 2023. As of December 31, 2023, in the event AAM is not successful in defending its position, the potential additional income tax expense, including estimated interest charges, related to tax years 2015 through 2023, is estimated to be in the range of approximately $300 million to $350 million. Reorganization of Global Operating Structure As a result of changes to non-U.S. corporate tax laws, we performed a review, in consultation with our tax and legal advisors, of AAM’s global operating structure in 2023. This involved a detailed analysis of the impact of legislation enacted or proposed by non-U.S. members of the OECD and G20 to implement pillar two of the Framework, as well as other recent global tax law developments, and the expected interaction of these developments with U.S. tax law. Based upon this analysis, AAM implemented certain actions to reorganize our global operating structure effective as of December 31, 2023. The review of our global operating structure was not related to the FBCSI income tax matter described above, however, this reorganization has also eliminated the FBCSI U.S. issue for tax years after 2023.

Earnings (Loss) Per Share (EPS)

Earnings (Loss) Per Share (EPS)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	10. EARNINGS (LOSS) PER SHARE (EPS) We present EPS using the two-class method. This method allocates undistributed earnings between common shares and non-vested share based payment awards that entitle the holder to non-forfeitable dividend rights. Our participating securities are our 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): 2023 2022 2021 (in millions, except per share data) Numerator Net income (loss) $ (33.6) $ 64.3 $ 5.9 Less: Net income allocated to participating securities — (2.7) (0.2) Net income (loss) attributable to common shareholders - Basic and Dilutive $ (33.6) $ 61.6 $ 5.7 Denominators Basic common shares outstanding - Weighted-average shares outstanding 120.3 119.4 118.5 Less: Weighted-average participating securities (3.7) (4.9) (4.6) Weighted-average common shares outstanding 116.6 114.5 113.9 Effect of dilutive securities - Dilutive stock-based compensation — 1.0 0.2 Diluted shares outstanding - Adjusted weighted-average shares after assumed conversions 116.6 115.5 114.1 Basic EPS $ (0.29) $ 0.54 $ 0.05 Diluted EPS $ (0.29) $ 0.53 $ 0.05

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	11. COMMITMENTS AND CONTINGENCIES PURCHASE COMMITMENTS Obligated purchase commitments for capital expenditures and related project expenses were approximately $137.8 million at December 31, 2023 and $110.7 million at December 31, 2022. Of the approximately $137.8 million of purchase commitments at December 31, 2023, $124.0 million is expected to be paid in 2024 and $13.8 million is expected to be paid in 2025 and thereafter. LEGAL PROCEEDINGS We are involved in, or potentially subject to, various legal proceedings or claims incidental to our business. These include, but are not limited to, matters arising out of product warranties, contractual matters, and environmental obligations. Although the outcome of these matters cannot be predicted with certainty, at this time we do not believe that any of these matters, individually or in the aggregate, will have a material adverse effect on our financial condition, results of operations or cash flows. We file U.S. federal, state and local income tax returns, as well as foreign income tax returns in jurisdictions throughout the world. We are also subject to examinations of these tax returns by the relevant tax authorities. Negative or unexpected outcomes of these examinations and audits, and any related litigation, could have a material adverse impact on our results of operations, financial condition and cash flows. See Note 9 - Income Taxes for additional discussion regarding examinations and audits of our tax returns and pending litigation. We are subject to various federal, state, local and foreign environmental and occupational safety and health laws, regulations and ordinances, including those regulating air emissions, water discharge, waste management and environmental cleanup. We will continue to closely monitor our environmental conditions to ensure that we are in compliance with all laws, regulations and ordinances. We have made, and anticipate continuing to make, capital and other expenditures (including recurring administrative costs) to comply with environmental requirements at our current and former facilities. Such expenditures were not significant in 2023, 2022 and 2021. ENVIRONMENTAL OBLIGATIONS Due to the nature of our manufacturing operations, we have legal obligations to perform asset retirement activities pursuant to federal, state, and local requirements at our current and former facilities. The process of estimating environmental liabilities is complex. Significant uncertainty may exist related to the timing and method of the settlement of these obligations. Therefore, these liabilities are not reasonably estimable until a triggering event occurs that allows us to estimate a range and assess the probabilities of potential settlement dates and the potential methods of settlement. In the future, we will update our estimated costs and potential settlement dates and methods and their associated probabilities based on available information. Any update may change our estimate and could result in a material adjustment to this liability. 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 monitor actual warranty claim data and adjust the liability, as necessary, on a quarterly basis. During 2023 and 2022, we also made adjustments to our warranty accrual to reflect revised estimates regarding our projected future warranty obligations. The following table provides a reconciliation of changes in the product warranty liability: December 31, 2023 2022 (in millions) Beginning balance $ 54.1 $ 59.5 Accruals 26.4 14.1 Settlements (11.4) (10.8) Adjustments to prior period accruals (3.1) (7.9) Foreign currency translation 0.3 (0.8) Ending balance $ 66.3 $ 54.1 In 2023, we recorded $7 million of expense related to a field action with one of our largest customers for a die cast component included in transmission assemblies. We reached agreement on this field action with our customer in the fourth quarter of 2023 and we do not expect to record any additional liabilities associated with this item.

Reclassifications out of Accumu

Reclassifications out of Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2023
Reclassifications out of Accumulated Other Comprehensive Income [Abstract]
Disclosure of Reclassification Amount [Text Block]	12. RECLASSIFICATIONS OUT OF ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Reclassification adjustments and other activity impacting accumulated other comprehensive income (loss) (AOCI) during the years ended December 31, 2023, December 31, 2022 and December 31, 2021 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Gain (Loss) on Cash Flow Hedges Total Balance at January 1, 2021 $ (311.0) $ (101.1) $ (20.1) $ (432.2) Other comprehensive income (loss) before reclassifications 33.9 (10.7) 22.2 45.4 Income tax effect of other comprehensive income (loss) before reclassifications (7.0) — (4.8) (11.8) Amounts reclassified from accumulated other comprehensive loss into net income 53.4 (a) 0.5 (9.8) (b) 44.1 Income taxes reclassified into net income (11.2) — 0.9 (10.3) Net current period other comprehensive income (loss) 69.1 (10.2) 8.5 67.4 Balance at December 31, 2021 $ (241.9) $ (111.3) $ (11.6) $ (364.8) Other comprehensive income (loss) before reclassifications 119.5 (38.4) 62.2 143.3 Income tax effect of other comprehensive income (loss) before reclassifications (30.2) — (9.9) (40.1) Amounts reclassified from accumulated other comprehensive loss into net income 7.3 (a) — (22.9) (b) (15.6) Income taxes reclassified into net income (1.6) — 3.4 1.8 Net current period other comprehensive income (loss) 95.0 (38.4) 32.8 89.4 Balance at December 31, 2022 $ (146.9) $ (149.7) $ 21.2 $ (275.4) Other comprehensive income before reclassifications 5.5 7.4 18.5 31.4 Income tax effect of other comprehensive income before reclassifications (1.8) — 2.4 0.6 Amounts reclassified from accumulated other comprehensive income (loss) into net loss (3.5) (a) — (16.9) (b) (20.4) Income taxes reclassified into net loss 1.4 — (0.5) 0.9 Net current period other comprehensive income 1.6 7.4 3.5 12.5 Balance at December 31, 2023 $ (145.3) $ (142.3) $ 24.7 $ (262.9) (a) The amount reclassified for 2021 includes a credit to AOCI of $42.3 million related to the effect of the Pension Annuity Purchase. See Note 7 - Employee Benefit Plans for more detail. (b) The amounts reclassified from AOCI included $(19.9) million in COGS, $(3.6) million in interest expense and $6.6 million in other income (expense), net for the year ended December 31, 2023, $(6.5) million in COGS, $(2.7) million in interest expense and $(13.7) million in other income (expense), net for the year ended December 31, 2022 and $(5.6) million in COGS, $14.8 million in interest expense and $(19.0) million in other income (expense), net for the year ended December 31, 2021.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customers [Abstract]
Revenue from Contract with Customer [Text Block]	13. REVENUE FROM CONTRACTS WITH CUSTOMERS The guidance in ASC 606 - Revenue from Contracts with Customers 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 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 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 front and rear axles, driveshafts, differential assemblies, clutch modules, balance shaft systems, disconnecting driveline technology, and electric and hybrid driveline products and systems for light trucks, sport utility vehicles (SUVs), crossover vehicles (CUVs), passenger cars and commercial vehicles; and • Metal Forming products consist primarily of engine, transmission, driveline and safety-critical components for traditional internal combustion engine and electric vehicle architectures including light vehicles, commercial vehicles and off-highway vehicles, as well as products for industrial markets. Our contracts with customers, which are comprised of purchase orders and delivery releases issued by our 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 - Commitments and Contingencies for further information on our product warranties. 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 years ended December 31, 2023, 2022 and 2021. Net sales are attributed to regions based on the location of production. Intersegment sales have been excluded from the table. Twelve Months Ended December 31, 2023 Driveline Metal Forming Total (in millions) North America $ 3,133.8 $ 1,303.2 $ 4,437.0 Asia 506.4 38.3 544.7 Europe 441.2 472.2 913.4 South America 95.1 89.3 184.4 Total $ 4,176.5 $ 1,903.0 $ 6,079.5 Twelve Months Ended December 31, 2022 Driveline Metal Forming Total North America $ 3,139.8 $ 1,301.4 $ 4,441.2 Asia 449.8 43.5 493.3 Europe 391.6 338.9 730.5 South America 82.3 55.1 137.4 Total $ 4,063.5 $ 1,738.9 $ 5,802.4 Twelve Months Ended December 31, 2021 Driveline Metal Forming Total North America $ 2,793.4 $ 1,189.0 $ 3,982.4 Asia 441.6 47.4 489.0 Europe 374.8 216.1 590.9 South America 85.3 9.0 94.3 Total $ 3,695.1 $ 1,461.5 $ 5,156.6 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 (in millions) : Accounts Receivable, Net Contract Liabilities (Current) Contract Liabilities (Long-term) December 31, 2022 $ 820.2 $ 28.1 $ 73.4 December 31, 2023 818.5 16.6 70.4 Increase/(decrease) $ (1.7) $ (11.5) $ (3.0) Contract liabilities relate to deferred revenue associated with various settlements and commercial agreements for which we have future performance obligations 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. During the twelve months ended December 31, 2023 and December 31, 2022 we amortized $30.2 million and $31.3 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.

Leasing

Leasing	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Lessee, Operating Leases and Finance Leases	14. LEASING When an agreement grants us the right to substantially all of the economic benefits associated with an identified asset, and we are able to direct the use of that asset throughout the term of the agreement, we have a lease. We lease certain facilities, manufacturing machinery and equipment under finance leases, and we also lease certain commercial office and production facilities, manufacturing machinery and equipment, vehicles and other assets under operating leases. Some of our leases include options to extend or terminate the leases and these options have been included in the relevant lease term to the extent that they are reasonably certain to be exercised. The lease consideration for some of our facilities and machinery and equipment is variable, as it is based on various indices or usage of the underlying assets, respectively. Variable lease payments based on indices have been included in the related right-of-use assets and lease liabilities on our Consolidated Balance Sheets, while variable lease payments based on usage of the underlying asset have been excluded as they do not represent present rights or obligations. Lease cost consists of the following: Twelve Months Ended December 31, 2023 2022 2021 (in millions) Finance lease cost Amortization of right-of-use assets $ 12.3 $ 9.9 $ 4.2 Interest on lease liabilities 5.1 4.7 2.0 Total finance lease cost 17.4 14.6 6.2 Operating lease cost 30.9 32.6 33.3 Short-term lease cost 2.1 1.4 1.6 Variable lease cost 5.8 5.6 3.2 Total lease cost $ 56.2 $ 54.2 $ 44.3 For the year ended December 31, 2023, $33.4 million and $5.4 million were recorded to Cost of goods sold (COGS) and Selling, general and administrative expenses (SG&A), respectively, related to our operating leases, on our Consolidated Statements of Operations, as compared to $31.8 million and $7.8 million, respectively, for the year ended December 31, 2022 and $29.1 million and $9.0 million, respectively, for the year ended December 31, 2021. The following table summarizes additional information related to our lease agreements. Twelve Months Ended December 31, 2023 2022 2021 (in millions, except lease term and rate) Cash paid for amounts included in measurement of lease liabilities Operating cash flows from finance leases $ 5.1 $ 4.7 $ 2.0 Operating cash flows from operating leases 36.1 37.6 35.9 Financing cash flows from finance leases 13.7 11.2 5.0 Weighted-average remaining lease term - finance leases 12.7 years 13.1 years 16.4 years Weighted-average remaining lease term - operating leases 7.9 years 8.4 years 8.6 years Weighted-average discount rate - finance leases 5.0 % 4.9 % 4.8 % Weighted-average discount rate - operating leases 6.4 % 5.4 % 5.2 % As the rate implicit in the lease is typically unknown, the discount rate used to determine the lease liability for the majority of our leases is the collateralized incremental borrowing rate in the applicable geographic area for a similar term and amount as the lease agreement. Future undiscounted minimum payments under non-cancelable leases are as follows: Finance Leases Operating Leases (in millions) 2024 $ 15.8 $ 28.7 2025 12.9 24.1 2026 11.5 17.7 2027 9.6 13.6 2028 8.3 10.6 Thereafter 73.2 54.4 Total future undiscounted minimum lease payments 131.3 149.1 Less: Impact of discounting (32.8) (31.7) Total $ 98.5 $ 117.4 The right-of-use assets and lease liabilities recorded on our Consolidated Balance Sheets are as follows: December 31, 2023 December 31, 2022 Finance Leases Operating Leases Finance Leases Operating Leases (in millions) (in millions) Property, plant and equipment, net $ 102.4 $ — $ 106.2 $ — Operating lease right-of-use assets — 115.6 — 107.2 Total $ 102.4 $ 115.6 $ 106.2 $ 107.2 Current portion of operating lease liabilities $ — $ 21.9 $ — $ 21.1 Accrued expenses and other 11.2 — 13.0 — Long-term portion of operating lease liabilities — 95.5 — 87.2 Postretirement benefits and other long-term liabilities 87.3 — 92.4 — Total $ 98.5 $ 117.4 $ 105.4 $ 108.3 Leases Not Yet Commenced

Manufacturing Facility Fire and

Manufacturing Facility Fire and Insurance Recovery	12 Months Ended
	Dec. 31, 2023
Insurance Recoveries [Abstract]
Manufacturing Facility Fire and Insurance Recovery	15. MANUFACTURING FACILITY FIRE AND INSURANCE RECOVERY On September 22, 2020, a significant industrial fire occurred at our Malvern Manufacturing Facility in Ohio (Malvern Fire). All associates were evacuated safely and without injury and we were able to maintain continuity of supply to our customers without any significant disruptions. In the fourth quarter of 2022, we finalized the claim with our insurance providers. In January 2023, we collected the final $24.0 million associated with this claim, of which $7.0 million has been presented as an operating cash inflow and $17.0 million has been presented as an investing cash inflow in our Consolidated Statement of Cash Flows for the year ended December 31, 2023. There was no impact on our Consolidated Statement of Operations for the year ended December 31, 2023. The amounts detailed in this footnote represent the final claim eligible expenses and recoveries associated with the Malvern Fire. Since the date of the Malvern Fire and the establishment of the insurance claim, we incurred $55.1 million of total charges primarily related to site services and clean-up, transportation and freight, asset repairs and other costs incurred to resume or relocate operations and ensure continuity of supply to our customers. In addition, we recorded a total of $27.0 million of costs primarily associated with the write-down of PP&E as a result of damage from the fire. We recorded total insurance recoveries and received total reimbursements under our insurance policies of $123.3 million, of which $11.1 million was received in 2020, $59.1 million was received in 2021, $29.1 million was received in 2022 and $24.0 million was received in 2023.

Acquisitions and Dispositions

Acquisitions and Dispositions	12 Months Ended
	Dec. 31, 2023
Acquisitions and Dispositions [Abstract]
Acquisitions and Dispositions [Text Block]	16. ACQUISITIONS AND DISPOSITIONS Acquisition of Tekfor Group On June 1, 2022, our acquisition of Tekfor Group became effective and we paid a total purchase price of $94.4 million, which was funded entirely with cash on hand. Tekfor Group manufactures high-performance components, modules and fasteners, including traditional powertrain and driveline components (for both internal combustion and hybrid applications), and e-mobility components. Our acquisition of Tekfor contributes to diversifying our geographic and customer sales mix, while also increasing our electrification product portfolio. The acquisition of Tekfor Group was accounted for under the acquisition method under ASC 805 - Business Combinations 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 (in millions) : December 31, 2022 Total consideration transferred $ 94.4 Cash and cash equivalents $ 14.3 Accounts receivable 33.7 Inventories 46.3 Prepaid expenses and other long-term assets 30.1 Deferred income tax assets 5.0 Property, plant and equipment 105.5 Total assets acquired $ 234.9 Accounts payable 33.5 Accrued expenses and other 28.1 Debt 23.4 Postretirement benefits and other long-term liabilities 41.9 Net assets acquired $ 108.0 Gain on bargain purchase of business $ 13.6 The gain on bargain purchase of business was primarily the result of macroeconomic factors at the time of acquisition such as the supply chain disruptions that have impacted the automotive industry, including the conflict between Russia and Ukraine, the semiconductor supply shortage, and increasing input costs, including materials, freight and utilities. We finalized the valuation of the assets and liabilities of Tekfor in the first quarter of 2023 as we concluded the customary post-closing reviews associated with the acquisition. There were no adjustments to the purchase price allocation in the year ended December 31, 2023. Included in net sales and net loss for the year ended December 31, 2023 was approximately $397.2 million and a loss of approximately $19.8 million, respectively, attributable to Tekfor. Included in net sales and net income for the period from the acquisition effective date on June 1, 2022 through December 31, 2022 was $204.0 million and a net loss of $5.1 million, respectively, attributable to Tekfor Group. The 2022 net loss attributable to Tekfor includes a one-time expense of approximately $4.0 million, net of tax, for the step-up of inventory to fair value. Unaudited Pro Forma Financial Information Unaudited pro forma net sales for AAM, on a combined basis with Tekfor Group for the years ended December 31, 2022 and December 31, 2021, were $5.95 billion and $5.50 billion, respectively, excluding Tekfor Group sales to AAM during those periods. Unaudited pro forma net income amounts for the years ended December 31, 2022 and December 31, 2021 were approximately $55 million and $15 million, respectively. Unaudited pro forma earnings per share amounts for the year ended December 31, 2022 and December 31, 2021 were $0.46 per share and $0.13 per share, respectively. Unaudited pro forma net income for the year ended December 31, 2021 includes a one-time gain of approximately $15 million associated with a Tekfor Group entity as a result of a favorable tax ruling in a foreign jurisdiction. The unaudited pro forma net income amounts for the years ended December 31, 2022 and December 31, 2021 have been adjusted for approximately $4 million, net of tax, related to the step-up of inventory to fair value as a result of the acquisition, approximately $5 million, net of tax, for acquisition-related costs, and approximately $14 million for the gain on bargain purchase of business, which was not subject to tax. This resulted in a net reclassification of approximately $5 million from unaudited pro forma net income in 2022 into unaudited pro forma net income in 2021, as we are required to disclose the unaudited pro forma amounts as if the acquisition of Tekfor Group had been completed on January 1, 2021. 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 Manufacturing Facility in Emporium, Pennsylvania In May 2021, AAM completed our acquisition of Emporium, under which we acquired $14.9 million of net assets that consisted of $5.9 million of inventory and $9.0 million of property, plant and equipment. The purchase price was $14.9 million, which consisted of $4.9 million of cash and $10.0 million of a deferred consideration liability that will be paid to the seller at $2.5 million annually over the period 2022 through 2025. As the value of the net assets acquired was equal to the purchase price, no goodwill or gain on bargain purchase was recognized for this acquisition for the year ended December 31, 2021. The operating results of this manufacturing facility for the period from our acquisition date through December 31, 2021 were insignificant to AAM's Consolidated Statements of Operations for this period. Further we have not disclosed pro forma revenue and earnings for the year ended December 31, 2021 as the operating results of this manufacturing facility would be insignificant to AAM's consolidated results for this period. Following the completion of our acquisition of Emporium, we determined that we would cease production at the facility and relocate the production capacity to other AAM manufacturing facilities. In 2023, we completed the exit of Emporium. See Note 2 - Restructuring and Acquisition-Related Costs for additional detail on the restructuring charges we have incurred related to the closure of the facility. Sale of Interest in Consolidated Joint Venture

Segment and Geographic Informat

Segment and Geographic Information	12 Months Ended
	Dec. 31, 2023
Segments, Geographical Areas [Abstract]
Segment Reporting Disclosure [Text Block]	17. SEGMENT AND GEOGRAPHIC INFORMATION Our business is organized into Driveline and Metal Forming segments, with each representing a reportable segment under ASC 280 - Segment Reporting . The results of each segment are regularly reviewed by the chief operating decision maker to assess the performance of the segment and make decisions regarding the allocation of resources to the segments. Our product offerings by segment are as follows: • Driveline products consist primarily of front and rear axles, driveshafts, differential assemblies, clutch modules, balance shaft systems, disconnecting driveline technology, and electric and hybrid driveline products and systems for light trucks, SUVs, CUVs, passenger cars and commercial vehicles; and • Metal Forming products consist primarily of engine, transmission, driveline and safety-critical components for traditional internal combustion engine and electric vehicle architectures including light vehicles, commercial vehicles and off-highway vehicles, as well as products for industrial markets. We use Segment Adjusted EBITDA as the measure of earnings to assess the performance of each segment and determine the resources to be allocated to the segments. We define EBITDA to be earnings before interest expense, income taxes, depreciation and amortization. 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, loss on the sale of a business, pension curtailment and settlement charges, unrealized gains or losses on equity securities, and non-recurring items. In the first quarter of 2023, we moved a plant location that was previously reported under our Driveline segment to our Metal Forming segment in order to better align our product and process technologies. The amounts in the tables below for years ended December 31, 2022 and December 31, 2021 have been recast to reflect this reorganization. On June 1, 2022, our acquisition of Tekfor became effective and we began consolidating the results of Tekfor on that date, which are reported in our Metal Forming segment for the years ended December 31, 2023 and December 31, 2022. Year Ended December 31, 2023 Driveline Metal Forming Corporate and Eliminations Total (in millions) Sales $ 4,176.7 $ 2,454.3 $ — $ 6,631.0 Less: Intersegment sales 0.2 551.3 — 551.5 Net external sales $ 4,176.5 $ 1,903.0 $ — $ 6,079.5 Segment adjusted EBITDA $ 543.6 $ 149.7 $ — $ 693.3 Depreciation and amortization $ 260.3 $ 226.9 $ — $ 487.2 Capital expenditures $ 105.9 $ 80.1 $ 8.6 $ 194.6 Total assets $ 2,554.3 $ 1,788.7 $ 1,013.3 $ 5,356.3 Year Ended December 31, 2022 Driveline Metal Forming Corporate and Eliminations Total Sales $ 4,063.5 $ 2,280.7 $ — $ 6,344.2 Less: Intersegment sales — 541.8 — 541.8 Net external sales $ 4,063.5 $ 1,738.9 $ — $ 5,802.4 Segment adjusted EBITDA $ 510.9 $ 236.4 $ — $ 747.3 Depreciation and amortization $ 272.7 $ 219.4 $ — $ 492.1 Capital expenditures $ 103.3 $ 62.9 $ 5.2 $ 171.4 Total assets $ 2,542.0 $ 1,900.3 $ 1,027.1 $ 5,469.4 Year Ended December 31, 2021 Driveline Metal Forming Corporate and Eliminations Total Sales $ 3,695.3 $ 1,912.8 $ — $ 5,608.1 Less: Intersegment sales 0.2 451.3 — 451.5 Net external sales $ 3,695.1 $ 1,461.5 $ — $ 5,156.6 Segment adjusted EBITDA $ 541.8 $ 291.5 $ — $ 833.3 Depreciation and amortization $ 293.8 $ 250.5 $ — $ 544.3 Capital expenditures $ 123.4 $ 53.9 $ 3.9 $ 181.2 Total assets $ 2,852.0 $ 1,650.5 $ 1,133.2 $ 5,635.7 Assets included in the Corporate and Eliminations column of the tables above represent AAM corporate assets, as well as eliminations of intercompany assets. The following table represents a reconciliation of Segment Adjusted EBITDA to consolidated income (loss) before income taxes for the years ended December 31, 2023, 2022 and 2021: Year Ended December 31, 2023 2022 2021 (in millions) Segment adjusted EBITDA $ 693.3 $ 747.3 $ 833.3 Interest expense (201.7) (174.5) (195.2) Depreciation and amortization (487.2) (492.1) (544.3) Restructuring and acquisition-related costs (25.2) (30.2) (49.4) Pension curtailment and settlement charges (1.3) — (42.3) Loss on sale of business — — (2.7) Unrealized gain (loss) on equity securities (1.1) (25.5) 24.4 Debt refinancing and redemption costs (1.3) (6.4) (34.0) Malvern Fire insurance recoveries, net of charges — 39.1 11.4 Acquisition-related fair value inventory adjustment — (5.0) — Gain on bargain purchase of business — 13.6 — Income (loss) before income taxes $ (24.5) $ 66.3 $ 1.2 Financial information relating to our operations by geographic area is presented in the following table. Net sales are attributed to countries based upon location of production. Long-lived assets exclude deferred income taxes. December 31, 2023 2022 2021 (in millions) Net sales United States $ 2,163.5 $ 2,148.0 $ 1,923.5 Mexico 2,273.5 2,293.2 2,058.9 South America 184.4 137.4 94.3 China 271.6 280.0 299.6 All other Asia 273.1 213.3 189.4 Europe 913.4 730.5 590.9 Total net sales $ 6,079.5 $ 5,802.4 $ 5,156.6 Long-lived assets United States $ 1,694.3 $ 1,778.9 $ 1,976.5 Mexico 778.4 821.3 888.1 South America 75.8 71.2 40.9 China 110.9 130.1 164.8 All other Asia 79.2 80.5 87.1 Europe 441.7 475.0 501.2 Total long-lived assets $ 3,180.3 $ 3,357.0 $ 3,658.6

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2023
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Schedule II - VALUATION AND QUALIFYING ACCOUNTS Additions - Balance at Charged to Acquisitions Balance Beginning of Costs and and At End of Period Expenses Disposals (a) Deductions Period (in millions) Year Ended December 31, 2021: Allowance for credit losses (1) $ 4.5 $ 7.8 $ — $ 10.1 $ 2.2 Allowance for deferred taxes (3) 208.0 2.7 — 9.0 201.7 Inventory valuation allowance (2) 23.4 17.7 — 22.5 18.6 Year Ended December 31, 2022: Allowance for credit losses (1) 2.2 10.1 1.0 4.0 9.3 Allowance for deferred taxes (3) 201.7 9.5 7.8 1.5 217.5 Inventory valuation allowance (2) 18.6 35.7 4.9 31.7 27.5 Year Ended December 31, 2023: Allowance for credit losses (1) 9.3 4.4 — 8.4 5.3 Allowance for deferred taxes (3) 217.5 54.5 — 4.9 267.1 Inventory valuation allowance (2) 27.5 22.1 — 17.5 32.1 (a ) Amounts represent reserves recognized in conjunction with our acquisition of Tekfor in 2022. (1) Uncollectible accounts charged off, net of recoveries. (2) Primarily relates to write-offs of excess and obsolete inventories, as well as adjustments for physical quantity discrepancies. (3) Primarily reflects an increase in valuation allowance related to certain U.S. federal tax attributes, as well as new net operating losses established with a corresponding valuation allowance at certain foreign locations, partially offset by adjustments to previously established valuation allowances and foreign currency translation.

Organization and Basis of Prese

Organization and Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidation, Policy [Policy Text Block]	PRINCIPLES OF CONSOLIDATION
Cash and Cash Equivalents, Policy [Policy Text Block]	CASH AND CASH EQUIVALENTS Cash and cash equivalents include all cash balances, savings accounts, sweep accounts, and highly liquid investments in money market funds and certificates of deposit with maturities of 90 days or less at the time of purchase.
Revenue [Policy Text Block]	REVENUE RECOGNITION 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. See Note 13 - Revenue from Contracts with Customers for more detail on our revenue.
Accounts Receivable [Policy Text Block]	ACCOUNTS RECEIVABLE The majority of our accounts receivable are due from original equipment manufacturers (OEMs) in the automotive industry and are considered past due when payment is not received within the terms stated within the contract. Trade accounts receivable for our customers are generally due within approximately 50 days from the date our customers receive our product. Amounts due from customers are stated net of allowances for credit losses. We determine our allowances by considering our expected credit losses, in addition to factors such as our previous loss history, customers' ability to pay their obligations to us, and the condition of the general economy and industry as a whole. The allowance for credit losses was $5.3 million and $9.3 million as of December 31, 2023 and 2022, respectively. We write-off accounts receivable when they become uncollectible. We have agreements in place with factoring companies to sell customer receivables on a nonrecourse basis from certain of our locations in Europe. The factoring companies collect payment for the sold receivables and AAM has no continuing involvement with such receivables.
Property, Plant and Equipment, Preproduction Design and Development Costs [Policy Text Block]	CUSTOMER TOOLING AND PRE-PRODUCTION COSTS RELATED TO LONG-TERM SUPPLY AGREEMENTS Engineering, research and development (R&D), and other pre-production design and development costs for products sold on long-term supply arrangements are expensed as incurred unless we have a contractual guarantee for reimbursement from the customer. Reimbursements received for pre-production costs relating to awarded programs are deferred and recognized into revenue over the life of the associated program. Reimbursements received for pre-production costs relating to future programs that have not been awarded, or amounts received for programs that become discontinued prior to production, are recorded as a reduction of expense.
Inventory, Policy [Policy Text Block]	INVENTORIES
Maintenance, Repair & Operations (MRO) [Policy Text Block]	MAINTENANCE, REPAIR AND OPERATIONS (MRO) MATERIALS
Property, Plant and Equipment, Policy [Policy Text Block]	PROPERTY, PLANT AND EQUIPMENT (PP&E) We state property, plant and equipment, including amortizable tooling, at historical cost, as adjusted for impairments. Construction in progress includes costs incurred for the construction of buildings and building improvements, and machinery and equipment in process. Repair and maintenance costs that do not extend the useful life or otherwise improve the utility of the asset beyond its existing useful state are expensed in the period incurred. We record depreciation and tooling amortization using the straight-line method over the estimated useful lives of the depreciable assets. Depreciation and tooling amortization amounted to $346.0 million, $350.4 million and $396.9 million in 2023, 2022 and 2021, respectively.
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	IMPAIRMENT OF LONG-LIVED ASSETS
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]	GOODWILL We record goodwill when the purchase price of acquired businesses exceeds the value of their identifiable net tangible and intangible assets acquired. We test our goodwill annually as of October 1, or more frequently if necessary, for impairment in accordance with the accounting guidance for goodwill and other indefinite-lived intangibles. See Note 3 - Goodwill and Other Intangible Assets, for more detail on our goodwill.
Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]	OTHER INTANGIBLE ASSETS Intangible assets are valued using primarily the relief from royalty method or the multi-period excess earnings method, both of which utilize significant unobservable inputs. These inputs are defined in the fair value hierarchy as Level 3 inputs, which require management to make estimates and assumptions regarding certain financial measures using forecasted or projected information. See Note 3 - Goodwill and Other Intangible Assets, for more detail on our intangible assets.
Lessee, Leases [Policy Text Block]	LEASING
Debt, Policy [Policy Text Block]	DEBT ISSUANCE COSTS
Derivatives, Policy [Policy Text Block]	DERIVATIVES
Foreign Currency Transactions and Translations Policy [Policy Text Block]	CURRENCY TRANSLATION AND REMEASUREMENT We translate the assets and liabilities of our foreign subsidiaries to United States (U.S.) dollars at end-of-period exchange rates. We translate the income statement elements of our foreign subsidiaries to U.S. dollars at average-period exchange rates. We report the effect of translation for our foreign subsidiaries that use the local currency as their functional currency as a separate component of stockholders' equity. Gains and losses resulting from the remeasurement of assets and liabilities in a currency other than the functional currency of a subsidiary are reported in current period income. We also report any gains and losses arising from transactions denominated in a currency other than the functional currency of a subsidiary in current period income. These foreign currency gains and losses resulted in net gains of $12.8 million and $1.9 million for the years 2023 and 2022, respectively and a net loss of $1.7 million for the year 2021 in Other income (expense), net.
Postemployment Benefit Plans, Policy [Policy Text Block]	PENSION AND OTHER POSTRETIREMENT DEFINED BENEFIT PLANS Net pension and postretirement benefit expenses and the related liabilities are determined on an actuarial basis. These plan expenses and obligations are dependent on management's assumptions developed in consultation with our actuaries. We review these actuarial assumptions at least annually and make modifications when appropriate. See Note 7 - Employee Benefit Plans, for more detail on our pension and other postretirement defined benefit plans.
Share-based Payment Arrangement [Policy Text Block]	STOCK-BASED COMPENSATION AND OTHER INCENTIVE COMPENSATION We award stock-based compensation in the form of restricted stock units (RSUs) and performance shares. For the RSUs, the grant date fair value is measured as the stock price at the date of grant. For certain performance based awards, fair value is estimated using valuation techniques that require management to use estimates and assumptions. Certain awards require that management's estimates and assumptions be evaluated at each reporting date to determine if compensation expense related to the award should be adjusted, both on a catch-up and go-forward basis. We also award incentive compensation in the form of long-term cash awards (LTCAs) and performance units (PUs). We grant the LTCAs payable in cash to certain associates which vest in full over a three-year period. We also grant PUs payable in cash to officers and certain other associates which vest in full over a three-year performance period and are based primarily on AAM's three-year cumulative free cash flow. Compensation expense is recognized over the period during which the requisite service is provided, referred to as the vesting period. See Note 8 - Stock-Based Compensation and Other Incentive Compensation, for more detail on our accounting for stock-based compensation and other incentive compensation.
Research and Development Expense, Policy [Policy Text Block]	RESEARCH AND DEVELOPMENT COSTS We expense R&D, as incurred, in selling, general and administrative expenses on our Consolidated Statements of Operations. R&D spending was $155.4 million, $144.0 million and $116.8 million in 2023, 2022 and 2021, respectively. In 2023, 2022 and 2021, our R&D expense is net of approximately $37.0 million, $20.0 million and $15.0 million, respectively, of costs capitalized as a result of contractual guarantees with customers to recover engineering, design and development costs.
Income Tax, Policy [Policy Text Block]	DEFERRED INCOME TAX ASSETS AND LIABILITIES AND VALUATION ALLOWANCES Our deferred income tax assets and liabilities reflect the impact of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the basis of such assets and liabilities for income tax purposes. In accordance with the accounting guidance for income taxes, we review the likelihood that we will realize the benefit of deferred tax assets and estimate whether recoverability of our deferred tax assets is “more likely than not,” based on forecasts of taxable income in the related tax jurisdictions. In determining the requirement for a valuation allowance, the historical results, projected future operating results based upon approved business plans, eligible carry forward periods, and tax planning opportunities are considered, along with other relevant positive and negative evidence. If, based upon available evidence, it is more likely than not the deferred tax assets will not be realized, a valuation allowance is recorded. We record uncertain tax positions on the basis of a two-step process whereby: 1) we determine whether it is "more likely than not" that the tax positions will be sustained based on the technical merits of the position: and 2) for those positions that meet the "more likely than not" recognition threshold, we recognize the largest amount of tax benefit that is greater than 50% likely to be realized upon ultimate settlement with the related tax authority. We record interest and penalties on uncertain tax positions in income tax expense (benefit). See Note 9 - Income Taxes, for more detail on our accounting for income taxes.
Earnings Per Share, Policy [Policy Text Block]	EARNINGS (LOSS) PER SHARE (EPS) We present EPS using the two-class method. This method allocates undistributed earnings between common shares and non-vested share based payment awards that entitle the holder to non-forfeitable dividend rights. Our participating securities are our non-vested restricted stock units. See Note 10 - Earnings (Loss) Per Share (EPS), for more detail on our accounting for EPS.
Standard Product Warranty, Policy [Policy Text Block]	PRODUCT WARRANTY We record estimated warranty obligation liabilities at the dates our products are sold, 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. See Note 11 - Commitments and Contingencies, for detail on our accounting for product warranties.
Use of Estimates, Policy [Policy Text Block]	USE OF ESTIMATES In order to prepare consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP), we are required to make estimates and assumptions that affect the reported amounts and disclosures in our consolidated financial statements. Actual results could differ from those estimates.
New Accounting Pronouncements, Policy [Policy Text Block]	EFFECT OF NEW ACCOUNTING STANDARDS Standards Not Yet Adopted Accounting Standards Update 2023-07 On November 27, 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2023-07 - Improvements to Reportable Segment Disclosures (Topic 280). ASU 2023-07 enhances existing annual segment requirements to include disclosure of significant segment expenses and other segment items by reportable segment that are regularly used by the Chief Operating Decision Maker (CODM) to evaluate segment performance. This guidance also requires annual disclosure of the title and position of the CODM. ASU 2023-07 also expands interim segment disclosure requirements to include all existing annual segment disclosures in addition to the new disclosure requirements for significant segment expenses and other segment items. This guidance becomes effective at the beginning of our 2024 fiscal year for annual requirements, and at the beginning of our 2025 fiscal year for interim requirements, using a retrospective transition method. We will adopt this guidance retrospectively on January 1, 2024 for the annual requirements and will adopt the interim requirements on January 1, 2025. We are currently assessing the impact that this standard will have on our consolidated financial statements. Accounting Standards Update 2023-09 On December 14, 2023, the FASB issued ASU 2023-09 - Improvements to Income Tax Disclosures (Topic 740).

Organization and Basis of Pre_2

Organization and Basis of Presentation (Tables)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Inventory, Current [Table Text Block]	Inventories consist of the following: December 31, 2023 2022 (in millions) Raw materials and work-in-progress $ 411.5 $ 398.9 Finished goods 103.5 92.5 Gross inventories 515.0 491.4 Inventory valuation reserves (32.1) (27.5) Inventories, net $ 482.9 $ 463.9
Property, Plant and Equipment [Table Text Block]	Property, plant and equipment consists of the following: Estimated December 31, Useful Lives 2023 2022 (years) (in millions) Land Indefinite $ 55.4 $ 57.8 Land improvements 10 - 15 26.9 26.5 Buildings and building improvements 15 - 40 694.9 682.0 Machinery and equipment 3 - 12 3,771.1 3,739.7 Construction in progress 151.5 140.2 4,699.8 4,646.2 Accumulated depreciation and amortization (2,938.9) (2,743.2) Property, plant and equipment, net $ 1,760.9 $ 1,903.0

Restructuring and Acquisition_2

Restructuring and Acquisition-Related Costs (Tables)	12 Months Ended
	Dec. 31, 2023
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs [Table Text Block]	A summary of our restructuring activity for the years 2023, 2022 and 2021 is shown below: Severance Charges Implementation Costs Total (in millions) Accrual at January 1, 2021 $ 1.7 $ 9.8 $ 11.5 Charges 2.9 40.3 43.2 Cash utilization (3.9) (47.4) (51.3) Accrual at December 31, 2021 0.7 2.7 3.4 Charges 3.5 18.2 21.7 Cash utilization (1.8) (19.5) (21.3) Accrual at December 31, 2022 2.4 1.4 3.8 Charges 7.2 11.1 18.3 Cash utilization (6.6) (10.8) (17.4) Accrual at December 31, 2023 $ 3.0 $ 1.7 $ 4.7
Business Combination, Separately Recognized Transactions [Table Text Block]	The following table represents a summary of charges incurred in 2023, 2022 and 2021 associated with acquisition and integration costs: Acquisition-Related Costs Integration Expenses Total (in millions) 2023 Charges $ — $ 6.9 $ 6.9 2022 Charges 6.0 2.5 8.5 2021 Charges 0.4 5.8 6.2

Schedule of Goodwill and Finite

Schedule of Goodwill and Finite Lived Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets [Abstract]
Schedule of Goodwill [Table Text Block]	The following table provides a reconciliation of changes in goodwill for the year ended December 31, 2023 and the year ended December 31, 2022: Consolidated (in millions) Balance as of January 1, 2022 $ 183.8 Foreign currency translation (2.2) Balance as of December 31, 2022 $ 181.6 Foreign currency translation 0.5 Balance as of December 31, 2023 $ 182.1
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 other intangible assets, which are all subject to amortization, as of December 31, 2023 and December 31, 2022: December 31, December 31, 2023 2022 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in millions) Capitalized computer software $ 54.2 $ (49.2) $ 5.0 $ 52.2 $ (43.2) $ 9.0 Customer platforms 856.2 (428.2) 428.0 856.2 (364.7) 491.5 Customer relationships 53.0 (23.1) 29.9 53.0 (19.7) 33.3 Technology and other 154.3 (84.4) 69.9 154.1 (71.7) 82.4 Total $ 1,117.7 $ (584.9) $ 532.8 $ 1,115.5 $ (499.3) $ 616.2

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	Long-term debt, net consists of the following: December 31, 2023 2022 (in millions) Revolving credit facility $ — $ 25.0 Term Loan A Facility 484.3 520.0 Term Loan B Facility 648.0 675.0 6.875% Notes due 2028 400.0 400.0 6.50% Notes due 2027 500.0 500.0 6.25% Notes due 2026 127.6 180.0 5.00% Notes due 2029 600.0 600.0 Foreign credit facilities 51.8 72.7 Total debt 2,811.7 2,972.7 Less: Current portion of long-term debt 17.0 75.9 Long-term debt 2,794.7 2,896.8 Less: Debt issuance costs 42.8 51.7 Long-term debt, net $ 2,751.9 $ 2,845.1
Schedule of Maturities of Long-term Debt [Table Text Block]	Aggregate maturities of long-term debt are as follows (in millions) : 2024 $ 29.1 2025 46.3 2026 190.2 2027 900.0 2028 411.7 Thereafter 1,234.4 Total $ 2,811.7

Gain (Loss) on Derivative Instr

Gain (Loss) on Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2023
Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) [Table Text Block]	The following table summarizes the reclassification of pre-tax derivative gains and losses into net income (loss) from accumulated other comprehensive income (loss) for those derivative instruments designated as cash flow hedges under Accounting Standards Codification (ASC) 815 - Derivatives and Hedging: Location of Gain (Loss) Reclassified into Net Income (Loss) Gain (Loss) Reclassified During the Twelve Months Ended December 31, Total of Financial Statement Line Item Gain Expected to be Reclassified During the Next 12 Months 2023 2022 2021 2023 (in millions) Currency forward contracts Cost of Goods Sold $ 19.9 $ 6.5 $ 5.6 $ 5,455.2 $ 15.9 Fixed-to-fixed cross-currency swap Other Income (Expense), net (6.6) 13.7 19.0 8.1 0.6 Variable-to-fixed interest rate swap Interest Expense 3.6 2.7 (14.8) (201.7) 1.2
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) [Table Text Block]	The following table summarizes the amount and location of gains recognized in the Consolidated Statements of Operations for those derivative instruments not designated as hedging instruments under ASC 815: Location of Gain (Loss) Recognized in Net Income (Loss) Gain Recognized During the Twelve Months Ended December 31, Total of Financial Statement Line Item 2023 2022 2021 2023 (in millions) Currency forward contracts Other Income (Expense), Net $ 4.7 $ 2.5 $ 0.2 $ 8.1

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	The estimated fair values 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: Fair Value December 31, 2023 December 31, 2022 Input (in millions) Balance Sheet Classification Cash equivalents $ 328.3 $ 363.6 Level 1 Prepaid expenses and other Cash flow hedges - currency forward contracts 15.9 8.2 Level 2 Cash flow hedges - variable-to-fixed interest rate swap — 2.4 Level 2 Nondesignated - currency forward contracts 0.8 0.5 Level 2 Other assets and deferred charges Cash flow hedges - currency forward contracts 5.4 3.0 Level 2 Cash flow hedges - variable-to-fixed interest rate swap — 8.5 Level 2 Investment in equity securities 0.8 1.9 Level 1 Accrued expenses and other Cash flow hedges - fixed-to-fixed cross-currency swap 9.4 — Level 2 Cash flow hedges - variable-to-fixed interest rate swap 5.0 — Level 2 Postretirement benefits and other long-term liabilities Cash flow hedges - fixed-to-fixed cross-currency swap — 1.5 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 16.5 — Level 2
Fair Value, by Balance Sheet Grouping [Table Text Block]	We estimated the fair value of our outstanding debt using available market information and other observable data to be as follows: December 31, 2023 December 31, 2022 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Revolving Credit Facility $ — $ — $ 25.0 $ 25.0 Level 2 Term Loan A Facility 484.3 483.6 520.0 510.3 Level 2 Term Loan B Facility 648.0 649.6 675.0 658.1 Level 2 6.875% Notes due 2028 400.0 387.0 400.0 355.4 Level 2 6.50% Notes due 2027 500.0 501.9 500.0 452.5 Level 2 6.25% Notes due 2026 127.6 126.3 180.0 165.7 Level 2 5.00% Notes due 2029 600.0 529.5 600.0 474.9 Level 2

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined Benefit Plan, Assumptions [Table Text Block]	Pension Benefits OPEB 2023 2022 2021 2023 2022 2021 U.S. Non-U.S. U.S. Non-U.S. U.S. Non-U.S. Discount rate 5.15 % 4.50 % 5.50 % 4.40 % 2.90 % 1.85 % 5.15 % 5.50 % 2.90 % Expected return on plan assets 6.75 % 4.90 % 6.75 % 4.00 % 7.00 % 4.00 % N/A N/A N/A Rate of compensation increase N/A 3.30 % N/A 3.25 % N/A 3.70 % 4.00 % 4.00 % 4.00 %
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]	The following table summarizes the changes in projected benefit obligations and plan assets and reconciles the funded status of the benefit plans, which is the net benefit plan liability: Pension Benefits OPEB December 31, December 31, 2023 2022 2023 2022 (in millions) Change in benefit obligation Benefit obligation at beginning of year $ 482.4 $ 674.1 $ 329.6 $ 509.6 Service cost 1.1 1.7 0.2 0.3 Interest cost 24.4 16.5 10.1 8.4 Plan amendments (0.6) — — (0.5) Actuarial loss (gain) 6.7 (175.9) (21.4) (101.3) Change in GM portion of OPEB obligation — — (18.2) (75.0) Participant contributions 0.2 0.2 — — Curtailments (0.5) — — — Settlements (6.1) — — — Benefit payments (27.5) (27.4) (12.5) (11.9) Tekfor acquisition — 14.3 — — Currency fluctuations 6.8 (21.1) — — Net change 4.5 (191.7) (41.8) (180.0) Benefit obligation at end of year $ 486.9 $ 482.4 $ 287.8 $ 329.6 Change in plan assets Fair value of plan assets at beginning of year $ 406.9 $ 573.8 $ — $ — Actual return on plan assets 19.0 (127.1) — — Employer contributions 9.2 2.5 12.5 11.9 Participant contributions 0.2 0.2 — — Benefit payments (27.5) (27.4) (12.5) (11.9) Settlements (6.1) — — — Tekfor acquisition — 7.5 — — Currency fluctuations 6.4 (22.6) — — Net change 1.2 (166.9) — — Fair value of plan assets at end of year $ 408.1 $ 406.9 $ — $ —
Schedule of Amounts Recognized in Balance Sheet [Table Text Block]	Amounts recognized in our Consolidated Balance Sheets are as follows: Pension Benefits OPEB December 31, December 31, 2023 2022 2023 2022 (in millions) Noncurrent assets $ 1.7 $ 5.1 $ — $ — Current liabilities (5.8) (7.1) (18.9) (24.8) Noncurrent liabilities (74.7) (73.5) (268.9) (304.8) Net liability $ (78.8) $ (75.5) $ (287.8) $ (329.6)
Schedule of Pre-tax Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	Pre-tax amounts recorded in accumulated other comprehensive income (loss) (AOCI), not yet recognized in net periodic benefit cost (credit) as of December 31, 2023 and 2022, consists of: Pension Benefits OPEB December 31, December 31, 2023 2022 2023 2022 (in millions) Net actuarial gain (loss) $ (212.2) $ (200.0) $ 146.0 $ 133.1 Net prior service credit (cost) 0.3 (1.5) 0.7 1.2 Total amounts recorded $ (211.9) $ (201.5) $ 146.7 $ 134.3
Schedule of Net Benefit Costs [Table Text Block]	The components of net periodic benefit cost (credit) are as follows: Pension Benefits OPEB 2023 2022 2021 2023 2022 2021 (in millions) Service cost $ 1.1 $ 1.7 $ 2.0 $ 0.2 $ 0.3 $ 0.3 Interest cost 24.4 16.5 17.3 10.1 8.4 8.4 Expected asset return (29.3) (31.0) (39.0) — — — Amortized actuarial loss (gain) 4.1 7.6 10.8 (8.5) 0.5 1.7 Amortized prior service cost (credit) 0.1 0.1 0.1 (0.5) (0.9) (1.5) Curtailment charge 1.2 — — — — — Settlement charge 0.1 — 42.3 — — — Net periodic benefit cost (credit) $ 1.7 $ (5.1) $ 33.5 $ 1.3 $ 8.3 $ 8.9
Schedule of Allocation of Plan Assets [Table Text Block]	U.S. Non-U.S. Target Target 2023 2022 Allocation 2023 2022 Allocation Equity securities 23.8 % 28.0 % 25% - 35% 17.8 % 13.5 % 15% - 25% Fixed income securities 69.3 64.8 60% - 70% 61.7 64.7 60% - 70% Alternative assets 5.6 6.1 0% - 10% 15.4 15.6 5% - 15% Cash 1.3 1.1 0% - 5% 5.1 6.2 0% - 5% Total 100.0 % 100.0 % 100.0 % 100.0 % The primary objective of our pension plan assets is to provide a source of retirement income for participants and beneficiaries. Our primary financial objectives for the pension plan assets have been established in conjunction with a comprehensive review of our current and projected financial requirements. These objectives include having the ability to pay all future benefits and expenses when due, maintaining flexibility and minimizing volatility. These objectives are based on a long-term investment horizon. Defined Benefit Pension Plan Assets Investments in our defined benefit plans are stated at fair value. Level 1 assets are valued using quoted market prices that represent the asset value of the shares held by the trusts. The level 2 assets are investments in pooled funds, which are valued using a model to reflect the valuation of their underlying assets that are publicly traded with observable values. The fair values of our pension plan assets are as follows: December 31, 2023 Asset Categories Level 1 Level 2 Level 3 Total (in millions) Cash and Cash Equivalents $ 8.5 $ 1.3 $ — $ 9.8 Equity U.S. Large Cap 37.2 2.2 — 39.4 U.S. Small/Mid Cap 11.5 — — 11.5 World Equity 36.2 3.0 — 39.2 Fixed Income Securities Government & Agencies 60.3 37.6 — 97.9 Corporate Bonds - Investment Grade 150.2 0.9 — 151.1 Corporate Bonds - Non-investment Grade 10.3 0.4 — 10.7 Emerging Market Debt 10.6 — — 10.6 Other 2.5 1.0 — 3.5 Other Property Funds (a) — — — 22.6 Other (a) — — — 11.8 Total Plan Assets $ 327.3 $ 46.4 $ — $ 408.1 December 31, 2022 Asset Categories Level 1 Level 2 Level 3 Total (in millions) Cash and Cash Equivalents $ 8.6 $ 1.8 $ — $ 10.4 Equity U.S. Large Cap 40.2 0.1 — 40.3 U.S. Small/Mid Cap 12.8 — — 12.8 World Equity 40.7 3.4 — 44.1 Fixed Income Securities Government & Agencies 57.9 60.0 — 117.9 Corporate Bonds - Investment Grade 123.5 0.5 — 124.0 Corporate Bonds - Non-investment Grade 9.0 0.4 — 9.4 Emerging Market Debt 8.2 — — 8.2 Other 1.7 2.3 — 4.0 Other Property Funds (a) — — — 24.9 Other (a) — — — 10.9 Total Plan Assets $ 302.6 $ 68.5 $ — $ 406.9 (a) In accordance with ASC 820 - Fair Value Measurement certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

Stock Based Compensation and _2

Stock Based Compensation and Other Incentive Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]	The following table summarizes activity relating to our RSUs: Weighted Average Number of Grant Date Fair Shares/Units Value per Share/Unit (in millions, except per share data) Outstanding at January 1, 2021 4.9 $ 9.20 Granted 0.9 10.29 Vested (1.0) 13.65 Canceled (0.4) 8.40 Outstanding at December 31, 2021 4.4 $ 8.43 Granted 1.4 8.98 Vested (0.8) 14.73 Canceled (0.1) 6.47 Outstanding at December 31, 2022 4.9 $ 7.66 Granted 1.3 8.36 Vested (2.6) 5.62 Canceled (0.2) 9.53 Outstanding at December 31, 2023 3.4 $ 9.34
Share-based Payment Arrangement, Performance Shares, Outstanding Activity [Table Text Block]	The following table summarizes activity relating to our performance shares: Weighted Average Number of Grant Date Fair Shares Value per Share TSR Awards (in millions, except per share data) Outstanding at January 1, 2021 0.6 $ 18.86 Granted — — Vested (0.3) 13.91 Canceled — — Outstanding at December 31, 2021 0.3 $ 24.36 Granted — — Vested (0.3) 24.36 Canceled — — Outstanding at December 31, 2022 — $ — Granted — — Vested — — Canceled — — Outstanding at December 31, 2023 — $ — Free Cash Flow Awards Outstanding at January 1, 2021 1.2 $ 7.50 Granted 0.4 11.26 Vested (0.3) 14.28 Canceled (0.1) 6.96 Outstanding at December 31, 2021 1.2 $ 6.96 Granted 0.5 9.83 Vested — — Canceled (0.1) 9.26 Outstanding at December 31, 2022 1.6 $ 7.81 Granted 0.6 9.19 Vested (0.9) 5.93 Canceled (0.1) 10.20 Outstanding at December 31, 2023 1.2 $ 9.80

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]	The components of income (loss) before income taxes are as follows: 2023 2022 2021 (in millions) U.S. loss $ (212.5) $ (57.0) $ (186.8) Non - U.S. income 188.0 123.3 188.0 Total income (loss) before income taxes $ (24.5) $ 66.3 $ 1.2
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The following is a summary of the components of our provision for income taxes: 2023 2022 2021 (in millions) Current Federal $ 8.5 $ 11.7 $ 3.5 State and local 0.9 1.3 0.3 Foreign 38.0 21.8 34.0 Total current $ 47.4 $ 34.8 $ 37.8 Deferred Federal $ (38.5) $ (23.2) $ (40.7) State and local (0.5) 0.1 (0.9) Foreign 0.7 (9.7) (0.9) Total deferred (38.3) (32.8) (42.5) Total income tax expense (benefit) $ 9.1 $ 2.0 $ (4.7)
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The following is a reconciliation of income taxes calculated at the U.S. federal statutory income tax rate of 21% in 2023, 2022 and 2021 to our provision for income taxes: 2023 2022 2021 (in millions) Federal statutory $ (5.1) $ 13.9 $ 0.3 Foreign income taxes (14.9) (14.7) (14.0) Change in enacted tax rate 0.2 — 0.1 State and local (7.5) 2.4 3.0 Tax credits (14.2) (9.6) (11.0) Valuation allowance 45.0 9.5 2.7 Withholding taxes 7.3 4.4 3.2 U.S. tax on unremitted foreign earnings 0.5 1.6 2.2 Tax benefit on loss carryback — — (5.2) Global intangible low-taxed income (GILTI) 15.3 6.4 6.5 Foreign derived intangible income deduction (0.1) (13.9) — Uncertain tax positions 1.3 3.8 1.2 Reorganization and restructuring actions (26.1) — — Other 7.4 (1.8) 6.3 Effective income tax expense (benefit) $ 9.1 $ 2.0 $ (4.7)
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	The approximate tax effect of each significant type of temporary difference and carryforward that results in a deferred tax asset or liability is as follows: December 31, 2023 2022 (in millions) Deferred tax assets Employee benefits $ 112.1 $ 109.0 Inventory 39.3 38.9 Net operating loss (NOL) carryforwards 173.1 203.7 Tax credit carryforwards 36.6 64.5 Capital allowance carryforwards 12.9 11.5 Capitalized expenditures 86.1 63.1 Interest carryforward 87.0 42.4 Operating lease liabilities 27.5 24.4 Other 71.3 33.3 Valuation allowances (267.1) (217.5) Deferred tax assets $ 378.8 $ 373.3 Deferred tax liabilities Other intangible assets $ (127.4) $ (136.8) Fixed assets (48.1) (88.7) Operating lease right-of-use assets (27.1) (24.2) Other (23.3) (15.3) Deferred tax liabilities $ (225.9) $ (265.0) Deferred tax assets, net $ 152.9 $ 108.3 Deferred tax assets and liabilities recognized in our Consolidated Balance Sheets are as follows: December 31, 2023 2022 (in millions) U.S. federal and state deferred tax asset, net $ 88.2 $ 47.6 Other foreign deferred tax asset, net 64.7 60.7 Deferred tax asset, net $ 152.9 $ 108.3
Schedule of Unrecognized Income Tax Benefits [Table Text Block]	A reconciliation of the beginning and ending amounts of unrecognized income tax benefits is as follows: Unrecognized Income Tax Interest and Benefits Penalties (in millions) Balance at January 1, 2021 $ 20.2 $ 2.0 Increase in prior year tax positions — — Decrease in prior year tax positions (1.0) (0.1) Increase in current year tax positions 2.0 0.3 Foreign currency remeasurement adjustment — — Balance at December 31, 2021 $ 21.2 $ 2.2 Increase in prior year tax positions 3.6 1.1 Decrease in prior year tax positions (0.8) — Increase in current year tax positions 0.5 — Tekfor acquisition 12.6 — Foreign currency remeasurement adjustment 0.1 — Balance at December 31, 2022 $ 37.2 $ 3.3 Increase in prior year tax positions 1.7 0.5 Decrease in prior year tax positions (9.3) (0.6) Increase in current year tax positions 11.8 — Settlement (6.9) (0.3) Foreign currency remeasurement adjustment 0.7 — Balance at December 31, 2023 $ 35.2 $ 2.9

Earnings (Loss) Per Share (EP_2

Earnings (Loss) Per Share (EPS) (Tables)	12 Months Ended
	Dec. 31, 2023
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): 2023 2022 2021 (in millions, except per share data) Numerator Net income (loss) $ (33.6) $ 64.3 $ 5.9 Less: Net income allocated to participating securities — (2.7) (0.2) Net income (loss) attributable to common shareholders - Basic and Dilutive $ (33.6) $ 61.6 $ 5.7 Denominators Basic common shares outstanding - Weighted-average shares outstanding 120.3 119.4 118.5 Less: Weighted-average participating securities (3.7) (4.9) (4.6) Weighted-average common shares outstanding 116.6 114.5 113.9 Effect of dilutive securities - Dilutive stock-based compensation — 1.0 0.2 Diluted shares outstanding - Adjusted weighted-average shares after assumed conversions 116.6 115.5 114.1 Basic EPS $ (0.29) $ 0.54 $ 0.05 Diluted EPS $ (0.29) $ 0.53 $ 0.05

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Product Warranty Liability [Table Text Block]	The following table provides a reconciliation of changes in the product warranty liability: December 31, 2023 2022 (in millions) Beginning balance $ 54.1 $ 59.5 Accruals 26.4 14.1 Settlements (11.4) (10.8) Adjustments to prior period accruals (3.1) (7.9) Foreign currency translation 0.3 (0.8) Ending balance $ 66.3 $ 54.1

Reclassifications out of Accu_2

Reclassifications out of Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2023
Reclassifications out of Accumulated Other Comprehensive Income [Abstract]
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]	Reclassification adjustments and other activity impacting accumulated other comprehensive income (loss) (AOCI) during the years ended December 31, 2023, December 31, 2022 and December 31, 2021 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Gain (Loss) on Cash Flow Hedges Total Balance at January 1, 2021 $ (311.0) $ (101.1) $ (20.1) $ (432.2) Other comprehensive income (loss) before reclassifications 33.9 (10.7) 22.2 45.4 Income tax effect of other comprehensive income (loss) before reclassifications (7.0) — (4.8) (11.8) Amounts reclassified from accumulated other comprehensive loss into net income 53.4 (a) 0.5 (9.8) (b) 44.1 Income taxes reclassified into net income (11.2) — 0.9 (10.3) Net current period other comprehensive income (loss) 69.1 (10.2) 8.5 67.4 Balance at December 31, 2021 $ (241.9) $ (111.3) $ (11.6) $ (364.8) Other comprehensive income (loss) before reclassifications 119.5 (38.4) 62.2 143.3 Income tax effect of other comprehensive income (loss) before reclassifications (30.2) — (9.9) (40.1) Amounts reclassified from accumulated other comprehensive loss into net income 7.3 (a) — (22.9) (b) (15.6) Income taxes reclassified into net income (1.6) — 3.4 1.8 Net current period other comprehensive income (loss) 95.0 (38.4) 32.8 89.4 Balance at December 31, 2022 $ (146.9) $ (149.7) $ 21.2 $ (275.4) Other comprehensive income before reclassifications 5.5 7.4 18.5 31.4 Income tax effect of other comprehensive income before reclassifications (1.8) — 2.4 0.6 Amounts reclassified from accumulated other comprehensive income (loss) into net loss (3.5) (a) — (16.9) (b) (20.4) Income taxes reclassified into net loss 1.4 — (0.5) 0.9 Net current period other comprehensive income 1.6 7.4 3.5 12.5 Balance at December 31, 2023 $ (145.3) $ (142.3) $ 24.7 $ (262.9) (a) The amount reclassified for 2021 includes a credit to AOCI of $42.3 million related to the effect of the Pension Annuity Purchase. See Note 7 - Employee Benefit Plans for more detail. (b) The amounts reclassified from AOCI included $(19.9) million in COGS, $(3.6) million in interest expense and $6.6 million in other income (expense), net for the year ended December 31, 2023, $(6.5) million in COGS, $(2.7) million in interest expense and $(13.7) million in other income (expense), net for the year ended December 31, 2022 and $(5.6) million in COGS, $14.8 million in interest expense and $(19.0) million in other income (expense), net for the year ended December 31, 2021.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customers [Abstract]
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 years ended December 31, 2023, 2022 and 2021. Net sales are attributed to regions based on the location of production. Intersegment sales have been excluded from the table. Twelve Months Ended December 31, 2023 Driveline Metal Forming Total (in millions) North America $ 3,133.8 $ 1,303.2 $ 4,437.0 Asia 506.4 38.3 544.7 Europe 441.2 472.2 913.4 South America 95.1 89.3 184.4 Total $ 4,176.5 $ 1,903.0 $ 6,079.5 Twelve Months Ended December 31, 2022 Driveline Metal Forming Total North America $ 3,139.8 $ 1,301.4 $ 4,441.2 Asia 449.8 43.5 493.3 Europe 391.6 338.9 730.5 South America 82.3 55.1 137.4 Total $ 4,063.5 $ 1,738.9 $ 5,802.4 Twelve Months Ended December 31, 2021 Driveline Metal Forming Total North America $ 2,793.4 $ 1,189.0 $ 3,982.4 Asia 441.6 47.4 489.0 Europe 374.8 216.1 590.9 South America 85.3 9.0 94.3 Total $ 3,695.1 $ 1,461.5 $ 5,156.6 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 (in millions) : Accounts Receivable, Net Contract Liabilities (Current) Contract Liabilities (Long-term) December 31, 2022 $ 820.2 $ 28.1 $ 73.4 December 31, 2023 818.5 16.6 70.4 Increase/(decrease) $ (1.7) $ (11.5) $ (3.0)

Leasing (Tables)

Leasing (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Components of lease cost [Table Text Block]	Lease cost consists of the following: Twelve Months Ended December 31, 2023 2022 2021 (in millions) Finance lease cost Amortization of right-of-use assets $ 12.3 $ 9.9 $ 4.2 Interest on lease liabilities 5.1 4.7 2.0 Total finance lease cost 17.4 14.6 6.2 Operating lease cost 30.9 32.6 33.3 Short-term lease cost 2.1 1.4 1.6 Variable lease cost 5.8 5.6 3.2 Total lease cost $ 56.2 $ 54.2 $ 44.3
Supplemental lease information [Table Text Block]	The following table summarizes additional information related to our lease agreements. Twelve Months Ended December 31, 2023 2022 2021 (in millions, except lease term and rate) Cash paid for amounts included in measurement of lease liabilities Operating cash flows from finance leases $ 5.1 $ 4.7 $ 2.0 Operating cash flows from operating leases 36.1 37.6 35.9 Financing cash flows from finance leases 13.7 11.2 5.0 Weighted-average remaining lease term - finance leases 12.7 years 13.1 years 16.4 years Weighted-average remaining lease term - operating leases 7.9 years 8.4 years 8.6 years Weighted-average discount rate - finance leases 5.0 % 4.9 % 4.8 % Weighted-average discount rate - operating leases 6.4 % 5.4 % 5.2 %
Future minimum lease payments [Table Text Block]	Future undiscounted minimum payments under non-cancelable leases are as follows: Finance Leases Operating Leases (in millions) 2024 $ 15.8 $ 28.7 2025 12.9 24.1 2026 11.5 17.7 2027 9.6 13.6 2028 8.3 10.6 Thereafter 73.2 54.4 Total future undiscounted minimum lease payments 131.3 149.1 Less: Impact of discounting (32.8) (31.7) Total $ 98.5 $ 117.4
Right of use assets and lease liabilities [Table Text Block]	The right-of-use assets and lease liabilities recorded on our Consolidated Balance Sheets are as follows: December 31, 2023 December 31, 2022 Finance Leases Operating Leases Finance Leases Operating Leases (in millions) (in millions) Property, plant and equipment, net $ 102.4 $ — $ 106.2 $ — Operating lease right-of-use assets — 115.6 — 107.2 Total $ 102.4 $ 115.6 $ 106.2 $ 107.2 Current portion of operating lease liabilities $ — $ 21.9 $ — $ 21.1 Accrued expenses and other 11.2 — 13.0 — Long-term portion of operating lease liabilities — 95.5 — 87.2 Postretirement benefits and other long-term liabilities 87.3 — 92.4 — Total $ 98.5 $ 117.4 $ 105.4 $ 108.3

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	12 Months Ended
	Dec. 31, 2023
Tekfor Group
Business Acquisition [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The following represents the fair values of the assets acquired and liabilities assumed resulting from the acquisition (in millions) : December 31, 2022 Total consideration transferred $ 94.4 Cash and cash equivalents $ 14.3 Accounts receivable 33.7 Inventories 46.3 Prepaid expenses and other long-term assets 30.1 Deferred income tax assets 5.0 Property, plant and equipment 105.5 Total assets acquired $ 234.9 Accounts payable 33.5 Accrued expenses and other 28.1 Debt 23.4 Postretirement benefits and other long-term liabilities 41.9 Net assets acquired $ 108.0 Gain on bargain purchase of business $ 13.6

Segment and Geographic Inform_2

Segment and Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2023
Segments, Geographical Areas [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Year Ended December 31, 2023 Driveline Metal Forming Corporate and Eliminations Total (in millions) Sales $ 4,176.7 $ 2,454.3 $ — $ 6,631.0 Less: Intersegment sales 0.2 551.3 — 551.5 Net external sales $ 4,176.5 $ 1,903.0 $ — $ 6,079.5 Segment adjusted EBITDA $ 543.6 $ 149.7 $ — $ 693.3 Depreciation and amortization $ 260.3 $ 226.9 $ — $ 487.2 Capital expenditures $ 105.9 $ 80.1 $ 8.6 $ 194.6 Total assets $ 2,554.3 $ 1,788.7 $ 1,013.3 $ 5,356.3 Year Ended December 31, 2022 Driveline Metal Forming Corporate and Eliminations Total Sales $ 4,063.5 $ 2,280.7 $ — $ 6,344.2 Less: Intersegment sales — 541.8 — 541.8 Net external sales $ 4,063.5 $ 1,738.9 $ — $ 5,802.4 Segment adjusted EBITDA $ 510.9 $ 236.4 $ — $ 747.3 Depreciation and amortization $ 272.7 $ 219.4 $ — $ 492.1 Capital expenditures $ 103.3 $ 62.9 $ 5.2 $ 171.4 Total assets $ 2,542.0 $ 1,900.3 $ 1,027.1 $ 5,469.4 Year Ended December 31, 2021 Driveline Metal Forming Corporate and Eliminations Total Sales $ 3,695.3 $ 1,912.8 $ — $ 5,608.1 Less: Intersegment sales 0.2 451.3 — 451.5 Net external sales $ 3,695.1 $ 1,461.5 $ — $ 5,156.6 Segment adjusted EBITDA $ 541.8 $ 291.5 $ — $ 833.3 Depreciation and amortization $ 293.8 $ 250.5 $ — $ 544.3 Capital expenditures $ 123.4 $ 53.9 $ 3.9 $ 181.2 Total assets $ 2,852.0 $ 1,650.5 $ 1,133.2 $ 5,635.7
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block]	The following table represents a reconciliation of Segment Adjusted EBITDA to consolidated income (loss) before income taxes for the years ended December 31, 2023, 2022 and 2021: Year Ended December 31, 2023 2022 2021 (in millions) Segment adjusted EBITDA $ 693.3 $ 747.3 $ 833.3 Interest expense (201.7) (174.5) (195.2) Depreciation and amortization (487.2) (492.1) (544.3) Restructuring and acquisition-related costs (25.2) (30.2) (49.4) Pension curtailment and settlement charges (1.3) — (42.3) Loss on sale of business — — (2.7) Unrealized gain (loss) on equity securities (1.1) (25.5) 24.4 Debt refinancing and redemption costs (1.3) (6.4) (34.0) Malvern Fire insurance recoveries, net of charges — 39.1 11.4 Acquisition-related fair value inventory adjustment — (5.0) — Gain on bargain purchase of business — 13.6 — Income (loss) before income taxes $ (24.5) $ 66.3 $ 1.2
Schedule of Disclosure on Geographic Areas, Revenue and Long-Lived Assets by Country [Table Text Block]	Financial information relating to our operations by geographic area is presented in the following table. Net sales are attributed to countries based upon location of production. Long-lived assets exclude deferred income taxes. December 31, 2023 2022 2021 (in millions) Net sales United States $ 2,163.5 $ 2,148.0 $ 1,923.5 Mexico 2,273.5 2,293.2 2,058.9 South America 184.4 137.4 94.3 China 271.6 280.0 299.6 All other Asia 273.1 213.3 189.4 Europe 913.4 730.5 590.9 Total net sales $ 6,079.5 $ 5,802.4 $ 5,156.6 Long-lived assets United States $ 1,694.3 $ 1,778.9 $ 1,976.5 Mexico 778.4 821.3 888.1 South America 75.8 71.2 40.9 China 110.9 130.1 164.8 All other Asia 79.2 80.5 87.1 Europe 441.7 475.0 501.2 Total long-lived assets $ 3,180.3 $ 3,357.0 $ 3,658.6

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Tables)	12 Months Ended
	Dec. 31, 2023
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Schedule II - VALUATION AND QUALIFYING ACCOUNTS Additions - Balance at Charged to Acquisitions Balance Beginning of Costs and and At End of Period Expenses Disposals (a) Deductions Period (in millions) Year Ended December 31, 2021: Allowance for credit losses (1) $ 4.5 $ 7.8 $ — $ 10.1 $ 2.2 Allowance for deferred taxes (3) 208.0 2.7 — 9.0 201.7 Inventory valuation allowance (2) 23.4 17.7 — 22.5 18.6 Year Ended December 31, 2022: Allowance for credit losses (1) 2.2 10.1 1.0 4.0 9.3 Allowance for deferred taxes (3) 201.7 9.5 7.8 1.5 217.5 Inventory valuation allowance (2) 18.6 35.7 4.9 31.7 27.5 Year Ended December 31, 2023: Allowance for credit losses (1) 9.3 4.4 — 8.4 5.3 Allowance for deferred taxes (3) 217.5 54.5 — 4.9 267.1 Inventory valuation allowance (2) 27.5 22.1 — 17.5 32.1 (a ) Amounts represent reserves recognized in conjunction with our acquisition of Tekfor in 2022. (1) Uncollectible accounts charged off, net of recoveries. (2) Primarily relates to write-offs of excess and obsolete inventories, as well as adjustments for physical quantity discrepancies. (3) Primarily reflects an increase in valuation allowance related to certain U.S. federal tax attributes, as well as new net operating losses established with a corresponding valuation allowance at certain foreign locations, partially offset by adjustments to previously established valuation allowances and foreign currency translation.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies - Organization (Details)	Dec. 31, 2023 Countries Facilities
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of Facilities | Facilities	80
Number of Countries in which Entity Operates | Countries	18

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies - Accounts Receivable Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue, Performance Obligation, Description of Payment Terms	50 days
Accounts Receivable, Allowance for Credit Loss	$ 5.3	$ 9.3

Organization and Summary of S_4

Organization and Summary of Significant Accounting Policies - Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Inventory [Line Items]
Raw materials and work-in-progress	$ 411.5	$ 398.9
Finished goods	103.5	92.5
Gross inventories	515	491.4
Inventory valuation reserves	(32.1)	(27.5)
Inventories, net	$ 482.9	$ 463.9

Organization and Summary of S_5

Organization and Summary of Significant Accounting Policies - Maintenance, Repair and Operations (MRO) Materials (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Maintenance, Repair and Operations (MRO) Materials [Abstract]
Maintenance, Repair and Operations (MRO) Materials Amortization	$ 55.6	$ 56	$ 61.6

Organization and Summary of S_6

Organization and Summary of Significant Accounting Policies - Property, Plant, & Equipment Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation and tooling amortization	$ 346	$ 350.4	$ 396.9
Noncash or part noncash acquisition, fixed assets acquired	$ 43.1	$ 34.2	$ 20.1

Organization and Summary of S_7

Organization and Summary of Significant Accounting Policies - Schedule of Property, Plant & Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Land	$ 55.4	$ 57.8
Land improvements	26.9	26.5
Buildings and building improvements	694.9	682
Machinery and equipment	3,771.1	3,739.7
Construction in progress	151.5	140.2
Property, plant and equipment, gross	4,699.8	4,646.2
Accumulated depreciation and amortization	(2,938.9)	(2,743.2)
Property, plant and equipment, net	$ 1,760.9	$ 1,903
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	Indefinite [Member]	Indefinite [Member]
Minimum [Member] | Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years	10 years
Minimum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	15 years	15 years
Minimum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years	3 years
Maximum [Member] | Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	15 years	15 years
Maximum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years	40 years
Maximum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	12 years	12 years

Organization and Summary of S_8

Organization and Summary of Significant Accounting Policies - Debt Issuance Costs Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 42.8	$ 51.7
Total Debt Instruments including Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	51.6	60.9
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 8.8	$ 9.2

Organization and Summary of S_9

Organization and Summary of Significant Accounting Policies - Currency Translation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Foreign currency transaction gain (loss), before tax	$ 12.8	$ 1.9	$ (1.7)

Organization and Summary of _10

Organization and Summary of Significant Accounting Policies - Research and Development Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Research and development expense	$ 155.4	$ 144	$ 116.8
Engineering, Design & Development Recoveries	$ 37	$ 20	$ 15

Restructuring and Acquisition_3

Restructuring and Acquisition-Related Costs - Restructuring Reserve Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restructuring Reserve [Roll Forward]
Restructuring reserve	$ 3.8	$ 3.4	$ 11.5
Restructuring charges	18.3	21.7	43.2
Cash utilization	(17.4)	(21.3)	(51.3)
Restructuring reserve	4.7	3.8	3.4
Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring reserve	2.4	0.7	1.7
Restructuring charges	7.2	3.5	2.9
Cash utilization	(6.6)	(1.8)	(3.9)
Restructuring reserve	3	2.4	0.7
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring reserve	1.4	2.7	9.8
Restructuring charges	11.1	18.2	40.3
Cash utilization	(10.8)	(19.5)	(47.4)
Restructuring reserve	$ 1.7	$ 1.4	$ 2.7

Restructuring and Acquisition_4

Restructuring and Acquisition-Related Costs - Restructuring Reserve Narrative (Details) - USD ($) $ in Millions	12 Months Ended			31 Months Ended	48 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2023
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 18.3	$ 21.7	$ 43.2
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost remaining	10			$ 10	$ 10
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost remaining	20			20	20
Driveline [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4.9	1.6	4.7
Metal Forming [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	11.3	14.3	6.5
2020 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	11.8				$ 112.4
Emporium, Pennsylvania [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4.4			$ 16.5
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	7.2	3.5	2.9
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	11.1	$ 18.2	$ 40.3
Tekfor Group
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 2.1

Restructuring and Acquisition_5

Restructuring and Acquisition-Related Costs - Business Combinations, Separately Recognized Transactions Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Acquisition-Related Costs	$ 0	$ 6	$ 0.4
Integration Expenses	6.9	2.5	5.8
Total acquisition-related charges	6.9	8.5	6.2
Restructuring and acquisition-related costs	$ 25.2	$ 30.2	$ 49.4

Goodwill and Intangible Assets

Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Goodwill [Roll Forward]
Beginning balance	$ 181.6	$ 183.8
Foreign currency translation	0.5	(2.2)
Ending balance	$ 182.1	$ 181.6

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill Narrative (Details) $ in Millions	Dec. 31, 2023 USD ($)
Goodwill [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss	$ 1,435.5

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Acquired Finite Lived Intangible Assets by Major Class (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 1,117.7	$ 1,115.5
Finite-Lived Intangible Assets, Accumulated Amortization	(584.9)	(499.3)
Finite-Lived Intangible Assets, Net	532.8	616.2
Amortization of intangible assets	85.6	85.7	$ 85.8
Minimum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Expected Amortization, Year One	80
Finite-Lived Intangible Asset, Expected Amortization, Year Two	80
Finite-Lived Intangible Asset, Expected Amortization, Year Three	80
Finite-Lived Intangible Asset, Expected Amortization, Year Four	80
Finite-Lived Intangible Asset, Expected Amortization, Year Five	80
Maximum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Expected Amortization, Year One	85
Finite-Lived Intangible Asset, Expected Amortization, Year Two	85
Finite-Lived Intangible Asset, Expected Amortization, Year Three	85
Finite-Lived Intangible Asset, Expected Amortization, Year Four	85
Finite-Lived Intangible Asset, Expected Amortization, Year Five	85
Computer Software, Intangible Asset [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	54.2	52.2
Finite-Lived Intangible Assets, Accumulated Amortization	(49.2)	(43.2)
Finite-Lived Intangible Assets, Net	5	9
Customer Platforms - Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	856.2	856.2
Finite-Lived Intangible Assets, Accumulated Amortization	(428.2)	(364.7)
Finite-Lived Intangible Assets, Net	428	491.5
Customer Relationships - Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	53	53
Finite-Lived Intangible Assets, Accumulated Amortization	(23.1)	(19.7)
Finite-Lived Intangible Assets, Net	29.9	33.3
Technology-Based Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	154.3	154.1
Finite-Lived Intangible Assets, Accumulated Amortization	(84.4)	(71.7)
Finite-Lived Intangible Assets, Net	$ 69.9	$ 82.4

Long-Term Debt - Long-term Debt

Long-Term Debt - Long-term Debt Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Total debt	$ 2,811.7	$ 2,972.7
Current portion of long-term debt	17	75.9
Long-term debt	2,794.7	2,896.8
Unamortized debt issuance costs	42.8	51.7
Long-term debt, net	2,751.9	2,845.1
Term Loan A [Member]
Debt Instrument [Line Items]
Secured Debt	484.3	520
Term Loan B [Member]
Debt Instrument [Line Items]
Secured Debt	648	675
6.875% Notes [Member]
Debt Instrument [Line Items]
Unsecured Debt	400	400
6.50% Notes [Member]
Debt Instrument [Line Items]
Unsecured Debt	500	500
6.25% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Unsecured Debt	127.6	180
5.00% Notes due 2029 [Member]
Debt Instrument [Line Items]
Unsecured Debt	$ 600	$ 600
Unsecured Debt [Member] | 6.875% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.875%	6.875%
Unsecured Debt [Member] | 6.50% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.50%	6.50%
Unsecured Debt [Member] | 6.25% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%	6.25%
Unsecured Debt [Member] | 5.00% Notes due 2029 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5%	5%	5%
Multi-Currency Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding	$ 0	$ 25
Foreign Credit Facilities and Other [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding	$ 51.8	$ 72.7

Long-Term Debt - Senior Secured

Long-Term Debt - Senior Secured Credit Facilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Payments of Debt Issuance Costs	$ 3.2	$ 31.4	$ 9.2
Interest Paid, Excluding Capitalized Interest, Operating Activities	186.4	172.6	184.9
Repayments of Long-term Debt	184.8	458.3	1,017.6
Payments of Revolving Credit Facility	25	0	0
Secured Debt [Member] | First Amendment to the Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Payments of Debt Issuance Costs	3.2
Secured Debt [Member] | Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Payments of Debt Issuance Costs		31.4
Payments of Debt Restructuring Costs		0.6
Interest Paid, Excluding Capitalized Interest, Operating Activities		3.4
Secured Debt [Member] | Term Loan A [Member]
Debt Instrument [Line Items]
Repayments of Long-term Debt	26		21.2
Secured Debt [Member] | Term Loan B [Member]
Debt Instrument [Line Items]
Repayments of Long-term Debt	20.2	100	238.8
Write off of Deferred Debt Issuance Cost		$ 0.6
Secured Debt [Member] | Term Loan A & Term Loan B [Member]
Debt Instrument [Line Items]
Write off of Deferred Debt Issuance Cost	1.1		$ 2.5
Multi-Currency Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	892.3
Letters of Credit Outstanding, Amount	32.7
Payments of Revolving Credit Facility	$ 25

Long-Term Debt - Long-Term De_2

Long-Term Debt - Long-Term Debt Notes Payable Narrative (Details) - USD ($) $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 01, 2022
Debt Instrument [Line Items]
Payments of long-term debt		$ 184.8	$ 458.3	$ 1,017.6
Interest Paid, Excluding Capitalized Interest, Operating Activities		186.4	172.6	184.9
Proceeds from issuance of long-term debt		35.8	247.9	634.7
Payments of Debt Issuance Costs		$ 3.2	31.4	$ 9.2
Tekfor Group
Debt Instrument [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-Term Debt	$ 23.4		$ 23.4
Unsecured Debt [Member] | 6.25% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%	6.25%	6.25%
Payments of long-term debt		$ 50	$ 220
Interest Paid, Excluding Capitalized Interest, Operating Activities		0.9	0.2
Write off of Deferred Debt Issuance Cost		0.2	1.8
Redemption Premium			$ 3.4
Unsecured Debt [Member] | 6.25% Notes Due 2026 [Member] | Open market repurchase
Debt Instrument [Line Items]
Payments of long-term debt		$ 2.4
Unsecured Debt [Member] | 5.00% Notes due 2029 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5%	5%	5%	5%
Proceeds from issuance of long-term debt				$ 600
Payments of Debt Issuance Costs				$ 9.2
Unsecured Debt [Member] | 6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				6.25%
Payments of long-term debt				$ 700
Interest Paid, Excluding Capitalized Interest, Operating Activities				19.4
Write off of Deferred Debt Issuance Cost				9.6
Redemption Premium				$ 21.9
Unsecured Debt [Member] | Tekfor Group Debt
Debt Instrument [Line Items]
Payments of long-term debt	$ 10.7
Unsecured Debt [Member] | Tekfor Group Debt | Tekfor Group
Debt Instrument [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-Term Debt					$ 23.4

Long-Term Debt - Foreign Credit

Long-Term Debt - Foreign Credit Facilities Narrative (Details) - Foreign Credit Facilities [Member] - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Line of credit facility, amount outstanding	$ 51.8	$ 72.7
Foreign Credit Facilities, Remaining Borrowing Capacity	$ 84.7	$ 57.8

Long-Term Debt - Long-term De_3

Long-Term Debt - Long-term Debt Maturity Schedule (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
2024	$ 29.1
2025	46.3
2026	190.2
2027	900
2028	411.7
Thereafter	1,234.4
Debt	$ 2,811.7	$ 2,972.7

Long-Term Debt - Interest Expen

Long-Term Debt - Interest Expense and Interest Income Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Interest Expense	$ 201.7	$ 174.5	$ 195.2
Interest Costs Capitalized	$ 8	$ 6.6	$ 6.2
Long-term Debt, Weighted Average Interest Rate, at Point in Time	7.10%	6.60%	5.60%
Investment Income, Interest	$ 26.2	$ 17	$ 10.9

Derivatives and Risk Manageme_2

Derivatives and Risk Management - Derivatives and Risk Management Narrative (Details) € in Millions, $ in Millions	Dec. 31, 2023 USD ($)	Dec. 31, 2023 EUR (€)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 EUR (€)	Jun. 27, 2022 USD ($)	Apr. 29, 2022 USD ($)
Foreign Currency Forward & Foreign Currency Option Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 206.9		$ 179.9
Currency Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount	220.7	€ 200	$ 213.9	€ 200
Fair value asset at the date of dedesignation						$ 9.7
Interest Rate Swap [Member]
Derivative [Line Items]
Fair value asset at the date of dedesignation	27.2				$ 6.1
Interest Rate Swap Through Q3 2027 | Debt [Member]
Derivative [Line Items]
Derivative, Notional Amount	700
Interest Rate Swap Q3 2027 Through Q4 2029 | Debt [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 200

Derivatives and Risk Manageme_3

Derivatives and Risk Management - Gain (Loss) Recognized for Designated and Undesignated Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Cost of Goods and Services Sold	$ 5,455.2	$ 5,097.5	$ 4,433.9
Other Nonoperating Income (Expense)	8.1	(1.8)	(3.2)
Interest expense	(201.7)	(174.5)	(195.2)
Foreign Exchange Forward [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 19.9	$ 6.5	$ 5.6
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of Goods and Services Sold	Cost of Goods and Services Sold	Cost of Goods and Services Sold
Foreign Exchange Forward [Member] | Cost of Sales [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 15.9
Foreign Exchange Forward [Member] | Other Nonoperating Income (Expense) [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	4.7	$ 2.5	$ 0.2
Currency Swap [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (6.6)	$ 13.7	$ 19
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Currency Swap [Member] | Other Nonoperating Income (Expense) [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 0.6
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 3.6	$ 2.7	$ (14.8)
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest expense	Interest expense	Interest expense
Interest Rate Swap [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 1.2

Derivatives and Risk Manageme_4

Derivatives and Risk Management - Sales, Receivables and Postretirement Cost Sharing Asset by Major Customer Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue, Major Customer [Line Items]
Total GM postretirement cost sharing asset	$ 120	$ 138.2
General Motors [Member]
Revenue, Major Customer [Line Items]
Fair value, concentration of risk, accounts receivable	$ 305.7	$ 334.4
General Motors [Member] | Customer Concentration Risk | Revenue Benchmark
Revenue, Major Customer [Line Items]
Entity-wide revenue, major customer, percentage	39%	40%	37%
Stellantis [Member]
Revenue, Major Customer [Line Items]
Fair value, concentration of risk, accounts receivable	$ 108.1	$ 115.3
Stellantis [Member] | Customer Concentration Risk | Revenue Benchmark
Revenue, Major Customer [Line Items]
Entity-wide revenue, major customer, percentage	16%	18%	19%
Ford [Member]
Revenue, Major Customer [Line Items]
Fair value, concentration of risk, accounts receivable	$ 118.1	$ 101.7
Ford [Member] | Customer Concentration Risk | Revenue Benchmark
Revenue, Major Customer [Line Items]
Entity-wide revenue, major customer, percentage	12%	12%	12%

Fair Value - Fair Value of Asse

Fair Value - Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2023	Dec. 31, 2022
REE Automotive Ltd.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	$ 0.8
Share Price	$ 5.14
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, at fair value	$ 328.3	$ 363.6
Other Noncurrent Assets [Member] | Fair Value, Inputs, Level 1 [Member] | REE Automotive Ltd.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	0.8	1.9
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Carrying Value and Fair Value Disclosure	15.9	8.2
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Carrying Value and Fair Value Disclosure	5.4	3
Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Carrying Value and Fair Value Disclosure	0.8	0.5
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [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 Carrying and Fair Value	0	2.4
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Assets [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 Carrying and Fair Value	0	8.5
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Accrued Liabilities [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 Carrying and Fair Value	5	0
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [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 Carrying and Fair Value	16.5	0
Currency Swap [Member] | Designated as Hedging Instrument [Member] | Accrued Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contracts, Liability, Carrying and Fair Value Disclosure	9.4	0
Currency Swap [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contracts, Liability, Carrying and Fair Value Disclosure	$ 0	$ 1.5

Fair Value - Fair Value of Debt

Fair Value - Fair Value of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Revolving Credit Facility [Member] | Carrying (Reported) Amount, Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility, amount outstanding	$ 0	$ 25
Revolving Credit Facility [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]
Line of credit facility, amount outstanding	0	25
Term Loan A [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Secured Debt	484.3	520
Term Loan A [Member] | Carrying (Reported) Amount, Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Secured Debt	484.3	520
Term Loan A [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]
Secured Debt	483.6	510.3
Term Loan B [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Secured Debt	648	675
Term Loan B [Member] | Carrying (Reported) Amount, Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Secured Debt	648	675
Term Loan B [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]
Secured Debt	649.6	658.1
6.875% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	400	400
6.875% Notes [Member] | Carrying (Reported) Amount, Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	400	400
6.875% Notes [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]
Unsecured Debt	387	355.4
6.50% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	500	500
6.50% Notes [Member] | Carrying (Reported) Amount, Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	500	500
6.50% Notes [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]
Unsecured Debt	501.9	452.5
6.25% Notes Due 2026 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	127.6	180
6.25% Notes Due 2026 [Member] | Carrying (Reported) Amount, Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	127.6	180
6.25% Notes Due 2026 [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]
Unsecured Debt	126.3	165.7
5.00% Notes due 2029 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	600	600
5.00% Notes due 2029 [Member] | Carrying (Reported) Amount, Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	600	600
5.00% Notes due 2029 [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]
Unsecured Debt	$ 529.5	$ 474.9

Employee Benefit Plans - Define

Employee Benefit Plans - Defined Benefit Plan, Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.15%	5.50%	2.90%
Expected return on plan assets	6.75%	6.75%	7%
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.50%	4.40%	1.85%
Expected return on plan assets	4.90%	4%	4%
Rate of compensation increase	3.30%	3.25%	3.70%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.15%	5.50%	2.90%
Rate of compensation increase	4%	4%	4%

Employee Benefit Plans - Accumu

Employee Benefit Plans - Accumulated Benefit Obligation and Underfunded Pension Plan Detail Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined benefit plan, accumulated benefit obligation	$ 486.9	$ 481.8
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	399
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	399
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets	$ 318.5

Employee Benefit Plans - GM Cos

Employee Benefit Plans - GM Cost Sharing Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Total GM postretirement cost sharing asset	$ 120	$ 138.2
Current GM postretirement cost sharing asset	8.1
Noncurrent GM postretirement cost sharing asset	$ 111.9	$ 127.6

Employee Benefit Plans - Change

Employee Benefit Plans - Change in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	$ 406.9
Fair value of plan assets at end of year	408.1	$ 406.9
Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	482.4	674.1
Service cost	1.1	1.7	$ 2
Interest cost	24.4	16.5	17.3
Plan amendments	(0.6)	0
Actuarial loss (gain)	6.7	(175.9)
Change in GM portion of OPEB obligation	0	0
Participant contributions	0.2	0.2
Curtailments	(0.5)	0
Settlements	(6.1)	0
Benefit payments	(27.5)	(27.4)
Tekfor acquisition	0	14.3
Currency fluctuations	6.8	(21.1)
Net change	4.5	(191.7)
Benefit obligation at end of year	486.9	482.4	674.1
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	406.9	573.8
Actual return on plan assets	19	(127.1)
Employer contributions	9.2	2.5
Participant contributions	0.2	0.2
Benefit payments	(27.5)	(27.4)
Settlements	(6.1)	0
Tekfor acquisition	0	7.5
Currency fluctuations	6.4	(22.6)
Net change	1.2	(166.9)
Fair value of plan assets at end of year	408.1	406.9	573.8
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	329.6	509.6
Service cost	0.2	0.3	0.3
Interest cost	10.1	8.4	8.4
Plan amendments	0	(0.5)
Actuarial loss (gain)	(21.4)	(101.3)
Change in GM portion of OPEB obligation	(18.2)	(75)
Participant contributions	0	0
Curtailments	0	0
Settlements	0	0
Benefit payments	(12.5)	(11.9)
Tekfor acquisition	0	0
Currency fluctuations	0	0
Net change	(41.8)	(180)
Benefit obligation at end of year	287.8	329.6	509.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	12.5	11.9
Participant contributions	0	0
Benefit payments	(12.5)	(11.9)
Settlements	0	0
Tekfor acquisition	0	0
Currency fluctuations	0	0
Net change	0	0
Fair value of plan assets at end of year	$ 0	$ 0	$ 0

Employee Benefit Plans - Amount

Employee Benefit Plans - Amounts Recognized in the Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Noncurrent assets	$ 1.7	$ 5.1
Liability, Defined Benefit Pension Plan, Current	(5.8)	(7.1)
Defined benefit pension plan, liabilities, noncurrent	(74.7)	(73.5)
Defined benefit plan, amounts recognized in balance sheet	(78.8)	(75.5)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Noncurrent assets	0	0
Postemployment Benefits Liability, Current	(18.9)	(24.8)
Other postretirement defined benefit plan, liabilities, noncurrent	(268.9)	(304.8)
Other postretirement defined benefit plan, liabilities	$ (287.8)	$ (329.6)

Employee Benefit Plans - Pre-ta

Employee Benefit Plans - Pre-tax Amounts Recorded in AOCI (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain (loss)	$ (212.2)	$ (200)
Net prior service credit (cost)	0.3	(1.5)
Total amounts recorded	(211.9)	(201.5)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain (loss)	146	133.1
Net prior service credit (cost)	0.7	1.2
Total amounts recorded	$ 146.7	$ 134.3

Employee Benefit Plans - Compon

Employee Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Settlement charge	$ 1.3	$ 0	$ 42.3
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	1.1	1.7	2
Interest cost	24.4	16.5	17.3
Expected asset return	(29.3)	(31)	(39)
Amortized actuarial loss (gain)	4.1	7.6	10.8
Amortized prior service cost (credit)	0.1	0.1	0.1
Curtailment charge	1.2	0	0
Settlement charge	0.1	0	42.3
Net periodic benefit cost (credit)	1.7	(5.1)	33.5
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.2	0.3	0.3
Interest cost	10.1	8.4	8.4
Expected asset return	0	0	0
Amortized actuarial loss (gain)	(8.5)	0.5	1.7
Amortized prior service cost (credit)	(0.5)	(0.9)	(1.5)
Curtailment charge	0	0	0
Settlement charge	0	0	0
Other postretirement benefit cost (credit)	$ 1.3	$ 8.3	$ 8.9

Employee Benefit Plans - All Ot

Employee Benefit Plans - All Other Relevant Defined Benefit Pension and Other Postretirement Benefit Disclosures Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	7%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5%
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2034
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 51.5
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	50.3
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	52.9
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	50.7
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	50.6
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	238.7
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	1
Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Payment for Pension and Other Postretirement Benefits	0.6
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 11

Employee Benefit Plans - U.S. P

Employee Benefit Plans - U.S. Pension Annuity Purchase (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) participant
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Settlement charge	$ 1.3	$ 0	$ 42.3
U.S. pension annuity purchase
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, number of plan participants included in settlement | participant			3,400
Settlements			$ 97.3
Settlement charge			$ 42.3

Employee Benefit Plans - Defi_2

Employee Benefit Plans - Defined Benefit Pension Plan Assets by Category and Fair Value Hierarchy (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 408.1	$ 406.9
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	327.3	302.6
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46.4	68.5
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9.8	10.4
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8.5	8.6
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.3	1.8
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. Large Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	39.4	40.3
U.S. Large Cap [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37.2	40.2
U.S. Large Cap [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.2	0.1
U.S. Large Cap [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. Small/Mid Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11.5	12.8
U.S. Small/Mid Cap [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11.5	12.8
U.S. Small/Mid Cap [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. Small/Mid Cap [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
World Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	39.2	44.1
World Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36.2	40.7
World Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	3.4
World Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Government & Agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	97.9	117.9
Government & Agencies [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	60.3	57.9
Government & Agencies [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37.6	60
Government & Agencies [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate Bonds - Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	151.1	124
Corporate Bonds - Investment Grade [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	150.2	123.5
Corporate Bonds - Investment Grade [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.9	0.5
Corporate Bonds - Investment Grade [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate Bonds - Non-investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.7	9.4
Corporate Bonds - Non-investment Grade [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.3	9
Corporate Bonds - Non-investment Grade [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.4	0.4
Corporate Bonds - Non-investment Grade [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Emerging Market Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.6	8.2
Emerging Market Debt [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.6	8.2
Emerging Market Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Emerging Market Debt [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed Income Securities - Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.5	4
Fixed Income Securities - Other [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.5	1.7
Fixed Income Securities - Other [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	2.3
Fixed Income Securities - Other [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Property Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22.6	24.9
Property Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Property Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Property Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Alternative Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11.8	10.9
Other Alternative Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Alternative Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Alternative Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	100%	100%
Domestic Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	23.80%	28%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	25% - 35%
Domestic Plan [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	69.30%	64.80%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	60% - 70%
Domestic Plan [Member] | Alternative assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	5.60%	6.10%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	0% - 10%
Domestic Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	1.30%	1.10%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	0% - 5%
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	100%	100%
Foreign Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	17.80%	13.50%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	15% - 25%
Foreign Plan [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	61.70%	64.70%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	60% - 70%
Foreign Plan [Member] | Alternative assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	15.40%	15.60%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	5% - 15%
Foreign Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	5.10%	6.20%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	0% - 5%

Employee Benefit Plans - Defi_3

Employee Benefit Plans - Defined Contribution Plans Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	50%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	10%
Defined contribution plans, salaried voluntary savings plan, matching contributions during the period	$ 9.4	$ 8.6	$ 8
Annual Retirement Contribution (ARC) [Member]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 9.9	$ 9	$ 8.3
Minimum [Member] | Annual Retirement Contribution (ARC) [Member]
Defined Contribution Plan, Employer Discretionary Contribution Percentage	3%
Maximum [Member] | Annual Retirement Contribution (ARC) [Member]
Defined Contribution Plan, Employer Discretionary Contribution Percentage	5%

Stock Based Compensation and _3

Stock Based Compensation and Other Incentive Compensation - Stock Based Compensation Narrative (Details) shares in Millions	Dec. 31, 2023 shares
Share-Based Payment Arrangement [Abstract]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	5.4

Stock Based Compensation and _4

Stock Based Compensation and Other Incentive Compensation - Restricted Stock Units Activity (Details) - Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Beginning balance	4.9	4.4	4.9
Restricted stock units granted	1.3	1.4	0.9
Restricted stock units vested	(2.6)	(0.8)	(1)
Restricted stock units canceled	(0.2)	(0.1)	(0.4)
Ending balance	3.4	4.9	4.4
Weighted-average grant date fair value outstanding	$ 9.34	$ 7.66	$ 8.43	$ 9.20
Weighted-average grant date fair value granted	8.36	8.98	10.29
Weighted-average grant date fair value vested	5.62	14.73	13.65
Weighted-average grant date fair value canceled	$ 9.53	$ 6.47	$ 8.40
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	$ 11.2
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition	2 years
Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested in period, total fair value	$ 23.2	$ 6

Stock Based Compensation and _5

Stock Based Compensation and Other Incentive Compensation - Performance Shares Activity (Details) - Performance Shares [Member] - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	$ 5.4
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition	2 years
Total Shareholder Return (TSR) Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Beginning balance	0	0.3	0.6
Performance shares granted	0	0	0
Performance shares vested	0	(0.3)	(0.3)
Performance shares canceled	0	0	0
Ending balance	0	0	0.3
Weighted-average grant date fair value outstanding	$ 0	$ 0	$ 24.36	$ 18.86
Weighted-average grant date fair value granted	0	0	0
Weighted-average grant date fair value vested	0	24.36	13.91
Weighted-average grant date fair value canceled	$ 0	$ 0	$ 0
Free Cash Flow (FCF) Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Beginning balance	1.6	1.2	1.2
Performance shares granted	0.6	0.5	0.4
Performance shares vested	(0.9)	0	(0.3)
Performance shares canceled	(0.1)	(0.1)	(0.1)
Ending balance	1.2	1.6	1.2
Weighted-average grant date fair value outstanding	$ 9.80	$ 7.81	$ 6.96	$ 7.50
Weighted-average grant date fair value granted	9.19	9.83	11.26
Weighted-average grant date fair value vested	5.93	0	14.28
Weighted-average grant date fair value canceled	$ 10.20	$ 9.26	$ 6.96

Stock Based Compensation and _6

Stock Based Compensation and Other Incentive Compensation - Long Term Cash Awards (LTCAs) (Details) - Long-Term Cash Awards (LTCAs) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive compensation arrangement, by award, grants in period	$ 5.2	$ 4.6	$ 7.8
Incentive compensation arrangement, cost not yet recognized, amount	$ 5.2
Incentive compensation arrangement, cost not yet recognized, period for recognition	2 years

Stock Based Compensation and _7

Stock Based Compensation and Other Incentive Compensation - Performance Units (Details) - Performance Units [Member] - Free Cash Flow (FCF) Awards [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive compensation arrangement, by award, grants in period	$ 12.8	$ 11.1	$ 11.7
Incentive compensation arrangement, cost not yet recognized, amount	$ 11.3
Incentive compensation arrangement, cost not yet recognized, period for recognition	2 years

Income Taxes - Income Before In

Income Taxes - Income Before Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
U.S. loss	$ (212.5)	$ (57)	$ (186.8)
Non - U.S. income	188	123.3	188
Income (loss) before income taxes	$ (24.5)	$ 66.3	$ 1.2

Income Taxes - Components of Pr

Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current
Federal	$ 8.5	$ 11.7	$ 3.5
State and local	0.9	1.3	0.3
Foreign	38	21.8	34
Total current	47.4	34.8	37.8
Deferred
Federal	(38.5)	(23.2)	(40.7)
State and local	(0.5)	0.1	(0.9)
Foreign	0.7	(9.7)	(0.9)
Total deferred	(38.3)	(32.8)	(42.5)
Total income tax expense (benefit)	$ 9.1	$ 2	$ (4.7)

Income Taxes - Rate Reconciliat

Income Taxes - Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal statutory	$ (5.1)	$ 13.9	$ 0.3
Foreign income taxes	(14.9)	(14.7)	(14)
Change in enacted tax rate	0.2	0	0.1
State and local	(7.5)	2.4	3
Tax credits	(14.2)	(9.6)	(11)
Valuation allowance	45	9.5	2.7
Withholding taxes	7.3	4.4	3.2
U.S. tax on unremitted foreign earnings	0.5	1.6	2.2
Tax benefit on loss carryback	0	0	(5.2)
Global intangible low-taxed income (GILTI)	15.3	6.4	6.5
Foreign derived intangible income deduction	(0.1)	(13.9)	0
Uncertain tax positions	1.3	3.8	1.2
Reorganization and restructuring actions	(26.1)	0	0
Other	7.4	(1.8)	6.3
Total income tax expense (benefit)	$ 9.1	$ 2	$ (4.7)

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Narrative (Details) - USD ($) $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Valuation allowance, deferred tax asset, increase (decrease), amount		$ 36.1	$ 8.9
Reorganization and restructuring actions		(26.1)	0	$ 0
Gain on bargain purchase of business		0	13.6	0
Tax benefit on loss carryback		0	0	$ (5.2)
Tekfor Group
Gain on bargain purchase of business	$ 13.6		13.6
US Tax Authority and Foreign Tax Authority
Valuation allowance, deferred tax asset, increase (decrease), amount		$ 36.1
Foreign Tax Authority [Member]
Valuation allowance, deferred tax asset, increase (decrease), amount			$ (7.5)

Income Taxes - Refundable Incom

Income Taxes - Refundable Income Taxes and Income Taxes Payable Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Refundable income taxes and income taxes payable [Line Items]
Refundable income taxes	$ 31.8
Prepaid Expenses and Other Current Assets [Member]
Refundable income taxes and income taxes payable [Line Items]
Refundable income taxes, Current	20	$ 17.1
Other assets and deferred charges
Refundable income taxes and income taxes payable [Line Items]
Refundable income taxes, Noncurrent	11.8	1.7
Accrued Liabilities [Member]
Refundable income taxes and income taxes payable [Line Items]
Taxes Payable, Current	$ 10.6	$ 7.5

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Valuation allowances	$ (267.1)	$ (217.5)
Deferred tax assets, net	152.9	108.3
Domestic [Member]
Deferred tax assets, net	88.2	47.6
Foreign [Member]
Deferred tax assets, net	64.7	60.7
Deferred Tax Assets [Member]
Employee benefits	112.1	109
Inventory	39.3	38.9
Net operating loss (NOL) carryforwards	173.1	203.7
Tax credit carryforwards	36.6	64.5
Capital allowance carryforwards	12.9	11.5
Capitalized expenditures	86.1	63.1
Interest carryforward	87	42.4
Operating lease liabilities	27.5	24.4
Other	71.3	33.3
Valuation allowances	(267.1)	(217.5)
Deferred tax assets	378.8	373.3
Deferred Tax Liabilities [Member]
Other intangible assets	(127.4)	(136.8)
Fixed assets	(48.1)	(88.7)
Operating lease right-of-use assets	(27.1)	(24.2)
Other	(23.3)	(15.3)
Deferred tax liabilities	$ (225.9)	$ (265)

Income Taxes - Deferred Income

Income Taxes - Deferred Income Tax Assets and Liabilities and Valuation Allowances Narrative (Details) - USD ($) $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Operating Loss and Tax Credit Carryforwards	$ 279.7	$ 222.6	$ 279.7
Deferred Tax Assets, Operating Loss and Tax Credit Carryforwards, Not Subject to Expiration		110.8
Deferred Tax Assets, Valuation Allowance	217.5	267.1	217.5
Valuation allowance, deferred tax asset, increase (decrease), amount		36.1	8.9
Tekfor Group
Tax Credit Carryforward [Line Items]
Deferred Taxes, Business Combination, Valuation Allowance, Available to Reduce Income Tax Expense	$ 7.8
United States
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Valuation Allowance				$ 7
Valuation allowance, deferred tax asset, increase (decrease), amount		31	15.7	1.9
Non-US
Tax Credit Carryforward [Line Items]
Valuation allowance, deferred tax asset, increase (decrease), amount		$ 8.9	$ 0.6	$ 0.8

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefts (Details) - USD ($) $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance		$ 37.2	$ 21.2	$ 20.2
Increase in prior year tax positions		1.7	3.6	0
Decrease in prior year tax positions		(9.3)	(0.8)	(1)
Increase in current year tax positions		11.8	0.5	2
Foreign currency remeasurement adjustment				0
Settlement		(6.9)
Unrecognized Tax Benefits, Increase Resulting from Foreign Currency Translation		0.7	0.1
Unrecognized tax benefits, ending balance	$ 37.2	35.2	37.2	21.2
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Unrecognized tax benefits, interest and penalties, beginning balance		3.3	2.2	2
Increase in prior year tax positions		0.5	1.1	0
Decrease in prior year tax positions		(0.6)	0	(0.1)
Increase in current year tax positions		0	0	0.3
Foreign currency remeasurement adjustment		0	0	0
Settlement		(0.3)
Unrecognized tax benefits, interest and penalties, ending balance	3.3	$ 2.9	3.3	$ 2.2
Tekfor Group
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Increase from acquisitions	$ 12.6		12.6
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Increase Resulting from Acquisition			$ 0

Income Taxes - Other Tax Disclo

Income Taxes - Other Tax Disclosure Narrative (Details) - USD ($) $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 37.2	$ 35.2	$ 37.2	$ 21.2	$ 20.2
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense		(0.1)	1.1	0.2
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	3.3	2.9	3.3	$ 2.2	$ 2
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		33.8
Income Taxes Receivable		31.8
Minimum [Member]
Income Tax Contingency [Line Items]
Income Tax Examination, Estimate of Possible Loss		300
Maximum [Member]
Income Tax Contingency [Line Items]
Income Tax Examination, Estimate of Possible Loss		350
Notice of Tax Due
Income Tax Contingency [Line Items]
Income Taxes Receivable		$ 10.1
Tekfor Group
Income Tax Contingency [Line Items]
Increase from acquisitions	$ 12.6		$ 12.6

Earnings (Loss) Per Share (EP_3

Earnings (Loss) Per Share (EPS) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator [Abstract]
Net income (loss)	$ (33.6)	$ 64.3	$ 5.9
Less: Net income allocated to participating securities	0	(2.7)	(0.2)
Net income (loss) attributable to common shareholders - Basic and Dilutive	$ (33.6)	$ 61.6	$ 5.7
Denominator [Abstract]
Weighted-average shares outstanding	120.3	119.4	118.5
Less: Participating securities	(3.7)	(4.9)	(4.6)
Weighted-average common shares outstanding	116.6	114.5	113.9
Dilutive stock-based compensation	0	1	0.2
Diluted shares outstanding - adjusted weighted-average shares after assumed conversions	116.6	115.5	114.1
Basic earnings (loss) per share	$ (0.29)	$ 0.54	$ 0.05
Diluted earnings (loss) per share	$ (0.29)	$ 0.53	$ 0.05

Earnings (Loss) Per Share (EP_4

Earnings (Loss) Per Share (EPS) - Antidilutive Shares (Details) shares in Millions	12 Months Ended
	Dec. 31, 2023 shares
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.3

Commitments and Contingencies -

Commitments and Contingencies - Purchase Obligations (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Obligated purchase commitments	$ 137.8	$ 110.7
Unrecorded Unconditional Purchase Obligation, Current	124
Unrecorded Unconditional Purchase Obligation, Noncurrent	$ 13.8

Commitments and Contingencies_2

Commitments and Contingencies - Product Liability (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Movement in Standard Product Warranty Accrual [Roll Forward]
Beginning balance	$ 54.1	$ 59.5
Accruals	26.4	14.1
Settlements	(11.4)	(10.8)
Adjustments to prior period accruals	(3.1)	(7.9)
Foreign currency translation	0.3	(0.8)
Ending balance	66.3	$ 54.1
Field Action
Movement in Standard Product Warranty Accrual [Roll Forward]
Standard Product Warranty Accrual, Increase for Warranties Issued	$ 7

Reclassifications out of Accu_3

Reclassifications out of Accumulated Other Comprehensive Income - Reclassifications out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax - Beginning Balance		$ (275.4)	$ (364.8)	$ (432.2)
Other Comprehensive Income (Loss) Arising During Period, Total, Before Tax		31.4	143.3	45.4
Other Comprehensive Income (Loss), Defined Benefit Plans, before Reclassification Adjustments, Tax		0.6	(40.1)	(11.8)
Other Comprehensive Income (Loss), Reclassification Adjustments, Total, Before Tax		(20.4)	(15.6)	44.1
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Defined Benefit Plans, Tax		0.9	1.8	(10.3)
Defined benefit plans, net		1.6	95	69.1
Foreign currency translation adjustments		7.4	(38.4)	(10.2)
Changes in cash flow hedges		3.5	32.8	8.5
Other Comprehensive Income (Loss), Net of Tax		12.5	89.4	67.4
Accumulated Other Comprehensive Income (Loss), Net of Tax - Ending Balance		(262.9)	(275.4)	(364.8)
Settlement charge		1.3	0	42.3
Cost of Sales [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		(19.9)	(6.5)	(5.6)
Interest Expense [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		(3.6)	(2.7)	14.8
Other Income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		6.6	(13.7)	(19)
Pension Plan [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Settlement charge		0.1	0	42.3
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax - Beginning Balance		(146.9)	(241.9)	(311)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		5.5	119.5	33.9
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, Tax		(1.8)	(30.2)	(7)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	[1]	(3.5)	7.3	53.4
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax		1.4	(1.6)	(11.2)
Defined benefit plans, net		1.6	95	69.1
Accumulated Other Comprehensive Income (Loss), Net of Tax - Ending Balance		(145.3)	(146.9)	(241.9)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax - Beginning Balance		(149.7)	(111.3)	(101.1)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax		7.4	(38.4)	(10.7)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax		0	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax		0	0	0.5
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Tax		0	0	0
Foreign currency translation adjustments		7.4	(38.4)	(10.2)
Accumulated Other Comprehensive Income (Loss), Net of Tax - Ending Balance		(142.3)	(149.7)	(111.3)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax - Beginning Balance		21.2	(11.6)	(20.1)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax		18.5	62.2	22.2
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax		2.4	(9.9)	(4.8)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	[2]	(16.9)	(22.9)	(9.8)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax		(0.5)	3.4	0.9
Changes in cash flow hedges		3.5	32.8	8.5
Accumulated Other Comprehensive Income (Loss), Net of Tax - Ending Balance		$ 24.7	$ 21.2	$ (11.6)
[1] The amount reclassified for 2021 includes a credit to AOCI of $42.3 million related to the effect of the Pension Annuity Purchase. See Note 7 - Employee Benefit Plans for more detail. The amounts reclassified from AOCI included $(19.9) million in COGS, $(3.6) million in interest expense and $6.6 million in other income (expense), net for the year ended December 31, 2023, $(6.5) million in COGS, $(2.7) million in interest expense and $(13.7) million in other income (expense), net for the year ended December 31, 2022 and $(5.6) million in COGS, $14.8 million in interest expense and $(19.0) million in other income (expense), net for the year ended December 31, 2021.

Revenue from Contracts with C_3

Revenue from Contracts with Customers (Details)	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customers [Abstract]
Revenue, Performance Obligation, Description of Payment Terms	50 days

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 6,079.5	$ 5,802.4	$ 5,156.6
North America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	4,437	4,441.2	3,982.4
Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	544.7	493.3	489
Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	913.4	730.5	590.9
South America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	184.4	137.4	94.3
Driveline [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	4,176.5	4,063.5	3,695.1
Driveline [Member] | North America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3,133.8	3,139.8	2,793.4
Driveline [Member] | Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	506.4	449.8	441.6
Driveline [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	441.2	391.6	374.8
Driveline [Member] | South America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	95.1	82.3	85.3
Metal Forming [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,903	1,738.9	1,461.5
Metal Forming [Member] | North America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,303.2	1,301.4	1,189
Metal Forming [Member] | Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	38.3	43.5	47.4
Metal Forming [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	472.2	338.9	216.1
Metal Forming [Member] | South America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 89.3	$ 55.1	$ 9

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Contract Asset and Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Receivables, net, current	$ 818.5	$ 820.2
Increase (decrease) in receivables	(1.7)
Contract Liabilities, current	16.6	28.1
Contract Liabilities, noncurrent	70.4	73.4
Increase (decrease) in deferred revenue	(16.1)	(16.8)	$ 13.3
Contract with customer, liability, revenue recognized	30.2	$ 31.3
Other Current Liabilities [Member]
Increase (decrease) in deferred revenue	(11.5)
Other Noncurrent Liabilities [Member]
Increase (decrease) in deferred revenue	$ (3)

Leasing - Components of Lease C

Leasing - Components of Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of lease expense [Line Items]
Amortization of right-of-use assets	$ 12.3	$ 9.9	$ 4.2
Interest on lease liabilities	5.1	4.7	2
Total finance lease cost	17.4	14.6	6.2
Operating lease cost	30.9	32.6	33.3
Short-term lease cost	2.1	1.4	1.6
Variable lease cost	5.8	5.6	3.2
Total lease cost	56.2	54.2	44.3
Cost of Sales [Member]
Components of lease expense [Line Items]
Lease expense	33.4	31.8	29.1
Selling, General and Administrative Expenses [Member]
Components of lease expense [Line Items]
Lease expense	$ 5.4	$ 7.8	$ 9

Leasing - Supplemental Lease In

Leasing - Supplemental Lease Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Supplemental lease information [Line Items]
Operating cash flows from finance leases	$ 5.1	$ 4.7	$ 2
Operating cash flows from operating leases	36.1	37.6	35.9
Financing cash flows from finance leases	$ 13.7	$ 11.2	$ 5
Weighted-average remaining lease term - finance leases	12 years 8 months 12 days	13 years 1 month 6 days	16 years 4 months 24 days
Weighted-average remaining lease term - operating leases	7 years 10 months 24 days	8 years 4 months 24 days	8 years 7 months 6 days
Weighted-average discount rate - finance leases	5%	4.90%	4.80%
Weighted-average discount rate - operating leases	6.40%	5.40%	5.20%

Leasing - Future Minimum Lease

Leasing - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Future minimum lease payments [Line Items]
Finance Lease, Liability	$ 98.5	$ 105.4
Operating Lease, Liability	117.4	$ 108.3
Finance Lease [Member]
Future minimum lease payments [Line Items]
Finance Lease, Liability, to be Paid, Year One	15.8
Finance Lease, Liability, Payments, Due Year Two	12.9
Finance Lease, Liability, Payments, Due Year Three	11.5
Finance Lease, Liability, Payments, Due Year Four	9.6
Finance Lease, Liability, Payments, Due Year Five	8.3
Finance Lease, Liability, Payments, Due after Year Five	73.2
Finance Lease, Liability, Payment, Due	131.3
Finance Lease, Liability, Undiscounted Excess Amount	(32.8)
Finance Lease, Liability	98.5
Operating lease [Member]
Future minimum lease payments [Line Items]
Lessee, Operating Lease, Liability, to be Paid, Year One	28.7
Lessee, Operating Lease, Liability, Payments, Due Year Two	24.1
Lessee, Operating Lease, Liability, Payments, Due Year Three	17.7
Lessee, Operating Lease, Liability, Payments, Due Year Four	13.6
Lessee, Operating Lease, Liability, Payments, Due Year Five	10.6
Lessee, Operating Lease, Liability, Payments, Due after Year Five	54.4
Lessee, Operating Lease, Liability, Payments, Due	149.1
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(31.7)
Operating Lease, Liability	$ 117.4

Leasing - Right of Use Assets a

Leasing - Right of Use Assets and Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Right of use assets and lease liabilities [Line Items]
Finance Lease, Right-of-Use Asset	$ 102.4	$ 106.2
Operating lease right-of-use assets	115.6	107.2
Finance Lease, Liability	98.5	105.4
Operating Lease, Liability	117.4	108.3
Property, plant and equipment, net [Member]
Right of use assets and lease liabilities [Line Items]
Finance Lease, Right-of-Use Asset	102.4	106.2
Operating lease right-of-use assets	0	0
Operating lease right-of-use assets [Member]
Right of use assets and lease liabilities [Line Items]
Finance Lease, Right-of-Use Asset	0	0
Operating lease right-of-use assets	115.6	107.2
Current portion of operating lease liabilities
Right of use assets and lease liabilities [Line Items]
Finance Lease, Liability	0	0
Operating Lease, Liability	21.9	21.1
Accrued expenses and other [Member]
Right of use assets and lease liabilities [Line Items]
Finance Lease, Liability	11.2	13
Operating Lease, Liability	0	0
Long-term portion of operating lease liabilities
Right of use assets and lease liabilities [Line Items]
Finance Lease, Liability	0	0
Operating Lease, Liability	95.5	87.2
Postretirement benefits and other long-term liabilities [Member]
Right of use assets and lease liabilities [Line Items]
Finance Lease, Liability	87.3	92.4
Operating Lease, Liability	$ 0	$ 0

Manufacturing Facility Fire a_2

Manufacturing Facility Fire and Insurance Recovery (Details) - USD ($) $ in Millions	12 Months Ended				27 Months Ended	39 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2023
Insurance Recoveries [Abstract]
Proceeds from Insurance Settlement, Operating and Investing Activities	$ 24	$ 29.1	$ 59.1	$ 11.1		$ 123.3
Proceeds from Insurance Settlement, Operating Activities	7
Proceeds from Insurance Settlement, Investing Activities	$ 17	$ 17	$ 23.1
Business Interruption Charges					$ 55.1
Tangible Asset Impairment Charges					$ 27

Acquisitions - Tekfor (Details)

Acquisitions - Tekfor (Details) - USD ($) $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Gain on bargain purchase of business		$ 0	$ 13.6	$ 0
Acquisition-related fair value inventory adjustment		0	5	$ 0
Tekfor Group
Business Acquisition [Line Items]
Business Acquisition, Name of Acquired Entity	Tekfor Group
Business Combination, Consideration Transferred	$ 94.4
Business Acquisition, Description of Acquired Entity	Tekfor Group manufactures high-performance components, modules and fasteners, including traditional powertrain and driveline components (for both internal combustion and hybrid applications), and e-mobility components. Our acquisition of Tekfor contributes to diversifying our geographic and customer sales mix, while also increasing our electrification product portfolio.
Cash and cash equivalents	$ 14.3		14.3
Accounts receivable	33.7		33.7
Inventories	46.3		46.3
Prepaid expenses and other long-term assets	30.1		30.1
Deferred income tax assets	5		5
Property, plant and equipment	105.5		105.5
Total assets acquired	234.9		234.9
Accounts payable	33.5		33.5
Accrued expenses and other	28.1		28.1
Debt	23.4		23.4
Postretirement benefits and other long-term liabilities	41.9		41.9
Net assets acquired	108		108
Gain on bargain purchase of business	$ 13.6		$ 13.6
Business Combination, Bargain Purchase, Gain Recognized, Description	The gain on bargain purchase of business was primarily the result of macroeconomic factors at the time of acquisition such as the supply chain disruptions that have impacted the automotive industry, including the conflict between Russia and Ukraine, the semiconductor supply shortage, and increasing input costs, including materials, freight and utilities.
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	$ 204	397.2
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	(5.1)	$ (19.8)
Acquisition-related fair value inventory adjustment	$ 4

Acquisitions - Tekfor Pro Forma

Acquisitions - Tekfor Pro Forma (Details) - USD ($) $ / shares in Units, $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Business Combination, Acquisition Related Costs		$ 0	$ 6	$ 0.4
Gain on bargain purchase of business		$ 0	13.6	0
Tekfor Group
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Business Acquisition, Pro Forma Revenue			5,950	5,500
Business Acquisition, Pro Forma Net Income (Loss)			$ 55	$ 15
Business Acquisition, Pro Forma Earnings Per Share, Diluted			$ 0.46	$ 0.13
Business Acquisition, Pro Forma Disclosure, Nonrecurring Amount				$ 15
Fair Value Inventory Adjustment from Acquisition of Tekfor, net of tax			$ 4
Business Combination, Acquisition Related Costs			5
Gain on bargain purchase of business	$ 13.6		13.6
Net adjustments reclassified in Pro Forma Net Income			$ 5

Acquisitions - Emporium (Detail

Acquisitions - Emporium (Details) - Emporium, Pennsylvania [Member] - USD ($) $ in Millions	7 Months Ended
	Dec. 31, 2021	May 17, 2021
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		$ 14.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory		5.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Equipment		$ 9
Business Combination, Consideration Transferred	$ 14.9
Business Combination, Consideration Transferred, Cash Paid	4.9
Business Combination, Consideration Transferred, Liabilities Incurred	10
Business Combination, Consideration Transferred, Liabilities Incurred, Annual Amount	$ 2.5

Dispositions (Details)

Dispositions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Combination and Asset Acquisition [Abstract]
Proceeds from Divestiture of Businesses			$ 2.6
Loss on sale of business	$ 0	$ 0	$ 2.7

Segment and Geographic Inform_3

Segment and Geographic Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Sales	$ 6,631	$ 6,344.2	$ 5,608.1
Less: Intersegment sales	551.5	541.8	451.5
Net external sales	6,079.5	5,802.4	5,156.6
Segment adjusted EBITDA	693.3	747.3	833.3
Depreciation and amortization	487.2	492.1	544.3
Capital expenditures	194.6	171.4	181.2
Total Assets	5,356.3	5,469.4	5,635.7
Driveline [Member]
Segment Reporting Information [Line Items]
Sales	4,176.7	4,063.5	3,695.3
Less: Intersegment sales	0.2	0	0.2
Net external sales	4,176.5	4,063.5	3,695.1
Segment adjusted EBITDA	543.6	510.9	541.8
Depreciation and amortization	260.3	272.7	293.8
Capital expenditures	105.9	103.3	123.4
Total Assets	2,554.3	2,542	2,852
Metal Forming [Member]
Segment Reporting Information [Line Items]
Sales	2,454.3	2,280.7	1,912.8
Less: Intersegment sales	551.3	541.8	451.3
Net external sales	1,903	1,738.9	1,461.5
Segment adjusted EBITDA	149.7	236.4	291.5
Depreciation and amortization	226.9	219.4	250.5
Capital expenditures	80.1	62.9	53.9
Total Assets	1,788.7	1,900.3	1,650.5
Corporate and Eliminations [Member]
Segment Reporting Information [Line Items]
Sales	0	0	0
Less: Intersegment sales	0	0	0
Net external sales	0	0	0
Segment adjusted EBITDA	0	0	0
Depreciation and amortization	0	0	0
Capital expenditures	8.6	5.2	3.9
Total Assets	$ 1,013.3	$ 1,027.1	$ 1,133.2

Segment and Geographic Inform_4

Segment and Geographic Information - Reconciliation of Operating Profit Loss from Segments to Consolidated (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment adjusted EBITDA	$ 693.3	$ 747.3	$ 833.3
Interest expense	(201.7)	(174.5)	(195.2)
Depreciation and amortization	(487.2)	(492.1)	(544.3)
Restructuring and acquisition-related costs	(25.2)	(30.2)	(49.4)
Pension curtailment and settlement charges	(1.3)	0	(42.3)
Loss on sale of business	0	0	(2.7)
Unrealized gain (loss) on equity securities	(1.1)	(25.5)	24.4
Debt refinancing and redemption costs	(1.3)	(6.4)	(34)
Malvern Fire insurance recoveries, net of charges	0	39.1	11.4
Acquisition-related fair value inventory adjustment	0	(5)	0
Gain on bargain purchase of business	0	13.6	0
Income (loss) before income taxes	$ (24.5)	$ 66.3	$ 1.2

Segment and Geographic Inform_5

Segment and Geographic Information - Schedule of Disclosure on Geographic Areas (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 6,079.5	$ 5,802.4	$ 5,156.6
Long-lived assets	3,180.3	3,357	3,658.6
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	2,163.5	2,148	1,923.5
Long-lived assets	1,694.3	1,778.9	1,976.5
Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	2,273.5	2,293.2	2,058.9
Long-lived assets	778.4	821.3	888.1
South America
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	184.4	137.4	94.3
Long-lived assets	75.8	71.2	40.9
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	271.6	280	299.6
Long-lived assets	110.9	130.1	164.8
Asia, excluding China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	273.1	213.3	189.4
Long-lived assets	79.2	80.5	87.1
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	913.4	730.5	590.9
Long-lived assets	$ 441.7	$ 475	$ 501.2

Schedule II - Valuation and Q_3

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, balance	[1]	$ 9.3	$ 2.2	$ 4.5
Additions, charged to costs and expenses	[1]	4.4	10.1	7.8
Acquisitions and other	[1],[2]	0	1	0
Deductions	[1]	8.4	4	10.1
Valuation allowances and reserves, balance	[1]	5.3	9.3	2.2
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, balance	[3]	217.5	201.7	208
Additions, charged to costs and expenses	[3]	54.5	9.5	2.7
Acquisitions and other	[2],[3]	0	7.8	0
Deductions	[3]	4.9	1.5	9
Valuation allowances and reserves, balance	[3]	267.1	217.5	201.7
SEC Schedule, 12-09, Reserve, Inventory [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, balance	[4]	27.5	18.6	23.4
Additions, charged to costs and expenses	[4]	22.1	35.7	17.7
Acquisitions and other	[2],[4]	0	4.9	0
Deductions	[4]	17.5	31.7	22.5
Valuation allowances and reserves, balance	[4]	$ 32.1	$ 27.5	$ 18.6
[1] Uncollectible accounts charged off, net of recoveries. Amounts represent reserves recognized in conjunction with our acquisition of Tekfor in 2022. Primarily reflects an increase in valuation allowance related to certain U.S. federal tax attributes, as well as new net operating losses established with a corresponding valuation allowance at certain foreign locations, partially offset by adjustments to previously established valuation allowances and foreign currency translation.