American Axle & Manufacturing (AXL) 10-K 11 Feb 22 2021 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Feb. 08, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
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
Entity Shell Company	false
Entity Public Float			$ 1,162.9
Entity Common Stock, Shares Outstanding		114,077,937
Documents Incorporated by Reference	Portions of the registrant's Annual Report to Stockholders for the year ended December 31, 2021 and Proxy Statement for use in connection with its Annual Meeting of Stockholders to be held on May 5, 2022, to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after December 31, 2021, are incorporated by reference in Part I (Items 1, 1A, 1B, 2, 3 and 4), Part II (Items 5, 6, 7, 7A, 8, 9, 9A and 9B), 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	2021
Document Fiscal Period Focus	FY
Amendment Flag	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2021
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, 2021	Dec. 31, 2020	Dec. 31, 2019
Net sales	$ 5,156.6	$ 4,710.8	$ 6,530.9
Cost of goods sold	4,433.9	4,128.1	5,628.3
Gross profit	722.7	582.7	902.6
Selling, general and administrative expenses	344.2	313.9	364.7
Amortization of intangible assets	85.8	86.6	95.4
Impairment charges	0	510	665
Restructuring and acquisition-related costs	49.4	67.2	57.8
Loss on sale of business	2.7	1	21.3
Operating income (loss)	240.6	(396)	(301.6)
Interest expense	(195.2)	(212.3)	(217.3)
Interest income	10.9	11.6	5.8
Other income (expense)
Debt refinancing and redemption costs	(34)	(7.9)	(8.4)
Gain on bargain purchase of business	0	0	10.8
Pension settlement charges	(42.3)	(0.5)	(9.8)
Unrealized gain on equity securities	24.4	0	0
Other expense, net	(3.2)	(5.2)	(12.5)
Income (loss) before income taxes	1.2	(610.3)	(533)
Income tax benefit	(4.7)	(49.2)	(48.9)
Net income (loss)	5.9	(561.1)	(484.1)
Net income attributable to noncontrolling interests	0	(0.2)	(0.4)
Net income (loss) attributable to AAM	$ 5.9	$ (561.3)	$ (484.5)
Basic earnings (loss) per share	$ 0.05	$ (4.96)	$ (4.31)
Diluted earnings (loss) per share	$ 0.05	$ (4.96)	$ (4.31)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net income (loss)	$ 5.9	$ (561.1)	$ (484.1)
Other comprehensive income (loss)
Defined benefit plans, net of $(18.2) million, $12.7 million and $3.0 million of tax in 2021, 2020 and 2019, respectively	69.1	(51.1)	(18.3)
Foreign currency translation adjustments	(10.2)	(0.2)	(4.6)
Changes in cash flow hedges, net of tax of $(3.9) million, $1.3 million and $6.1 million in 2021, 2020 and 2019, respectively	8.5	(4.4)	(14.6)
Other comprehensive income (loss)	67.4	(55.7)	(37.5)
Comprehensive income (loss)	73.3	(616.8)	(521.6)
Net income attributable to noncontrolling interests	0	(0.2)	(0.4)
Foreign currency translation adjustments attributable to noncontrolling interests	0	0.3	0
Comprehensive income (loss) attributable to AAM	$ 73.3	$ (616.7)	$ (522)

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Comprehensive Income (Loss), Tax, Parenthetical Disclosures [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	$ (18.2)	$ 12.7	$ 3
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax	$ (3.9)	$ 1.3	$ 6.1

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 530.2	$ 557
Accounts receivable, net	762.8	793.2
Inventories, net	410.4	323.2
Prepaid expenses and other	152.6	203.6
Total current assets	1,856	1,877
Property, plant and equipment, net	1,996.1	2,163.8
Deferred income taxes	121.1	107.8
Goodwill	183.8	185.7
Other intangible assets, net	697.2	780.7
GM postretirement cost sharing asset	201.1	237
Operating lease right-of-use assets	123.7	116.6
Other assets and deferred charges	456.7	447.7
Total assets	5,635.7	5,916.3
Current liabilities
Current portion of long-term debt	18.8	13.7
Accounts payable	612.8	578.9
Accrued compensation and benefits	195.2	170.9
Deferred revenue	28.1	23.4
Current portion of operating lease liabilities	24.6	22.6
Accrued expenses and other	160.4	169.8
Total current liabilities	1,039.9	979.3
Long-term debt, net	3,085.7	3,441.3
Deferred revenue	94.8	91
Deferred income taxes	13.5	13.2
Long-term portion of operating lease liabilities	99.9	94.4
Postretirement benefits and other long-term liabilities	844.1	923.9
Total liabilities	5,177.9	5,543.1
Stockholders' equity
Preferred stock, par value $0.01 per share; 10.0 million shares authorized; no shares outstanding in 2021 or 2020	0	0
Series common stock, par value $0.01 per share; 40.0 million shares authorized; no shares outstanding in 2021 or 2020	0	0
Common stock, par value $0.01 per share; 150.0 million shares authorized; 122.5 million and 121.3 million shares issued as of December 31, 2021 and December 31, 2020, respectively	1.3	1.2
Paid-in capital	1,351.5	1,333.3
Accumulated deficit	(313.9)	(319.8)
Treasury stock at cost, 8.5 million shares in 2021 and 8.0 million shares in 2020	(216.3)	(212)
Accumulated other comprehensive loss
Defined benefit plans, net of tax	(241.9)	(311)
Foreign currency translation adjustments	(111.3)	(101.1)
Unrecognized loss on cash flow hedges, net of tax	(11.6)	(20.1)
Total AAM stockholders' equity	457.8	370.5
Noncontrolling interests in subsidiaries	0	2.7
Total stockholders' equity	457.8	373.2
Total liabilities and stockholders' equity	$ 5,635.7	$ 5,916.3

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Millions	Dec. 31, 2021	Dec. 31, 2020
Common stock, shares, outstanding	114	113.3
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	122.5	121.3
Treasury stock, shares	8.5	8

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net income (loss)	$ 5.9	$ (561.1)	$ (484.1)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization	544.3	521.9	536.9
Impairment charges	0	510	667.9
Deferred income taxes	(27.2)	(34.1)	(94.6)
Stock-based compensation	18.2	19.4	22.4
Pensions and other postretirement benefits, net of contributions	19.9	(15.7)	(8.8)
Loss on sale of business, net	2.7	1	10.5
Loss on disposal of property, plant and equipment, net	5.8	20.6	4.1
Unrealized gain on equity securities	(24.4)	0	0
Debt refinancing and redemption costs	34	7.9	8.4
Changes in operating assets and liabilities, net of amounts acquired or disposed
Accounts receivable	23.1	28.9	63.9
Inventories	(87.7)	53.7	56.1
Accounts payable and accrued expenses	62.7	(37.1)	(97.7)
Deferred revenue	13.3	5.5	(17.9)
Other assets and liabilities	(52.2)	(66.2)	(107.5)
Net cash provided by operating activities	538.4	454.7	559.6
Investing activities
Purchases of property, plant and equipment	(181.2)	(215.6)	(433.3)
Proceeds from sale of property, plant and equipment	2	1.7	5
Purchase buyouts of leased equipment	0	(0.1)	(0.9)
Final settlement on sale of business	0	(4.4)	0
Proceeds from sale of business, net	1	0	141.2
Acquisition of business, net of cash acquired	(4.9)	0	(9.4)
Investment in affiliates	(1.1)	0	(9.2)
Proceeds from insurance claim	23.1	0	0
Net cash used in investing activities	(161.1)	(218.4)	(306.6)
Financing activities
Proceeds from Revolving Credit Facility	0	350	0
Payments of Revolving Credit Facility	0	(350)	0
Proceeds from issuance of long-term debt	634.7	408	356.3
Payments of long-term debt	(1,017.6)	(607.2)	(544.4)
Debt issuance costs	(9.2)	(11)	(3.3)
Purchase of treasury stock	(4.3)	(2.7)	(7.5)
Finance lease obligations and other	(5)	(1.6)	(1.1)
Net cash used in financing activities	(401.4)	(214.5)	(200)
Effect of exchange rate changes on cash	(2.7)	3.2	0.1
Net increase (decrease) in cash, cash equivalents and restricted cash	(26.8)	25	53.1
Cash, cash equivalents and restricted cash at beginning of year	557	532	478.9
Cash, cash equivalents and restricted cash at end of year	530.2	557	532
Supplemental cash flow information
Interest paid	184.9	192.4	205.4
Income taxes paid, net	26.6	2.1	57.1
Non-cash investing activities: Deferred consideration for acquisition of business	10	0	0
Twelve year deferred payment obligation at 6% [Member]
Supplemental cash flow information
Non-cash investing activities: Debt security received for sale of U.S. Casting	$ 0	$ 0	$ 60

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	AOCI Attributable to Parent	Noncontrolling Interest in Subsidiaries
Common stock, shares, outstanding at Dec. 31, 2018	111.7
Total AAM stockholders' equity at Dec. 31, 2018		$ 1.2	$ 1,292.6	$ 703.5	$ (201.8)	$ (311.6)	$ 2.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to AAM	$ (484.5)			(484.5)
Net income attributable to noncontrolling interests	(0.4)						0.4
Changes in cash flow hedges	(14.6)					(14.6)
Foreign currency translation adjustments						(4.6)
Foreign currency translation adjustments attributable to noncontrolling interests	$ 0						0
Defined benefit plans, net						(18.3)
Stock issued during period, shares, share-based compensation, net of forfeitures	1.3
Stock-based compensation			21.3
New accounting pronouncement, effect of adoption | ASU 2016-02 [Member]				1.9
New accounting pronouncement, effect of adoption | ASU 2018-02 [Member]	$ 27.7			27.7		(27.7)
Treasury stock, shares, acquired	(0.4)
Purchase of treasury stock	$ 7.5				(7.5)
Common stock, shares, outstanding at Dec. 31, 2019	112.6
Total AAM stockholders' equity at Dec. 31, 2019		1.2	1,313.9	248.6	(209.3)	(376.8)	2.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to AAM	$ (561.3)			(561.3)
Net income attributable to noncontrolling interests	(0.2)						0.2
Changes in cash flow hedges	(4.4)					(4.4)
Foreign currency translation adjustments						0.1
Foreign currency translation adjustments attributable to noncontrolling interests	$ (0.3)						(0.3)
Defined benefit plans, net						(51.1)
Stock issued during period, shares, share-based compensation, net of forfeitures	1.1
Stock-based compensation			19.4
New accounting pronouncement, effect of adoption | ASU 2016-13 [Member]				(7.1)
Treasury stock, shares, acquired	(0.4)
Purchase of treasury stock	$ 2.7				(2.7)
Common stock, shares, outstanding at Dec. 31, 2020	113.3
Total AAM stockholders' equity at Dec. 31, 2020	$ 370.5	1.2	1,333.3	(319.8)	(212)	(432.2)	2.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to AAM	5.9			5.9
Net income attributable to noncontrolling interests	0						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						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	$ 457.8	$ 1.3	$ 1,351.5	$ (313.9)	$ (216.3)	$ (364.8)	$ 0

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
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 nearly 80 facilities in 17 countries, AAM is bringing the future faster for a safer and more sustainable future. 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 $2.2 million and $4.5 million as of December 31, 2021 and 2020, 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 and Asia. 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 saleable, we record a provision for such loss as a component of our inventory accounts. Inventories consist of the following: December 31, 2021 2020 (in millions) Raw materials and work-in-progress $ 339.7 $ 276.2 Finished goods 89.3 70.4 Gross inventories 429.0 346.6 Inventory valuation reserves (18.6) (23.4) Inventories, net $ 410.4 $ 323.2 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 $61.6 million, $62.4 million and $67.7 million for 2021, 2020 and 2019, 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 $396.9 million, $372.9 million and $373.8 million in 2021, 2020 and 2019, respectively. Property, plant and equipment consists of the following: Estimated December 31, Useful Lives 2021 2020 (years) (in millions) Land Indefinite $ 47.7 $ 49.2 Land improvements 10-15 26.8 26.3 Buildings and building improvements 15-40 635.8 554.3 Machinery and equipment 3-12 3,700.3 3,703.7 Construction in progress 171.2 122.1 4,581.8 4,455.6 Accumulated depreciation and amortization (2,585.7) (2,291.8) Property, plant and equipment, net $ 1,996.1 $ 2,163.8 As of December 31, 2021, 2020 and 2019, we had unpaid purchases of plant and equipment in our accounts payable of $20.1 million, $20.4 million and $46.0 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. 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, 2021 and December 31, 2020, our unamortized debt issuance costs were $42.3 million and $57.8 million, respectively. Debt issuance costs associated with our senior unsecured notes, as well as our Term Loan A Facility due 2024 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 $8.9 million and $12.2 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, 2021 and December 31, 2020, 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 losses of $1.7 million, $0.5 million and $6.5 million for the years 2021, 2020 and 2019, respectively, in Other 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 $116.8 million, $117.4 million and $144.7 million in 2021, 2020 and 2019, respectively. In both 2021 and 2020, our R&D amounts reflect customer engineering, design and development recoveries of approximately $15.0 million. 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 Recently Adopted Accounting Standard Update 2021-08 On October 28, 2021, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2021-08 - Business Combinations (Topic 805) - Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. This guidance amends previous guidance to now require that an acquirer recognize contract assets and liabilities obtained as part of a business combination in accordance with Accounting Standard Codification (ASC) Topic 606 - Revenue from Contracts with Customers . This guidance becomes effective at the beginning of our 2023 fiscal year, however, early adoption was permitted and we elected to adopt this guidance early as of December 31, 2021. The adoption of this standard did not have a material impact on our consolidated financial statements as the business combination completed during 2021 did not include material contract assets or contract liabilities. See Note 16 - Acquisitions and Dispositions for additional information. Accounting Standard Update 2020-04 On March 12, 2020, the FASB issued ASU 2020-04 - Reference Rate Reform (Topic 848) and has subsequently issued ASU 2021-01 - Reference Rate Reform (Topic 848) . This guidance provides optional expedients and exceptions that are intended to ease the burden of updating contracts to contain a new reference rate due to the discontinuation of the London Inter-Bank Offered Rate (LIBOR). At December 31, 2021, we have completed our analysis to identify the contracts that include LIBOR as the referenced rate and have concluded that these contracts are comprised primarily of those related to our Senior Secured Credit Facilities and our variable-to-fixed interest rate swap. See Note 4 - Long-Term Debt for additional detail on our Senior Secured Credit Facilities and Note 5 - Derivatives and Risk Management for additional detail on our interest rate swap. This guidance was available for adoption immediately following issuance on March 12, 2020 and may be implemented in any period prior to the guidance expiration on December 31, 2022. We have elected to adopt this guidance as of December 31, 2021 and the adoption of this guidance did not have a material impact on our financial statements. Accounting Standards Update 2019-12 On December 18, 2019, the FASB issued ASU 2019-12 - Income Taxes (Topic 740) . This guidance is intended to simplify the accounting and disclosure requirements for income taxes by removing various exceptions, and requires that the effect of an enacted change in tax laws or rates on current tax expense be included in the annual effective tax rate computation in the interim period of the enactment. This guidance became effective and we adopted this guidance on January 1, 2021. The adoption of this standard did not have a material impact on our consolidated financial statements. Standards Not Yet Adopted Accounting Standard Updated 2021-10 On November 17, 2021, the FASB issued ASU 2021-10 - Government Assistance (Topic 832) . This guidance establishes requirements for annual disclosures about certain types of material government assistance, including government grants and tax credits. This guidance becomes effective at the beginning of our 2022 fiscal year, and we expect to prospectively adopt this guidance on January 1, 2022. We do not expect this guidance to have a material impact on our consolidated financial statements. CORONAVIRIUS AID, RELIEF, AND ECONOMIC SECURITY ACT The Coronavirus Aid, Relief, and Economic Security Act (the CARES Act) was enacted on March 27, 2020 in the United States. The key provisions of the CARES Act, as applicable to AAM, included the following: • The ability to use net operating losses (NOLs) to offset income without the 80% taxable income limitation enacted as part of the Tax Cuts and Jobs Act (TCJA) of 2017, and to carry back NOLs to offset prior year income for five years. These are temporary provisions that apply to NOLs incurred in 2018, 2019 or 2020 tax years. We recognized a tax benefit of $5.2 million for the year ended December 31, 2021 and $14.4 million for the year ended December 31, 2020 related to our ability to carry back prior year losses under the CARES Act to years with the previous 35% tax rate. We received an income tax refund of approximately $6.0 million during 2021 and an income tax refund of approximately $31.0 million during 2020 as a result of these provisions of the CARES Act. • The ability to defer the payment of the employer portion of social security taxes incurred between March 27, 2020 and December 31, 2020, with 50% of the deferred amount to be paid by December 31, 2021 and the remaining 50% to be paid by December 31, 2022. In the year ended December 31, 2021 we paid $7.6 million of deferred social security taxes, and the remaining $7.6 million of deferred social security taxes will be paid in 2022. • The ability to claim an Employee Retention Credit (ERC), which is a refundable payroll tax credit, for 50% of qualified wages or benefits, subject to certain limitations, that are paid to an employee when they are not providing services due to COVID-19. The ERC applies to qualified wages paid or incurred during the period March 13, 2020 through December 31, 2020 and is available to eligible employers whose operations were fully or partially suspended due to COVID-19, or whose gross receipts declined by more than 50% when compared to the applicable period in the prior year. At December 31, 2021, we have a refundable ERC amount of $2.6 million included in Prepaid expenses and other in our Consolidated Balance Sheet.

Restructuring and Acquisition-R

Restructuring and Acquisition-Related Costs	12 Months Ended
	Dec. 31, 2021
Restructuring and Related Activities [Abstract]
Business Acquisition, Integration, Restructuring and Other Related Costs [Text Block]	2. RESTRUCTURING AND ACQUISITION-RELATED COSTS In 2019, we initiated a global restructuring program (the 2019 Program). The primary objectives of the 2019 Program were to further the integration of Metaldyne Performance Group, Inc. (MPG), align AAM's product and process technologies, and to achieve efficiencies within our corporate and business unit support teams to reduce cost in our business. In the first quarter of 2020, we initiated a new global restructuring program (the 2020 Program) that superseded the 2019 Program. The primary objectives of the 2020 Program are 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. We expect to incur costs under the 2020 Program into 2023. In 2021, we completed our acquisition of a manufacturing facility in Emporium, Pennsylvania (Emporium), and subsequently determined that we will cease production at the facility and relocate the production capacity to other AAM manufacturing facilities. As a result, during 2021 we incurred restructuring charges related to the anticipated closure of the facility, and expect to incur costs associated with the closure of the facility through 2022. See Note 16 - Acquisitions and Dispositions for further detail. A summary of our restructuring activity for the years 2021, 2020 and 2019 is shown below: Severance Charges Implementation Costs Total (in millions) Accrual at January 1, 2019 $ 2.4 $ 1.6 $ 4.0 Charges 19.4 20.4 39.8 Cash utilization (17.0) (14.6) (31.6) Accrual at December 31, 2019 4.8 7.4 12.2 Charges 22.3 36.1 58.4 Cash utilization (25.4) (33.7) (59.1) Accrual at December 31, 2020 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 As part of our restructuring actions during 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. We incurred $39.5 million of restructuring costs in 2021 under the 2020 Program, and incurred $3.7 million of costs associated with the anticipated closure of Emporium. We have incurred $87.3 million of total restructuring costs under the 2020 Program since inception. 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. In 2020, we incurred severance charges of approximately $22.3 million, as well as implementation costs, consisting primarily of plant exit costs and professional fees, of approximately $36.1 million. Approximately $19.3 million and $16.0 million of our total restructuring costs in 2020 related to our Driveline and Metal Forming segments, respectively, while the remainder were corporate costs. In 2019, we incurred severance charges of approximately $19.4 million, as well as implementation costs, consisting primarily of plant exit costs, of approximately $20.4 million. Approximately $6.4 million, $21.5 million and $0.7 million of our total restructuring costs in 2019 related to our Driveline, Metal Forming and former Casting segments, respectively, while the remainder were corporate costs. We expect to incur approximately $20 million to $30 million of total restructuring charges in 2022, substantially all of which are under the 2020 Program. In 2021, we completed our acquisition of Emporium, and in 2019, we completed our acquisition of certain operations of Mitec Automotive AG. We also continue to incur integration costs related to our acquisition of MPG in 2017. The following table represents a summary of charges incurred in 2021, 2020 and 2019 associated with acquisition and integration costs: Acquisition-Related Costs Integration Expenses Total 2021 Charges $ 0.4 $ 5.8 $ 6.2 2020 Charges — 8.8 8.8 2019 Charges 1.8 16.2 18.0 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 the acquisitions. Total restructuring charges and acquisition-related charges of $49.4 million, $67.2 million and $57.8 million are shown on a separate line item titled "Restructuring and Acquisition-Related Costs" in our Consolidated Statements of Operations for 2021, 2020 and 2019, respectively.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2021
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, 2021 and the year ended December 31, 2020: Driveline Metal Forming Consolidated (in millions) Balance as of January 1, 2020 $ 398.3 $ 300.8 $ 699.1 Impairment charge (210.8) (299.2) (510.0) Foreign currency translation (1.8) (1.6) (3.4) Balance as of December 31, 2020 $ 185.7 $ — $ 185.7 Foreign currency translation (1.9) — (1.9) Balance as of December 31, 2021 $ 183.8 $ — $ 183.8 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 2021 and no impairment was identified. In the first quarter of 2020, the reduction in global automotive production volumes caused by the impact of COVID-19 represented an indicator to test our goodwill for impairment. This reduction in production volumes began in March of 2020 and resulted in lower forecasted sales volumes in the periods included in our long-range plan as revised in the first quarter of 2020. As a result of this goodwill impairment test in the first quarter of 2020, we determined that the carrying values of both our Driveline and Metal Forming reporting units were greater than their respective fair values. As such, we recorded a goodwill impairment charge of $510.0 million in the first quarter of 2020, of which $210.8 million was associated with our Driveline reporting unit and $299.2 million was associated with our Metal Forming reporting unit. The Metal Forming impairment charge represented a full impairment of the goodwill associated with that reporting unit. As a result, all remaining goodwill is attributable to our Driveline reporting unit. These impairment charges were primarily the result of a decline in the projected cash flows of these reporting units under our revised long-range plan completed in the first quarter of 2020. The revision to our long-range plan was driven by lower forecasted sales volumes in the internal and external data sources used to form our projections primarily due to the reduction in global automotive production volumes caused by the impact of COVID-19. The impairment charges were also the result of changes in certain market-related inputs to the analysis to reflect macro-economic changes caused by the impact of COVID-19, including increased discount rates and lower pricing multiples for comparable public companies. At December 31, 2021, accumulated goodwill impairment losses were $1,435.5 million. The reduction in production volumes and changes to macro-economic factors caused by the impact of COVID-19 also represented an indicator to test our long-lived assets, including other intangible assets and property, plant and equipment, for impairment. We completed this test in the first quarter of 2020 and there was no impairment of these assets. As a result of our annual goodwill impairment test in the fourth quarter of 2019, we determined that the carrying value of our Metal Forming reporting unit was greater than its fair value. As such, we recorded a goodwill impairment charge of $440.0 million in 2019 associated with this reporting unit. This impairment was primarily the result of a decline in the projected cash flows of this reporting unit under our long-range plan completed in the fourth quarter of 2019, as compared to the long-range plan completed in the fourth quarter of 2018. This was driven, in part, by lower forecasted sales volumes in the internal and external data sources used to form our projections. 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, 2021 and December 31, 2020: December 31, December 31, 2021 2020 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in millions) Capitalized computer software $ 47.3 $ (37.0) $ 10.3 $ 47.6 $ (33.9) $ 13.7 Customer platforms 856.2 (301.3) 554.9 856.2 (237.9) 618.3 Customer relationships 53.0 (16.2) 36.8 53.0 (12.8) 40.2 Technology and other 156.1 (60.9) 95.2 156.7 (48.2) 108.5 Total $ 1,112.6 $ (415.4) $ 697.2 $ 1,113.5 $ (332.8) $ 780.7 Amortization expense for our intangible assets was $85.8 million for the year ended December 31, 2021, $86.6 million for the year ended December 31, 2020, and $95.4 million for the year ended December 31, 2019. Amortization expense for the years 2022 through 2026 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, 2021
Debt Disclosure [Abstract]
Long-term Debt [Text Block]	4. LONG-TERM DEBT Long-term debt, net consists of the following: December 31, 2021 2020 (in millions) Revolving credit facility $ — $ — Term Loan A Facility due 2024 301.8 323.0 Term Loan B Facility due 2024 850.0 1,088.8 6.875% Notes due 2028 400.0 400.0 6.50% Notes due 2027 500.0 500.0 6.25% Notes due 2026 400.0 400.0 6.25% Notes due 2025 — 700.0 5.00% Notes due 2029 600.0 — Foreign credit facilities 86.1 88.8 Total debt 3,137.9 3,500.6 Less: Current portion of long-term debt 18.8 13.7 Long-term debt 3,119.1 3,486.9 Less: Debt issuance costs 33.4 45.6 Long-term debt, net $ 3,085.7 $ 3,441.3 SENIOR SECURED CREDIT FACILITIES In 2017, Holdings and American Axle & Manufacturing, Inc. (AAM Inc.) entered into a credit agreement (the Credit Agreement). In connection with the Credit Agreement, Holdings, AAM, Inc. and certain of their restricted subsidiaries entered into a Collateral Agreement and Guarantee Agreement with the financial institutions party thereto. The Credit Agreement, as amended in July 2019 (First Amendment), includes a $340 million term loan A facility (the Term Loan A Facility due 2024, a $1.55 billion term loan B facility (the Term Loan B Facility due 2024) and a $925 million multi-currency revolving credit facility (the Revolving Credit Facility, and together with the Term Loan A Facility due 2024 and the Term Loan B Facility due 2024, the Senior Secured Credit Facilities). The Term Loan A Facility due 2024 and the Term Loan B Facility due 2024 have been paid down from the original amounts through both scheduled and voluntary payments. There are no current maturities under the Term Loan A due 2024 and there are no scheduled payments under the Term Loan B due 2024 until maturity. In April 2020, Holdings, AAM, Inc., and certain subsidiaries of Holdings entered into the Second Amendment (Second Amendment) to the Credit Agreement. For the period from April 1, 2020 through March 31, 2022 (the Amendment Period), the Second Amendment, among other things, replaced the total net leverage ratio covenant with a new senior secured net leverage ratio covenant, reduced the minimum levels of the cash interest expense coverage ratio covenant, and modified certain covenants restricting the ability of Holdings, AAM and certain subsidiaries of Holdings to create, incur, assume or permit to exist certain additional indebtedness and liens and to make certain restricted payments, voluntary payments and distributions. The Second Amendment also increased the maximum levels of the total net leverage ratio covenant after the Amendment Period, modified the applicable margin with respect to interest rates under the Term Loan A Facility due 2024 and interest rates and commitment fees under the Revolving Credit Facility, and increased the minimum adjusted London Interbank Offered Rate for Eurodollar-based loans under the Term Loan A Facility due 2024 and Revolving Credit Facility. The applicable margin for the Term Loan B Facility remains unchanged. We paid debt issuance costs of $4.6 million in the year ended December 31, 2020 related to the Second Amendment. In June 2021, Holdings, AAM, Inc., and certain subsidiaries of Holdings entered into an agreement (the Agreement) amending the Second Amendment to the Credit Agreement. For the Amendment Period, the Agreement modified a covenant in the Second Amendment restricting the ability of Holdings, AAM and certain subsidiaries of Holdings to make certain voluntary payments and distributions of, or in respect of, certain senior unsecured notes of AAM during the Amendment Period, which modification permits voluntary payments and redemptions of the 6.25% Notes due 2025 issued by AAM. In December 2019, we used a portion of the cash proceeds from the sale of the U.S. operations of our Casting segment (the Casting Sale) to make a payment on our Term Loan B Facility Due 2024, which included a principal payment of $59.8 million and $0.4 million in accrued interest. We also expensed approximately $1.0 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 December 2020, we made a voluntary prepayment of $100 million on our Term Loan B Facility and paid approximately $15 million on our Term Loan A Facility due 2024. As a result, we expensed approximately $1.2 million for the write-off of a portion of the unamortized debt issuance costs that we had been amortizing over the life of these borrowings. In 2021, we made voluntary prepayments totaling $21.2 million on our Term Loan A Facility due 2024 and $238.8 million on our Term Loan B Facility due 2024. 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, 2021, $893.2 million was available under the Revolving Credit Facility. This availability reflects a reduction of $31.8 million for standby letters of credit issued against the facility. The proceeds of the Revolving Credit Facility are used for general corporate purposes. 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. 5.00% NOTES DUE 2029 In the third quarter of 2021, we issued $600 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 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. 6.875% NOTES DUE 2028 In 2020, we issued $400 million in aggregate principal amount of 6.875% Notes due 2028 (the 6.875% Notes). Proceeds from the 6.875% Notes were used primarily to fund a portion of the redemption of the 6.625% Notes due 2022 described below and for general corporate purposes. We paid debt issuance costs of $6.4 million in the year ended December 31, 2020 related to the 6.875% Notes. REDEMPTION OF 6.625% NOTES DUE 2022 In 2020, we voluntarily redeemed the remaining amount outstanding under our 6.625% Notes due 2022. This resulted in principal payments totaling $450.0 million and $7.7 million in accrued interest. We also expensed approximately $1.7 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 $5.0 million for an early redemption premium. REDEMPTION OF 7.75% NOTES DUE 2019 In 2019, we voluntarily redeemed the remaining balance outstanding under our 7.75% Notes due 2019. This resulted in a principal payment of $100.0 million and $0.3 million in accrued interest. We also expensed approximately $0.1 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 $2.2 million for an early redemption premium. 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 May 2023. At December 31, 2021, $86.1 million was outstanding under our foreign credit facilities and an additional $65.1 million was available. At December 31, 2020, $88.8 million was outstanding under these facilities and an additional $72.8 million was available. DEBT MATURITIES Aggregate maturities of long-term debt are as follows (in millions) : 2022 $ 46.5 2023 69.4 2024 1,122.0 2025 — 2026 400.0 Thereafter 1,500.0 Total $ 3,137.9 INTEREST EXPENSE AND INTEREST INCOME Interest expense was $195.2 million in 2021, $212.3 million in 2020 and $217.3 million in 2019. We capitalized interest of $6.2 million in 2021, $7.9 million in 2020 and $15.5 million in 2019. The weighted-average interest rate of our long-term debt outstanding at December 31, 2021 was 5.6%, as compared to 5.8% at December 31, 2020 and December 31, 2019. Interest income was $10.9 million in 2021, $11.6 million in 2020 and $5.8 million in 2019. Interest income primarily includes interest earned on cash and cash equivalents, realized and unrealized gains and losses on our short-term investments during the period, and 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, 2021
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. We had currency forward contracts outstanding with a notional amount of $164.7 million and $178.2 million at December 31, 2021 and 2020, respectively, that hedge our exposure to changes in foreign currency exchange rates for certain payroll expenses into the third quarter of 2024 and the purchase of certain direct and indirect inventory and other working capital items into the third quarter of 2022. FIXED-TO-FIXED CROSS-CURRENCY SWAP In 2019, we entered into a 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. In the first quarter of 2020, we discontinued this fixed-to-fixed cross-currency swap, which was in an asset position of $9.8 million on the date that it was discontinued. Also in the first quarter of 2020, 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. The notional amount of the fixed-to fixed cross-currency swap is €200.0 million, which was equivalent to $226.9 million and $244.2 million at December 31, 2021 and 2020, 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 2019, we entered into a variable-to-fixed interest rate swap to reduce the variability of cash flows associated with interest payments on our variable rate debt. As of December 31, 2021, we have the following notional amounts hedged in relation to our variable-to-fixed interest rate swap: $750.0 million through May 2022, $600.0 million through May 2023 and $500.0 million through May 2024. The following table summarizes the reclassification of pre-tax derivative gains (losses) into net income (loss) from accumulated other comprehensive income (loss) for those derivative instruments designated as cash flow hedges under Accounting Standards Codification 815 - Derivatives and Hedging (ASC 815): 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 (Loss) Expected to be Reclassified During the Next 12 Months 2021 2020 2019 2021 (in millions) Currency forward contracts Cost of Goods Sold $ 5.6 $ (2.9) $ 2.4 $ 4,433.9 $ 1.9 Fixed-to-fixed cross-currency swap Other Expense, net 19.0 (18.7) 1.3 (3.2) 1.7 Variable-to-fixed interest rate swap Interest Expense (14.8) (14.2) (2.0) (195.2) (10.2) 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, 2021, December 31, 2020 and December 31, 2019. The following table summarizes the amount and location of gains (losses) 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 (Loss) Recognized During the Twelve Months Ended December 31, Total of Financial Statement Line Item 2021 2020 2019 2021 (in millions) Currency forward contracts Cost of Goods Sold $ — $ (6.7) $ 3.9 $ 4,433.9 Currency forward contracts Other Expense, Net 0.2 0.6 — (3.2) 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 37% of our consolidated net sales in 2021, 39% in 2020, and 37% in 2019. Accounts and other receivables due from GM were $290.2 million at year-end 2021 and $297.5 million at year-end 2020. Sales to Stellantis N.V. (Stellantis), were approximately 19% of our consolidated net sales in both 2021 and 2020, and 17% in 2019. Accounts and other receivables due from Stellantis were $137.1 million at year-end 2021 and $157.0 million at year-end 2020. Sales to Ford Motor Company (Ford) were approximately 12% of our consolidated net sales in both 2021 and 2020, and 9% in 2019. Accounts and other receivables due from Ford were $108.8 million at year-end 2021 and $116.5 million at year end 2020. 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 $213.2 million as of December 31, 2021 and $250.0 million as of December 31, 2020. 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, 2021
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	6. FAIR VALUE The fair value accounting guidance 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: December 31, 2021 December 31, 2020 Fair Value Fair Value Input (in millions) Balance Sheet Classification Cash equivalents $ 196.5 $ 206.7 Level 1 Prepaid expenses and other Cash flow hedges - currency forward contracts 2.2 5.8 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 1.9 4.9 Level 2 Nondesignated - currency forward contracts 0.2 0.2 Level 2 Other assets and deferred charges Cash flow hedges - currency forward contracts 1.4 3.3 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 2.2 8.6 Level 2 Investment in equity securities 27.4 — Level 1 Accrued expenses and other Cash flow hedges - currency forward contracts 0.3 0.1 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 9.6 17.8 Level 2 Postretirement benefits and other long-term liabilities Cash flow hedges - currency forward contracts 0.6 0.1 Level 2 Cash flow hedges - fixed-to-fixed cross-currency swap 3.7 20.6 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 12.7 32.1 Level 2 The carrying values of our cash, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the short-term maturities of these instruments. The carrying values of our borrowings under the foreign credit facilities approximate their fair 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 that completed a merger with a Special Purpose Acquisition Company in the third quarter of 2021 and became a publicly traded entity. 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 Statement of Operations. As of December 31, 2021, our investment in REE shares was valued at $27.4 million based on a closing price on that date of $5.55 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, 2021 December 31, 2020 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Revolving Credit Facility $ — $ — $ — $ — Level 2 Term Loan A Facility due 2024 301.8 301.8 323.0 318.6 Level 2 Term Loan B Facility due 2024 850.0 847.9 1,088.8 1,071.1 Level 2 6.875% Notes due 2028 400.0 430.0 400.0 426.0 Level 2 6.50% Notes due 2027 500.0 519.4 500.0 523.8 Level 2 6.25% Notes due 2026 400.0 408.5 400.0 411.0 Level 2 6.25% Notes due 2025 — — 700.0 724.3 Level 2 5.00% Notes due 2029 600.0 588.0 — — Level 2

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2021
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, 2021 and 2020. 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 United Kingdom (U.K.) discount rates 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 2021 2020 2019 2021 2020 2019 U.S. U.K. U.S. U.K. U.S. U.K. Discount rate 2.90 % 1.85 % 2.50 % 1.55 % 3.40 % 2.05 % 2.90 % 2.55 % 3.35 % Expected return on plan assets 7.00 % 4.00 % 7.25 % 4.00 % 7.25 % 4.00 % N/A N/A N/A Rate of compensation increase N/A 3.70 % N/A 3.15 % N/A 3.15 % 4.00 % 4.00 % 4.00 % The accumulated benefit obligation for all defined benefit pension plans was $672.4 million and $796.6 million at December 31, 2021 and December 31, 2020, respectively. As of December 31, 2021, the accumulated benefit obligation for our underfunded defined benefit pension plans was $494.6 million, the projected benefit obligation was $494.6 million and the fair value of assets for these plans was $366.7 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 $213.2 million and $250.0 million at December 31, 2021 and December 31, 2020, respectively. We have also recorded a corresponding asset for these amounts on our Consolidated Balance Sheets, $12.1 million that is classified as a current asset and $201.1 million that is classified as a noncurrent asset as of December 31, 2021. 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, 2021 2020 2021 2020 (in millions) Change in benefit obligation Benefit obligation at beginning of year $ 798.9 $ 740.2 $ 586.5 $ 549.1 Service cost 2.0 2.0 0.3 0.4 Interest cost 17.3 21.4 8.4 10.2 Actuarial loss (gain) (6.5) 63.5 (34.6) 25.3 Change in GM portion of OPEB obligation — — (36.8) 14.0 Participant contributions 0.2 0.2 — — Settlements (99.0) (3.3) — — Benefit payments (34.4) (34.4) (14.2) (12.5) Currency fluctuations (4.4) 8.7 — — Other — 0.6 — — Net change (124.8) 58.7 (76.9) 37.4 Benefit obligation at end of year $ 674.1 $ 798.9 $ 509.6 $ 586.5 Change in plan assets Fair value of plan assets at beginning of year $ 669.9 $ 636.6 $ — $ — Actual return on plan assets 31.6 55.7 — — Employer contributions 7.8 8.5 14.2 12.5 Participant contributions 0.2 0.2 — — Benefit payments (34.4) (34.4) (14.2) (12.5) Settlements (99.0) (3.3) — — Currency fluctuations (2.3) 6.6 — — Net change (96.1) 33.3 — — Fair value of plan assets at end of year $ 573.8 $ 669.9 $ — $ — Amounts recognized in our Consolidated Balance Sheets are as follows: Pension Benefits OPEB December 31, December 31, 2021 2020 2021 2020 (in millions) Noncurrent assets $ 27.6 $ 20.2 $ — $ — Current liabilities (6.6) (8.0) (28.4) (29.8) Noncurrent liabilities (121.3) (141.2) (481.2) (556.7) Net liability $ (100.3) $ (129.0) $ (509.6) $ (586.5) Pre-tax amounts recorded in accumulated other comprehensive income (loss) (AOCI), not yet recognized in net periodic benefit cost (credit) as of December 31, 2021 and 2020, consists of: Pension Benefits OPEB December 31, December 31, 2021 2020 2021 2020 (in millions) Net actuarial gain (loss) $ (225.4) $ (278.0) $ 31.3 $ (4.9) Net prior service credit (cost) (1.6) (1.8) 1.6 3.1 Total amounts recorded $ (227.0) $ (279.8) $ 32.9 $ (1.8) The decrease in net actuarial loss for pension benefits was primarily attributable to the accelerated recognition of certain deferred losses as a result of our Pension Annuity Purchase, as defined below, and as a result of amortization of actuarial losses throughout 2021. The change in net actuarial gain (loss) for OPEB was primarily attributable to an increase in the discount rates used in the valuation at December 31, 2021, as compared to prior year, and as a result of the impact of a change in prescription drug coverage for certain plan participants from a Medicare Part D subsidy to an Employer Group Waiver Plan effective January 1, 2022. The components of net periodic benefit cost (credit) are as follows: Pension Benefits OPEB 2021 2020 2019 2021 2020 2019 (in millions) Service cost $ 2.0 $ 2.0 $ 1.5 $ 0.3 $ 0.4 $ 0.3 Interest cost 17.3 21.4 28.0 8.4 10.2 12.8 Expected asset return (39.0) (38.4) (41.1) — — — Amortized actuarial loss 10.8 8.6 6.4 1.7 1.0 0.1 Amortized prior service cost (credit) 0.1 0.1 — (1.5) (1.5) (1.5) Settlement charge 42.3 0.5 10.4 — — — Net periodic benefit cost (credit) $ 33.5 $ (5.8) $ 5.2 $ 8.9 $ 10.1 $ 11.7 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 6.60% was assumed for 2022. The rate was assumed to decrease gradually to 5.00% by 2030 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: $50.6 million in 2022; $47.5 million in 2023; $49.0 million in 2024; $49.7 million in 2025; $51.5 million in 2026 and $253.1 million for 2027 through 2031. These amounts were estimated using the same assumptions that were used to measure our 2021 year-end pension and OPEB obligations and include an estimate of future employee service. Contributions We contributed $4.1 million to our pension trusts in 2021. 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 2022 to be less than $1.0 million. We expect our cash payments, net of GM cost sharing, for OPEB to be approximately $16.5 million in 2022. U.S. pension annuity purchase In the fourth quarter of 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. Voluntary terminated vested lump sum payment In 2019, we offered a voluntary one-time lump sum payment option to certain eligible terminated vested participants in our U.S. pension plans that, if accepted, settled our pension obligations to them (AAM Voluntary Pension Payout). The lump sum settlements, which were paid from plan assets, reduced our liabilities and administrative costs going forward. The AAM Voluntary Pension Payout was offered to approximately 2,000 of our U.S. pension plan participants, of which 616 participants accepted the offer. We made a one-time lump sum payment from our pension trust of $28.4 million in 2019. 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 $32.5 million and resulted in a non-cash settlement charge of $9.8 million in the fourth quarter of 2019 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, 2021 and 2020 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. U.K. Target Target 2021 2020 Allocation 2021 2020 Allocation Equity securities 27.9 % 34.7 % 25% - 35% 21.6 % 21.8 % 15% - 30% Fixed income securities 63.8 57.3 60% - 70% 66.0 65.9 70% - 80% Alternative assets 7.5 7.3 0% - 10% 9.9 8.9 5% - 10% Cash 0.8 0.7 0% - 5% 2.5 3.4 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, 2021 Asset Categories Level 1 Level 2 Level 3 Total (in millions) Cash and Cash Equivalents $ 7.8 $ 0.8 $ — $ 8.6 Equity U.S. Large Cap 54.0 0.1 — 54.1 U.S. Small/Mid Cap 15.2 — — 15.2 World Equity 66.9 10.7 — 77.6 Fixed Income Securities Government & Agencies 80.2 52.7 — 132.9 Corporate Bonds - Investment Grade 189.9 1.3 — 191.2 Corporate Bonds - Non-investment Grade 15.7 0.5 — 16.2 Emerging Market Debt 12.5 — — 12.5 Other 11.2 5.8 — 17.0 Other Property Funds (a) — — — 38.2 Liquid Alternatives Fund (a) — — — 1.9 Structured Credit Fund (a) — — — 8.4 Total Plan Assets $ 453.4 $ 71.9 $ — $ 573.8 December 31, 2020 Asset Categories Level 1 Level 2 Level 3 Total (in millions) Cash and Cash Equivalents $ 7.4 $ 2.9 $ — $ 10.3 Equity U.S. Large Cap 88.1 2.7 — 90.8 U.S. Small/Mid Cap 20.5 — — 20.5 World Equity 87.0 7.8 — 94.8 Fixed Income Securities Government & Agencies 84.1 45.9 — 130.0 Corporate Bonds - Investment Grade 219.0 2.7 — 221.7 Corporate Bonds - Non-investment Grade 22.4 0.7 — 23.1 Emerging Market Debt 21.1 1.1 — 22.2 Other 3.6 0.3 — 3.9 Other Property Funds (a) — — — 44.2 Liquid Alternatives Fund (a) — — — 1.8 Structured Credit Fund (a) — — — 6.6 Total Plan Assets $ 553.2 $ 64.1 $ — $ 669.9 (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 $8.0 million in 2021, $7.9 million in 2020 and $11.5 million in 2019. 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 $8.3 million, $8.0 million and $10.3 million in 2021, 2020 and 2019, respectively.

Stock Based Compensation and Ot

Stock Based Compensation and Other Incentive Compensation	12 Months Ended
	Dec. 31, 2021
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, 2021, 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, 2021 were 7.2 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, 2019 3.5 $ 16.00 Granted 1.0 15.78 Vested (0.7) 15.53 Canceled (0.7) 16.05 Outstanding at December 31, 2019 3.1 $ 16.03 Granted 3.2 5.08 Vested (0.8) 18.22 Canceled (0.6) 10.33 Outstanding at December 31, 2020 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 As of December 31, 2021, unrecognized compensation cost related to unvested RSUs totaled $11.1 million. The weighted average period over which this cost is expected to be recognized is approximately two years. In 2021 and 2020, the total fair market value of RSUs vested was $10.6 million and $5.0 million, respectively. PERFORMANCE SHARES As of December 31, 2021, we have performance shares (PS) outstanding under our 2018 Omnibus Incentive Plan. We grant performance shares payable in stock to officers which vest in full over a three-year performance period. In 2021, these grants 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. In 2020, these grants were based on AAM's three-year cumulative free cash flow, adjusted based on a TSR measure, and in 2019 these grants were based on a 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. Based on these free cash flow and relative TSR performance metrics, the number of performance shares that become exercisable will be between 0% and 230% 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, 2019 0.8 $ 16.25 Granted 0.3 24.36 Vested (0.2) 17.54 Canceled (0.1) 20.49 Outstanding at December 31, 2019 0.8 $ 20.13 Granted — — Vested (0.2) 24.63 Canceled — — Outstanding at December 31, 2020 0.6 $ 18.86 Granted — — Vested (0.3) 13.91 Canceled — — Outstanding at December 31, 2021 0.3 $ 24.36 Free Cash Flow Awards Outstanding at January 1, 2019 0.3 $ 14.28 Granted — — Vested — — Canceled — — Outstanding at December 31, 2019 0.3 $ 14.28 Granted 0.9 5.18 Vested — — Canceled — — Outstanding at December 31, 2020 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 We estimate the fair value of our TSR performance shares 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. 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. Based on the current fair value, the estimated unrecognized compensation cost related to unvested PS totaled $7.7 million, as of December 31, 2021. 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, 2021, we have long-term cash awards (LTCAs) outstanding under our 2018 Omnibus Incentive Plan. The $7.8 million of LTCAs granted during 2021 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, 2021, unrecognized compensation cost related to unvested LTCAs totaled $5.4 million. The weighted average period over which this cost is expected to be recognized is approximately two years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	9. INCOME TAXES The components of income (loss) before income taxes are as follows: 2021 2020 2019 (in millions) U.S. loss $ (186.8) $ (721.6) $ (889.0) Non - U.S. income 188.0 111.3 356.0 Total income (loss) before income taxes $ 1.2 $ (610.3) $ (533.0) The following is a summary of the components of our provision for income taxes: 2021 2020 2019 (in millions) Current Federal $ 3.5 $ 2.0 $ (11.9) State and local 0.3 0.5 0.1 Foreign 34.0 20.2 49.3 Total current $ 37.8 $ 22.7 $ 37.5 Deferred Federal $ (40.7) $ (60.0) $ (73.5) State and local (0.9) (0.7) (1.5) Foreign (0.9) (11.2) (11.4) Total deferred (42.5) (71.9) (86.4) Total income tax benefit $ (4.7) $ (49.2) $ (48.9) The following is a reconciliation of income taxes calculated at the U.S. federal statutory income tax rate of 21% in 2021, 2020 and 2019 to our provision for income taxes: 2021 2020 2019 (in millions) Federal statutory $ 0.3 $ (128.2) $ (111.9) Foreign income taxes (14.0) (21.5) (40.2) Change in enacted tax rate 0.1 2.1 0.2 Transition tax — — (7.5) State and local 3.0 (5.0) (20.0) Tax credits (11.0) (9.7) (9.6) Valuation allowance 2.7 19.8 12.6 Goodwill impairment — 107.1 92.4 Withholding taxes 3.2 5.6 4.0 U.S. tax on unremitted foreign earnings 2.2 — (2.8) Tax benefit on loss carryback (5.2) (14.4) — Global intangible low-taxed income 6.5 2.3 31.1 Uncertain tax positions 1.2 (8.8) 5.9 Other 6.3 1.5 (3.1) Effective income tax benefit $ (4.7) $ (49.2) $ (48.9) 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. In 2020, our effective income tax rate varied from the U.S. federal statutory rate primarily as a result of the goodwill impairment charge, which resulted in no income tax benefit, as well as favorable foreign tax rates, the impact of tax credits, and the finalization of an advance pricing agreement in a foreign jurisdiction, which resulted in a tax benefit of approximately $6.8 million. We also recognized a tax benefit of approximately $14.4 million related to our ability to carry back prior year losses, as well as projected current year losses, under the CARES Act to years with the previous 35% tax rate. These income tax benefits were partially offset by our inability to realize an income tax benefit for losses incurred in certain foreign and state jurisdictions, as well as a partial valuation allowance of approximately $5.3 million on certain U.S. federal income tax attributes. In 2019, our income tax benefit varied from the tax benefit computed at the U.S. federal statutory rate primarily as a result of the goodwill impairment charge, which resulted in no income tax benefit, as well as the incremental tax expense associated with the global intangible low-taxed income inclusion under the Tax Cuts and Jobs Act of 2017 (the 2017 Act), and our inability to realize an income tax benefit for losses incurred in certain foreign and state jurisdictions. These items were partially offset by the impact of favorable foreign tax rates and income tax credits. In addition, as part of the 2017 Act, a one-time transition tax (Transition Tax) was imposed on certain foreign earnings for which U.S. income tax was previously deferred. The Department of Treasury and Internal Revenue Service issued final regulations on February 5, 2019 regarding the Transition Tax, which changed the manner in which we are required to compute the Transition Tax when it is recognized over a two-year period. The application of the final regulations resulted in a $9.3 million income tax benefit, which was recorded in 2019, the period in which the final regulations were issued. The 2017 Act subjects a U.S. shareholder to tax on global intangible low-taxed income (GILTI) earned by certain foreign subsidiaries. Under GAAP, we made an accounting policy election to provide for the tax expense related to GILTI in the year the tax is incurred as a period expense. As of December 31, 2021, we have refundable income taxes of approximately $16 million, $9 million of which is classified as Prepaid expenses and other and $7 million classified as Other assets and deferred charges on our Consolidated Balance Sheet, as compared to approximately $14 million classified as Prepaid expenses and other as of December 31, 2020. We also have income taxes payable of approximately $12 million and $6 million classified as Accrued expenses and other on our Consolidated Balance Sheets as of December 31, 2021 and 2020, 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, 2021 2020 (in millions) Deferred tax assets Employee benefits $ 163.1 $ 162.4 Inventory 31.7 32.9 Net operating loss (NOL) carryforwards 186.7 221.4 Tax credit carryforwards 83.6 88.6 Capital allowance carryforwards 10.8 10.2 Capitalized expenditures 41.8 45.9 Interest carryforward 26.0 10.4 Operating lease liabilities 28.0 25.7 Other 41.6 50.6 Valuation allowances (201.7) (208.0) Deferred tax assets $ 411.6 $ 440.1 Deferred tax liabilities Other intangible assets $ (160.7) $ (179.9) Fixed assets (103.3) (137.5) Operating lease right-of-use assets (27.8) (25.6) Other (12.2) (2.5) Deferred tax liabilities $ (304.0) $ (345.5) Deferred tax assets, net $ 107.6 $ 94.6 Deferred tax assets and liabilities recognized in our Consolidated Balance Sheets are as follows: December 31, 2021 2020 (in millions) U.S. federal and state deferred tax asset, net $ 56.9 $ 44.1 Other foreign deferred tax asset, net 50.7 50.5 Deferred tax asset, net $ 107.6 $ 94.6 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, 2021 and December 31, 2020, we had deferred tax assets from domestic and foreign net operating loss and tax credit carryforwards of $281.1 million and $320.2 million, respectively. Approximately $95.9 million of the deferred tax assets at December 31, 2021 relate to NOL and tax credits that can be carried forward indefinitely with the remainder expiring between 2022 and 2041. 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. We have provided deferred income taxes for the estimated U.S. federal income tax, 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 2020, we determined that a portion of our deferred tax assets related to certain U.S. federal income tax attributes that are being carried forward were not more likely than not to be realized and, as such, we recorded a valuation allowance resulting in tax expense of approximately $5.3 million during the year ended December 31, 2020. During 2021, we determined that the valuation allowance related to certain U.S. federal income tax attributes should be increased and, as such, we increased the valuation allowance to approximately $7.0 million as of December 31, 2021. Due to the uncertainty associated with the extent and ultimate impact of COVID-19 and the semiconductor shortage on global automotive production volumes, we may experience lower than projected earnings in certain jurisdictions in future periods, and 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 2021, 2020 and 2019, we recorded a net tax expense of $0.8 million, $14.5 million and $25.4 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 2021 and 2020 and partially offset in 2019 by a net tax expense of $1.9 million and $5.3 million, and a net tax benefit of $12.8 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 of December 31, 2021 and December 31, 2020, we have a valuation allowance of $201.7 million and $208.0 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, 2019 $ 38.7 $ 6.9 Increase in prior year tax positions 0.2 4.5 Decrease in prior year tax positions (3.1) (0.1) Increase in current year tax positions 4.4 — Foreign currency remeasurement adjustment 0.9 0.2 Balance at December 31, 2019 $ 41.1 $ 11.5 Increase in prior year tax positions 0.2 — Decrease in prior year tax positions (6.6) (1.7) Increase in current year tax positions 0.7 — Settlement (12.2) (6.3) Foreign currency remeasurement adjustment (3.0) (1.5) Balance at December 31, 2020 $ 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 At December 31, 2021 and December 31, 2020, we had $21.2 million and $20.2 million of gross unrecognized income tax benefits, respectively. In 2021, 2020, and 2019, we recognized a tax expense/(benefit) of $0.2 million, $(1.7) million and $4.4 million, respectively, related to interest and penalties in Income tax benefit on our Consolidated Statements of Operations. We have a liability of $2.2 million and $2.0 million related to the estimated future payment of interest and penalties at December 31, 2021 and 2020, respectively. The amount of the unrecognized income tax benefits, including interest and penalties, as of December 31, 2021 that, if recognized, would affect the effective tax rate is $20.2 million. In the second quarter of 2020, we finalized an advance pricing agreement in a foreign jurisdiction, which resulted in a cash payment to the tax authorities of $18.5 million and a reduction of our liability for unrecognized tax benefits and related interest and penalties of $25.3 million. We monitor the progress and conclusions of all ongoing audits and other communications with tax authorities and adjust our estimated liability as necessary. Other Income Tax Matters We operate in multiple jurisdictions throughout the world and the income tax returns of several subsidiaries in various tax jurisdictions are currently under examination. 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 believes that the proposed adjustment is without merit and we have contested the matter, which is currently under review in the IRS’s administrative appeals process. We believe it is 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 December 31, 2021, 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 2021, is estimated to be in the range of approximately $275 million to $325 million. The cash flow impact in 2022 related to this issue is not expected to be significant as a result of available net operating losses and income tax credits. In a matter of related interest, on May 5, 2020, the U.S Tax Court ruled against another U.S. corporation, finding that the income it earned through a Mexican branch of its Luxembourg subsidiary corporation was FBCSI. In that situation, the taxpayer appealed the U.S. Tax Court decision to the U.S. Court of Appeals for the Sixth Circuit. On December 6, 2021, the U.S. Court of Appeals affirmed, in a split decision, the Tax Court decision in favor of the IRS. On January 20, 2022, the taxpayer in the above referenced matter, filed a petition for rehearing. The court’s decision on whether such a rehearing will be granted is pending. Notwithstanding the decisions rendered thus far in that case, and because our position is based upon different facts and circumstances, including but not limited to, differences in structure, and different income tax regulations in effect for our tax years under examination, we continue to believe, after consultation with tax and legal counsel that it is more likely than not that our structure does not give rise to FBCSI. We intend to continue to vigorously contest the conclusions reached in the NOPA through the IRS’s administrative appeals process, and, if necessary, through litigation.

Earnings Per Share (EPS)

Earnings Per Share (EPS)	12 Months Ended
	Dec. 31, 2021
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): 2021 2020 2019 (in millions, except per share data) Numerator Net income (loss) attributable to AAM $ 5.9 $ (561.3) $ (484.5) Less: Net income allocated to participating securities (0.2) — — Net income (loss) attributable to common shareholders - Basic and Dilutive $ 5.7 $ (561.3) $ (484.5) Denominators Basic common shares outstanding - Weighted-average shares outstanding 118.5 117.9 115.6 Less: Weighted-average participating securities (4.6) (4.8) (3.3) Weighted-average common shares outstanding 113.9 113.1 112.3 Effect of dilutive securities - Dilutive stock-based compensation 0.2 — — Diluted shares outstanding - Adjusted weighted-average shares after assumed conversions 114.1 113.1 112.3 Basic EPS $ 0.05 $ (4.96) $ (4.31) Diluted EPS $ 0.05 $ (4.96) $ (4.31)

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
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 $105.5 million at December 31, 2021 and $90.8 million at December 31, 2020. Of the approximately $105.5 million of purchase commitments at December 31, 2021, $95.0 million is expected to be paid in 2022 and $10.5 million is expected to be paid in 2023 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. 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 2021, 2020 and 2019. 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 2021 and 2020, 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, 2021 2020 (in millions) Beginning balance $ 66.7 $ 62.0 Accruals 19.4 21.9 Settlements (17.6) (14.1) Adjustments to prior period accruals (8.6) (3.5) Foreign currency translation (0.4) 0.4 Ending balance $ 59.5 $ 66.7

Reclassifications out of Accumu

Reclassifications out of Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2021
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, 2021, December 31, 2020 and December 31, 2019 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at January 1, 2019 $ (213.9) $ (96.6) $ (1.1) $ (311.6) Other comprehensive loss before reclassifications (61.5) (c) (4.6) (19.0) (85.1) Income tax effect of other comprehensive loss before reclassifications 5.6 — 6.3 11.9 Amounts reclassified from accumulated other comprehensive loss into net loss 12.5 (a) — (1.7) (b) 10.8 Income taxes reclassified into net loss (2.6) — (0.2) (2.8) Net current period other comprehensive loss (46.0) (4.6) (14.6) (65.2) Balance at December 31, 2019 $ (259.9) $ (101.2) $ (15.7) $ (376.8) Other comprehensive income (loss) before reclassifications (72.0) 0.1 (41.5) (113.4) Income tax effect of other comprehensive income (loss) before reclassifications 14.2 — 8.2 22.4 Amounts reclassified from accumulated other comprehensive loss into net loss 8.2 (a) — 35.8 (b) 44.0 Income taxes reclassified into net loss (1.5) — (6.9) (8.4) Net current period other comprehensive income (loss) (51.1) 0.1 (4.4) (55.4) Balance at December 31, 2020 $ (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) (a) The amount reclassified for 2021 includes a credit to AOCI of $42.3 million related to the effect of the Pension Annuity Purchase, and the amount reclassified for 2019 includes a credit to AOCI of $7.4 million related to the net effect of the AAM Pension Payout Offer and the Casting Sale. See Note 7 - Employee Benefit Plans and Note 16 - Acquisitions and Dispositions for more detail. (b) The amounts reclassified from AOCI included $(5.6) million in COGS, $14.8 million in interest expense and $(19.0) million in other expense, net for the year ended December 31, 2021, $2.9 million in COGS, $14.2 million in interest expense and $18.7 million in other expense, net for the year ended December 31, 2020 and $(2.4) million in COGS, $2.0 million in interest expense and $(1.3) million in other expense, net for the year ended December 31, 2019. (c) ASU 2018-02 became effective on January 1, 2019, and we elected to reclassify the stranded tax effects caused by the 2017 Tax Cuts and Jobs Act, resulting in a decrease in Accumulated other comprehensive income (loss) of $27.7 million at January 1, 2019.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2021
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 axle and transmission shafts, ring and pinion gears, differential gears and assemblies, connecting rods and variable valve timing products for OEMs and Tier 1 automotive suppliers. 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, 2021, 2020 and 2019. Net sales are attributed to regions based on the location of production. Intersegment sales have been excluded from the table. In 2021, we reorganized our segments and moved certain of our Driveline facilities to our Metal Forming segment. The amounts previously reported in the tables below for the years ended December 31, 2020 and 2019 have been retrospectively recast to reflect this change. In 2019, we finalized the Casting Sale. The Casting Sale did not qualify for classification as discontinued operations, as it did not represent a strategic shift in our business that had a major effect on our operations and financial results. As such, we continue to present Casting as a segment in the tables below, which is comprised entirely of the U.S. casting operations that were included in the sale. Twelve Months Ended December 31, 2021 Driveline Metal Forming Casting Total (in millions) North America $ 2,839.8 $ 1,142.6 $ — $ 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 $ 3,741.5 $ 1,415.1 $ — $ 5,156.6 Twelve Months Ended December 31, 2020 Driveline Metal Forming Casting Total North America $ 2,537.2 $ 1,087.9 $ — $ 3,625.1 Asia 433.7 43.8 — 477.5 Europe 352.5 198.0 — 550.5 South America 49.2 8.5 — 57.7 Total $ 3,372.6 $ 1,338.2 $ — $ 4,710.8 Twelve Months Ended December 31, 2019 Driveline Metal Forming Casting Total North America $ 3,225.7 $ 1,393.7 $ 627.7 $ 5,247.1 Asia 533.6 37.6 — 571.2 Europe 351.0 256.3 — 607.3 South America 98.8 6.5 — 105.3 Total $ 4,209.1 $ 1,694.1 $ 627.7 $ 6,530.9 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, 2020 $ 793.2 $ 23.4 $ 91.0 December 31, 2021 762.8 28.1 94.8 Increase/(decrease) $ (30.4) $ 4.7 $ 3.8 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, 2021 and December 31, 2020 we amortized $23.3 million and $22.7 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, 2021
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, and furniture 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, 2021 2020 2019 (in millions) Finance lease cost Amortization of right-of-use assets $ 4.2 $ 1.8 $ 1.0 Interest on lease liabilities 2.0 0.4 0.3 Total finance lease cost 6.2 2.2 1.3 Operating lease cost 33.3 32.7 28.9 Short-term lease cost 1.6 3.0 5.9 Variable lease cost 3.2 2.9 7.2 Total lease cost $ 44.3 $ 40.8 $ 43.3 For the year ended December 31, 2021, $29.1 million and $9.0 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 $28.4 million and $10.2 million, respectively, for the year ended December 31, 2020 and $31.9 million and $10.1 million, respectively, for the year ended December 31, 2019. The following table summarizes additional information related to our lease agreements. Twelve Months Ended December 31, 2021 2020 2019 (in millions, except lease term and rate) Cash paid for amounts included in measurement of lease liabilities Operating cash flows from finance leases $ 2.0 $ 0.3 $ 0.3 Operating cash flows from operating leases 35.9 35.1 29.0 Financing cash flows from finance leases 5.0 3.0 1.0 Weighted-average remaining lease term - finance leases 16.4 years 15.8 years 2.8 years Weighted-average remaining lease term - operating leases 8.6 years 8.7 years 9.2 years Weighted-average discount rate - finance leases 4.8 % 4.2 % 5.1 % Weighted-average discount rate - operating leases 5.2 % 5.7 % 6.1 % 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) 2022 $ 10.4 $ 30.4 2023 8.3 23.8 2024 7.4 17.4 2025 7.3 13.9 2026 7.3 10.7 Thereafter 85.5 60.2 Total future undiscounted minimum lease payments 126.2 156.4 Less: Impact of discounting (37.4) (31.9) Total $ 88.8 $ 124.5 The right-of-use assets and lease liabilities recorded on our Consolidated Balance Sheets are as follows: December 31, 2021 December 31, 2020 Finance Leases Operating Leases Finance Leases Operating Leases (in millions) (in millions) Property, plant and equipment, net $ 113.4 $ — $ 24.9 $ — Operating lease right-of-use assets — 123.7 — 116.6 Total $ 113.4 $ 123.7 $ 24.9 $ 116.6 Current portion of operating lease liabilities $ — $ 24.6 $ — $ 22.6 Accrued expenses and other 6.3 — 3.3 — Long-term portion of operating lease liabilities — 99.9 — 94.4 Postretirement benefits and other long-term liabilities 82.5 — 18.3 — Total $ 88.8 $ 124.5 $ 21.6 $ 117.0 ASC 842 Adoption of Practical Expedients We have elected to adopt, for all classes of underlying assets, a package of practical expedients provided under ASC 842 that allowed us at adoption to 1) not reassess whether existing or expired contracts contain or contained a lease; 2) not reassess the lease classification (operating or financing) of our existing leases at adoption; and 3) not reassess initial direct costs for existing leases. ASC 842 also provides a practical expedient that allows companies to exclude balance sheet recognition of right-of-use assets and associated liabilities for lease terms of 12 months or less, which we have elected as part of our adoption of ASC 842 for all classes of underlying assets. We do not include right-of-use assets and operating lease liabilities on our Consolidated Balance Sheet for leases with a term of 12 months or less. We have also elected to adopt the practical expedient under ASC 842 to not separate lease and non-lease components in contracts that contain both. These lease agreements are accounted for as a single lease component for all classes of underlying assets. Leases Not Yet Commenced

Manufacturing Facility Fire and

Manufacturing Facility Fire and Insurance Recovery	12 Months Ended
	Dec. 31, 2021
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. Our insurance policies are expected to cover the repair, replacement or actual cash value of the assets that incurred loss or damage, less our applicable deductible of $1.0 million. In addition, our insurance policies are expected to provide coverage for interruption to our business, including lost or reduced profits and reimbursement for certain expenses and costs that are incurred relating to the fire. In 2021, we recorded $15.9 million of charges primarily related to transportation and freight, asset repairs and other costs incurred to resume or relocate operations and ensure continuity of supply to our customers. We also recorded an estimated insurance recovery of $27.3 million and received reimbursements and advances under our insurance policies of approximately $59.1 million, of which approximately $36.0 million is presented as an operating cash flow and approximately $23.1 million is presented as an investing cash flow in our Consolidated Statement of Cash Flows. This resulted in net pre-tax income in our Consolidated Statement of Operations of approximately $11.4 million in Cost of goods sold for the twelve months ended December 31, 2021. At December 31, 2021, $11.3 million of insurance recovery receivable is included in Prepaid expenses and other in our Consolidated Balance Sheet. Since the date of the Malvern Fire and the establishment of the insurance claim, we have incurred $52.4 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 have recorded total estimated insurance recoveries of $81.5 million and have received total reimbursements and advances under our insurance policies of $70.2 million, of which $11.1 million was received in 2020 and $59.1 million was received in 2021. In the fourth quarter of 2020, we determined that we will cease production at the Malvern Manufacturing Facility and relocate production capacity to other AAM manufacturing facilities. As such, we cannot estimate the total claim eligible costs that we will incur as a result of the Malvern Fire and the associated relocation of production capacity to other AAM manufacturing facilities. At December 31, 2021, we have estimated the amount of expected insurance proceeds recoverable in consideration of the policy provisions, estimated repair costs or actual cash value of damaged assets, and claim eligible expenses incurred from the date of the fire. Based on the provisions of the policy, we expect the claim settlement process to conclude in 2022. We will update our estimates as additional information becomes available, however, the actual impact on our results of operations, financial position or cash flows, or the timing of such impact, could differ from our estimates.

Acquisitions and Dispositions

Acquisitions and Dispositions	12 Months Ended
	Dec. 31, 2021
Mergers, Acquisitions and Dispositions [Abstract]
Mergers, Acquisitions and Dispositions Disclosures	16. ACQUISITIONS AND DISPOSITIONS 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 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 Statement of Operations for this period. Further we have not disclosed pro forma revenue and earnings for the years ended December 31, 2021 and December 2020 as the operating results of this manufacturing facility would be insignificant to AAM's consolidated results for these periods. Subsequent to the acquisition of Emporium, we determined that we will cease production at the facility and relocate the production capacity to other AAM manufacturing facilities. As a result, during 2021 we incurred restructuring charges related to the anticipated closure of the facility. See Note 2 - Restructuring and Acquisition-Related Costs for further detail. Acquisition of Mitec In December 2019, AAM completed our acquisition of certain operations of Mitec Automotive AG (Mitec), under which we acquired $20.2 million of net assets for a purchase price of $9.4 million, which was funded entirely with available cash. We recognized a gain on bargain purchase of $10.8 million, which was primarily the result of Mitec's insolvency prior to the acquisition. This gain is presented in the Gain on bargain purchase of business line item in our Consolidated Statement of Operations for the year ended December 31, 2019. The operating results of Mitec for the period from our acquisition date through December 31, 2019, were insignificant to AAM's Consolidated Statement of Operations for this period. Further we have not disclosed pro forma revenue and earnings for the years ended December 31, 2019 and December 31, 2018, as the operating results of Mitec would be insignificant to AAM's consolidated results for these periods. Sale of Interest in Consolidated Joint Venture In the year ended December 31, 2021, we completed the sale of our ownership interest in a consolidated joint venture and received cash proceeds of approximately $2.6 million. As a result of the sale and deconsolidation of this joint venture, we recognized a loss of $2.7 million. Subsequent to the sale of this joint venture, we no longer present noncontrolling interest in our consolidated financial statements as all consolidated entities are wholly-owned. Sale of U.S. Casting Operations

Segment and Geographic Informat

Segment and Geographic Information	12 Months Ended
	Dec. 31, 2021
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 . In the first quarter of 2021, we completed a reorganization of our segments, which included moving certain locations that were 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 the year ended December 31, 2020 and the year ended December 31, 2019 have been retrospectively recast to reflect this reorganization. In the fourth quarter of 2019, we completed the Casting Sale. The Casting Sale did not qualify for classification as discontinued operations, as it did not represent a strategic shift in our business that had a major effect on our operations and financial results. As such, we continue to present Casting as a segment in the tables below, which is comprised entirely of the U.S. casting operations that were included in the sale. 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. 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, crossover vehicles (CUVs), passenger cars and commercial vehicles; and • Metal Forming products consist primarily of axle and transmission shafts, ring and pinion gears, differential gears and assemblies, connecting rods and variable valve timing products for OEMs and Tier 1 automotive suppliers. We use Segment Adjusted EBITDA as the measure of earnings to assess the performance of each segment and determine the resources to be allocated to the segments. Segment Adjusted EBITDA is defined as earnings before interest expense, income taxes, depreciation and amortization for our reportable segments, excluding the impact of restructuring and acquisition-related costs, debt refinancing and redemption costs, loss on the sale of a business, impairment charges, pension settlements, unrealized gains or losses on equity securities, and non-recurring items. Year Ended December 31, 2021 Driveline Metal Forming Casting Corporate and Eliminations Total (in millions) Sales $ 3,744.9 $ 1,762.2 $ — $ — $ 5,507.1 Less: Intersegment sales 3.4 347.1 — — 350.5 Net external sales $ 3,741.5 $ 1,415.1 $ — $ — $ 5,156.6 Segment adjusted EBITDA $ 577.7 $ 255.6 $ — $ — $ 833.3 Depreciation and amortization $ 301.9 $ 242.4 $ — $ — $ 544.3 Capital expenditures $ 126.8 $ 50.5 $ — $ 3.9 $ 181.2 Total assets $ 2,925.6 $ 1,576.9 $ — $ 1,133.2 $ 5,635.7 Year Ended December 31, 2020 Driveline Metal Forming Casting Corporate and Eliminations Total Sales $ 3,375.5 $ 1,652.0 $ — $ — $ 5,027.5 Less: Intersegment sales 2.9 313.8 — — 316.7 Net external sales $ 3,372.6 $ 1,338.2 $ — $ — $ 4,710.8 Segment adjusted EBITDA $ 474.8 $ 245.0 $ — $ — $ 719.8 Depreciation and amortization $ 306.1 $ 215.8 $ — $ — $ 521.9 Capital expenditures $ 125.3 $ 81.9 $ — $ 8.4 $ 215.6 Total assets $ 3,035.7 $ 1,680.3 $ — $ 1,200.3 $ 5,916.3 Year Ended December 31, 2019 Driveline Metal Forming Casting Corporate and Eliminations Total Sales $ 4,220.4 $ 2,062.7 $ 669.2 $ — $ 6,952.3 Less: Intersegment sales 11.3 368.6 41.5 — 421.4 Net external sales $ 4,209.1 $ 1,694.1 $ 627.7 $ — $ 6,530.9 Segment adjusted EBITDA $ 579.0 $ 348.3 $ 43.0 $ — $ 970.3 Depreciation and amortization $ 288.0 $ 206.6 $ 42.3 $ — $ 536.9 Capital expenditures $ 250.3 $ 139.0 $ 28.5 $ 15.5 $ 433.3 Total assets $ 3,557.9 $ 2,120.9 $ — $ 965.8 $ 6,644.6 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, 2021, 2020 and 2019: Year Ended December 31, 2021 2020 2019 (in millions) Segment adjusted EBITDA $ 833.3 $ 719.8 $ 970.3 Interest expense (195.2) (212.3) (217.3) Depreciation and amortization (544.3) (521.9) (536.9) Impairment charges — (510.0) (665.0) Restructuring and acquisition-related costs (49.4) (67.2) (57.8) Pension settlements (42.3) (0.5) (9.8) Loss on sale of business (2.7) (1.0) (21.3) Gain on bargain purchase of business — — 10.8 Unrealized gain on equity securities 24.4 — — Debt refinancing and redemption costs (34.0) (7.9) (8.4) Malvern Fire charges, net of recoveries 11.4 (9.3) — Other — — 2.4 Income (loss) before income taxes $ 1.2 $ (610.3) $ (533.0) 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, 2021 2020 2019 (in millions) Net sales United States $ 1,923.5 $ 1,816.7 $ 2,894.0 Mexico 2,058.9 1,808.5 2,353.1 South America 94.3 57.6 105.3 China 299.6 317.1 315.4 All other Asia 189.4 160.4 255.8 Europe 590.9 550.5 607.3 Total net sales $ 5,156.6 $ 4,710.8 $ 6,530.9 Long-lived assets United States $ 1,976.5 $ 2,099.4 $ 2,805.8 Mexico 888.1 1,021.6 1,117.4 South America 40.9 49.7 61.9 China 164.8 185.1 191.4 All other Asia 87.1 84.2 106.8 Europe 501.2 491.5 439.4 Total long-lived assets $ 3,658.6 $ 3,931.5 $ 4,722.7

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2021
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, 2019: Allowance for credit losses (1) $ 8.4 $ 13.2 $ (0.8) $ 12.8 $ 8.0 Allowance for deferred taxes (3) 183.3 25.4 — 12.7 196.0 Inventory valuation allowance (2) 14.4 31.0 1.4 26.3 20.5 Year Ended December 31, 2020: Allowance for credit losses (1) 8.0 7.0 — 10.5 4.5 Allowance for deferred taxes (4) 196.0 19.8 — 7.8 208.0 Inventory valuation allowance (2) 20.5 31.7 — 28.8 23.4 Year Ended December 31, 2021: Allowance for credit losses (1) 4.5 7.8 — 10.1 2.2 Allowance for deferred taxes (4) 208.0 2.7 — 9.0 201.7 Inventory valuation allowance (2) 23.4 17.7 — 22.5 18.6 (a ) Amounts represent reserves recognized in conjunction with our acquisition of Mitec and reserves derecognized in conjunction with the Casting Sale in 2019. (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 the reversal of a valuation allowance against certain deferred tax assets in foreign locations, as well as changes due to foreign currency translation. (4) Primarily reflects 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, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidation, Policy [Policy Text Block]	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, 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 $2.2 million and $4.5 million as of December 31, 2021 and 2020, 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 and Asia. 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 We state our inventories at the lower of cost or net realizable value. The cost of our inventories is determined using the first-in-first-out method.  When we determine that our gross inventories exceed usage requirements, or if inventories become obsolete or otherwise not saleable, we record a provision for such loss as a component of our inventory accounts.
Maintenance, Repair & Operations (MRO) [Policy Text Block]	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 $61.6 million, $62.4 million and $67.7 million for 2021, 2020 and 2019, respectively.
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 $396.9 million, $372.9 million and $373.8 million in 2021, 2020 and 2019, respectively.
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	IMPAIRMENT OF LONG-LIVED ASSETS When impairment indicators exist, we evaluate the carrying value of long-lived assets for potential impairment. We consider projected future undiscounted cash flows, trends and other circumstances in making such estimates and evaluations. If impairment is deemed to exist, the carrying amount of the asset is adjusted based on its fair value. Recoverability of assets “held for use” is determined by comparing the forecasted undiscounted cash flows of the operations to which the assets relate to their carrying amount. When the carrying value of an asset group exceeds its fair value and is therefore nonrecoverable, those assets are written down to fair value. Fair value is determined based on market prices, when available, or a discounted cash flow analysis is performed using management estimates.
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]	GOODWILL We record goodwill when the purchase price of acquired businesses exceeds the value of their identifiable net tangible and intangible assets acquired. We test our goodwill annually as of October 1, or more frequently if necessary, for impairment in accordance with the accounting guidance for goodwill and other indefinite-lived intangibles. 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 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. 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, Policy [Policy Text Block]	DEBT ISSUANCE COSTS
Derivatives, Policy [Policy Text Block]	DERIVATIVES We recognize all derivatives on the balance sheet at fair value and we are not subject to master netting agreements. If a derivative qualifies under the accounting guidance as a hedge, depending on the nature of the hedge, changes in the fair value of the derivative are either offset against the change in fair value of the hedged asset, liability or firm commitment through earnings or recognized in other comprehensive income until the hedged item is recognized in earnings. 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.
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 losses of $1.7 million, $0.5 million and $6.5 million for the years 2021, 2020 and 2019, respectively, in Other 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 $116.8 million, $117.4 million and $144.7 million in 2021, 2020 and 2019, respectively. In both 2021 and 2020, our R&D amounts reflect customer engineering, design and development recoveries of approximately $15.0 million.
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).
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 Recently Adopted Accounting Standard Update 2021-08 On October 28, 2021, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2021-08 - Business Combinations (Topic 805) - Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. This guidance amends previous guidance to now require that an acquirer recognize contract assets and liabilities obtained as part of a business combination in accordance with Accounting Standard Codification (ASC) Topic 606 - Revenue from Contracts with Customers . This guidance becomes effective at the beginning of our 2023 fiscal year, however, early adoption was permitted and we elected to adopt this guidance early as of December 31, 2021. The adoption of this standard did not have a material impact on our consolidated financial statements as the business combination completed during 2021 did not include material contract assets or contract liabilities. See Note 16 - Acquisitions and Dispositions for additional information. Accounting Standard Update 2020-04 On March 12, 2020, the FASB issued ASU 2020-04 - Reference Rate Reform (Topic 848) and has subsequently issued ASU 2021-01 - Reference Rate Reform (Topic 848) . This guidance provides optional expedients and exceptions that are intended to ease the burden of updating contracts to contain a new reference rate due to the discontinuation of the London Inter-Bank Offered Rate (LIBOR). At December 31, 2021, we have completed our analysis to identify the contracts that include LIBOR as the referenced rate and have concluded that these contracts are comprised primarily of those related to our Senior Secured Credit Facilities and our variable-to-fixed interest rate swap. See Note 4 - Long-Term Debt for additional detail on our Senior Secured Credit Facilities and Note 5 - Derivatives and Risk Management for additional detail on our interest rate swap. This guidance was available for adoption immediately following issuance on March 12, 2020 and may be implemented in any period prior to the guidance expiration on December 31, 2022. We have elected to adopt this guidance as of December 31, 2021 and the adoption of this guidance did not have a material impact on our financial statements. Accounting Standards Update 2019-12 On December 18, 2019, the FASB issued ASU 2019-12 - Income Taxes (Topic 740) . This guidance is intended to simplify the accounting and disclosure requirements for income taxes by removing various exceptions, and requires that the effect of an enacted change in tax laws or rates on current tax expense be included in the annual effective tax rate computation in the interim period of the enactment. This guidance became effective and we adopted this guidance on January 1, 2021. The adoption of this standard did not have a material impact on our consolidated financial statements. Standards Not Yet Adopted Accounting Standard Updated 2021-10 On November 17, 2021, the FASB issued ASU 2021-10 - Government Assistance (Topic 832) . This guidance establishes requirements for annual disclosures about certain types of material government assistance, including government grants and tax credits. This guidance becomes effective at the beginning of our 2022 fiscal year, and we expect to prospectively adopt this guidance on January 1, 2022. We do not expect this guidance to have a material impact on our consolidated financial statements. CORONAVIRIUS AID, RELIEF, AND ECONOMIC SECURITY ACT The Coronavirus Aid, Relief, and Economic Security Act (the CARES Act) was enacted on March 27, 2020 in the United States. The key provisions of the CARES Act, as applicable to AAM, included the following: • The ability to use net operating losses (NOLs) to offset income without the 80% taxable income limitation enacted as part of the Tax Cuts and Jobs Act (TCJA) of 2017, and to carry back NOLs to offset prior year income for five years. These are temporary provisions that apply to NOLs incurred in 2018, 2019 or 2020 tax years. We recognized a tax benefit of $5.2 million for the year ended December 31, 2021 and $14.4 million for the year ended December 31, 2020 related to our ability to carry back prior year losses under the CARES Act to years with the previous 35% tax rate. We received an income tax refund of approximately $6.0 million during 2021 and an income tax refund of approximately $31.0 million during 2020 as a result of these provisions of the CARES Act. • The ability to defer the payment of the employer portion of social security taxes incurred between March 27, 2020 and December 31, 2020, with 50% of the deferred amount to be paid by December 31, 2021 and the remaining 50% to be paid by December 31, 2022. In the year ended December 31, 2021 we paid $7.6 million of deferred social security taxes, and the remaining $7.6 million of deferred social security taxes will be paid in 2022. • The ability to claim an Employee Retention Credit (ERC), which is a refundable payroll tax credit, for 50% of qualified wages or benefits, subject to certain limitations, that are paid to an employee when they are not providing services due to COVID-19. The ERC applies to qualified wages paid or incurred during the period March 13, 2020 through December 31, 2020 and is available to eligible employers whose operations were fully or partially suspended due to COVID-19, or whose gross receipts declined by more than 50% when compared to the applicable period in the prior year. At December 31, 2021, we have a refundable ERC amount of $2.6 million included in Prepaid expenses and other in our Consolidated Balance Sheet.

Organization and Basis of Pre_2

Organization and Basis of Presentation (Tables)	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Inventory, Current [Table Text Block]	Inventories consist of the following: December 31, 2021 2020 (in millions) Raw materials and work-in-progress $ 339.7 $ 276.2 Finished goods 89.3 70.4 Gross inventories 429.0 346.6 Inventory valuation reserves (18.6) (23.4) Inventories, net $ 410.4 $ 323.2
Property, Plant and Equipment [Table Text Block]	Property, plant and equipment consists of the following: Estimated December 31, Useful Lives 2021 2020 (years) (in millions) Land Indefinite $ 47.7 $ 49.2 Land improvements 10-15 26.8 26.3 Buildings and building improvements 15-40 635.8 554.3 Machinery and equipment 3-12 3,700.3 3,703.7 Construction in progress 171.2 122.1 4,581.8 4,455.6 Accumulated depreciation and amortization (2,585.7) (2,291.8) Property, plant and equipment, net $ 1,996.1 $ 2,163.8

Restructuring and Acquisition_2

Restructuring and Acquisition-Related Costs (Tables)	12 Months Ended
	Dec. 31, 2021
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs [Table Text Block]	A summary of our restructuring activity for the years 2021, 2020 and 2019 is shown below: Severance Charges Implementation Costs Total (in millions) Accrual at January 1, 2019 $ 2.4 $ 1.6 $ 4.0 Charges 19.4 20.4 39.8 Cash utilization (17.0) (14.6) (31.6) Accrual at December 31, 2019 4.8 7.4 12.2 Charges 22.3 36.1 58.4 Cash utilization (25.4) (33.7) (59.1) Accrual at December 31, 2020 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
Business Combination, Separately Recognized Transactions [Table Text Block]	The following table represents a summary of charges incurred in 2021, 2020 and 2019 associated with acquisition and integration costs: Acquisition-Related Costs Integration Expenses Total 2021 Charges $ 0.4 $ 5.8 $ 6.2 2020 Charges — 8.8 8.8 2019 Charges 1.8 16.2 18.0

Schedule of Goodwill and Finite

Schedule of Goodwill and Finite Lived Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2021
Goodwill and Intangible Assets [Abstract]
Schedule of Goodwill [Table Text Block]	Goodwill The following table provides a reconciliation of changes in goodwill for the year ended December 31, 2021 and the year ended December 31, 2020: Driveline Metal Forming Consolidated (in millions) Balance as of January 1, 2020 $ 398.3 $ 300.8 $ 699.1 Impairment charge (210.8) (299.2) (510.0) Foreign currency translation (1.8) (1.6) (3.4) Balance as of December 31, 2020 $ 185.7 $ — $ 185.7 Foreign currency translation (1.9) — (1.9) Balance as of December 31, 2021 $ 183.8 $ — $ 183.8
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The following table provides a reconciliation of the gross carrying amount and associated accumulated amortization for AAM's other intangible assets, which are all subject to amortization, as of December 31, 2021 and December 31, 2020: December 31, December 31, 2021 2020 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in millions) Capitalized computer software $ 47.3 $ (37.0) $ 10.3 $ 47.6 $ (33.9) $ 13.7 Customer platforms 856.2 (301.3) 554.9 856.2 (237.9) 618.3 Customer relationships 53.0 (16.2) 36.8 53.0 (12.8) 40.2 Technology and other 156.1 (60.9) 95.2 156.7 (48.2) 108.5 Total $ 1,112.6 $ (415.4) $ 697.2 $ 1,113.5 $ (332.8) $ 780.7

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	Long-term debt, net consists of the following: December 31, 2021 2020 (in millions) Revolving credit facility $ — $ — Term Loan A Facility due 2024 301.8 323.0 Term Loan B Facility due 2024 850.0 1,088.8 6.875% Notes due 2028 400.0 400.0 6.50% Notes due 2027 500.0 500.0 6.25% Notes due 2026 400.0 400.0 6.25% Notes due 2025 — 700.0 5.00% Notes due 2029 600.0 — Foreign credit facilities 86.1 88.8 Total debt 3,137.9 3,500.6 Less: Current portion of long-term debt 18.8 13.7 Long-term debt 3,119.1 3,486.9 Less: Debt issuance costs 33.4 45.6 Long-term debt, net $ 3,085.7 $ 3,441.3
Schedule of Maturities of Long-term Debt [Table Text Block]	DEBT MATURITIES Aggregate maturities of long-term debt are as follows (in millions) : 2022 $ 46.5 2023 69.4 2024 1,122.0 2025 — 2026 400.0 Thereafter 1,500.0 Total $ 3,137.9

Gain (Loss) on Derivative Instr

Gain (Loss) on Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2021
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 (losses) into net income (loss) from accumulated other comprehensive income (loss) for those derivative instruments designated as cash flow hedges under Accounting Standards Codification 815 - Derivatives and Hedging (ASC 815): 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 (Loss) Expected to be Reclassified During the Next 12 Months 2021 2020 2019 2021 (in millions) Currency forward contracts Cost of Goods Sold $ 5.6 $ (2.9) $ 2.4 $ 4,433.9 $ 1.9 Fixed-to-fixed cross-currency swap Other Expense, net 19.0 (18.7) 1.3 (3.2) 1.7 Variable-to-fixed interest rate swap Interest Expense (14.8) (14.2) (2.0) (195.2) (10.2)
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 (losses) 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 (Loss) Recognized During the Twelve Months Ended December 31, Total of Financial Statement Line Item 2021 2020 2019 2021 (in millions) Currency forward contracts Cost of Goods Sold $ — $ (6.7) $ 3.9 $ 4,433.9 Currency forward contracts Other Expense, Net 0.2 0.6 — (3.2)

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2021
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]	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: December 31, 2021 December 31, 2020 Fair Value Fair Value Input (in millions) Balance Sheet Classification Cash equivalents $ 196.5 $ 206.7 Level 1 Prepaid expenses and other Cash flow hedges - currency forward contracts 2.2 5.8 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 1.9 4.9 Level 2 Nondesignated - currency forward contracts 0.2 0.2 Level 2 Other assets and deferred charges Cash flow hedges - currency forward contracts 1.4 3.3 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 2.2 8.6 Level 2 Investment in equity securities 27.4 — Level 1 Accrued expenses and other Cash flow hedges - currency forward contracts 0.3 0.1 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 9.6 17.8 Level 2 Postretirement benefits and other long-term liabilities Cash flow hedges - currency forward contracts 0.6 0.1 Level 2 Cash flow hedges - fixed-to-fixed cross-currency swap 3.7 20.6 Level 2 Cash flow hedges - variable-to-fixed interest rate swap 12.7 32.1 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, 2021 December 31, 2020 Carrying Amount Fair Value Carrying Amount Fair Value Input (in millions) Revolving Credit Facility $ — $ — $ — $ — Level 2 Term Loan A Facility due 2024 301.8 301.8 323.0 318.6 Level 2 Term Loan B Facility due 2024 850.0 847.9 1,088.8 1,071.1 Level 2 6.875% Notes due 2028 400.0 430.0 400.0 426.0 Level 2 6.50% Notes due 2027 500.0 519.4 500.0 523.8 Level 2 6.25% Notes due 2026 400.0 408.5 400.0 411.0 Level 2 6.25% Notes due 2025 — — 700.0 724.3 Level 2 5.00% Notes due 2029 600.0 588.0 — — Level 2

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined Benefit Plan, Assumptions [Table Text Block]	Pension Benefits OPEB 2021 2020 2019 2021 2020 2019 U.S. U.K. U.S. U.K. U.S. U.K. Discount rate 2.90 % 1.85 % 2.50 % 1.55 % 3.40 % 2.05 % 2.90 % 2.55 % 3.35 % Expected return on plan assets 7.00 % 4.00 % 7.25 % 4.00 % 7.25 % 4.00 % N/A N/A N/A Rate of compensation increase N/A 3.70 % N/A 3.15 % N/A 3.15 % 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, 2021 2020 2021 2020 (in millions) Change in benefit obligation Benefit obligation at beginning of year $ 798.9 $ 740.2 $ 586.5 $ 549.1 Service cost 2.0 2.0 0.3 0.4 Interest cost 17.3 21.4 8.4 10.2 Actuarial loss (gain) (6.5) 63.5 (34.6) 25.3 Change in GM portion of OPEB obligation — — (36.8) 14.0 Participant contributions 0.2 0.2 — — Settlements (99.0) (3.3) — — Benefit payments (34.4) (34.4) (14.2) (12.5) Currency fluctuations (4.4) 8.7 — — Other — 0.6 — — Net change (124.8) 58.7 (76.9) 37.4 Benefit obligation at end of year $ 674.1 $ 798.9 $ 509.6 $ 586.5 Change in plan assets Fair value of plan assets at beginning of year $ 669.9 $ 636.6 $ — $ — Actual return on plan assets 31.6 55.7 — — Employer contributions 7.8 8.5 14.2 12.5 Participant contributions 0.2 0.2 — — Benefit payments (34.4) (34.4) (14.2) (12.5) Settlements (99.0) (3.3) — — Currency fluctuations (2.3) 6.6 — — Net change (96.1) 33.3 — — Fair value of plan assets at end of year $ 573.8 $ 669.9 $ — $ —
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, 2021 2020 2021 2020 (in millions) Noncurrent assets $ 27.6 $ 20.2 $ — $ — Current liabilities (6.6) (8.0) (28.4) (29.8) Noncurrent liabilities (121.3) (141.2) (481.2) (556.7) Net liability $ (100.3) $ (129.0) $ (509.6) $ (586.5)
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, 2021 and 2020, consists of: Pension Benefits OPEB December 31, December 31, 2021 2020 2021 2020 (in millions) Net actuarial gain (loss) $ (225.4) $ (278.0) $ 31.3 $ (4.9) Net prior service credit (cost) (1.6) (1.8) 1.6 3.1 Total amounts recorded $ (227.0) $ (279.8) $ 32.9 $ (1.8)
Schedule of Net Benefit Costs [Table Text Block]	The components of net periodic benefit cost (credit) are as follows: Pension Benefits OPEB 2021 2020 2019 2021 2020 2019 (in millions) Service cost $ 2.0 $ 2.0 $ 1.5 $ 0.3 $ 0.4 $ 0.3 Interest cost 17.3 21.4 28.0 8.4 10.2 12.8 Expected asset return (39.0) (38.4) (41.1) — — — Amortized actuarial loss 10.8 8.6 6.4 1.7 1.0 0.1 Amortized prior service cost (credit) 0.1 0.1 — (1.5) (1.5) (1.5) Settlement charge 42.3 0.5 10.4 — — — Net periodic benefit cost (credit) $ 33.5 $ (5.8) $ 5.2 $ 8.9 $ 10.1 $ 11.7
Schedule of Allocation of Plan Assets [Table Text Block]	U.S. U.K. Target Target 2021 2020 Allocation 2021 2020 Allocation Equity securities 27.9 % 34.7 % 25% - 35% 21.6 % 21.8 % 15% - 30% Fixed income securities 63.8 57.3 60% - 70% 66.0 65.9 70% - 80% Alternative assets 7.5 7.3 0% - 10% 9.9 8.9 5% - 10% Cash 0.8 0.7 0% - 5% 2.5 3.4 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, 2021 Asset Categories Level 1 Level 2 Level 3 Total (in millions) Cash and Cash Equivalents $ 7.8 $ 0.8 $ — $ 8.6 Equity U.S. Large Cap 54.0 0.1 — 54.1 U.S. Small/Mid Cap 15.2 — — 15.2 World Equity 66.9 10.7 — 77.6 Fixed Income Securities Government & Agencies 80.2 52.7 — 132.9 Corporate Bonds - Investment Grade 189.9 1.3 — 191.2 Corporate Bonds - Non-investment Grade 15.7 0.5 — 16.2 Emerging Market Debt 12.5 — — 12.5 Other 11.2 5.8 — 17.0 Other Property Funds (a) — — — 38.2 Liquid Alternatives Fund (a) — — — 1.9 Structured Credit Fund (a) — — — 8.4 Total Plan Assets $ 453.4 $ 71.9 $ — $ 573.8 December 31, 2020 Asset Categories Level 1 Level 2 Level 3 Total (in millions) Cash and Cash Equivalents $ 7.4 $ 2.9 $ — $ 10.3 Equity U.S. Large Cap 88.1 2.7 — 90.8 U.S. Small/Mid Cap 20.5 — — 20.5 World Equity 87.0 7.8 — 94.8 Fixed Income Securities Government & Agencies 84.1 45.9 — 130.0 Corporate Bonds - Investment Grade 219.0 2.7 — 221.7 Corporate Bonds - Non-investment Grade 22.4 0.7 — 23.1 Emerging Market Debt 21.1 1.1 — 22.2 Other 3.6 0.3 — 3.9 Other Property Funds (a) — — — 44.2 Liquid Alternatives Fund (a) — — — 1.8 Structured Credit Fund (a) — — — 6.6 Total Plan Assets $ 553.2 $ 64.1 $ — $ 669.9 (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, 2021
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, 2019 3.5 $ 16.00 Granted 1.0 15.78 Vested (0.7) 15.53 Canceled (0.7) 16.05 Outstanding at December 31, 2019 3.1 $ 16.03 Granted 3.2 5.08 Vested (0.8) 18.22 Canceled (0.6) 10.33 Outstanding at December 31, 2020 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
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, 2019 0.8 $ 16.25 Granted 0.3 24.36 Vested (0.2) 17.54 Canceled (0.1) 20.49 Outstanding at December 31, 2019 0.8 $ 20.13 Granted — — Vested (0.2) 24.63 Canceled — — Outstanding at December 31, 2020 0.6 $ 18.86 Granted — — Vested (0.3) 13.91 Canceled — — Outstanding at December 31, 2021 0.3 $ 24.36 Free Cash Flow Awards Outstanding at January 1, 2019 0.3 $ 14.28 Granted — — Vested — — Canceled — — Outstanding at December 31, 2019 0.3 $ 14.28 Granted 0.9 5.18 Vested — — Canceled — — Outstanding at December 31, 2020 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

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
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: 2021 2020 2019 (in millions) U.S. loss $ (186.8) $ (721.6) $ (889.0) Non - U.S. income 188.0 111.3 356.0 Total income (loss) before income taxes $ 1.2 $ (610.3) $ (533.0)
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: 2021 2020 2019 (in millions) Current Federal $ 3.5 $ 2.0 $ (11.9) State and local 0.3 0.5 0.1 Foreign 34.0 20.2 49.3 Total current $ 37.8 $ 22.7 $ 37.5 Deferred Federal $ (40.7) $ (60.0) $ (73.5) State and local (0.9) (0.7) (1.5) Foreign (0.9) (11.2) (11.4) Total deferred (42.5) (71.9) (86.4) Total income tax benefit $ (4.7) $ (49.2) $ (48.9)
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 2021, 2020 and 2019 to our provision for income taxes: 2021 2020 2019 (in millions) Federal statutory $ 0.3 $ (128.2) $ (111.9) Foreign income taxes (14.0) (21.5) (40.2) Change in enacted tax rate 0.1 2.1 0.2 Transition tax — — (7.5) State and local 3.0 (5.0) (20.0) Tax credits (11.0) (9.7) (9.6) Valuation allowance 2.7 19.8 12.6 Goodwill impairment — 107.1 92.4 Withholding taxes 3.2 5.6 4.0 U.S. tax on unremitted foreign earnings 2.2 — (2.8) Tax benefit on loss carryback (5.2) (14.4) — Global intangible low-taxed income 6.5 2.3 31.1 Uncertain tax positions 1.2 (8.8) 5.9 Other 6.3 1.5 (3.1) Effective income tax benefit $ (4.7) $ (49.2) $ (48.9)
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, 2021 2020 (in millions) Deferred tax assets Employee benefits $ 163.1 $ 162.4 Inventory 31.7 32.9 Net operating loss (NOL) carryforwards 186.7 221.4 Tax credit carryforwards 83.6 88.6 Capital allowance carryforwards 10.8 10.2 Capitalized expenditures 41.8 45.9 Interest carryforward 26.0 10.4 Operating lease liabilities 28.0 25.7 Other 41.6 50.6 Valuation allowances (201.7) (208.0) Deferred tax assets $ 411.6 $ 440.1 Deferred tax liabilities Other intangible assets $ (160.7) $ (179.9) Fixed assets (103.3) (137.5) Operating lease right-of-use assets (27.8) (25.6) Other (12.2) (2.5) Deferred tax liabilities $ (304.0) $ (345.5) Deferred tax assets, net $ 107.6 $ 94.6 Deferred tax assets and liabilities recognized in our Consolidated Balance Sheets are as follows: December 31, 2021 2020 (in millions) U.S. federal and state deferred tax asset, net $ 56.9 $ 44.1 Other foreign deferred tax asset, net 50.7 50.5 Deferred tax asset, net $ 107.6 $ 94.6
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, 2019 $ 38.7 $ 6.9 Increase in prior year tax positions 0.2 4.5 Decrease in prior year tax positions (3.1) (0.1) Increase in current year tax positions 4.4 — Foreign currency remeasurement adjustment 0.9 0.2 Balance at December 31, 2019 $ 41.1 $ 11.5 Increase in prior year tax positions 0.2 — Decrease in prior year tax positions (6.6) (1.7) Increase in current year tax positions 0.7 — Settlement (12.2) (6.3) Foreign currency remeasurement adjustment (3.0) (1.5) Balance at December 31, 2020 $ 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

Earnings Per Share (EPS) (Table

Earnings Per Share (EPS) (Tables)	12 Months Ended
	Dec. 31, 2021
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): 2021 2020 2019 (in millions, except per share data) Numerator Net income (loss) attributable to AAM $ 5.9 $ (561.3) $ (484.5) Less: Net income allocated to participating securities (0.2) — — Net income (loss) attributable to common shareholders - Basic and Dilutive $ 5.7 $ (561.3) $ (484.5) Denominators Basic common shares outstanding - Weighted-average shares outstanding 118.5 117.9 115.6 Less: Weighted-average participating securities (4.6) (4.8) (3.3) Weighted-average common shares outstanding 113.9 113.1 112.3 Effect of dilutive securities - Dilutive stock-based compensation 0.2 — — Diluted shares outstanding - Adjusted weighted-average shares after assumed conversions 114.1 113.1 112.3 Basic EPS $ 0.05 $ (4.96) $ (4.31) Diluted EPS $ 0.05 $ (4.96) $ (4.31)

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021 2020 (in millions) Beginning balance $ 66.7 $ 62.0 Accruals 19.4 21.9 Settlements (17.6) (14.1) Adjustments to prior period accruals (8.6) (3.5) Foreign currency translation (0.4) 0.4 Ending balance $ 59.5 $ 66.7

Reclassifications out of Accu_2

Reclassifications out of Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021, December 31, 2020 and December 31, 2019 are as follows (in millions) : Defined Benefit Plans Foreign Currency Translation Adjustments Unrecognized Loss on Cash Flow Hedges Total Balance at January 1, 2019 $ (213.9) $ (96.6) $ (1.1) $ (311.6) Other comprehensive loss before reclassifications (61.5) (c) (4.6) (19.0) (85.1) Income tax effect of other comprehensive loss before reclassifications 5.6 — 6.3 11.9 Amounts reclassified from accumulated other comprehensive loss into net loss 12.5 (a) — (1.7) (b) 10.8 Income taxes reclassified into net loss (2.6) — (0.2) (2.8) Net current period other comprehensive loss (46.0) (4.6) (14.6) (65.2) Balance at December 31, 2019 $ (259.9) $ (101.2) $ (15.7) $ (376.8) Other comprehensive income (loss) before reclassifications (72.0) 0.1 (41.5) (113.4) Income tax effect of other comprehensive income (loss) before reclassifications 14.2 — 8.2 22.4 Amounts reclassified from accumulated other comprehensive loss into net loss 8.2 (a) — 35.8 (b) 44.0 Income taxes reclassified into net loss (1.5) — (6.9) (8.4) Net current period other comprehensive income (loss) (51.1) 0.1 (4.4) (55.4) Balance at December 31, 2020 $ (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) (a) The amount reclassified for 2021 includes a credit to AOCI of $42.3 million related to the effect of the Pension Annuity Purchase, and the amount reclassified for 2019 includes a credit to AOCI of $7.4 million related to the net effect of the AAM Pension Payout Offer and the Casting Sale. See Note 7 - Employee Benefit Plans and Note 16 - Acquisitions and Dispositions for more detail. (b) The amounts reclassified from AOCI included $(5.6) million in COGS, $14.8 million in interest expense and $(19.0) million in other expense, net for the year ended December 31, 2021, $2.9 million in COGS, $14.2 million in interest expense and $18.7 million in other expense, net for the year ended December 31, 2020 and $(2.4) million in COGS, $2.0 million in interest expense and $(1.3) million in other expense, net for the year ended December 31, 2019. (c) ASU 2018-02 became effective on January 1, 2019, and we elected to reclassify the stranded tax effects caused by the 2017 Tax Cuts and Jobs Act, resulting in a decrease in Accumulated other comprehensive income (loss) of $27.7 million at January 1, 2019.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021, 2020 and 2019. Net sales are attributed to regions based on the location of production. Intersegment sales have been excluded from the table. In 2021, we reorganized our segments and moved certain of our Driveline facilities to our Metal Forming segment. The amounts previously reported in the tables below for the years ended December 31, 2020 and 2019 have been retrospectively recast to reflect this change. In 2019, we finalized the Casting Sale. The Casting Sale did not qualify for classification as discontinued operations, as it did not represent a strategic shift in our business that had a major effect on our operations and financial results. As such, we continue to present Casting as a segment in the tables below, which is comprised entirely of the U.S. casting operations that were included in the sale. Twelve Months Ended December 31, 2021 Driveline Metal Forming Casting Total (in millions) North America $ 2,839.8 $ 1,142.6 $ — $ 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 $ 3,741.5 $ 1,415.1 $ — $ 5,156.6 Twelve Months Ended December 31, 2020 Driveline Metal Forming Casting Total North America $ 2,537.2 $ 1,087.9 $ — $ 3,625.1 Asia 433.7 43.8 — 477.5 Europe 352.5 198.0 — 550.5 South America 49.2 8.5 — 57.7 Total $ 3,372.6 $ 1,338.2 $ — $ 4,710.8 Twelve Months Ended December 31, 2019 Driveline Metal Forming Casting Total North America $ 3,225.7 $ 1,393.7 $ 627.7 $ 5,247.1 Asia 533.6 37.6 — 571.2 Europe 351.0 256.3 — 607.3 South America 98.8 6.5 — 105.3 Total $ 4,209.1 $ 1,694.1 $ 627.7 $ 6,530.9 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, 2020 $ 793.2 $ 23.4 $ 91.0 December 31, 2021 762.8 28.1 94.8 Increase/(decrease) $ (30.4) $ 4.7 $ 3.8

Leasing (Tables)

Leasing (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Components of lease cost [Table Text Block]	Lease cost consists of the following: Twelve Months Ended December 31, 2021 2020 2019 (in millions) Finance lease cost Amortization of right-of-use assets $ 4.2 $ 1.8 $ 1.0 Interest on lease liabilities 2.0 0.4 0.3 Total finance lease cost 6.2 2.2 1.3 Operating lease cost 33.3 32.7 28.9 Short-term lease cost 1.6 3.0 5.9 Variable lease cost 3.2 2.9 7.2 Total lease cost $ 44.3 $ 40.8 $ 43.3
Supplemental lease information [Table Text Block]	The following table summarizes additional information related to our lease agreements. Twelve Months Ended December 31, 2021 2020 2019 (in millions, except lease term and rate) Cash paid for amounts included in measurement of lease liabilities Operating cash flows from finance leases $ 2.0 $ 0.3 $ 0.3 Operating cash flows from operating leases 35.9 35.1 29.0 Financing cash flows from finance leases 5.0 3.0 1.0 Weighted-average remaining lease term - finance leases 16.4 years 15.8 years 2.8 years Weighted-average remaining lease term - operating leases 8.6 years 8.7 years 9.2 years Weighted-average discount rate - finance leases 4.8 % 4.2 % 5.1 % Weighted-average discount rate - operating leases 5.2 % 5.7 % 6.1 %
Future minimum lease payments [Table Text Block]	Future undiscounted minimum payments under non-cancelable leases are as follows: Finance Leases Operating Leases (in millions) 2022 $ 10.4 $ 30.4 2023 8.3 23.8 2024 7.4 17.4 2025 7.3 13.9 2026 7.3 10.7 Thereafter 85.5 60.2 Total future undiscounted minimum lease payments 126.2 156.4 Less: Impact of discounting (37.4) (31.9) Total $ 88.8 $ 124.5
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, 2021 December 31, 2020 Finance Leases Operating Leases Finance Leases Operating Leases (in millions) (in millions) Property, plant and equipment, net $ 113.4 $ — $ 24.9 $ — Operating lease right-of-use assets — 123.7 — 116.6 Total $ 113.4 $ 123.7 $ 24.9 $ 116.6 Current portion of operating lease liabilities $ — $ 24.6 $ — $ 22.6 Accrued expenses and other 6.3 — 3.3 — Long-term portion of operating lease liabilities — 99.9 — 94.4 Postretirement benefits and other long-term liabilities 82.5 — 18.3 — Total $ 88.8 $ 124.5 $ 21.6 $ 117.0

Segment and Geographic Inform_2

Segment and Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2021
Segments, Geographical Areas [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Year Ended December 31, 2021 Driveline Metal Forming Casting Corporate and Eliminations Total (in millions) Sales $ 3,744.9 $ 1,762.2 $ — $ — $ 5,507.1 Less: Intersegment sales 3.4 347.1 — — 350.5 Net external sales $ 3,741.5 $ 1,415.1 $ — $ — $ 5,156.6 Segment adjusted EBITDA $ 577.7 $ 255.6 $ — $ — $ 833.3 Depreciation and amortization $ 301.9 $ 242.4 $ — $ — $ 544.3 Capital expenditures $ 126.8 $ 50.5 $ — $ 3.9 $ 181.2 Total assets $ 2,925.6 $ 1,576.9 $ — $ 1,133.2 $ 5,635.7 Year Ended December 31, 2020 Driveline Metal Forming Casting Corporate and Eliminations Total Sales $ 3,375.5 $ 1,652.0 $ — $ — $ 5,027.5 Less: Intersegment sales 2.9 313.8 — — 316.7 Net external sales $ 3,372.6 $ 1,338.2 $ — $ — $ 4,710.8 Segment adjusted EBITDA $ 474.8 $ 245.0 $ — $ — $ 719.8 Depreciation and amortization $ 306.1 $ 215.8 $ — $ — $ 521.9 Capital expenditures $ 125.3 $ 81.9 $ — $ 8.4 $ 215.6 Total assets $ 3,035.7 $ 1,680.3 $ — $ 1,200.3 $ 5,916.3 Year Ended December 31, 2019 Driveline Metal Forming Casting Corporate and Eliminations Total Sales $ 4,220.4 $ 2,062.7 $ 669.2 $ — $ 6,952.3 Less: Intersegment sales 11.3 368.6 41.5 — 421.4 Net external sales $ 4,209.1 $ 1,694.1 $ 627.7 $ — $ 6,530.9 Segment adjusted EBITDA $ 579.0 $ 348.3 $ 43.0 $ — $ 970.3 Depreciation and amortization $ 288.0 $ 206.6 $ 42.3 $ — $ 536.9 Capital expenditures $ 250.3 $ 139.0 $ 28.5 $ 15.5 $ 433.3 Total assets $ 3,557.9 $ 2,120.9 $ — $ 965.8 $ 6,644.6
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, 2021, 2020 and 2019: Year Ended December 31, 2021 2020 2019 (in millions) Segment adjusted EBITDA $ 833.3 $ 719.8 $ 970.3 Interest expense (195.2) (212.3) (217.3) Depreciation and amortization (544.3) (521.9) (536.9) Impairment charges — (510.0) (665.0) Restructuring and acquisition-related costs (49.4) (67.2) (57.8) Pension settlements (42.3) (0.5) (9.8) Loss on sale of business (2.7) (1.0) (21.3) Gain on bargain purchase of business — — 10.8 Unrealized gain on equity securities 24.4 — — Debt refinancing and redemption costs (34.0) (7.9) (8.4) Malvern Fire charges, net of recoveries 11.4 (9.3) — Other — — 2.4 Income (loss) before income taxes $ 1.2 $ (610.3) $ (533.0)
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, 2021 2020 2019 (in millions) Net sales United States $ 1,923.5 $ 1,816.7 $ 2,894.0 Mexico 2,058.9 1,808.5 2,353.1 South America 94.3 57.6 105.3 China 299.6 317.1 315.4 All other Asia 189.4 160.4 255.8 Europe 590.9 550.5 607.3 Total net sales $ 5,156.6 $ 4,710.8 $ 6,530.9 Long-lived assets United States $ 1,976.5 $ 2,099.4 $ 2,805.8 Mexico 888.1 1,021.6 1,117.4 South America 40.9 49.7 61.9 China 164.8 185.1 191.4 All other Asia 87.1 84.2 106.8 Europe 501.2 491.5 439.4 Total long-lived assets $ 3,658.6 $ 3,931.5 $ 4,722.7

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2019: Allowance for credit losses (1) $ 8.4 $ 13.2 $ (0.8) $ 12.8 $ 8.0 Allowance for deferred taxes (3) 183.3 25.4 — 12.7 196.0 Inventory valuation allowance (2) 14.4 31.0 1.4 26.3 20.5 Year Ended December 31, 2020: Allowance for credit losses (1) 8.0 7.0 — 10.5 4.5 Allowance for deferred taxes (4) 196.0 19.8 — 7.8 208.0 Inventory valuation allowance (2) 20.5 31.7 — 28.8 23.4 Year Ended December 31, 2021: Allowance for credit losses (1) 4.5 7.8 — 10.1 2.2 Allowance for deferred taxes (4) 208.0 2.7 — 9.0 201.7 Inventory valuation allowance (2) 23.4 17.7 — 22.5 18.6 (a ) Amounts represent reserves recognized in conjunction with our acquisition of Mitec and reserves derecognized in conjunction with the Casting Sale in 2019. (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 the reversal of a valuation allowance against certain deferred tax assets in foreign locations, as well as changes due to foreign currency translation. (4) Primarily reflects 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, 2021FacilitiesCountries
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of Facilities | Facilities	80
Number of Countries in which Entity Operates | Countries	17

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, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue, Performance Obligation, Description of Payment Terms	50 days
Accounts Receivable, Allowance for Credit Loss	$ 2.2	$ 4.5

Organization and Summary of S_4

Organization and Summary of Significant Accounting Policies - Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Inventory [Line Items]
Raw materials and work-in-progress	$ 339.7	$ 276.2
Finished goods	89.3	70.4
Gross inventories	429	346.6
Inventory valuation reserves	(18.6)	(23.4)
Inventories, net	$ 410.4	$ 323.2

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Maintenance, Repair and Operations (MRO) Materials [Abstract]
Maintenance, Repair and Operations (MRO) Materials Amortization	$ 61.6	$ 62.4	$ 67.7

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation and tooling amortization	$ 396.9	$ 372.9	$ 373.8
Noncash or part noncash acquisition, fixed assets acquired	$ 20.1	$ 20.4	$ 46

Organization and Summary of S_7

Organization and Summary of Significant Accounting Policies - Schedule of Property, Plant & Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Land	$ 47.7	$ 49.2
Land improvements	26.8	26.3
Buildings and building improvements	635.8	554.3
Machinery and equipment	3,700.3	3,703.7
Construction in progress	171.2	122.1
Property, plant and equipment, gross	4,581.8	4,455.6
Accumulated depreciation and amortization	(2,585.7)	(2,291.8)
Property, plant and equipment, net	$ 1,996.1	$ 2,163.8
Land [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	Indefinite	Indefinite
Minimum [Member] | Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	10	10
Minimum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	15	15
Minimum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3	3
Maximum [Member] | Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	15	15
Maximum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	40	40
Maximum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	12	12

Organization and Summary of S_8

Organization and Summary of Significant Accounting Policies - Debt Issuance Costs Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 42.3	$ 57.8
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 8.9	$ 12.2

Organization and Summary of S_9

Organization and Summary of Significant Accounting Policies - Currency Translation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Foreign currency transaction gain (loss), before tax	$ (1.7)	$ (0.5)	$ (6.5)

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Research and development expense	$ 116.8	$ 117.4	$ 144.7
Engineering, Design & Development Recoveries	$ 15	$ 15

Organization and Summary of _11

Organization and Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred payments of social security tax repaid	$ 7.6
Deferred payments of social security tax	7.6
CARES Act [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Refundable payroll tax credit	2.6
Loss carryback related to the CARES Act [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Tax Expense (Benefit)	(5.2)	$ (14.4)
CARES Act [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from Income Tax Refunds	$ 6	$ 31

Restructuring and Acquisition_3

Restructuring and Acquisition-Related Costs - Restructuring Reserve Table (Details) - USD ($) $ in Millions	12 Months Ended			24 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021
Restructuring Reserve [Roll Forward]
Restructuring reserve	$ 11.5	$ 12.2	$ 4	$ 12.2
Restructuring charges	43.2	58.4	39.8
Cash utilization	(51.3)	(59.1)	(31.6)
Restructuring reserve	3.4	11.5	12.2	3.4
Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring reserve	1.7	4.8	2.4	4.8
Restructuring charges	2.9	22.3	19.4
Cash utilization	(3.9)	(25.4)	(17)
Restructuring reserve	0.7	1.7	4.8	0.7
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring reserve	9.8	7.4	1.6	7.4
Restructuring charges	40.3	36.1	20.4
Cash utilization	(47.4)	(33.7)	(14.6)
Restructuring reserve	$ 2.7	$ 9.8	$ 7.4	$ 2.7

Restructuring and Acquisition_4

Restructuring and Acquisition-Related Costs - Restructuring Reserve Narrative (Details) - USD ($) $ in Millions	12 Months Ended			24 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 43.2	$ 58.4	$ 39.8
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost remaining	20			$ 20
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost remaining	30			30
Driveline [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4.7	19.3	6.4
Metal Forming [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6.5	16	21.5
Casting [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			0.7
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2.9	22.3	19.4
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	40.3	$ 36.1	$ 20.4
2020 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	39.5			$ 87.3
Emporium, Pennsylvania [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 3.7

Restructuring and Acquisition_5

Restructuring and Acquisition-Related Costs - Business Combinations, Separately Recognized Transactions Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Acquisition-Related Costs	$ 0.4	$ 0	$ 1.8
Integration Expenses	5.8	8.8	16.2
Total acquisition-related charges	6.2	8.8	18
Restructuring and acquisition-related costs	$ 49.4	$ 67.2	$ 57.8

Goodwill and Intangible Assets

Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Beginning balance	$ 185.7	$ 699.1
Impairment charge		(510)
Foreign currency translation	(1.9)	(3.4)
Ending balance	183.8	185.7	$ 699.1
Driveline [Member]
Goodwill [Roll Forward]
Beginning balance	185.7	398.3
Impairment charge		(210.8)
Foreign currency translation	(1.9)	(1.8)
Ending balance	183.8	185.7	398.3
Metal Forming [Member]
Goodwill [Roll Forward]
Beginning balance	0	300.8
Impairment charge		(299.2)	(440)
Foreign currency translation	0	(1.6)
Ending balance	$ 0	$ 0	$ 300.8

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 510
Goodwill, Impaired, Facts and Circumstances Leading to Impairment	These impairment charges were primarily the result of a decline in the projected cash flows of these reporting units under our revised long-range plan completed in the first quarter of 2020. The revision to our long-range plan was driven by lower forecasted sales volumes in the internal and external data sources used to form our projections primarily due to the reduction in global automotive production volumes caused by the impact of COVID-19. The impairment charges were also the result of changes in certain market-related inputs to the analysis to reflect macro-economic changes caused by the impact of COVID-19, including increased discount rates and lower pricing multiples for comparable public companies.	This impairment was primarily the result of a decline in the projected cash flows of this reporting unit under our long-range plan completed in the fourth quarter of 2019, as compared to the long-range plan completed in the fourth quarter of 2018. This was driven, in part, by lower forecasted sales volumes in the internal and external data sources used to form our projections.
Goodwill, Impaired, Accumulated Impairment Loss			$ 1,435.5
Driveline [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 210.8
Metal Forming [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 299.2	$ 440

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 1,112.6	$ 1,113.5
Finite-Lived Intangible Assets, Accumulated Amortization	(415.4)	(332.8)
Finite-Lived Intangible Assets, Net	697.2	780.7
Amortization of intangible assets	85.8	86.6	$ 95.4
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	47.3	47.6
Finite-Lived Intangible Assets, Accumulated Amortization	(37)	(33.9)
Finite-Lived Intangible Assets, Net	10.3	13.7
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	(301.3)	(237.9)
Finite-Lived Intangible Assets, Net	554.9	618.3
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	(16.2)	(12.8)
Finite-Lived Intangible Assets, Net	36.8	40.2
Technology-Based Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	156.1	156.7
Finite-Lived Intangible Assets, Accumulated Amortization	(60.9)	(48.2)
Finite-Lived Intangible Assets, Net	$ 95.2	$ 108.5

Long-Term Debt - Long-term Debt

Long-Term Debt - Long-term Debt Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Jul. 29, 2019	Apr. 06, 2017
Debt Instrument [Line Items]
Total debt	$ 3,137.9	$ 3,500.6
Current portion of long-term debt	18.8	13.7
Long-term debt	3,119.1	3,486.9
Unamortized debt issuance costs	42.3	57.8
Long-term debt, net	3,085.7	3,441.3
Term Loan A Due 2024 [Member]
Debt Instrument [Line Items]
Secured Debt	301.8	323	$ 340
Term Loan B due 2024 [Member]
Debt Instrument [Line Items]
Secured Debt	850	1,088.8		$ 1,550
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	400	400
6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Unsecured Debt	0	700
5.00% Notes due 2029
Debt Instrument [Line Items]
Unsecured Debt	600	0
Total Debt Instruments excluding Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	33.4	45.6
Multi-Currency Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding	0	0
Foreign Credit Facilities and Other [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding	$ 86.1	$ 88.8

Long-Term Debt - Senior Secured

Long-Term Debt - Senior Secured Credit Facilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jul. 29, 2019	Apr. 06, 2017
Debt Instrument [Line Items]
Payments of Debt Issuance Costs	$ 9.2	$ 11	$ 3.3
Repayments of Long-term Debt	1,017.6	607.2	544.4
Term Loan A Due 2024 [Member]
Debt Instrument [Line Items]
Secured Debt	301.8	323		$ 340
Term Loan B due 2024 [Member]
Debt Instrument [Line Items]
Secured Debt	850	1,088.8			$ 1,550
Multi-Currency Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 925
Multi-Currency Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	893.2
Letters of Credit Outstanding, Amount	31.8
Secured Debt [Member] | Term Loan A Due 2024 [Member]
Debt Instrument [Line Items]
Repayments of Long-term Debt	21.2	15
Secured Debt [Member] | Term Loan B due 2024 [Member]
Debt Instrument [Line Items]
Repayments of Long-term Debt	238.8	100	59.8
Interest Paid, Including Capitalized Interest, Operating and Investing Activities			0.4
Write off of Deferred Debt Issuance Cost			$ 1
Secured Debt [Member] | Second Amendment to the Credit Amendments [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs		4.6
Secured Debt [Member] | Term Loan A & Term Loan B [Member]
Debt Instrument [Line Items]
Write off of Deferred Debt Issuance Cost	$ 2.5	$ 1.2
Unsecured Debt [Member] | 6.25% Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Interest Paid, Including Capitalized Interest, Operating and Investing Activities	$ 19.4
Write off of Deferred Debt Issuance Cost	$ 9.6

Long-Term Debt - Long-Term De_2

Long-Term Debt - Long-Term Debt Notes Payable Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt		$ 634.7	$ 408	$ 356.3
Payments of Debt Issuance Costs		9.2	11	$ 3.3
Unsecured Debt [Member] | 5.00% Notes due 2029
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt	$ 600
Debt Instrument, Interest Rate, Stated Percentage	5.00%
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%
Debt Instrument, Repurchase Amount		$ 700
Interest Paid, Including Capitalized Interest, Operating and Investing Activities		19.4
Write off of Deferred Debt Issuance Cost		9.6
Redemption Premium		$ 21.9
Unsecured Debt [Member] | 6.875% Notes [Member]
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt			$ 400
Debt Instrument, Interest Rate, Stated Percentage			6.875%
Payments of Debt Issuance Costs			$ 6.4
Unsecured Debt [Member] | 6.625% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			6.625%
Debt Instrument, Repurchase Amount			$ 450
Interest Paid, Including Capitalized Interest, Operating and Investing Activities			7.7
Write off of Deferred Debt Issuance Cost			1.7
Redemption Premium			$ 5
Unsecured Debt [Member] | 7.75% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				7.75%
Debt Instrument, Repurchase Amount				$ 100
Interest Paid, Including Capitalized Interest, Operating and Investing Activities				0.3
Write off of Deferred Debt Issuance Cost				0.1
Redemption Premium				$ 2.2

Long-Term Debt - Foreign Credit

Long-Term Debt - Foreign Credit Facilities Narrative (Details) - Foreign Credit Facilities [Member] - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Line of Credit Facility [Line Items]
Line of credit facility, amount outstanding	$ 86.1	$ 88.8
Foreign Credit Facilities, Remaining Borrowing Capacity	$ 65.1	$ 72.8

Long-Term Debt - Long-term De_3

Long-Term Debt - Long-term Debt Maturity Schedule (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
2022	$ 46.5
2023	69.4
2024	1,122
2025	0
2026	400
Thereafter	1,500
Debt	$ 3,137.9	$ 3,500.6

Long-Term Debt - Interest Expen

Long-Term Debt - Interest Expense and Interest Income Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Interest Expense	$ 195.2	$ 212.3	$ 217.3
Interest Costs Capitalized	$ 6.2	$ 7.9	$ 15.5
Long-term Debt, Weighted Average Interest Rate, at Point in Time	5.60%	5.80%	5.80%
Investment Income, Interest	$ 10.9	$ 11.6	$ 5.8

Derivatives and Risk Manageme_2

Derivatives and Risk Management - Derivatives and Risk Management Narrative (Details) € in Millions, $ in Millions	Dec. 31, 2021USD ($)	Dec. 31, 2021EUR (€)	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Mar. 09, 2020USD ($)
Foreign Currency Forward & Foreign Currency Option Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 164.7		$ 178.2
Currency Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount	226.9	€ 200	$ 244.2	€ 200
Fair value asset at the date of dedesignation					$ 9.8
Interest Rate Swap [Member] | Debt [Member]
Derivative [Line Items]
Derivative, Amount of Hedged Item, Through May 2022	750
Derivative, Amount of Hedged Item, Through May 2023	600
Derivative, Amount of Hedged Item, Through May 2024	$ 500

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Cost of Goods and Services Sold	$ 4,433.9	$ 4,128.1	$ 5,628.3
Other Nonoperating Income (Expense)	(3.2)	(5.2)	(12.5)
Interest expense	$ (195.2)	$ (212.3)	$ (217.3)
Cost of Sales [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Description of Location of Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments in Financial Statements	Cost of Goods Sold	Cost of Goods Sold	Cost of Goods Sold
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 0	$ (6.7)	$ 3.9
Cost of Sales [Member] | Cash Flow Hedging [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Derivative Instruments, Income Statement Location of Gain (Loss) Reclassified from Accumulated OCI	Cost of Goods Sold	Cost of Goods Sold	Cost of Goods Sold
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 5.6	$ (2.9)	$ 2.4
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 1.9
Other Nonoperating Income (Expense) [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Description of Location of Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments in Financial Statements	Other Expense, Net	Other Expense, Net	Other Expense, Net
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 0.2	$ 0.6	$ 0
Other Nonoperating Income (Expense) [Member] | Cash Flow Hedging [Member] | Currency Swap [Member]
Derivative [Line Items]
Derivative Instruments, Income Statement Location of Gain (Loss) Reclassified from Accumulated OCI	Other Expense, net	Other Expense, net	Other Expense, net
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 19	$ (18.7)	$ 1.3
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 1.7
Interest Expense [Member] | Cash Flow Hedging [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Instruments, Income Statement Location of Gain (Loss) Reclassified from Accumulated OCI	Interest Expense	Interest Expense	Interest Expense
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (14.8)	$ (14.2)	$ (2)
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ (10.2)

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue, Major Customer [Line Items]
Total GM postretirement cost sharing asset	$ 213.2	$ 250
General Motors [Member]
Revenue, Major Customer [Line Items]
Fair value, concentration of risk, accounts receivable	$ 290.2	$ 297.5
General Motors [Member] | Customer Concentration Risk | Revenue Benchmark
Revenue, Major Customer [Line Items]
Entity-wide revenue, major customer, percentage	37.00%	39.00%	37.00%
Stellantis [Member]
Revenue, Major Customer [Line Items]
Fair value, concentration of risk, accounts receivable	$ 137.1	$ 157
Stellantis [Member] | Customer Concentration Risk | Revenue Benchmark
Revenue, Major Customer [Line Items]
Entity-wide revenue, major customer, percentage	19.00%	19.00%	17.00%
Ford [Member]
Revenue, Major Customer [Line Items]
Fair value, concentration of risk, accounts receivable	$ 108.8	$ 116.5
Ford [Member] | Customer Concentration Risk | Revenue Benchmark
Revenue, Major Customer [Line Items]
Entity-wide revenue, major customer, percentage	12.00%	12.00%	9.00%

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, 2021	Dec. 31, 2020
REE Automotive Ltd.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	$ 27.4
Share Price	$ 5.55
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, at fair value	$ 196.5	$ 206.7
Other Noncurrent Assets [Member] | Fair Value, Inputs, Level 1 [Member] | REE Automotive Ltd. | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	27.4	0
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	2.2	5.8
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	1.4	3.3
Foreign Exchange Forward [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	0.3	0.1
Foreign Exchange Forward [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	0.6	0.1
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	0.2	0.2
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	1.9	4.9
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	2.2	8.6
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	9.6	17.8
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	12.7	32.1
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	$ 3.7	$ 20.6

Fair Value - Fair Value of Debt

Fair Value - Fair Value of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Jul. 29, 2019	Apr. 06, 2017
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	$ 0
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	0
Term Loan A Due 2024 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Secured Debt	301.8	323	$ 340
Term Loan A Due 2024 [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	301.8	323
Term Loan A Due 2024 [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	301.8	318.6
Term Loan B due 2024 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Secured Debt	850	1,088.8		$ 1,550
Term Loan B due 2024 [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	850	1,088.8
Term Loan B due 2024 [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	847.9	1,071.1
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	430	426
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	519.4	523.8
6.25% Notes Due 2026 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	400	400
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	400	400
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	408.5	411
6.25% Notes due 2025 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	0	700
6.25% Notes due 2025 [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	0	700
6.25% Notes due 2025 [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	0	724.3
5.00% Notes due 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Debt	600	0
5.00% Notes due 2029 | 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	0
5.00% Notes due 2029 | 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	$ 588	$ 0

Employee Benefit Plans - Define

Employee Benefit Plans - Defined Benefit Plan, Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.90%	2.50%	3.40%
Expected return on plan assets	7.00%	7.25%	7.25%
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	1.85%	1.55%	2.05%
Expected return on plan assets	4.00%	4.00%	4.00%
Rate of compensation increase	3.70%	3.15%	3.15%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.90%	2.55%	3.35%
Rate of compensation increase	4.00%	4.00%	4.00%

Employee Benefit Plans - Accumu

Employee Benefit Plans - Accumulated Benefit Obligation and Underfunded Pension Plan Detail Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined benefit plan, accumulated benefit obligation	$ 672.4	$ 796.6
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	494.6
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	494.6
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets	$ 366.7

Employee Benefit Plans - GM Cos

Employee Benefit Plans - GM Cost Sharing Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Total GM postretirement cost sharing asset	$ 213.2	$ 250
Current GM postretirement cost sharing asset	12.1
Noncurrent GM postretirement cost sharing asset	$ 201.1	$ 237

Employee Benefit Plans - Change

Employee Benefit Plans - Change in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	$ 669.9
Fair value of plan assets at end of year	573.8	$ 669.9
Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	798.9	740.2
Service cost	2	2	$ 1.5
Interest cost	17.3	21.4	28
Actuarial loss (gain)	(6.5)	63.5
Change in GM portion of OPEB obligation	0	0
Participant contributions	0.2	0.2
Settlements	(99)	(3.3)
Benefit payments	(34.4)	(34.4)
Currency fluctuations	(4.4)	8.7
Other	0	0.6
Net change	(124.8)	58.7
Benefit obligation at end of year	674.1	798.9	740.2
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	669.9	636.6
Actual return on plan assets	31.6	55.7
Employer contributions	7.8	8.5
Participant contributions	0.2	0.2
Benefit payments	(34.4)	(34.4)
Settlements	(99)	(3.3)
Currency fluctuations	(2.3)	6.6
Net change	(96.1)	33.3
Fair value of plan assets at end of year	573.8	669.9	636.6
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	586.5	549.1
Service cost	0.3	0.4	0.3
Interest cost	8.4	10.2	12.8
Actuarial loss (gain)	(34.6)	25.3
Change in GM portion of OPEB obligation	(36.8)	14
Participant contributions	0	0
Settlements	0	0
Benefit payments	(14.2)	(12.5)
Currency fluctuations	0	0
Other	0	0
Net change	(76.9)	37.4
Benefit obligation at end of year	509.6	586.5	549.1
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	14.2	12.5
Participant contributions	0	0
Benefit payments	(14.2)	(12.5)
Settlements	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, 2021	Dec. 31, 2020
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Noncurrent assets	$ 27.6	$ 20.2
Liability, Defined Benefit Pension Plan, Current	(6.6)	(8)
Defined benefit pension plan, liabilities, noncurrent	(121.3)	(141.2)
Defined benefit plan, amounts recognized in balance sheet	(100.3)	(129)
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	(28.4)	(29.8)
Other postretirement defined benefit plan, liabilities, noncurrent	(481.2)	(556.7)
Other postretirement defined benefit plan, liabilities	$ (509.6)	$ (586.5)

Employee Benefit Plans - Pre-ta

Employee Benefit Plans - Pre-tax Amounts Recorded in AOCI (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain (loss)	$ (225.4)	$ (278)
Net prior service credit (cost)	(1.6)	(1.8)
Total amounts recorded	(227)	(279.8)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain (loss)	31.3	(4.9)
Net prior service credit (cost)	1.6	3.1
Total amounts recorded	$ 32.9	$ (1.8)

Employee Benefit Plans - Compon

Employee Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Settlement charge	$ 42.3	$ 0.5	$ 9.8
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	2	2	1.5
Interest cost	17.3	21.4	28
Expected asset return	(39)	(38.4)	(41.1)
Amortized actuarial loss	10.8	8.6	6.4
Amortized prior service cost (credit)	0.1	0.1	0
Settlement charge	42.3	0.5	10.4
Net periodic benefit cost (credit)	33.5	(5.8)	5.2
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.3	0.4	0.3
Interest cost	8.4	10.2	12.8
Expected asset return	0	0	0
Amortized actuarial loss	1.7	1	0.1
Amortized prior service cost (credit)	(1.5)	(1.5)	(1.5)
Settlement charge	0	0	0
Other postretirement benefit cost (credit)	$ 8.9	$ 10.1	$ 11.7

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, 2021USD ($)
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	6.60%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2030
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 50.6
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	47.5
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	49
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	49.7
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	51.5
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	253.1
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	4.1
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	$ 16.5

Employee Benefit Plans - U.S. P

Employee Benefit Plans - U.S. Pension Annuity Purchase (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)Facilities	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Settlement charge	$ 42.3	$ 0.5	$ 9.8
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 | Facilities	3,400
Settlements	$ 97.3
Settlement charge	$ 42.3

Employee Benefit Plans - Termin

Employee Benefit Plans - Terminated vested lump sum payment offer (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)Employees
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Settlement charge	$ 42.3	$ 0.5	$ 9.8
Terminated vested lump sum payment offer [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, number of plan participants eligible for settlement | Employees			2,000
Defined benefit plan, number of plan participants included in settlement | Employees			616
Defined Benefit Plan, Benefit Obligation, Payment for Settlement			$ 28.4
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement			32.5
Settlement charge			$ 9.8

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, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 573.8	$ 669.9
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	453.4	553.2
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	71.9	64.1
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	8.6	10.3
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7.8	7.4
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.8	2.9
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	54.1	90.8
U.S. Large Cap [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54	88.1
U.S. Large Cap [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.1	2.7
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	15.2	20.5
U.S. Small/Mid Cap [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15.2	20.5
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	77.6	94.8
World Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	66.9	87
World Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.7	7.8
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	132.9	130
Government & Agencies [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	80.2	84.1
Government & Agencies [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	52.7	45.9
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	191.2	221.7
Corporate Bonds - Investment Grade [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	189.9	219
Corporate Bonds - Investment Grade [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.3	2.7
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	16.2	23.1
Corporate Bonds - Non-investment Grade [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15.7	22.4
Corporate Bonds - Non-investment Grade [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.5	0.7
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	12.5	22.2
Emerging Market Debt [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12.5	21.1
Emerging Market Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1.1
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	17	3.9
Fixed Income Securities - Other [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11.2	3.6
Fixed Income Securities - Other [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.8	0.3
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	38.2	44.2
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
Liquid Alternatives Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.9	1.8
Liquid Alternatives Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Liquid Alternatives Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Liquid Alternatives Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Structured Credit Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8.4	6.6
Structured Credit Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Structured Credit Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Structured Credit Fund [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	100.00%	100.00%
Domestic Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	27.90%	34.70%
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	63.80%	57.30%
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	7.50%	7.30%
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	0.80%	0.70%
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	100.00%	100.00%
Foreign Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	21.60%	21.80%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	15% - 30%
Foreign Plan [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	66.00%	65.90%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	70% - 80%
Foreign Plan [Member] | Alternative assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	9.90%	8.90%
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	5% - 10%
Foreign Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	2.50%	3.40%
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, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	50.00%
Defined contribution plans, ARC, maximum employee contribution percentage	10.00%
Defined contribution plans, salaried voluntary savings plan, matching contributions during the period	$ 8	$ 7.9	$ 11.5
Annual Retirement Contribution (ARC) [Member]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 8.3	$ 8	$ 10.3
Minimum [Member] | Annual Retirement Contribution (ARC) [Member]
Defined Contribution Plan, Employer Discretionary Contribution Percentage	3.00%
Maximum [Member] | Annual Retirement Contribution (ARC) [Member]
Defined Contribution Plan, Employer Discretionary Contribution Percentage	5.00%

Stock Based Compensation and _3

Stock Based Compensation and Other Incentive Compensation - Stock Based Compensation Narrative (Details) shares in Millions	Dec. 31, 2021shares
Share-based Payment Arrangement [Abstract]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	7.2

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, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Beginning balance	4.9	3.1	3.5
Restricted stock units granted	0.9	3.2	1
Restricted stock units vested	(1)	(0.8)	(0.7)
Restricted stock units canceled	(0.4)	(0.6)	(0.7)
Ending balance	4.4	4.9	3.1
Weighted-average grant date fair value outstanding	$ 8.43	$ 9.20	$ 16.03	$ 16
Weighted-average grant date fair value granted	10.29	5.08	15.78
Weighted-average grant date fair value vested	13.65	18.22	15.53
Weighted-average grant date fair value canceled	$ 8.40	$ 10.33	$ 16.05
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	$ 11.1
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	$ 10.6	$ 5

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, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
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	$ 7.7
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	0.6	0.8	0.8
Performance shares granted	0	0	0.3
Performance shares vested	(0.3)	(0.2)	(0.2)
Performance shares canceled	0	0	(0.1)
Ending balance	0.3	0.6	0.8
Weighted-average grant date fair value outstanding	$ 24.36	$ 18.86	$ 20.13	$ 16.25
Weighted-average grant date fair value granted	0	0	24.36
Weighted-average grant date fair value vested	13.91	24.63	17.54
Weighted-average grant date fair value canceled	$ 0	$ 0	$ 20.49
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	1.2	0.3	0.3
Performance shares granted	0.4	0.9	0
Performance shares vested	(0.3)	0	0
Performance shares canceled	(0.1)	0	0
Ending balance	1.2	1.2	0.3
Weighted-average grant date fair value outstanding	$ 6.96	$ 7.50	$ 14.28	$ 14.28
Weighted-average grant date fair value granted	11.26	5.18	0
Weighted-average grant date fair value vested	14.28	0	0
Weighted-average grant date fair value canceled	$ 6.96	$ 0	$ 0

Stock Based Compensation and _6

Stock Based Compensation and Other Incentive Compensation - Long Term Cash Awards (LTCAs) (Details) - Long-Term Cash Awards (LTCAs) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive compensation arrangement, by award, grants in period | shares	7.8
Incentive compensation arrangement, cost not yet recognized, amount | $	$ 5.4
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 ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive compensation arrangement, by award, grants in period	11.7	13.6	14.2
Incentive compensation arrangement, cost not yet recognized, amount	$ 17.4
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, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
U.S. loss	$ (186.8)	$ (721.6)	$ (889)
Non - U.S. income	188	111.3	356
Income (loss) before income taxes	$ 1.2	$ (610.3)	$ (533)

Income Taxes - Components of Pr

Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current
Federal	$ 3.5	$ 2	$ (11.9)
State and local	0.3	0.5	0.1
Foreign	34	20.2	49.3
Total current	37.8	22.7	37.5
Deferred
Federal	(40.7)	(60)	(73.5)
State and local	(0.9)	(0.7)	(1.5)
Foreign	(0.9)	(11.2)	(11.4)
Total deferred	(42.5)	(71.9)	(86.4)
Total income tax benefit	$ (4.7)	$ (49.2)	$ (48.9)

Income Taxes - Rate Reconciliat

Income Taxes - Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Federal statutory	$ 0.3	$ (128.2)	$ (111.9)
Foreign income taxes	(14)	(21.5)	(40.2)
Change in enacted tax rate	0.1	2.1	0.2
Transition tax	0	0	(7.5)
State and local	3	(5)	(20)
Tax credits	(11)	(9.7)	(9.6)
Valuation allowance	2.7	19.8	12.6
Goodwill impairment	0	107.1	92.4
Withholding taxes	3.2	5.6	4
U.S. tax on unremitted foreign earnings	2.2	0	(2.8)
Tax benefit on loss carryback	(5.2)	(14.4)	0
Global intangible low-taxed income	6.5	2.3	31.1
Uncertain tax positions	1.2	(8.8)	5.9
Other	6.3	1.5	(3.1)
Total income tax benefit	$ (4.7)	$ (49.2)	$ (48.9)

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Valuation allowance, deferred tax asset, increase (decrease), amount	$ 0.8	$ 14.5	$ 25.4
United States
Valuation allowance, deferred tax asset, increase (decrease), amount	1.9	5.3
Loss carryback related to the CARES Act [Member]
Other Tax Expense (Benefit)	$ (5.2)	(14.4)
Settlement with Taxing Authority [Member]
Other Tax Expense (Benefit)		$ (6.8)
Transition tax [Member]
Other Tax Expense (Benefit)			$ (9.3)

Income Taxes - Refundable Incom

Income Taxes - Refundable Income Taxes and Income Taxes Payable Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Refundable income taxes and income taxes payable [Line Items]
Refundable income taxes	$ 16
Prepaid Expenses and Other Current Assets [Member]
Refundable income taxes and income taxes payable [Line Items]
Refundable income taxes, Current	9	$ 14
Other assets and deferred charges
Refundable income taxes and income taxes payable [Line Items]
Refundable income taxes, Noncurrent	7
Accrued Liabilities [Member]
Refundable income taxes and income taxes payable [Line Items]
Taxes Payable, Current	$ 12	$ 6

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Valuation allowances	$ (201.7)	$ (208)
Deferred tax assets, net	107.6	94.6
Domestic [Member]
Deferred tax assets, net	56.9	44.1
Foreign [Member]
Deferred tax assets, net	50.7	50.5
Deferred Tax Assets [Member]
Employee benefits	163.1	162.4
Inventory	31.7	32.9
Net operating loss (NOL) carryforwards	186.7	221.4
Tax credit carryforwards	83.6	88.6
Capital allowance carryforwards	10.8	10.2
Capitalized expenditures	41.8	45.9
Interest carryforward	26	10.4
Operating lease liabilities	28	25.7
Other	41.6	50.6
Valuation allowances	(201.7)	(208)
Deferred tax assets	411.6	440.1
Deferred Tax Liabilities [Member]
Other intangible assets	(160.7)	(179.9)
Fixed assets	(103.3)	(137.5)
Operating lease right-of-use assets	(27.8)	(25.6)
Other	(12.2)	(2.5)
Deferred tax liabilities	$ (304)	$ (345.5)

Income Taxes - Deferred Income

Income Taxes - Deferred Income Tax Assets and Liabilities and Valuation Allowances Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Operating Loss and Tax Credit Carryforwards	$ 281.1	$ 320.2
Deferred Tax Assets, Operating Loss and Tax Credit Carryforwards, Not Subject to Expiration	95.9
Valuation allowance, deferred tax asset, increase (decrease), amount	0.8	14.5	$ 25.4
Deferred Tax Assets, Valuation Allowance	201.7	208
United States
Tax Credit Carryforward [Line Items]
Valuation allowance, deferred tax asset, increase (decrease), amount	1.9	$ 5.3
Deferred Tax Assets, Valuation Allowance	$ 7
Foreign Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Valuation allowance, deferred tax asset, increase (decrease), amount			$ 12.8

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefts (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance		$ 20.2	$ 41.1	$ 38.7
Increase in prior year tax positions		0	0.2	0.2
Decrease in prior year tax positions		(1)	(6.6)	(3.1)
Increase in current year tax positions		2	0.7	4.4
Settlement	$ (25.3)		(12.2)
Unrecognized Tax Benefits, Increase Resulting from Foreign Currency Translation				0.9
Foreign currency remeasurement adjustment		0	(3)
Unrecognized tax benefits, ending balance		21.2	20.2	41.1
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Unrecognized tax benefits, interest and penalties, beginning balance		2	11.5	6.9
Increase in prior year tax positions		0	0	4.5
Decrease in prior year tax positions		(0.1)	(1.7)	(0.1)
Increase in current year tax positions		0.3	0	0
Settlement			(6.3)
Foreign currency remeasurement adjustment		0	(1.5)	0.2
Unrecognized tax benefits, interest and penalties, ending balance		$ 2.2	$ 2	$ 11.5

Income Taxes - Other Tax Disclo

Income Taxes - Other Tax Disclosure Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits		$ 21.2	$ 20.2	$ 41.1	$ 38.7
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense		0.2	(1.7)	4.4
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued		2.2	2	$ 11.5	$ 6.9
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		20.2
Tax Adjustments, Settlements, and Unusual Provisions	$ 18.5
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	$ 25.3		$ 12.2
Minimum [Member]
Income Tax Contingency [Line Items]
Income Tax Examination, Estimate of Possible Loss		275
Maximum [Member]
Income Tax Contingency [Line Items]
Income Tax Examination, Estimate of Possible Loss		$ 325

Earnings Per Share (EPS) (Detai

Earnings Per Share (EPS) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator [Abstract]
Net income (loss) attributable to AAM	$ 5.9	$ (561.3)	$ (484.5)
Less: Net income allocated to participating securities	(0.2)	0	0
Net income (loss) attributable to common shareholders - Basic and Dilutive	$ 5.7	$ (561.3)	$ (484.5)
Denominator [Abstract]
Weighted-average shares outstanding	118.5	117.9	115.6
Less: Participating securities	(4.6)	(4.8)	(3.3)
Weighted-average common shares outstanding	113.9	113.1	112.3
Dilutive stock-based compensation	0.2	0	0
Diluted shares outstanding - adjusted weighted-average shares after assumed conversions	114.1	113.1	112.3
Basic earnings (loss) per share	$ 0.05	$ (4.96)	$ (4.31)
Diluted earnings (loss) per share	$ 0.05	$ (4.96)	$ (4.31)

Earnings Per Share (EPS) - Anti

Earnings Per Share (EPS) - Antidilutive Shares (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0.4

Commitments and Contingencies -

Commitments and Contingencies - Purchase Obligations (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Obligated purchase commitments	$ 105.5	$ 90.8
Unrecorded Unconditional Purchase Obligation, Current	95
Unrecorded Unconditional Purchase Obligation, Noncurrent	$ 10.5

Commitments and Contingencies_2

Commitments and Contingencies - Product Liability (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Movement in Standard Product Warranty Accrual [Roll Forward]
Beginning balance	$ 66.7	$ 62
Accruals	19.4	21.9
Settlements	(17.6)	(14.1)
Adjustments to prior period accruals	(8.6)	(3.5)
Foreign currency translation	(0.4)	0.4
Ending balance	$ 59.5	$ 66.7

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, 2021	Dec. 31, 2020	Dec. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Defined benefit plans, net of $(18.2) million, $12.7 million and $3.0 million of tax in 2021, 2020 and 2019, respectively		$ 69.1	$ (51.1)	$ (18.3)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		(10.2)	(0.2)	(4.6)
Changes in cash flow hedges		8.5	(4.4)	(14.6)
Other Comprehensive Income (Loss), Net of Tax		67.4	(55.7)	(37.5)
Settlement charge		42.3	0.5	9.8
ASU 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
New accounting pronouncement, effect of adoption				27.7
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		(5.6)	2.9	(2.4)
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		14.8	14.2	2
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		(19)	18.7	(1.3)
Other Income [Member] | Net effect of AAM Pension Payout and the Casting Sale [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax				7.4
Pension Plan [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Settlement charge		42.3	0.5	10.4
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax - Beginning Balance		(311)	(259.9)	(213.9)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		33.9	(72)	(61.5)	[1]
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, Tax		(7)	14.2	5.6
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	[2]	53.4	8.2	12.5
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax		(11.2)	(1.5)	(2.6)
Defined benefit plans, net of $(18.2) million, $12.7 million and $3.0 million of tax in 2021, 2020 and 2019, respectively		69.1	(51.1)	(46)
Accumulated Other Comprehensive Income (Loss), Net of Tax - Ending Balance		(241.9)	(311)	(259.9)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax - Beginning Balance		(101.1)	(101.2)	(96.6)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax		(10.7)	0.1	(4.6)
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		0.5	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Tax		0	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		(10.2)	0.1	(4.6)
Accumulated Other Comprehensive Income (Loss), Net of Tax - Ending Balance		(111.3)	(101.1)	(101.2)
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax - Beginning Balance		(20.1)	(15.7)	(1.1)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax		22.2	(41.5)	(19)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax		(4.8)	8.2	6.3
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	[3]	(9.8)	35.8	(1.7)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax		0.9	(6.9)	(0.2)
Changes in cash flow hedges		8.5	(4.4)	(14.6)
Accumulated Other Comprehensive Income (Loss), Net of Tax - Ending Balance		(11.6)	(20.1)	(15.7)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax - Beginning Balance		(432.2)	(376.8)	(311.6)
Other Comprehensive Income (Loss) Arising During Period, Total, Before Tax		45.4	(113.4)	(85.1)
Other Comprehensive Income (Loss), Defined Benefit Plans, before Reclassification Adjustments, Tax		(11.8)	22.4	11.9
Other Comprehensive Income (Loss), Reclassification Adjustments, Total, Before Tax		44.1	44	10.8
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Defined Benefit Plans, Tax		(10.3)	(8.4)	(2.8)
Other Comprehensive Income (Loss), Net of Tax		67.4	(55.4)	(65.2)
Accumulated Other Comprehensive Income (Loss), Net of Tax - Ending Balance		$ (364.8)	$ (432.2)	$ (376.8)
[1]	ASU 2018-02 became effective on January 1, 2019, and we elected to reclassify the stranded tax effects caused by the 2017 Tax Cuts and Jobs Act, resulting in a decrease in Accumulated other comprehensive income (loss) of $27.7 million at January 1, 2019.
[2]	The amount reclassified for 2021 includes a credit to AOCI of $42.3 million related to the effect of the Pension Annuity Purchase, and the amount reclassified for 2019 includes a credit to AOCI of $7.4 million related to the net effect of the AAM Pension Payout Offer and the Casting Sale. See Note 7 - Employee Benefit Plans and Note 16 - Acquisitions and Dispositions for more detail.
[3]	The amounts reclassified from AOCI included $(5.6) million in COGS, $14.8 million in interest expense and $(19.0) million in other expense, net for the year ended December 31, 2021, $2.9 million in COGS, $14.2 million in interest expense and $18.7 million in other expense, net for the year ended December 31, 2020 and $(2.4) million in COGS, $2.0 million in interest expense and $(1.3) million in other expense, net for the year ended December 31, 2019.

Revenue from Contracts with C_3

Revenue from Contracts with Customers (Details)	12 Months Ended
	Dec. 31, 2021
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, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 5,156.6	$ 4,710.8	$ 6,530.9
North America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3,982.4	3,625.1	5,247.1
Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	489	477.5	571.2
Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	590.9	550.5	607.3
South America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	94.3	57.7	105.3
Driveline [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3,741.5	3,372.6	4,209.1
Driveline [Member] | North America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,839.8	2,537.2	3,225.7
Driveline [Member] | Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	441.6	433.7	533.6
Driveline [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	374.8	352.5	351
Driveline [Member] | South America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	85.3	49.2	98.8
Metal Forming [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,415.1	1,338.2	1,694.1
Metal Forming [Member] | North America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,142.6	1,087.9	1,393.7
Metal Forming [Member] | Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	47.4	43.8	37.6
Metal Forming [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	216.1	198	256.3
Metal Forming [Member] | South America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	9	8.5	6.5
Casting [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	627.7
Casting [Member] | North America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	627.7
Casting [Member] | Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0
Casting [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0
Casting [Member] | South America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 0	$ 0	$ 0

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Contract Asset and Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Receivables, net, current	$ 762.8	$ 793.2
Increase (decrease) in receivables	(30.4)
Contract Liabilities, current	28.1	23.4
Contract Liabilities, noncurrent	94.8	91
Increase (decrease) in deferred revenue	13.3	5.5	$ (17.9)
Contract with customer, liability, revenue recognized	23.3	$ 22.7
Other Current Liabilities [Member]
Increase (decrease) in deferred revenue	4.7
Other Noncurrent Liabilities [Member]
Increase (decrease) in deferred revenue	$ 3.8

Leasing - Components of Lease C

Leasing - Components of Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Components of lease expense [Line Items]
Amortization of right-of-use assets	$ 4.2	$ 1.8	$ 1
Interest on lease liabilities	2	0.4	0.3
Total finance lease cost	6.2	2.2	1.3
Operating lease cost	33.3	32.7	28.9
Short-term lease cost	1.6	3	5.9
Variable lease cost	3.2	2.9	7.2
Total lease cost	44.3	40.8	43.3
Cost of Sales [Member]
Components of lease expense [Line Items]
Lease expense	29.1	28.4	31.9
Selling, General and Administrative Expenses [Member]
Components of lease expense [Line Items]
Lease expense	$ 9	$ 10.2	$ 10.1

Leasing - Supplemental Lease In

Leasing - Supplemental Lease Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Supplemental lease information [Line Items]
Operating cash flows from finance leases	$ 2	$ 0.3	$ 0.3
Operating cash flows from operating leases	35.9	35.1	29
Financing cash flows from finance leases	$ 5	$ 3	$ 1
Weighted-average remaining lease term - finance leases	16 years 4 months 24 days	15 years 9 months 18 days	2 years 9 months 18 days
Weighted-average remaining lease term - operating leases	8 years 7 months 6 days	8 years 8 months 12 days	9 years 2 months 12 days
Weighted-average discount rate - finance leases	4.80%	4.20%	5.10%
Weighted-average discount rate - operating leases	5.20%	5.70%	6.10%

Leasing - Future Minimum Lease

Leasing - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Future minimum lease payments [Line Items]
Finance Lease, Liability	$ 88.8	$ 21.6
Operating Lease, Liability	124.5	$ 117
Finance Lease [Member]
Future minimum lease payments [Line Items]
Finance Lease, Liability, to be Paid, Year One	10.4
Finance Lease, Liability, Payments, Due Year Two	8.3
Finance Lease, Liability, Payments, Due Year Three	7.4
Finance Lease, Liability, Payments, Due Year Four	7.3
Finance Lease, Liability, Payments, Due Year Five	7.3
Finance Lease, Liability, Payments, Due after Year Five	85.5
Finance Lease, Liability, Payment, Due	126.2
Finance Lease, Liability, Undiscounted Excess Amount	(37.4)
Finance Lease, Liability	88.8
Operating lease [Member]
Future minimum lease payments [Line Items]
Lessee, Operating Lease, Liability, to be Paid, Year One	30.4
Lessee, Operating Lease, Liability, Payments, Due Year Two	23.8
Lessee, Operating Lease, Liability, Payments, Due Year Three	17.4
Lessee, Operating Lease, Liability, Payments, Due Year Four	13.9
Lessee, Operating Lease, Liability, Payments, Due Year Five	10.7
Lessee, Operating Lease, Liability, Payments, Due after Year Five	60.2
Lessee, Operating Lease, Liability, Payments, Due	156.4
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(31.9)
Operating Lease, Liability	$ 124.5

Leasing - Right of Use Assets a

Leasing - Right of Use Assets and Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Right of use assets and lease liabilities [Line Items]
Finance Lease, Right-of-Use Asset	$ 113.4	$ 24.9
Operating lease right-of-use assets	123.7	116.6
Finance Lease, Liability	88.8	21.6
Operating Lease, Liability	124.5	117
Property, plant and equipment, net [Member]
Right of use assets and lease liabilities [Line Items]
Finance Lease, Right-of-Use Asset	113.4	24.9
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	123.7	116.6
Current portion of operating lease liabilities
Right of use assets and lease liabilities [Line Items]
Finance Lease, Liability	0	0
Operating Lease, Liability	24.6	22.6
Accrued expenses and other [Member]
Right of use assets and lease liabilities [Line Items]
Finance Lease, Liability	6.3	3.3
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	99.9	94.4
Postretirement benefits and other long-term liabilities [Member]
Right of use assets and lease liabilities [Line Items]
Finance Lease, Liability	82.5	18.3
Operating Lease, Liability	$ 0	$ 0

Leasing - Leases Not Yet Commen

Leasing - Leases Not Yet Commenced (Details) $ in Millions	Dec. 31, 2021USD ($)
Leases not yet commenced [Line Items]
Lessee, Operating and financing leases, Leases not yet commenced	$ 0

Manufacturing Facility Fire a_2

Manufacturing Facility Fire and Insurance Recovery (Details) - USD ($) $ in Millions	12 Months Ended			15 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021
Insurance Recoveries [Abstract]
Insurance Deductible Expense		$ 1
Business Interruption Charges	$ 15.9			$ 52.4
Estimated insurance recoveries, before amounts collected	27.3			81.5
Proceeds from Insurance Settlement, Operating and Investing Activities	59.1	11.1		70.2
Proceeds from Insurance Settlement, Operating Activities	36
Proceeds from Insurance Settlement, Investing Activities	23.1	$ 0	$ 0
Gain (Loss) Related to Insurance Settlement	11.4
Estimated Insurance Recoveries	$ 11.3			11.3
Tangible Asset Impairment Charges				$ 27

Acquisitions and Dispositions (

Acquisitions and Dispositions (Details) - USD ($) $ in Millions	May 17, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 02, 2019
Business Acquisition [Line Items]
Gain on bargain purchase of business		$ 0	$ 0	$ 10.8
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of business		2.7	1	21.3
Proceeds from sale of business, net		1	0	141.2
Consolidated Joint Venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses		2.6
Loss on sale of business		$ 2.7
Sale of U.S. Casting Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of business			$ 1	21.3
Proceeds from sale of business, net				141.2
Impairment of Long-Lived Assets to be Disposed of				225
Emporium, Pennsylvania [Member]
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
Mitec Automotive AG [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets					$ 20.2
Business Combination, Consideration Transferred				9.4
Gain on bargain purchase of business				$ 10.8

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Sales	$ 5,507.1	$ 5,027.5	$ 6,952.3
Less: Intersegment sales	350.5	316.7	421.4
Net external sales	5,156.6	4,710.8	6,530.9
Segment adjusted EBITDA	833.3	719.8	970.3
Depreciation and amortization	544.3	521.9	536.9
Capital expenditures	181.2	215.6	433.3
Total Assets	5,635.7	5,916.3	6,644.6
Driveline [Member]
Segment Reporting Information [Line Items]
Sales	3,744.9	3,375.5	4,220.4
Less: Intersegment sales	3.4	2.9	11.3
Net external sales	3,741.5	3,372.6	4,209.1
Segment adjusted EBITDA	577.7	474.8	579
Depreciation and amortization	301.9	306.1	288
Capital expenditures	126.8	125.3	250.3
Total Assets	2,925.6	3,035.7	3,557.9
Metal Forming [Member]
Segment Reporting Information [Line Items]
Sales	1,762.2	1,652	2,062.7
Less: Intersegment sales	347.1	313.8	368.6
Net external sales	1,415.1	1,338.2	1,694.1
Segment adjusted EBITDA	255.6	245	348.3
Depreciation and amortization	242.4	215.8	206.6
Capital expenditures	50.5	81.9	139
Total Assets	1,576.9	1,680.3	2,120.9
Casting [Member]
Segment Reporting Information [Line Items]
Sales	0	0	669.2
Less: Intersegment sales	0	0	41.5
Net external sales	0	0	627.7
Segment adjusted EBITDA	0	0	43
Depreciation and amortization	0	0	42.3
Capital expenditures	0	0	28.5
Total Assets	0	0	0
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	3.9	8.4	15.5
Total Assets	$ 1,133.2	$ 1,200.3	$ 965.8

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment adjusted EBITDA	$ 833.3	$ 719.8	$ 970.3
Interest expense	(195.2)	(212.3)	(217.3)
Depreciation and amortization	(544.3)	(521.9)	(536.9)
Impairment charges	0	(510)	(665)
Restructuring and acquisition-related costs	(49.4)	(67.2)	(57.8)
Pension settlements	(42.3)	(0.5)	(9.8)
Loss on sale of business	(2.7)	(1)	(21.3)
Gain on bargain purchase of business	0	0	10.8
Unrealized gain on equity securities	24.4	0	0
Debt refinancing and redemption costs	(34)	(7.9)	(8.4)
Malvern Fire charges, net of recoveries	11.4	(9.3)	0
Other	0	0	2.4
Income (loss) before income taxes	$ 1.2	$ (610.3)	$ (533)

Segment and Geographic Inform_5

Segment and Geographic Information - Schedule of Disclosure on Geographic Areas (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 5,156.6	$ 4,710.8	$ 6,530.9
Long-lived assets	3,658.6	3,931.5	4,722.7
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	1,923.5	1,816.7	2,894
Long-lived assets	1,976.5	2,099.4	2,805.8
Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	2,058.9	1,808.5	2,353.1
Long-lived assets	888.1	1,021.6	1,117.4
South America
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	94.3	57.6	105.3
Long-lived assets	40.9	49.7	61.9
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	299.6	317.1	315.4
Long-lived assets	164.8	185.1	191.4
Asia, excluding China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	189.4	160.4	255.8
Long-lived assets	87.1	84.2	106.8
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	590.9	550.5	607.3
Long-lived assets	$ 501.2	$ 491.5	$ 439.4

Schedule II - Valuation and Q_3

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
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]	$ 4.5		$ 8		$ 8.4
Additions, charged to costs and expenses	[1]	7.8		7		13.2
Acquisitions and other	[1],[2]	0		0		(0.8)
Deductions	[1]	10.1		10.5		12.8
Valuation allowances and reserves, balance	[1]	2.2		4.5		8
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		208	[3]	196	[3],[4]	183.3	[4]
Additions, charged to costs and expenses		2.7	[3]	19.8	[3]	25.4	[4]
Acquisitions and other	[2]	0	[3]	0	[3]	0	[4]
Deductions		9	[3]	7.8	[3]	12.7	[4]
Valuation allowances and reserves, balance	[3]	201.7		208		196	[4]
SEC Schedule, 12-09, Reserve, Inventory [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, balance	[5]	23.4		20.5		14.4
Additions, charged to costs and expenses	[5]	17.7		31.7		31
Acquisitions and other	[2],[5]	0		0		1.4
Deductions	[5]	22.5		28.8		26.3
Valuation allowances and reserves, balance	[5]	$ 18.6		$ 23.4		$ 20.5
[1]	Uncollectible accounts charged off, net of recoveries.
[2]	Amounts represent reserves recognized in conjunction with our acquisition of Mitec and reserves derecognized in conjunction with the Casting Sale in 2019.
[3]	Primarily reflects 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.
[4]	Primarily reflects the reversal of a valuation allowance against certain deferred tax assets in foreign locations, as well as changes due to foreign currency translation.
[5]	Primarily relates to write-offs of excess and obsolete inventories, as well as adjustments for physical quantity discrepancies.