Spirit AeroSystems (SPR) 10-Q 7 May 24 2024 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 28, 2024	Apr. 18, 2024
Cover [Abstract]
Security Exchange Name	NYSE
Title of 12(b) Security	Class A common stock, par value $0.01 per share
Entity Address, Postal Zip Code	67210
City Area Code	316
Local Phone Number	526-9000
Entity Address, State or Province	KS
Entity Address, City or Town	Wichita
Entity Address, Address Line One	3801 South Oliver
Entity Tax Identification Number	20-2436320
Entity Incorporation, State or Country Code	DE
Entity File Number	001-33160
Document Transition Report	false
Document Quarterly Report	true
Entity Registrant Name	Spirit AeroSystems Holdings, Inc.
Entity Central Index Key	0001364885
Document Type	10-Q
Document Period End Date	Mar. 28, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Amendment Flag	false
Trading Symbol	SPR
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		116,552,203

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Income Statement [Abstract]
Revenues	$ 1,702.8	$ 1,431.4
Operating costs and expenses
Cost of sales	2,138.3	1,432.2
Selling, general and administrative	81.5	77.4
Restructuring Charges	0	6.3
Research and development	10.6	10.6
Total operating costs and expenses	2,230.4	1,526.5
Operating loss	(527.6)	(95.1)
Interest expense and financing fee amortization	(80.2)	(72.4)
Other income (expense), net	(2.3)	117.4
Loss before income taxes and equity in net loss of affiliates	(605.5)	(284.9)
Income tax (provision) benefit	(11)	4.3
Loss before equity in net loss of affiliates	(616.5)	(280.6)
Equity in net loss of affiliates	(0.1)	(0.7)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(616.6)	(281.3)
Net loss	(616.7)	(281.2)
Net Income (Loss) Attributable to Noncontrolling Interest	$ (0.1)	$ 0.1
Loss per share
Earnings Per Share, Basic	$ (5.31)	$ (2.68)
Diluted (in dollars per share)	$ (5.31)	$ (2.68)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Statement of Comprehensive Income [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	$ 0.3	$ 49.2
Other Comprehensive Income Unrealized Gain Loss On Intercompany Loan Net Of Tax	(0.4)	0.9
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	(1.2)	3.4
Total other comprehensive (loss) gain, net of tax	(7.6)	76.3
Total comprehensive loss	(624.3)	(204.9)
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	1.2	(3.4)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	(1)	7.2
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	(0.1)	0.1
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(616.6)	(281.3)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(5.3)	15.6
Total other comprehensive (loss) gain, net of tax	(7.6)	76.3
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	0.6	(16.6)
Unrealized exchange (loss) on intercompany loan, tax	0.1	(0.4)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax	0.7	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax	$ 0	$ 0

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Unaudited) (Parentheticals) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Statement of Comprehensive Income [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	$ 0.6	$ (16.6)
Unrealized exchange (loss) on intercompany loan, tax	0.1	(0.4)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax	0	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax	$ 0.7	$ 0

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 28, 2024	Dec. 31, 2023
Assets
Cash and cash equivalents	$ 352	$ 823.5
Restricted Cash, Current	0.1	0.1
Accounts receivable, net	577.5	585.5
Unbilled Receivables, Current	824.2	522.9
Inventory, net	1,797.5	1,767.3
Other current assets	56.9	52.5
Total current assets	3,608.2	3,751.8
Property, plant and equipment, net	2,040.1	2,084.2
Operating Lease, Right-of-Use Asset	90.9	92.1
Unbilled Receivable, Non Current	8.1	0
Pension assets	37.2	33.5
Pension reversion assets	50	61.1
Deferred Income Tax Assets, Net	0.1	0.1
Goodwill	631.2	631.2
Intangible Assets, Net (Excluding Goodwill)	192.4	196.2
Deferred income taxes	106.3	99.9
Other assets	6,764.5	6,950.1
Liabilities, Current [Abstract]
Accounts Payable, Current	1,138.3	1,106.8
Accrued Liabilities, Current	483.9	420.1
Deferred Compensation Liability, Current	22.4	15.7
Long-term Debt and Lease Obligation, Current	81	64.8
Operating Lease, Liability, Current	9.4	9.1
Customer Advances, Current	67.8	38.3
Contract with Customer, Liability, Current	152.3	192.6
Provision for Loss on Contracts	313.2	256.6
Deferred Credits and Other Liabilities, Current	57	49.6
Other Liabilities, Current	42.4	44.7
Liabilities Noncurrent
Long-term debt	3,991.2	4,018.7
Operating Lease, Liability, Noncurrent	83.5	84.3
Advance payments, long-term	283.6	301.9
Pension/OPEB obligation	29.4	30.3
Contract with Customer, Liability, Noncurrent	153.5	161.3
Provision for Loss on Contacts, Non Current	545.2	224.1
Deferred Credits and Other Liabilities, Noncurrent	66.3	76.7
Deferred grant income liability - non-current	27.1	25.8
Deferred Income Tax Liabilities, Net	16.5	9.1
Deferred income taxes	314.3	315.5
Additional Paid in Capital [Abstract]
Additional paid-in capital	1,435.4	1,429.1
AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract
Accumulated other comprehensive loss	(97.2)	(89.6)
Retained Earnings Accumulated Deficit [Abstract]
Retained earnings	$ (0.4)	$ 616.3
Treasury Stock, Shares	41,587,480	41,587,480
Treasury Stock, Value	$ (2,456.7)	$ (2,456.7)
Total stockholders’ equity	(1,117.7)	(499.7)
Noncontrolling interest	3.9	3.8
Total equity	(1,113.8)	(495.9)
Total liabilities and equity	6,764.5	6,950.1
Liabilities, Current	2,367.7	2,198.3
Class A [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Common stock	$ 1.2	$ 1.2
Retained Earnings Accumulated Deficit [Abstract]
Common Stock, Shares Authorized	200,000,000	200,000,000
Class B [Member]
Retained Earnings Accumulated Deficit [Abstract]
Common Stock, Shares Authorized	150,000,000	150,000,000

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 28, 2024	Dec. 31, 2023
Shareholders' equity
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Treasury Stock, Shares	41,587,480	41,587,480
Stockholders' Equity Attributable to Parent	$ (1,117.7)	$ (499.7)
Class A [Member]
Shareholders' equity
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	116,276,706	116,054,291
Class B [Member]
Shareholders' equity
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	0	0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Mar. 28, 2024	Dec. 31, 2023	Mar. 30, 2023	Dec. 31, 2023
Operating activities
Net loss	$ (616.7)		$ (281.2)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	77.9		79.9
Amortization of deferred financing fees	1.7		1.7
Accretion of customer supply agreement	0.8		0.6
Employee Benefit and Share-based Payment Arrangement, Noncash	10.8		9
Loss on Derivative Instruments, Pretax	(1.2)		3.4
(Gain) loss from foreign currency transactions	(5.9)		4
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property	(0.7)		(0.1)
Deferred taxes	9		(16.4)
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(2.8)		63.6
Grant liability amortization	(0.3)		(0.3)
Unrealized Gain (Loss) on Investments	0.1		0.7
Increase (Decrease) in Forward Provision	378.1		6.9
Changes in assets and liabilities
Accounts receivable, net	7.4		(116.6)
Inventory, net	(34.8)		(75.8)
Accounts payable and accrued liabilities	99.7		152.9
Profit sharing/deferred compensation	6.7		(18.4)
Advance payments	12.2		(3.3)
Income taxes receivable/payable	2.7		11.8
Pension plans employer contributions	(0.5)		(3)
Other	(2.3)		(8.4)
Net cash used in operating activities	(415.6)		(46.2)
Investing activities
Purchase of property, plant, and equipment	(28.7)		(22.9)
Payments to Acquire Businesses, Net of Cash Acquired		$ (31.3)
Net cash used in investing activities	(28.7)		(22.9)
Financing activities
Proceeds from Lines of Credit	0		0.7
Principal payments of debt	(16.5)		(15.5)
Payment, Tax Withholding, Share-based Payment Arrangement	(4.5)		(4.8)
Debt issuance and financing costs	(0.5)		(0.5)
Proceeds from Other Debt				$ 180
Net cash used in financing activities	(21.5)		(20.1)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(466.1)		(88.3)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning Balance	845.9		678.4	678.4
Cash, cash equivalents, and restricted cash, end of period	379.8	845.9	590.1	845.9
Cash and Cash Equivalents, at Carrying Value, Ending Balance	352	823.5	567.8	823.5
Reconciliation of Cash, Cash Equivalents, and Restricted Cash [Abstract]
Restricted Cash, Current	0.1	0.1	0.2	0.1
Restricted Cash, Noncurrent	27.7	22.3	22.1	$ 22.3
Increase (Decrease) in Income Taxes Payable	2.7		11.8
Increase (Decrease) in Contract with Customer, Liability	(48)		(13.8)
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Assets Transferred to (from) Plan	(0.7)		179
Payments to Acquire Businesses, Net of Cash Acquired		$ 31.3
Increase (Decrease) in Contract with Customer, Asset	309.8		22
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations	(0.3)		0.9
Gain (Loss) on Contract Termination	(0.5)		(0.5)
Increase (Decrease) in Deferred Liabilities	(0.5)		(3)
Proceeds from Lines of Credit	0		0.7
Increase (Decrease) in Customer Advances	12.2		(3.3)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (616.6)		$ (281.3)

Condensed Statement of Changes

Condensed Statement of Changes in Stockholders' Equity Statement - USD ($) $ in Millions	Total	Class A [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock, Common [Member]	AOCI Including Portion Attributable to Noncontrolling Interest [Member]	Noncontrolling Interest
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ (243.8)
Stockholders' Equity Attributable to Noncontrolling Interest	$ 3.7
Common Stock, Shares, Outstanding at Dec. 31, 2022			105,252,421
Common Stock, Value, Outstanding at Dec. 31, 2022			$ 1.1
Additional Paid in Capital, Common Stock at Dec. 31, 2022				$ 1,179.5
Treasury Stock, Value at Dec. 31, 2022						$ (2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Dec. 31, 2022							$ (203.9)
Retained Earnings (Accumulated Deficit) at Dec. 31, 2022					$ 1,232.5
Common Stock, Dividends, Per Share, Declared	$ 0
Net Income (Loss) Attributable to Parent	$ (281.2)				(281.2)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			266,321
Shares Granted, Value, Share-based Payment Arrangement, before Forfeiture			$ 0
Stock Issued During Period, Value, Restricted Stock Award, Gross	9			9
Shares Issued, Shares, Share-based Payment Arrangement, Forfeited			(230,108)
Shares Granted, Value, Share-based Payment Arrangement, Forfeited			$ 0
Payment, Tax Withholding, Share-based Payment Arrangement	(4.8)		$ 0	(4.8)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation			(137,007)
Stockholders' Equity, Other	(0.1)				0
Other Comprehensive Income (Loss), Net of Tax	76.3						76.3
Common Stock, Shares, Outstanding at Mar. 30, 2023			105,151,627
Additional Paid in Capital, Common Stock at Mar. 30, 2023				1,183.7
Treasury Stock, Value at Mar. 30, 2023						(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Mar. 30, 2023							(127.6)
Retained Earnings (Accumulated Deficit) at Mar. 30, 2023					951.3
Common Stock, Value, Outstanding at Mar. 30, 2023			$ 1.1
Other retained earnings								$ (0.1)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(444.6)
Stockholders' Equity Attributable to Noncontrolling Interest	3.6
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(495.9)
Stockholders' Equity Attributable to Noncontrolling Interest	3.8
Common Stock, Shares, Outstanding at Dec. 31, 2023			116,054,291
Common Stock, Value, Outstanding at Dec. 31, 2023		$ 1.2	$ 1.2
Additional Paid in Capital, Common Stock at Dec. 31, 2023	1,429.1			1,429.1
Treasury Stock, Value at Dec. 31, 2023	2,456.7					(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Dec. 31, 2023	(89.6)						(89.6)
Retained Earnings (Accumulated Deficit) at Dec. 31, 2023	$ 616.3				616.3
Common Stock, Dividends, Per Share, Declared	$ 0
Net Income (Loss) Attributable to Parent	$ (616.7)				(616.7)
Employee Benefits and Share-Based Compensation	0.7			0.7
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			375,822
Shares Granted, Value, Share-based Payment Arrangement, before Forfeiture			$ 0
Stock Issued During Period, Value, Restricted Stock Award, Gross	10.1			10.1
Payment, Tax Withholding, Share-based Payment Arrangement	(4.5)		$ 0	(4.5)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation			(153,407)
Stockholders' Equity, Other	0.1				0
Other Comprehensive Income (Loss), Net of Tax	(7.6)						(7.6)
Common Stock, Shares, Outstanding at Mar. 28, 2024			116,276,706
Additional Paid in Capital, Common Stock at Mar. 28, 2024	1,435.4			$ 1,435.4
Treasury Stock, Value at Mar. 28, 2024	2,456.7					$ (2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Mar. 28, 2024	(97.2)						$ (97.2)
Retained Earnings (Accumulated Deficit) at Mar. 28, 2024	(0.4)				$ (0.4)
Common Stock, Value, Outstanding at Mar. 28, 2024			$ 1.2
Other retained earnings								$ 0.1
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(1,113.8)
Stockholders' Equity Attributable to Noncontrolling Interest	$ 3.9

Organization and Basis of Inter

Organization and Basis of Interim Presentation	3 Months Ended
	Mar. 28, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Interim Presentation	Organization, Basis of Interim Presentation and Recent Developments Unless the context otherwise indicates or requires, as used in this Quarterly Report on Form 10-Q, references to “we,” “us,” “our,” and the “Company” refer to Spirit AeroSystems Holdings, Inc. and its consolidated subsidiaries. References to “Spirit” refer only to our subsidiary, Spirit AeroSystems, Inc., and references to “Holdings” refer only to Spirit AeroSystems Holdings, Inc. The Company provides manufacturing and design expertise in a wide range of fuselage, propulsion, and wing products and services for aircraft original equipment manufacturers (“OEM”) and operators through its subsidiaries including Spirit. The Company’s headquarters are in Wichita, Kansas, with manufacturing and assembly facilities in Tulsa, Oklahoma; Prestwick, Scotland; Wichita, Kansas; Kinston, North Carolina; Subang, Malaysia; Saint-Nazaire, France; Biddeford, Maine; Woonsocket, Rhode Island; Belfast, Northern Ireland; Casablanca, Morocco; and Dallas, Texas. The accompanying unaudited interim condensed consolidated financial statements include the Company’s financial statements and the financial statements of its majority-owned or controlled subsidiaries and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and the instructions to Form 10-Q and Article 10 of Regulation S-X. The Company’s fiscal quarters are 13 weeks in length. Since the Company’s fiscal year ends on December 31, the number of days in the Company’s first and fourth quarters varies slightly from year to year. All intercompany balances and transactions have been eliminated in consolidation. As part of the monthly consolidation process, the Company’s international subsidiaries that have functional currencies other than the U.S. dollar are translated to U.S. dollars using the end-of-month translation rate for balance sheet accounts and average period currency translation rates for revenue and income accounts. The subsidiaries in Prestwick, Scotland and Subang, Malaysia use the British pound as their functional currency. All other foreign subsidiaries and branches use the U.S. dollar as their functional currency. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all adjustments (consisting of normal recurring adjustments and elimination of intercompany balances and transactions) considered necessary to fairly present the results of operations for the interim period. The results of operations for the three months ended March 28, 2024, are not necessarily indicative of the results that may be expected for the year ending December 31, 2024. In connection with the preparation of the condensed consolidated financial statements, the Company evaluated subsequent events through the date the financial statements were issued. The interim financial statements should be read in conjunction with the audited consolidated financial statements, including the notes thereto, included in the Company’s 2023 Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on February 22, 2024 (the “2023 Form 10-K”). The Company’s significant accounting policies are described in Note 3 Summary of Significant Accounting Policies to our consolidated financial statements in the 2023 Form 10-K. Merger Discussions with Boeing

Changes in Estimates

Changes in Estimates	3 Months Ended
	Mar. 28, 2024
Changes in Estimates [Abstract]
Change In Estimate [Text Block]	. Changes in Estimates The Company has a periodic forecasting process in which management assesses the progress and performance of the Company’s programs. This process requires management to review each program’s progress by evaluating the program schedule, changes to identified risks and opportunities, changes to estimated revenues and costs for the accounting contracts (and options if applicable), and any outstanding contract matters. Risks and opportunities include but are not limited to management’s judgment about the cost associated with the Company’s ability to achieve the schedule, technical requirements (e.g., a newly-developed product versus a mature product), and any other program requirements. Due to the span of years it may take to completely satisfy the performance obligations for the accounting contracts (and options, if any) and the scope and nature of the work required to be performed on those contracts, the estimation of total revenue and costs is subject to many variables and, accordingly, is subject to change based upon judgment. The Company’s estimate of costs depends on maintaining continuing, uninterrupted production at its manufacturing facilities and its suppliers’ facilities. The continued fragility of the global aerospace supply chain may lead to interruptions in deliveries of or increased prices for components or raw materials used in the Company’s products, labor disruptions, and could delay production and/or materially adversely affect the Company’s business. When adjustments in estimated total consideration or estimated total cost are required, any changes from prior estimates for fully satisfied performance obligations are recognized in the current period as a cumulative catch-up adjustment for the inception-to-date effect of such changes. Cumulative catch-up adjustments are driven by several factors including production efficiencies, assumed rate of production, the rate of overhead absorption, changes to scope of work, and contract modifications. Cumulative catch-up adjustments are primarily related to changes in the estimated margin of contracts with performance obligations that are satisfied over time. Changes in estimates could materially adversely affect the Company’s future financial performance. While certain increases in raw material costs can generally be passed on to the Company’s customers, in most instances the Company must fully absorb cost overruns. Some of the factors that may cause the costs incurred in fulfilling contracts to vary substantially from current estimates are technical problems, production rate changes, production stoppages, materials shortages, supplier difficulties, realization targets, existence of and execution to recovery plans caused by these factors, and multiple other events, including those identified in Item 1A. “Risk Factors” of the 2023 Form 10-K. The risk particularly applies to products such as the B787, A220, and A350, which are in forward loss positions. During the first quarter ended March 28, 2024, the Company recognized unfavorable changes in estimates of $534.6, which included net forward loss charges of $495.4, and unfavorable cumulative catch-up adjustments related to periods prior to the first quarter of 2024 of $39.2. The forward losses in the first quarter were primarily driven by a change in strategic pricing conversations with our customer, Airbus, incremental orders Airbus secured, foreign currency impacts, and supply chain cost growth on the A350 and A220 programs, additional labor and supply chain cost growth on the B787 program, and increased costs related to factory performance on the B767 program. The forward losses on the Airbus A350 and A220 programs include net incremental losses for anticipated performance obligations beyond 2026 of $168.3 related to the incremental firm orders Airbus secured. The unfavorable cumulative catch-up adjustments primarily relate to increased production costs associated with changes implemented by Boeing in March 2024 to introduce a new product verification process in Wichita, KS. This change in business process has delayed delivery acceptances and caused a build up of undelivered units in Wichita, KS. Additionally, the Company is maintaining a higher cost profile for an expected increase in production rates that has now been delayed due to the FAA’s imposed limitation on Boeing increasing its production rates, and production cost overruns on the A320 program. During the first quarter ended March 30, 2023, the Company recognized unfavorable changes in estimates of $121.9, which included net forward loss charges of $110.0, and unfavorable cumulative catch-up adjustments related to periods prior to the first quarter of 2023 of $11.9. The forward losses in the quarter ended March 30, 2023 were primarily driven by supplier price negotiations and estimated supply chain costs including certain non-recurring cost estimates, schedule revisions, and foreign exchange headwinds on the A220 program, schedule changes and other supply chain cost growth on the A350 program, additional labor and supply chain cost growth on the B787 program, and increased cost projections on the CL650 program. The unfavorable cumulative catch-up adjustments primarily relate to the Company’s preliminary assessment of the impact to production costs including factory disruption related to the notice of escapement issued to Boeing for the B737 Vertical Fin Attach Fittings and supply chain cost growth. Changes in estimates are summarized below: For the Three Months Ended Changes in Estimates March 28, 2024 March 30, 2023 (Unfavorable) Favorable Cumulative Catch-up Adjustment by Segment Commercial $ (38.9) $ (11.0) Defense & Space (0.3) (0.9) Aftermarket — — Total (Unfavorable) Favorable Cumulative Catch-up Adjustment $ (39.2) $ (11.9) Changes in Estimates on Loss Programs (Forward Loss) by Segment Commercial $ (493.8) $ (109.9) Defense & Space (1.6) (0.1) Aftermarket — — Total Changes in Estimates (Forward Loss) on Loss Programs $ (495.4) $ (110.0) Total Change in Estimate $ (534.6) $ (121.9) EPS Impact (diluted per share based upon applicable forecasted effective tax rate) $ (4.68) $ (1.14)

Accounts Receivable and Allowan

Accounts Receivable and Allowance for Credit Losses Accounts Receivable and Allowance for Credit Loss (Notes)	3 Months Ended
	Mar. 28, 2024
Receivables [Abstract]
Loans, Notes, Trade and Other Receivables Disclosure [Text Block]	. Accounts Receivable and Allowance for Credit Losses Accounts Receivable, net Accounts receivable represent the Company’s unconditional rights to consideration, subject to the payment terms of the contract, for which only the passage of time is required before payment. Unbilled receivables are reflected under contract assets on the Condensed Consolidated Balance Sheets. See also Allowance for Credit Losses, below . Accounts receivable, net consists of the following: March 28, December 31, Trade receivables $ 552.1 $ 555.8 Other 40.5 42.0 Less: allowance for credit losses (15.1) (12.3) Accounts receivable, net $ 577.5 $ 585.5 The Company has agreements (through its subsidiaries) to sell, on a revolving basis, certain trade accounts receivable balances with Boeing, Airbus Group SE and its affiliates (collectively, “Airbus”), and Rolls-Royce PLC and its affiliates (collectively, “Rolls-Royce”) to third-party financial institutions. These programs were primarily entered into as a result of customers seeking payment term extensions with the Company and they continue to allow the Company to monetize the receivables prior to their payment date, subject to payment of a discount. No guarantees are delivered under the agreements. The Company’s ability to continue using such agreements is primarily dependent upon the strength of the applicable customer’s financial condition. Transfers under these agreements are accounted for as sales of receivables resulting in the receivables being derecognized from the Company’s Condensed Consolidated Balance Sheets. For the three months ended March 28, 2024, $814.0 of accounts receivable were sold via these arrangements. The proceeds from these sales of receivables are included in cash from operating activities in the Condensed Consolidated Statements of Cash Flows. The recorded net loss on sale of receivables was $10.6 for the three months ended March 28, 2024 and is included in other income and expense. See Note 20 Other Income (Expense), Net . Allowance for Credit Losses During the three months ended March 28, 2024, there have been no significant changes in the factors that influenced management’s current estimate of expected credit losses, nor changes to the Company’s accounting policies or Current Expected Credit Losses methodology. The beginning balances, current period activity, and ending balances of the allocation for credit losses on accounts receivable and contract assets were not material.

Contract with customer, asset a

Contract with customer, asset and liability (Notes)	3 Months Ended
	Mar. 28, 2024
Revenue from Contract with Customer [Abstract]
contract with customer, asset and liability [Text Block]	Contract Assets and Contract Liabilities Contract assets primarily represent revenues recognized for performance obligations that have been satisfied but for which amounts have not been billed. Contract assets, current are those that are expected to be billed to our customer within 12 months. Contract assets, long-term are those that are expected to be billed to our customer over periods greater than 12 months. No impairments to contract assets were recorded for the period ended March 28, 2024 or the period ended March 30, 2023. See also Note 4 Accounts Receivable and Allowance for Credit Losses . Contract liabilities are established for cash received in excess of revenues recognized and are contingent upon the satisfaction of performance obligations. Contract liabilities primarily consist of cash received on contracts for which revenue has been deferred since the receipts are in excess of transaction price resulting from the allocation of consideration based on relative standalone selling price to future units (including those under option that the Company believes are likely to be exercised) with prices that are lower than standalone selling price. These contract liabilities will be recognized earlier if the options are not fully exercised, or immediately, if the contract is terminated prior to the options being fully exercised. March 28, 2024 December 31, 2023 Change Contract assets $ 832.3 $ 522.9 $ 309.4 Contract liabilities (305.8) (353.9) 48.1 Net contract assets (liabilities) $ 526.5 $ 169.0 $ 357.5 For the period ended March 28, 2024, the increase in contract assets reflects the net impact of more over time revenue recognition in relation to billed revenues during the period as well as the impact of changes implemented by Boeing in March 2024 to introduce a new product verification process in Wichita, KS. This change in business process has delayed delivery acceptances and caused a build up of undelivered units in Wichita, KS. The decrease in contract liabilities reflects the net impact of less deferred revenues recorded in excess of revenue recognized during the period. The Company recognized $49.5 of revenue that was included in the contract liability balance at the beginning of the period. March 30, 2023 December 31, 2022 Change Contract assets $ 525.6 $ 502.2 $ 23.4 Contract liabilities (342.8) (356.4) 13.6 Net contract assets (liabilities) $ 182.8 $ 145.8 $ 37.0 For the period ended March 30, 2023, the increase in contract assets reflects the net impact of more over time revenue recognition in relation to billed revenues during the period. The decrease in contract liabilities reflects the net impact of less deferred revenues recorded in excess of revenue recognized during the period. The Company recognized $25.8 of revenue that was included in the contract liability balance at the beginning of the period.
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]	March 28, 2024 December 31, 2023 Change Contract assets $ 832.3 $ 522.9 $ 309.4 Contract liabilities (305.8) (353.9) 48.1 Net contract assets (liabilities) $ 526.5 $ 169.0 $ 357.5

Revenue (Notes)

Revenue (Notes)	3 Months Ended
	Mar. 28, 2024
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	Disaggregation of Revenue The Company disaggregates revenue based on the method of measuring satisfaction of the performance obligation either over time or at a point in time, based upon the location where products and services are transferred to the customer, and based upon major customer. The Company’s principal operating segments and related revenue are noted in Note 22 Segment Information . The following tables show disaggregated revenues for the periods ended March 28, 2024 and March 30, 2023: For the Three Revenue March 28, March 30, Contracts with performance obligations satisfied over time $ 1,282.1 $ 1,112.8 Contracts with performance obligations satisfied at a point in time 420.7 318.6 Total Revenue $ 1,702.8 $ 1,431.4 The following table disaggregates revenue by major customer: For the Three Customer March 28, March 30, Boeing $ 1,088.6 $ 921.1 Airbus 317.1 267.6 Other 297.1 242.7 Total Revenue $ 1,702.8 $ 1,431.4 The following table disaggregates revenue based upon the location where control of products is transferred to the customer: For the Three Location March 28, March 30, United States $ 1,350.7 $ 1,149.7 International United Kingdom 157.3 170.3 Other 194.8 111.4 Total International 352.1 281.7 Total Revenue $ 1,702.8 $ 1,431.4 Remaining Performance Obligations Unsatisfied, or partially unsatisfied, performance obligations that are expected to be recognized in the future are noted in the table below. The Company expects options to be exercised in addition to the amounts presented below: Remaining in 2024 2025 2026 2027 and after Unsatisfied performance obligations $ 4,766.4 $ 3,152.2 $ 1,299.7 $ 754.5

Inventory

Inventory	3 Months Ended
	Mar. 28, 2024
Inventory Disclosure [Abstract]
Inventory	Inventory Inventory consists of raw materials used in the production process, work-in-process, which is direct material, direct labor, overhead and purchases, and capitalized pre-production costs. Raw materials are stated at lower of cost (principally on an actual or average cost basis) or net realizable value. Capitalized pre-production costs include certain contract costs, including applicable overhead, incurred before a product is manufactured on a recurring basis. These costs are typically amortized over a period that is consistent with the satisfaction of the underlying performance obligations to which these relate. March 28, December 31, Raw materials $ 423.7 $ 414.4 Work-in-process (1) 1,300.5 1,283.7 Finished goods 53.0 48.4 Product inventory 1,777.2 1,746.5 Capitalized pre-production 20.3 20.8 Total inventory, net $ 1,797.5 $ 1,767.3 (1) Work-in-process inventory includes direct labor, direct material, overhead, and purchases on contracts for which revenue is recognized at a point in time as well as sub-assembly parts that have not been issued to production on contracts for which revenue is recognized over time using an input method. For the periods ended March 28, 2024 and December 31, 2023, work-in-process inventory includes $232.4 an d $262.0, respectively, of costs incurred in anticipation of specific contracts and no impairments were recorded in the periods. Product inventory, summarized in the table above, is shown net of valuation reserves of $154.6 and $150.2 as of March 28, 2024 and December 31, 2023, respectively. Excess capacity and abnormal production costs are excluded from inventory and recognized as expense in the period incurred. Cost of sales for the three months ended March 28, 2024 includes period expense of $26.1 for

Property, Plant and Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 28, 2024
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, net	Property, Plant and Equipment, net Property, plant and equipment, net consists of the following: March 28, December 31, Land $ 30.5 $ 30.5 Buildings (including improvements) 1,314.0 1,307.6 Machinery and equipment 2,481.7 2,460.6 Tooling 1,071.9 1,064.8 Capitalized software 338.6 338.4 Construction-in-progress 110.6 119.0 Total 5,347.3 5,320.9 Less: accumulated depreciation (3,307.2) (3,236.7) Property, plant and equipment, net $ 2,040.1 $ 2,084.2 Capitalized interest was $1.2 and $1.6 for the three months ended March 28, 2024 and March 30, 2023, respectively. Repair and maintenance costs are expensed as incurred. The Company recognized repair and maintenance costs of $44.1 and $42.7 for the three months ended March 28, 2024 and March 30, 2023, respectively. The Company capitalizes certain costs, such as software coding, installation, and testing, that are incurred to purchase or to create and implement internal-use computer software. Depreciation expense related to capitalized software was $4.4 and $6.1 for the three months ended March 28, 2024 and March 30, 2023, respectively. The Company reviews capital and amortizing intangible assets (long-lived assets) for impairment on an annual basis or whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. F or the period ended March 28, 2024, there were no events which would require the Company to update its impairment analysis .

Leases (Notes)

Leases (Notes)	3 Months Ended
	Mar. 28, 2024
Leases [Abstract]
Leases of Lessee Disclosure [Text Block]	The Company determines if an arrangement is a lease at the inception of a signed agreement. Operating leases are included in right-of-use (“ROU”) assets (long-term), short-term operating lease liabilities, and long-term operating lease liabilities on the Company’s Condensed Consolidated Balance Sheets. Finance leases are included in Property, Plant and Equipment, current maturities of long-term debt, and long-term debt. ROU assets represent the right of the Company to use an underlying asset for the length of the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the lease commencement date based on the estimated present value of lease payments over the lease term. To determine the present value of lease payments, the Company uses its estimated incremental borrowing rate or the implicit rate, if readily determinable. The estimated incremental borrowing rate is based on information available at the lease commencement date, including any recent debt issuances and publicly available data for instruments with similar characteristics. The ROU asset also includes any lease payments made and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease and, when it is reasonably certain that an option will be exercised, those options are included in the net present value calculation. Leases with a term of 12 months or less, which are primarily related to automobiles and manufacturing equipment, are not recorded on the Condensed Consolidated Balance Sheets. The aggregate amount of lease cost for leases with a term of 12 months or less is not material. The Company has lease agreements that include lease and non-lease components, which are generally accounted for separately. For certain leases (primarily related to IT equipment), the Company does account for the lease and non-lease components as a single lease component. A portfolio approach is applied to effectively account for the ROU assets and liabilities for those specific leases referenced above. The Company does not have any material leases containing variable lease payments or residual value guarantees. The Company also does not have any material subleases. The Company currently has operating and finance leases for items such as manufacturing facilities, corporate offices, manufacturing equipment, transportation equipment, and vehicles. The majority of the Company’s active leases have remaining lease terms that range between less than one year to 17 years, some of which include options to extend the leases for up to 30 years, and some of which include options to terminate the leases within one year. Components of lease expense: For the Three March 28, March 30, Operating lease cost $ 3.5 $ 3.7 Finance lease cost: Amortization of assets 9.6 8.6 Interest on lease liabilities 2.1 1.8 Total net lease cost $ 15.2 $ 14.1 Supplemental cash flow information related to leases was as follows: For the Three March 28, March 30, Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 3.7 $ 3.5 Operating cash flows from finance leases $ 2.1 $ 1.9 Financing cash flows from finance leases $ 13.3 $ 11.3 ROU assets obtained in exchange for lease obligations: Operating leases $ 0.2 $ 0.1 Supplemental balance sheet information related to leases: March 28, 2024 December 31, 2023 Finance leases: Property and equipment, gross $ 336.4 $ 336.9 Accumulated amortization (145.4) (135.8) Property and equipment, net $ 191.0 $ 201.1 The weighted average remaining lease term as of March 28, 2024 for operating and finance leases was 33.5 years and 4.4 years, respectively. The weighted average discount rate as of March 28, 2024 for operating and finance leases was 6.2% and 6.4%, respectively. The weighted average remaining lease term as of December 31, 2023 for operating and finance leases was 33.2 years and 4.7 years, respectively. The weighted average discount rate as of December 31, 2023 for operating and finance leases was 6.2% and 6.3%, respectively. See Note 14 Debt for current and non-current finance lease obligations. As of March 28, 2024, remaining maturities of lease liabilities were as follows: 2024 2025 2026 2027 2028 2029 and thereafter Total Lease Payments Less: Imputed Interest Total Lease Obligations Operating Leases $ 11.1 $ 14.7 $ 12.2 $ 9.7 $ 8.8 $ 174.1 $ 230.6 $ (137.7) $ 92.9 Financing Leases $ 41.4 $ 42.8 $ 27.5 $ 12.8 $ 6.9 $ 22.3 $ 153.7 $ (20.9) $ 132.8 As of March 28, 2024, the Company had additional operating and financing lease commitments that have not yet commenced of approximately $0.4 and $15.2, respectively, f or manufacturing equipment, software, and facilities that are in various phases of construction or customization for the Company’s

Other Assets

Other Assets	3 Months Ended
	Mar. 28, 2024
Other Assets, Noncurrent [Abstract]
Goodwill Disclosure [Text Block]	Goodwill is summarized as follows: Changes in Goodwill Balance Balance at Balance at Segment December 31, Acquisitions Adjustments/Other Currency Exchange March 28, Commercial $ 296.6 $ — $ — $ — $ 296.6 Defense & Space $ 13.2 $ — $ — $ — $ 13.2 Aftermarket $ 321.4 $ — $ — $ — $ 321.4 $ 631.2 $ — $ — $ — $ 631.2 The total goodwill value includes no a ccumulated impairment loss in any of the periods present ed. The Company assesses goodwill for impairment annually or more frequently if events or circumstances indicate that the fair value of a reporting unit that includes goodwill may be lower than its carrying value. F

Advance Payments and Deferred R

Advance Payments and Deferred Revenue/Credits	3 Months Ended
	Mar. 28, 2024
Advance Payments And Deferred Revenue Credits [Abstract]
Advance Payments	Advance Payments Advances on the B787 Program. Boeing has made advance payments to Spirit under the B787 Special Business Provisions and General Terms Agreement (collectively, the “B787 Supply Agreement”) that are required to be repaid to Boeing by way of offset against the purchase price for future shipset deliveries. Advance repayments were initially scheduled to be spread evenly over the remainder of the first 1,000 B787 shipsets delivered to Boeing. On April 8, 2014, Spirit signed a memorandum of agreement with Boeing that suspended advance repayments related to the B787 program for a period of twelve months beginning April 1, 2014. Repayment recommenced on April 1, 2015, and any repayments that otherwise would have become due during such twelve-month period will offset the purchase price for shipsets 1001 through 1120. On December 21, 2018, Spirit signed a memorandum of agreement with Boeing that again suspended the advance repayments beginning with line unit 818. The advance repayments resumed in 2022 at a lower rate of $0.45 per shipset at line unit number 1135 and will continue through line number 1605. In the event Boeing does not take delivery of a sufficient number of shipsets to repay the full amount of advances prior to the termination of the B787 program or the B787 Supply Agreement, any advances not then repaid will be applied against any outstanding payments then due by Boeing to us, and any remaining balance will be repaid in annual installments of $27.0 due on December 15th of each year until the advance payments have been fully recovered by Boeing. As of March 28, 2024, the amount of advance payments received from Boeing under the B787 Supply Agreement and not yet repaid was approximately $183.2 . In support of tooling and capital expenditures for future production rate increases on the B787 program, the memorandum of agreement entered into on October 12, 2023 between Boeing and Spirit (the “2023 MOA”) included an agreement for Boeing to advance Spirit a total of $71.7 in quarterly installments beginning October 2023 through April 2025. Spirit will align the repayment plan to coincide with deliveries to Boeing beginning April 2025 through October 2027. In the event Boeing does not take delivery of a sufficient number of shipsets to repay the full amount of advance prior to October 31, 2027, the remaining balance up to the $71.7 will be due in the fourth quarter of 2027. As of March 28, 2024, the amount of advance payments received by Spirit from Boeing and not yet repaid was approximately $32.2. Advances on the A350 Program . During the twelve months ended December 31, 2023, the Company received an advance payment from Airbus of $100.0 under an agreement between Airbus S.A.S. and Spirit AeroSystems (Europe) Limited (“Spirit Europe”) signed on June 23, 2023 (the “A350 Agreement”). The A350 Agreement provides for up to $100.0 of advances that are required to be repaid along with a nominal fee to Airbus by way of offset against the purchase price of A350 FLE shipset deliveries in 2025. To the extent actual deliveries in 2025 are insufficient to offset the advance amount, any amount not offset against deliveries will be due and payable to Airbus on December 31, 2025. In connection with the A350 Agreement, Spirit Europe has pledged certain program assets including work in process inventories and raw materials at Spirit’s Scotland facility in an amount sufficient to cover the advances. Advances on the A220 Program . During the three months ended March 28, 2024, the Company received an advance payment from Airbus of $17.0 under a term sheet agreement between Airbus Canada Limited Partnership (“Airbus Canada”) and Shorts Brothers PLC (the Company’s facilities located in Belfast, Northern Ireland), for short term funding for increased freight costs incurred in the period from January to March 2024. This advance will form part of a financial support package under a proposed Memorandum of Agreement under negotiations between the parties and shall be used by the Company to enable timely delivery of aerostructures via air freight through March 31, 2024. The increased freight costs will be fully borne by the Company. The parties’ original intent was to have the method and timing of payment resolved by the end of April 2024, however, as of the date of this filing these issues have not been resolved. Other. The Advance payments, long-term line item on the Condensed Consolidated Balance Sheets for the period ended March 28, 2024 includes $18.9 related to payments received from an Aftermarket segment customer for contracted work that was impacted by the sanctions imposed by the U.S. and other governments on Russia following its invasion of Ukraine.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 28, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The FASB’s authoritative guidance on fair value measurements defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. It also establishes a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The guidance discloses three levels of inputs that may be used to measure fair value: Level 1 Quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 1 assets and liabilities include debt and equity securities and derivative contracts that are traded in an active exchange market. Level 2 Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 2 assets and liabilities include debt securities with quoted prices that are traded less frequently than exchange-traded instruments and derivative contracts whose value is determined using a pricing model with inputs that are observable in the market or can be derived principally from or corroborated by observable market data. Observable inputs, such as current and forward interest rates and foreign exchange rates, are used in determining the fair value of the interest rate swaps and foreign currency hedge contracts. Level 3 Unobservable inputs that are supported by little or no market activity and are significant to the fair value of assets and liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. At March 28, 2024, the Company’s long-term debt includes a senior secured term loan and senior notes described further under Note 14 Debt . The estimated fair value of the Company’s debt obligations is based on the quoted market prices for such obligations or the historical default rate for debt with similar credit ratings. The following table presents the carrying amount and estimated fair value of long-term debt. See also Note 13 Derivative and Hedging Activities and Note 15 Pension and Other Post-Retirement Benefits. March 28, 2024 December 31, 2023 Carrying Fair Carrying Fair Senior secured term loan B (including current portion) $ 572.3 $ 575.1 (2) $ 571.0 $ 573.1 (2) Exchangeable senior notes due 2028 222.5 313.7 (2) 222.2 292.6 (2) Senior notes due 2025 20.8 20.8 (1) 20.8 20.7 (1) Senior secured noted due 2026 299.2 288.1 (1) 299.1 288.0 (1) Senior notes due 2028 696.7 652.9 (1) 696.6 616.8 (1) Senior secured first lien notes due 2029 888.8 970.2 (1) 888.4 973.0 (1) Senior secured second lien notes due 2030 1,180.3 1,320.8 (1) 1,180.0 1,273.1 (1) Total $ 3,880.6 $ 4,141.6 $ 3,878.1 $ 4,037.3 (1) Level 1 Fair Value hierarchy (2)

Derivative and Hedging Activiti

Derivative and Hedging Activities	3 Months Ended
	Mar. 28, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative and Hedging Activities	Derivative and Hedging Activities Derivatives Accounted for as Hedges Cash Flow Hedges – Foreign Currency Forward Contract The Company has entered into currency forward contracts, each designated as a cash flow hedge upon the date of execution, for the purpose of reducing the variability of cash flows and hedging against the foreign currency exposure for forecasted payroll, pension and vendor disbursements that are expected to be made in the British Pound Sterling. The hedging program implemented is intended to reduce foreign currency exposure, and the associated forward currency contracts hedge forecasted transactions through December 2024. The following table summarizes the notional amounts (representing the gross contract/notional amount of the derivatives outstanding) and fair values of the derivative instruments in the Condensed Consolidated Balance Sheets as of March 28, 2024, and December 31, 2023. The foreign currency exchange contracts are measured within Level 1 of the Fair Value hierarchy. See Note 12 Fair Value Measurements . Notional amount Other assets Other liabilities March 28, 2024 December 31, 2023 March 28, 2024 December 31, 2023 March 28, 2024 December 31, 2023 Derivatives designated as hedging instruments: Foreign currency exchange contracts $ 161.8 $ 169.1 $ — $ 3.0 $ — $ — Total derivatives at fair value $ — $ 3.0 $ — $ — Changes in the fair value of cash flow hedges are recorded in AOCI and recorded in earnings in the period in which the hedged transaction settles. The gain (loss) recognized in AOCI associated with our hedging transactions is presented in the following table: Three Months Ended March 28, 2024 March 30, 2023 Recognized in total other comprehensive loss: Foreign currency exchange contracts $ (1.8) $ 2.5 The following table summarizes the gains/(losses) associated with our hedging transactions reclassified from AOCI to earnings: Three Months Ended March 28, 2024 March 30, 2023 Foreign currency exchange contracts: Other income (expense) $ 1.2 $ (3.4) Within the next 12 months, the Company expects to recognize a loss of $0.0 in earnings related to the foreign currency forward contracts. As of March 28, 2024, the maximum term of the hedged forecasted transaction was 9 months. Generally, the Company has agreements with its counterparties that contain a provision whereby if the Company defaults on its existing credit facilities and payment of the loans extended under such facilities is accelerated, the Company could be declared in default under its agreements, which may result in the early termination of the outstanding derivatives governed by such agreements and the payment of an early termination amount.

Debt

Debt	3 Months Ended
	Mar. 28, 2024
Debt Disclosure [Abstract]
Debt	Credit Agreement On October 5, 2020, Spirit entered into a term loan credit agreement (the “Credit Agreement”) providing for a $400.0 senior secured term loan B credit facility with the lenders party thereto and Bank of America, N.A., as administrative agent and collateral agent. On October 5, 2020, Spirit borrowed the full $400.0 of initial term loans available under the Credit Agreement. On November 15, 2021, the Company entered into a first refinancing, incremental assumption and amendment agreement (the “November 2021 Amendment”) to the Credit Agreement. The November 2021 Amendment provides for, among other things, (i) the refinancing of the $397.0 aggregate principal amount of term loans outstanding under the Credit Agreement immediately prior to the effectiveness of the November 2021 Amendment with term loans in an equal principal amount with a lower interest rate (the “Repriced Term Loans”) and (ii) an incremental term loan facility of $203.0 in aggregate principal amount with the same terms as the Repriced Term Loans. On November 23, 2022, the Company entered into a second refinancing amendment (the “November 2022 Amendment”) to the Credit Agreement (the Credit Agreement as amended by the November 2021 Amendment and the November 2022 Amendment, the “Amended Credit Agreement”). The November 2022 Amendment provides for, among other things, the refinancing of the $594.0 aggregate principal amount of term loans outstanding under the Credit Agreement immediately prior to the effectiveness of the November 2022 Amendment with term loans in an equal principal amount with a later maturity date. The obligations under the Amended Credit Agreement are guaranteed by Holdings and Spirit AeroSystems North Carolina, Inc., a wholly-owned subsidiary of Holdings (“Spirit NC” and, together with Holdings, the “Guarantors”) and will be guaranteed by each existing and future, direct and indirect, wholly-owned material domestic subsidiary of Holdings, subject to certain customary exceptions. The obligations are secured by a first-priority lien with respect to substantially all assets of Spirit and the Guarantors, subject to certain exceptions. As of March 28, 2024 , the outstanding balance of the Amended Credit Agreement was $586.6 and the carrying value was $572.3. As of March 28, 2024 , the Company was in compliance with all covenants in the Amended Credit Agreement. Exchangeable Notes On November 13, 2023, Spirit entered into an Indenture (the “Exchangeable Notes Indenture”), by and among Spirit, the Guarantors, and The Bank of New York Mellon Trust Company, N.A., as trustee, in connection with Spirit’s issuance of $230.0 aggregate principal amount of its 3.250% Exchangeable Senior Notes due 2028 (the “Exchangeable Senior Notes”). The Exchangeable Senior Notes are senior, unsecured obligations of Spirit and are fully and unconditionally guaranteed on a senior, unsecured basis by the Guarantors. The Exchangeable Senior Notes will be exchangeable at an initial exchange rate of 34.3053 shares of Holdings’ Class A common stock per $1,000.00 principal amount of Exchangeable Senior Notes (equivalent to an initial exchange price of approximately $29.15 per share of Class A common stock). At the initial exchange rate, the Exchangeable Senior Notes would be convertible into 7,890,219 shares of Holdings’ Class A common stock. The initial exchange rate is subject to adjustment, as provided in the Exchangeable Notes Indenture. In connection with certain corporate events, or if Spirit calls any Exchangeable Senior Notes for redemption, Spirit will, under certain circumstances, be required to increase the exchange rate for noteholders who elect to exchange their Exchangeable Senior Notes in connection with any such corporate event or exchange their Exchangeable Senior Notes called for redemption during the related redemption period. During the three months ended March 28, 2024, no adjustments were made to the conversion or exercise prices of the Exchangeable Senior Notes. As of March 28, 2024, the outstanding balance of the Exchangeable Senior Notes was $230.0 and the carrying value was $222.5. Interest expense recognized for the three months ended March 28, 2024 was $1.8. During the three months ended March 28, 2024, $0.4 of debt issuance costs were amortized. Unamortized debt issuance costs at March 28, 2024 related to the Exchangeable Senior Notes were $7.5. The Exchangeable Senior Notes mature on November 1, 2028, unless earlier exchanged, redeemed, or repurchased. Second Lien 2030 Notes On November 21, 2023, Spirit entered into an Indenture (the “Second Lien 2030 Notes Indenture”), by and among Spirit, the Guarantors, and The Bank of New York Mellon Trust Company, N.A., as trustee and collateral agent, in connection with Spirit’s offering of $1,200.0 aggregate principal amount of its 9.750% Senior Secured Second Lien Notes due 2030 (the “Second Lien 2030 Notes”). The Second Lien 2030 Notes are guaranteed by the Guarantors, and will be guaranteed by each existing and future, direct and indirect, wholly-owned material domestic subsidiary of Holdings that guarantee Holdings’ obligations under the Amended Credit Agreement and certain other indebtedness, subject to certain customary exceptions. The Second Lien 2030 Notes are secured by a second-priority lien with respect to substantially all assets of Spirit and the Guarantors, subject to certain exceptions. As of March 28, 2024, the outstanding balance of the Second Lien 2030 Notes was $1,200.0 and the carrying value was $1,180.3. The Second Lien 2030 Notes mature on November 15, 2030. First Lien 2029 Notes On November 23, 2022, Spirit entered into an Indenture by and among Spirit, the Guarantors, and The Bank of New York Mellon Trust Company, N.A., as trustee and collateral agent, in connection with Spirit’s offering of $900.0 aggregate principal amount of its 9.375% Senior Secured First Lien Notes due 2029 (the “First Lien 2029 Notes”). The First Lien 2029 Notes are guaranteed by the Guarantors, and will be guaranteed by each existing and future, direct and indirect, wholly-owned material domestic subsidiary of Holdings that guarantee Holdings’ obligations under the Amended Credit Agreement and certain other indebtedness. The First Lien 2029 Notes are secured by a first-priority lien with respect to substantially all assets of Spirit and the Guarantors, subject to certain exceptions. As of March 28, 2024 , the outstanding balance of the First Lien 2029 Notes was $900.0 and the carrying value was $888.8. The First Lien 2029 Notes mature on November 30, 2029. 2025 Notes On October 5, 2020, Spirit entered into an Indenture by and among Spirit, the Guarantors, and The Bank of New York Mellon Trust Company, N.A., as trustee and collateral agent, in connection with Spirit’s offering of $500.0 aggregate principal amount of its 5.500% Senior Secured First Lien Notes due 2025 (the “2025 Notes”). The 2025 Notes are guaranteed by the Guarantors and were initially secured by a first-priority lien with respect to substantially all assets of Spirit and the Guarantors, subject to certain exceptions, which lien was released on November 22, 2022. As of March 28, 2024 , the outstanding balance of the 2025 Notes was $20.8 and the carrying value was $20.8. The 2025 Notes mature on January 15, 2025. 2026 Notes In June 2016, the Company issued $300.0 in aggregate principal amount of 3.850% Senior Notes due June 15, 2026 (the “2026 Notes”). The 2026 Notes are guaranteed by the Guarantors, and each existing and future, direct and indirect, subsidiary of the Company that guarantee the Company’s obligations under the Amended Credit Agreement and certain other indebtedness. On October 5, 2020, Spirit entered into a Fourth Supplemental Indenture (the “Fourth Supplemental Indenture”), by and among Spirit, the Company, Spirit NC, and The Bank of New York Mellon Trust Company, N.A., as trustee in connection with 2026 Notes. Under the Fourth Supplemental Indenture, the holders of the 2026 Notes were granted security on an equal and ratable basis with the secured parties under the Credit Agreement. On November 23, 2022, Spirit entered into a Fifth Supplemental Indenture (the “Fifth Supplemental Indenture”), by and among Spirit, the Company, Spirit NC, and The Bank of New York Mellon Trust Company, N.A., as trustee in connection with 2026 Notes. Under the Fifth Supplemental Indenture, the holders of the 2026 Notes were granted security on an equal and ratable basis with the holders of the First Lien 2029 Notes. On November 21, 2023, Spirit entered into a Sixth Supplemental Indenture (the “Sixth Supplemental Indenture”), by and among Spirit, the Company, Spirit NC and The Bank of New York Mellon Trust Company, N.A., as trustee in connection with the 2026 Notes. Under the Sixth Supplemental Indenture, the holders of the 2026 Notes were granted security on an equal and ratable basis with the holders of the Second Lien 2030 Notes. As of March 28, 2024, the outstanding balance of the 2026 Notes was $300.0 and the carrying value was $299.2. The 2026 Notes mature on June 15, 2026. 2028 Notes On May 30, 2018, Spirit entered into an Indenture (the “2018 Indenture”) by and among Spirit, the Company and The Bank of New York Mellon Trust Company, N.A., as trustee in connection with Spirit’s offering of $300.0 aggregate principal amount of its Senior Floating Rate Notes due 2021 (the “Floating Rate Notes”), $300.0 aggregate principal amount of its 3.950% Senior Notes due 2023 (the “2023 Notes”) and $700.0 aggregate principal amount of its 4.600% Senior Notes due 2028 (the “2028 Notes” and, together with the Floating Rate Notes and the 2023 Notes, the “2018 Notes”). On February 24, 2021, Spirit redeemed the outstanding $300.0 principal amount of the Floating Rate Notes. On November 23, 2022, Spirit redeemed the outstanding $300.0 principal amount of the 2023 Notes. Holdings guarantees Spirit's obligations under the 2028 Notes on a senior unsecured basis. As of March 28, 2024 , the outstanding balance of the 2028 Notes was $700.0 and the carrying value was $696.7. The 2028 Notes mature on June 15, 2028. As of March 28, 2024, the Company was in compliance with all covenants contained in the indentures governing the Second Lien 2030 Notes, First Lien 2029 Notes, 2025 Notes, 2026 Notes, and the 2028 Notes.

Pension and Other Post-Retireme

Pension and Other Post-Retirement Benefits Defined Benefit Plan (Notes)	3 Months Ended
	Mar. 28, 2024
Retirement Benefits [Abstract]
Retirement Benefits [Text Block]	Pension and Other Post-Retirement Benefits Defined Benefit Plans For the Three Components of Net Periodic Pension Expense (Income) March 28, March 30, Service cost $ 0.6 $ 0.8 Interest cost 17.7 20.1 Expected return on plan assets (21.6) (21.8) Amortization of net loss — 0.1 Settlement loss (gain) (1) — 64.6 Net periodic pension expense (income) $ (3.3) $ 63.8 Other Benefits For the Three Components of Other Benefit Expense (Income) March 28, March 30, Service cost $ 0.2 $ 0.2 Interest cost 0.4 0.4 Amortization of prior service cost 0.3 (0.2) Amortization of net gain (0.4) (0.5) Net periodic other benefit income $ 0.5 $ (0.1) (1) Includes a $64.6 settlement charge for PVP A during the three months ended March 30, 2023. The components of net periodic pension expense (income) and other benefit income, other than the service cost component, are included in Other income (expense), net in the Company’s Condensed Consolidated Statements of Operations. See Note 20 Other Income (Expense), Net. Effective October 1, 2021, the Company spun off a portion of the existing PVP A, to a new plan called PVP B (“PVP B ” ). As part of the PVP B plan termination process, a lump sum offering was provided during 2021 for PVP B participants and the final asset distribution was completed in the first quarter of 2022. At March 28, 2024, a pension reversion asset of $50.0 is recorded on the Restricted plan assets line item on the Company’s Condensed Consolidated Balance Sheets. Restricted plan assets are expected to be reduced over the next five years as they are distributed to employees under a qualified compensation and benefit program. Restricted plan assets are valued at fair value with gain or loss on fair value adjustments recognized within other income. The underlying investments’ fair value measurement levels under the FASB’s authoritative guidance on fair value measurements are Level 2, see Note 12 Fair Value Measurements. Separately, during the three months ended March 30, 2023, the Company received an excess plan asset reversion of $179.5 of cash from PVP A. This transaction was accounted for as a negative contribution, and is included on the Pension plans employer contributions line item on the Company’s Condensed Consolidated Statement of Cash Flows for the three months ended March 30, 2023. Excise tax of $35.9 related to the reversion of excess plan assets was separately recorded to the Other (expense) income, net line item on the Company’s Condensed Consolidated Statements of Operations for the three months ended March 30, 2023. See also Note 20 Other Income (Expense), Net . I n July 2022, the Company adopted and communicated to participants a plan to terminate the PVP A. During the three months ended March 30, 2023, the Company r ecognized non-cash, pre-tax non-operating accounting charges of $64.6 related to the plan termination, primarily reflecting the accounting for a group annuity purchase made in the first quarter of 2023, which resulted in a settlement charge related to the accelerated recognition of the actuarial losses for the PVP A plan that were previously included in the Accumulated other comprehensive loss line item in the Stockholders’ Equity section of the Company’s Condensed Consolidated Balance Sheets. Employer Contributions

Stock Compensation

Stock Compensation	3 Months Ended
	Mar. 28, 2024
Share-Based Payment Arrangement, Noncash Expense [Abstract]
Stock Compensation	Stock Compensation Holdings has established the stockholder-approved Amended and Restated 2014 Omnibus Incentive Plan (the “Omnibus Plan”), to grant cash and equity awards of Holdings’ Class A Common Stock, par value $0.01 per share (the “Common Stock”), to certain individuals. Holdings has established the Long-Term Incentive Plan (the “LTIP”) under the Omnibus Plan to grant equity awards to certain employees of the Company. The Company recognized a net total of $10.1 and $9.0 of stock compensation expense for the three months ended March 28, 2024 and March 30, 2023, respectively. During the three months ended March 28, 2024, 409,170 time or service-based restricted stock units (“RSUs”) were granted with an aggregate grant date fair value of $11.9 under the Company’s LTIP. Awards vest over a three-year period, beginning on the date of grant. Values for these awards are based on the value of Common Stock on the grant date. During the three months ended March 28, 2024, 388,386 performance-based restricted stock units (“PBRSUs”) were granted with an aggregate grant date fair value of $14.9 under the Company’s LTIP. These awards are earned based on Holdings’ total shareholder return relative to its peer group over a three-year performance period. Values for these awards are initially measured on the grant date using the estimated payout levels derived from a Monte Carlo valuation model. During the three months ended March 28, 2024, 384,734 shares of Common Stock with an aggregate grant date value of $16.0 vested under the Company’s LTIP. The Company maintains the Spirit AeroSystems Holdings, Inc. Employee Stock Purchase Plan (the “ESPP”) which became effective on October 1, 2017 and was amended and restated on October 21, 2022. Under the amended plan, the per-share purchase price for the Company’s Common stock purchased under the ESPP is 85% of the lower of (a) the fair market value of a share on the first day of the applicable offering period or (b) the fair market value of a share on the applicable purchase date. The Company recognized $0.7 of stock compensation expense related to the ESPP for the three months ended March 28, 2024. The Company recognized no stock compensation expense related to the ESPP for the three months ended March 30, 2023.

Income Taxes (Notes)

Income Taxes (Notes)	3 Months Ended
	Mar. 28, 2024
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes The process for calculating the Company’s income tax expense involves estimating actual current taxes due plus assessing temporary differences arising from differing treatment for tax and accounting purposes that are recorded as deferred tax assets and liabilities. Deferred tax assets are periodically evaluated to determine their recoverability and whether a valuation allowance is necessary. A valuation allowance, if needed, reduces deferred tax assets to the amount expected to be realized. When determining the amount of net deferred tax assets that are more likely than not to be realized, the Company assesses all available positive and negative evidence. The weight given to the positive and negative evidence is commensurate with the extent the evidence may be objectively verified. As such, it is generally difficult for positive evidence regarding projected future taxable income exclusive of reversing taxable temporary differences to outweigh objective negative evidence of recent financial reporting losses. Based on these criteria and the relative weighting of both the positive and negative evidence available, and in particular the activity surrounding our prior earnings history, including the forward losses previously recognized in the U.S., the Company has recorded a valuation allowance against U.S. deferred tax assets. Increases in the valuation allowances recorded against U.S. deferred tax assets in the three months ended March 28, 2024 were $87.1. This is comprised of $0.0 related to other comprehensive income (“OCI”) and $87.1 from continuing operations. As of March 28, 2024, the total net U.S. deferred tax asset before the valuation allowance was $593.7 and the total net U.S. valuation allowance was $595.2. The net U.S. deferred tax liability after valuation allowances was $1.5. The Company has determined a valuation allowance on certain U.K. deferred tax assets is needed based upon cumulative losses generated in the U.K. Increases in the valuation allowances recorded against U.K. deferred tax assets in the three-month period ended March 28, 2024 were $72.3. This is comprised of ($0.5) related to other comprehensive income (“OCI”) and $72.8 from continuing operations, including utilization of net operating losses. As of March 28, 2024, the total net U.K. deferred tax asset before the valuation allowance was $418.2 and the total net U.K. valuation allowance was $431.5. The net U.K. deferred tax liability after valuation allowance was $13.3. The Company files income tax returns in all jurisdictions in which it operates. The Company establishes reserves to provide for additional income taxes that may be due upon audit. These reserves are established based on management’s assessment as to the potential exposure attributable to permanent tax adjustments and associated interest. All tax reserves are analyzed quarterly and adjustments made as events occur that warrant modification. In general, the Company records income tax expense each quarter based on its estimate as to the full year’s effective tax rate. Certain items, however, are given discrete period treatment and the tax effects for such items are therefore reported in the quarter that an event arises. Events or items that may give rise to discrete recognition include excess tax benefits with respect to share-based compensation, finalizing amounts in income tax returns filed, finalizing audit examinations for open tax years, expiration of statutes of limitations, and changes in tax law. T he (1.82%) effectiv e tax rate for the three months ended March 28, 2024 differs from the 1.50% effective tax rate for the same period of 2023 primarily due to changes in the valuation allowances recorded on U.S. and U.K. deferred tax assets. As the Company is currently reporting a pre-tax loss for the three months ended March 28, 2024, an increase in the effective tax rate results in an increase of income tax benefits while a decrease in the rate results in a reduction of income tax benefits. As allowed by the Coronavirus Aid, Relief, and Economic Security Act, the Company has filed a claim for a pre-tax employee retention credit of $18.8 for 2020 and $1.0 for 2021. The outstanding pre-tax employee retention credit refund claim as of March 28, 2024 is $3.1. The Company’s federal audit is conducted under the Internal Revenue Service Compliance Assurance Process (“CAP”) program. The Company will continue to participate in the CAP program for 2021 through 2024. The CAP program’s objective is to resolve issues in a timely, contemporaneous manner and eliminate the need for a lengthy post-filing examination. The Company has an open tax audit in the Kingdom of Morocco for tax years ending prior to the Company’s ownership of the Moroccan legal entity. There are ongoing audits in other jurisdictions that are not material to the financial statements and the Company believes appropriate provisions for all outstanding tax issues have been made for all jurisdictions and years. The Company operates under a tax holiday in Malaysia which is effective through September 30, 2024. The tax holiday is conditional upon remaining in good standing with the Malaysia taxing authorities, having at least 20% value-add and at least 30% of employees with diploma/degree in science/technical discipline. The tax benefit impact of this holiday has been $3.4, $3.0, and $3.4 for 2023, 2022, and 2021, respectively. The tax benefit for the three months ended March 28, 2024 was $0.6.

Equity

Equity	3 Months Ended
	Mar. 28, 2024
Stockholders' Equity Note [Abstract]
Equity	Equity Earnings per Share Calculation Basic net income per share is computed using the weighted-average number of outstanding shares of Common Stock during the measurement period. Diluted net income per share is computed using the weighted-average number of outstanding shares of Common Stock and, when dilutive, potential outstanding shares of Common Stock during the measurement period. Diluted earnings per share includes any dilutive impact of service-based restricted stock units, director restricted stock units, restricted stock awards, and performance-based restricted stock units. The Company accounts for treasury stock under the cost method and includes treasury stock as a component of stockholders’ equity. As of March 28, 2024, no treasury shares have been reissued or retired. The total authorization amount remaining under the current share repurchase program is approximately $925.0. During the three-month period ended March 28, 2024, the Company did not repurchase any shares of its Common Stock under this share repurchase program. Share repurchases are currently on hold. T he Credit Agreement imposes restrictions on the Company’s ability to repurchase shares. The following table sets forth the computation of basic and diluted earnings per share: For the Three Months Ended March 28, 2024 March 30, 2023 Income Shares Per Share Income Shares Per Share Basic EPS Loss available to common stockholders $ (616.7) 116.2 $ (5.31) $ (281.2) 104.9 $ (2.68) Income allocated to participating securities — — — — Net loss $ (616.7) $ (281.2) Diluted potential common shares — — Diluted EPS Net loss $ (616.7) 116.2 $ (5.31) $ (281.2) 104.9 $ (2.68) Included in the outstanding Common Stock were 0.0 million and 0.1 million of issued but unvested shares at March 28, 2024 and March 30, 2023, respectively, which are excluded from the basic Earnings Per Share (“EPS”) calculation. Shares of Common Stock of 9.6 million were excluded from diluted EPS as a result of incurring a net loss for the three months ended March 28, 2024 , as the effect would have been antidilutive. Additionally, diluted EPS for the three months ended March 28, 2024 excludes 0.2 million shares that may be dilutive shares of Common Stock in the future but were not included in the computation of diluted EPS because the effect was either antidilutive or the performance condition was not met. Shares of Common Stock of 0.9 million were excluded from diluted EPS as a result of incurring a net loss for the three months ended March 30, 2023, as the effect would have been antidilutive. Additionally, diluted EPS for the three months ended March 30, 2023 excludes 0.2 million shares that may be dilutive shares of Common Stock in the future but were not included in the computation of diluted EPS because the effect was either antidilutive or the performance condition was not met. Accumulated Other Comprehensive Loss Accumulated Other Comprehensive Loss is summarized by component as follows: As of As of March 28, 2024 December 31, 2023 Pension $ (18.4) $ (18.7) SERP/Retiree medical 6.7 6.8 Derivatives - foreign currency hedge — 2.2 Foreign currency impact on long-term intercompany loan (14.9) (14.6) Currency translation adjustment (70.6) (65.3) Total accumulated other comprehensive loss $ (97.2) $ (89.6) Amortization or settlement cost recognition of the pension plans’ net gain/(loss) reclassified from accumulated other comprehensive loss and realized into cost of sales and selling, general and administrative on the Condensed Consolidated Statements of Operations was $0.1 and ($64.0) for the three months ended March 28, 2024 and March 30, 2023, respectively.

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	3 Months Ended
	Mar. 28, 2024
Commitments Contingencies And Guarantees [Abstract]
Commitments and Contingencies Disclosure	. Commitments, Contingencies and Guarantees Litigation On May 3, 2023, a private securities class action lawsuit was filed in the U.S. District Court for the Southern District of New York against the Company, its former Chief Executive Officer, Tom Gentile III, and its Senior Vice President and Chief Financial Officer, Mark J. Suchinski. An Amended Complaint was filed on December 19, 2023, and a Second Amended Complaint was filed, with leave of the Court, on March 12, 2024. The lawsuit was brought on behalf of certain purchasers of securities of the Company, who allege purported misstatements and omissions concerning alleged faulty production controls and alleged quality and safety issues (the “ Securities Class Action ” ). The specific claims in the Securities Class Action include (i) violations of Section 10(b) of the Exchange Act and Rule 10b-5 promulgated thereunder against all defendants, and (ii) violations of Section 20(a) of the Exchange Act against the individual defendants. The plaintiffs seek monetary damages. The Company believes that the claims in this lawsuit are without merit and intends to defend against them vigorously. Spirit is also involved in litigation in the 10th Circuit Court of Appeals (“Appellate Court”) with its former Chief Executive Officer, Larry Lawson over Lawson’s disputed violation of a restrictive covenant in his retirement and consulting agreement. On October 19, 2021, the U.S. District Court for the District of Kansas (the “ District Court ” ) ruled in favor of Lawson and awarded him $44.8 for benefits withheld in connection with the disputed violation, as well as post-judgment interest at the rate of 4.25%. Spirit appealed the judgment to the Appellate Court. On February 27, 2023, the Appellate Court issued an opinion reversing the District Court decision and concluding that Lawson had violated the terms of the restrictive covenant and remanded for the District Court to address whether the restrictive covenant that Lawson violated was enforceable under Kansas law. On June 15, 2023, the District Court held that the restrictive covenant was enforceable as a matter of Kansas law. The District Court entered judgment in favor of Spirit on June 27, 2023. Lawson appealed the District Court’s latest decision, and this matter was argued before the Appellate Court on March 19, 2024. Spirit will continue to defend its position vigorously on appeal. A liability for the full amount of the award issued on October 19, 2021, plus accrued interest through March 28, 2023, was recognized and remains accrued in the Condensed Consolidated Balance Sheets as of December 31, 2023 and March 28, 2024. From time to time, in the ordinary course of business, the Company receives certain requests for information from government agencies in connection with their regulatory or investigational authority. The Company has received information and document requests related to the January 5, 2024 Alaska Airlines incident, the B737 MAX 9 door plug, and safety and quality processes in the B737 MAX line production. These include requests to assist the government in investigations or audits, including by the FAA, as a party representative to a National Transportation Safety Board investigation, grand jury subpoenas from the Department of Justice, and subpoenas or examination requests from the SEC and the Attorney General of the State of Texas. The Company reviews such requests and notices and takes appropriate action. Additionally, the Company is subject to federal and state requirements for protection of the environment, including those for disposal of hazardous waste and remediation of contaminated sites. As a result, the Company is required to participate in certain government investigations regarding environmental remediation actions. The Company is currently unable to reasonably estimate any impact this incident, including any impacts from these requests and investigations. In addition to the items addressed above, from time to time, the Company is subject to, and is presently involved in, litigation, legal proceedings, or other claims arising in the ordinary course of business. While the final outcome of the matters cannot be predicted with certainty, considering, among other things, the meritorious legal defenses available, the Company believes that, on a basis of information presently available, none of these items, when finally resolved, will have a material adverse effect on the Company’s long-term financial position or liquidity. Customer and Vendor Claims The Company receives, and is currently subject to, customer and vendor claims arising in the ordinary course of business, including, but not limited to, those related to product quality and late delivery. The Company accrues for matters when losses are deemed probable and reasonably estimable. In evaluating matters for accrual and disclosure purposes, the Company takes into consideration multiple factors including without limitation its historical experience with matters of a similar nature, the specific facts and circumstances asserted, the likelihood of an unfavorable outcome, and the severity of any potential loss. Any accruals deemed necessary are reevaluated at least quarterly and updated as matters progress over time. Contingencies During the first quarter, the Company updated its estimated cost to satisfy customer firm orders on the A350 and A220 programs. Based on these estimates, and management’s evaluation of key macroeconomic assumptions including the probability that these performance obligations would be exercised, management determined that it is probable each of these programs' performance obligations will extend beyond the period of time for which the Company has recorded forward losses. The key changes are based upon two primary factors, the change in strategic pricing conversations with our customer, Airbus, and incremental firm orders Airbus secured on the A350 and A220 programs. As a result, Company recorded incremental forward losses in the first quarter of $168.3 on the A350 and A220 programs for production of expected firm orders through January 2030. Additional losses beyond what has been reserved could occur if there are unexpected changes to current assumptions in macroeconomic factors relevant to the Company's cost to complete all firm orders, ongoing pricing discussions with its customers, and increases to our customers’ firm orders. As a result, while the Company does not believe incremental losses beyond those currently recorded are evident, it is reasonably possible one or more of these programs could be performed at a loss incremental to forward losses previously recorded for production outside of the timeframe or for orders that may be placed in addition to those assessed as of March 28, 2024, highlighted above. The Company continues to evaluate all options to reduce or eliminate recorded forward losses prospectively, including, but not limited to, continued active negotiations with its A220 and A350 customer, regarding, among other things, elements of price. Guarantees Contingent liabilities in the form of letters of guarantee have been provided by the Company. Outstanding guarantees were $22.7 and $23.1 at March 28, 2024 and December 31, 2023, respectively. Restricted Cash - Collateral Requirements The Company was required to maintain $27.7 and $22.3 of restricted cash as of March 28, 2024 and December 31, 2023, respectively, related to certain collateral requirements for obligations under its workers’ compensation programs. Restricted cash is included in Other assets in the Company's Condensed Consolidated Balance Sheets. Indemnification The Company has entered into customary indemnification agreements with its directors, and its bylaws and certain executive employment agreements include indemnification and advancement provisions. Under the bylaws and any applicable agreement, the Company agrees to indemnify individuals against claims arising out of events or occurrences related to that individual’s service as the Company’s agent or the agent of any of its subsidiaries to the fullest extent legally permitted. The Company has agreed to indemnify parties for specified liabilities incurred, or that may be incurred, in connection with transactions they have entered into with the Company. The Company is unable to assess the potential number of future claims that may be asserted under these indemnities, nor the amounts thereof (if any). As a result, the Company cannot estimate the maximum potential amount of future payments under these indemnities and therefore, no liability has been recorded. Service and Product Warranties and Extraordinary Rework Provisions for estimated expenses related to service and product warranties and certain extraordinary rework are evaluated on a quarterly basis. These costs are accrued and are recorded to unallocated cost of goods sold. These estimates are established using historical information on the nature, frequency, and average cost of warranty claims, including the experience of industry peers. In the case of new development products or new customers, the Company considers other factors including the experience of other entities in the same business and management judgment, among others. Service warranty and extraordinary work is reported in current liabilities and other liabilities on the Company’s Condensed Consolidated Balance Sheets. The warranty balance presented in the table below includes unresolved warranty claims that are in dispute in regard to their value as well as their contractual liability. The Company estimated the total costs related to some of these claims; however, there is significant uncertainty surrounding the disposition of these disputed claims and as such, the ultimate determination of the provision’s adequacy requires significant management judgment. The amount of the specific provisions recorded against disputed warranty claims was $2.3 as of March 28, 2024 and December 31, 2023. These specific provisions represent the Company’s best estimate of probable warranty claims. Should the Company incur higher than expected warranty costs and/or discover new or additional information related to these warranty provisions, the Company may incur additional charges that exceed these recorded provisions. The Company utilized available information to make appropriate assessments, however the Company recognizes that data on actual claims experience is of limited duration and therefore, claims projections are subject to significant judgment. The amount of the reasonably possible disputed warranty claims in excess of the specific warranty provision was $3.4 as of March 28, 2024 and December 31, 2023. The following is a roll forward of the service warranty and extraordinary rework balance at March 28, 2024: Balance, December 31, 2023 $ 82.7 Charges (release) to costs and expenses 1.0 Payouts (1.2) Exchange rate (0.1) Balance, March 28, 2024 $ 82.4

Other Income (Expense), Net

Other Income (Expense), Net	3 Months Ended
	Mar. 28, 2024
Other Nonoperating Income (Expense) [Abstract]
Other Income (Expense), Net	Other Income (Expense), Net Other income (expense), net is summarized as follows: For the Three March 28, March 30, Kansas Development Finance Authority bond $ 0.9 $ 0.7 Interest income 4.3 2.9 Foreign currency (losses) gains (1) 3.1 (8.5) (Loss) gain on foreign currency forward contract 1.2 (3.4) Loss on sale of accounts receivable (10.6) (11.2) Pension (expense) income (2) 3.6 (62.7) Excise tax on pension assets reversion (3) — (35.9) Other (0.2) 0.7 Total $ 2.3 $ (117.4) (1) Foreign currency gains and losses are due to the impact of movement in foreign currency exchange rates on long-term contractual rights/obligations, as well as cash and both trade and intercompany receivables/payables that are denominated in a currency other than the entity’s functional currency. (2) See Note 15 Pension and Other Post-Retirement Benefits. Pension expense for the three months ended March 30, 2023 includes a $64.6 non-cash, pre-tax non-operating settlement charge related to the PVP A termination. (3) Excise tax related to the reversion of excess plan assets for the three months ended March 30, 2023. See Note 15 Pension and Other Post-Retirement Benefits.

Other Liabilities

Other Liabilities	3 Months Ended
	Mar. 28, 2024
Other Liabilities Disclosure [Abstract]
Other Liabilities Disclosure	21. Other Liabilities Included on the Company’s Condensed Consolidated Balance Sheet for the three months ended March 28, 2024 is a liability related to the customer financing of $180.0 from Boeing received in the twelve months ended December 31, 2023. Per the terms of the amended agreement, $90.0 is payable in December 2025 and the remaining $90.0 is payable in equal $45.0 installments in December 2026 and 2027. Given those terms, the entire $180.0 of the advance is included in the Other non-current liabilities

Segment Information

Segment Information	3 Months Ended
	Mar. 28, 2024
Segment Reporting [Abstract]
Segment Information	Segment Information The Company operates in three principal segments: Commercial, Defense & Space and Aftermarket. Approximately 83% of the Company’s net revenues for the three months ended March 28, 2024 came from the Company’s two largest customers, Boeing and Airbus. Boeing represents a substantial portion of the Company’s revenues across segments. Airbus represents a substantial portion of revenues in the Commercial segment. The Company’s primary profitability measure to review a segment’s operating performance is segment operating income before corporate selling, general and administrative expenses and research and development. Corporate selling, general and administrative expenses include centralized functions such as accounting, treasury and human resources that are not specifically related to the Company’s operating segments and are not allocated in measuring the operating segments’ profitability and performance and net profit margins. Research and development includes research and development efforts that benefit the Company as a whole and are not unique to a specific segment. These items are not specifically related to the Company’s operating segments and are not utilized in measuring the operating segments’ profitability and performance. The Company’s Commercial segment includes design and manufacturing of forward, mid, and rear fuselage sections and systems, struts/pylons, nacelles (including thrust reversers) and related engine structural components, wings, and wing components (including flight control surfaces), as well as other miscellaneous structural parts for large commercial aircraft and/or business/regional jets. Sales from this segment are primarily to the aircraft OEMs or engine OEMs of large commercial aircraft and/or business/regional jet programs. Approximately 71% and 70% of Commercial segment net revenues came from the Company’s contracts with Boeing for the three months ended March 28, 2024, and March 30, 2023, respectively. Approximately 23% and 23% of Commercial segment net revenues came from the Company’s contracts with Airbus for the three months ended March 28, 2024, and March 30, 2023, respectively. The Commercial segment manufactures products at the Company’s facilities in Wichita, Kansas; Tulsa, Oklahoma; Kinston, North Carolina; Prestwick, Scotland; Casablanca, Morocco; Belfast, Northern Ireland; and Subang, Malaysia. The Commercial segment also includes an assembly plant for the A350 XWB aircraft in Saint-Nazaire, France. The Company’s Defense & Space segment includes design and manufacturing of fuselage, strut, nacelle, and wing aerostructures (primarily) for U.S. Government defense programs, including Boeing P-8 and KC-46 Tanker, which are commercial aircraft that are modified for military use. The segment also includes fabrication, bonding, assembly, testing tooling, processing, engineering analysis, and training on fixed wing aircraft aerostructures, missiles and hypersonics work, including solid rocket motor throats and nozzles and re-entry vehicle thermal protections systems, forward cockpit and cabin, and fuselage work on rotorcraft aerostructures. Sales from this segment are primarily to the prime contractors on various U.S. Government defense program contracts for which the Company is a sub-contractor. A significant portion of the Company’s Defense & Space segment revenues are represented by defense business that is classified by the U.S. Government and cannot be specifically described. A significant portion of Defense & Space segment net revenues came from the Company’s contracts with two individual customers for the three months ended March 28, 2024, and March 30, 2023. The Defense & Space segment manufactures products at the Company’s facilities in Wichita, KS; Tulsa, OK; Biddeford, ME; Woonsocket, RI; Belfast, Northern Ireland; and Prestwick, Scotland. The Company’s Aftermarket segment includes design, manufacturing, and marketing of spare parts and maintenance, repair, and overhaul ( “ MRO ” ) services, repairs for flight control surfaces and nacelles, radome repairs, rotable assets, engineering services, advanced composite repair, and other repair and overhaul services. Approximately 58% and 45% of Aftermarket segment net revenues came from the Company’s contracts with a single customer for the three months ended March 28, 2024, and March 30, 2023, respectively. The Aftermarket segment manufactures products at the Company's facilities in Wichita, KS; Tulsa, OK; Kinston, North Carolina; Dallas, TX; Prestwick, Scotland; Casablanca, Morocco; and Belfast, Northern Ireland. The Company’s segments are consistent with the organization and responsibilities of management reporting to the chief operating decision-maker for the purpose of assessing performance. The Company’s definition of segment operating income differs from Operating income as presented in its primary financial statements and a reconciliation of the segment and consolidated results is provided in the table set forth below. While some working capital accounts are maintained on a segment basis, much of the Company’s assets are not managed or maintained on a segment basis. Property, plant, and equipment, including tooling, is used in the design and production of products for each of the segments and, therefore, is not allocated to any individual segment. In addition, cash, prepaid expenses, other assets, and deferred taxes are managed and maintained on a consolidated basis and generally do not pertain to any particular segment. Raw materials and certain component parts are used in aerostructure production across all segments. Work-in-process inventory is identifiable by segment but is managed and evaluated at the program level. As there is no segmentation of the Company’s productive assets, depreciation expense (included in fixed manufacturing costs and selling, general and administrative expenses) and capital expenditures, no allocation of these amounts has been made solely for purposes of segment disclosure requirements. The following table shows segment revenues and operating income (loss) for the three months ended March 28, 2024 and March 30, 2023: Three Months Ended March 28, March 30, Segment Revenues Commercial $ 1,356.1 $ 1,148.5 Defense & Space 250.8 188.4 Aftermarket 95.9 94.5 $ 1,702.8 $ 1,431.4 Segment Operating Income (Loss) Commercial (1) $ (484.9) $ (45.5) Defense & Space (2) 32.2 19.2 Aftermarket 17.2 19.2 $ (435.5) $ (7.1) SG&A (81.5) (77.4) Research and development (10.6) (10.6) Total operating loss $ (527.6) $ (95.1) (1) The three months ended March 28, 2024 include excess capacity production costs of $24.9 related to the temporary B737 MAX and A220 production schedule changes. The three months ended March 30, 2023 include $40.9 of excess capacity costs related to the temporary B737 MAX, A320 and A220 production schedule changes and $5.4 of restructuring costs.

Restructuring Charges (Notes)

Restructuring Charges (Notes)	3 Months Ended
	Mar. 28, 2024
Restructuring Costs [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	Restructuring Costs Restructuring costs are presented separately as a component of operating loss on the Condensed Consolidated Statements of Operations. The total restructuring costs for the three months ended March 28, 2024 were $0.0 . The Company’s results of operations for the three months ended March 30, 2023 includes restructuring costs related to the Voluntary Separation Program (“VSP”) that was offered to reduce structural costs by reducing indirect headcount. Participants in the VSP received a lump sum severance payment based on their years of Company service.

Payables and Accruals

Payables and Accruals	3 Months Ended
	Mar. 28, 2024
Payables and Accruals [Abstract]
Supplier Finance Program	24. Supplier Financing The Company has provided certain suppliers with access to a supply chain financing program through facilities with third-party financing institutions. The Company’s suppliers’ ability to access the program is primarily dependent upon the strength of the Company’s financial condition and certain qualifying criteria. The program allows these suppliers to monetize their receivables prior to the contractual payment date, subject to payment of a discount. The capacity of the program is limited to $110.0 at any point in time. If a supplier’s request exceeds the program limit, then it will be honored when capacity is available. Under the supply chain financing program, the Company agrees to pay the third-party financing institution the stated amount of confirmed invoices from its designated suppliers on the original maturity dates of the invoices, and suppliers have the ability to be paid from the third-party financing institution on an accelerated basis. The Company’s suppliers’ election to sell one or more of the Company’s confirmed obligations under the supply chain financing program is optional. The Company’s responsibility is limited to making payment on the terms originally negotiated with its suppliers for up to 120 days, regardless of whether the suppliers elect to sell their receivables to the third-party financing institution. Within the current population of qualified suppliers, there are no payment discounts offered or taken at any point by the financing institution or by the Company. The Company or the third-party financing institution may terminate the agreement upon at least 45 days’ notice. The balance of confirmed obligations outstanding to suppliers who elect to participate in the supply chain financing program is included in the Company’s Accounts payable balance on the Company’s Condensed Consolidated Balance Sheets. As of March 28, 2024, the balance of confirmed obligations outstanding was $137.8, a decrease of $17.8 over the balance as of December 31, 2023 of $155.6. In the comparable prior year period, confirmed obligations outstanding were $110.6 as of March 30, 2023, an increase of $8.6 over the balance as of December 31, 2022. While changes in each perio

Business Combinations and Asset

Business Combinations and Asset Acquisitions	3 Months Ended
	Mar. 28, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Business Acquisition, Description of Acquired Entity	25. Acquisitions T.E.A.M., Inc. On November 23, 2022, Spirit AeroSystems Textiles, LLC, a fully owned subsidiary of Spirit AeroSystems, Inc. ( “ Spirit Textiles ” ) closed its purchase of substantially all of the assets and all of the liabilities of T.E.A.M., Inc., a Rhode Island corporation, which is engaged in the business of manufacturing and engineering textiles, composites, and textile and composite products, for cash consideration of $31.3. The acquisition was accounted for as a business combination in accordance with ASC Topic 805, Business Combinations. The purchase price has been allocated among assets acquired and liabilities assumed at fair value based on information currently available, with the excess purchase price recorded as goodwill, which is fully allocated to the Defense & Space segment. As of December 31, 2022, t he Company had preliminarily concluded, but not finalized, its assessment and purchase price allocation of the acquisition. The final fair value determination was subject to a contractual post-closing working capital true-up, which the Company concluded in the three months ended March 30, 2023. The final purchase price allocation resulte d in $0.6 adjustments to the assets acquired and the liabilities assumed that were recorded as of the acquisition date, which were included in the Condensed Consolidated Balance Sheet as of December 31, 2022. The adjusted assets acquired and the liabilities assumed included $8.3 of property, plant, and equipment, $1.7 of working capital, $13.5 of intangible assets and $7.7 allocated to goodwill, wh ich is expected to be deductible for tax purposes. Operating income for the first quarters of 2023 and 2024 was immaterial and reported within the Defense & Space segment. There were no acquisition-related expenses for the three months ended March 28, 2024 and March 30, 2023, respectively.

Subsequent Event (Notes)

Subsequent Event (Notes)	3 Months Ended
	Mar. 28, 2024
Subsequent Event [Line Items]
Subsequent Events [Text Block]	26. Subsequent Events As described in the Form 8-K filed by the Company on April 23, 2024, on April 18, 2024, the Company entered into the MOA with Boeing to provide $425.0 of cash advances, based upon the Company maintaining a production rate that supports Boeing’s production demand in accordance with certain long-term supply agreements, which Spirit expects to receive in the second quarter of 2024. The MOA requires repayment installments of $36.6 on June 12, 2024, $89.5 on July 17, 2024, $150.6 on August 14, 2024, $134.3 on September 18, 2024, and $14.0 on October 16, 2024. The Company’s repayment obligation will be accelerated, and any outstanding amount advanced under the agreement will immediately become due and payable, in the event that (i) the Company fails to make any repayment in full on the applicable Repayment Date, (ii) the Company fails to submit a satisfactory written confirmation that the Company is able to and intends to make the required repayment thirty days prior to each Repayment Date, as required under the agreement, (iii) the Company repudiates any performance obligation under this MOA or certain of the Company’s existing agreements with Boeing, (iv) there occurs, either as to Spirit, Spirit Holdings or any of their respective subsidiaries, any of the events of default (generally relating to insolvency, reorganization, liquidation or similar proceedings, or to business suspension, dissolution or winding-up) described in specified provisions of the Company’s existing agreements with Boeing, then all amounts of the advances from the MOA that remain outstanding to Boeing pursuant to the repayment provisions of the MOA as of such time will become immediately due and payable. Subsequent to the end of the first quarter, Spirit received indications that Boeing expects a slower increase in production and deliveries of B787 planes. While the Company has not received a formal schedule change from its customer, based on expected changes to production and delivery schedules, the Company has completed a preliminary assessment relevant to the expected impact of this schedule change. As a result of this preliminary assessment, the Company expects to incur an incremental forward loss of approximately $50 to $60 in the second quarter of 2024 due to the impact of reduced production volumes and the ability for the Company to reduce variable costs in a timely manner and the corresponding amount of fixed overhead absorption applied to lower deliveries. This preliminary assessment is subject to change if Boeing further revises its production and delivery plans.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss) Attributable to Parent	$ (616.7)	$ (281.2)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 28, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false

New Accounting Pronouncements (

New Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 28, 2024
Accounting Policies [Abstract]
New Accounting Pronouncements, Policy [Policy Text Block]	. New Accounting Pronouncements In December 2022, the FASB issued ASU No. 2022-06, which defers the sunset date of Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting from December 31, 2022 to December 31, 2024. ASU No. 2022-06 was effective upon issuance. ASU No. 2022-06 provides temporary optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting, providing optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. To date, the Company has not had a modification to which the application of this guidance is applicable. The Company will continue evaluating the potential impact of adopting this guidance on its consolidated financial statements, the impact of which is not expected to be material. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . ASU No. 2023-07 is effective on a retrospective basis for fiscal years beginning after December 15, 2023, and interim periods in fiscal years beginning after December 15, 2024. Early adoption is permitted, including in an interim period. The Company will continue evaluating the potential impact of adopting this guidance. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures , which modifies FASB Accounting Standards Codification 740 to enhance the transparency and decision usefulness of income tax disclosures. ASU No. 2023-09 is effective on a prospective basis for annual periods beginning after December 15, 2024, with early adoption permitted. The Company has not elected early adoption and implementation of this guidance. The guidance will be adopted and implemented for the Company’s fiscal year beginning January 1, 2025. The adoption is not expected to have a material impact to our financial position or results of operations. In March 2024, the FASB issued ASU No. 2024-01 Compensation - Stock Compensation (Topic 718) - Scope Application of Profits Interest and Similar Awards which clarifies how an entity determines whether a profits interest or similar award is within the scope of Topic 718 or if it is not a share-based payment arrangement and therefore within the scope of other guidance. ASU 2024-01 provides an illustrative example with multiple fact patterns and also amends certain language in the “Scope” and “Scope Exceptions” sections of Topic 718 to improve its clarity regarding scope application. Entities can apply the amendments either retrospectively to all prior periods presented in the financial statements or prospectively to profits interest and similar awards granted or modified on or after the date of adoption. ASU 2024-01 is effective January 1, 2025, including interim periods, and is not expected to have a significant impact on our financial statements. In March 2024, the FASB issued ASU 2024-02 Codification Improvements - Amendments to Remove References to the Concepts Statements which amends the Codification to remove references to various concepts statements and impacts a variety of topics in the Codification. The amendments apply to all reporting entities within the scope of the affected accounting guidance, but in most instances the references removed are extraneous and not required to understand or apply the guidance. Generally, the amendments in ASU 2024-02 are not intended to result in significant accounting changes for most entities. ASU 2024-02 is effective January 1, 2025 and is not expected to have a significant impact on our financial statements.

Accounts Receivable and Allow_2

Accounts Receivable and Allowance for Credit Losses Allowance for Credit Losses (Policies)	3 Months Ended
	Mar. 28, 2024
Credit Loss [Abstract]
Credit Loss, Financial Instrument [Text Block]	Allowance for Credit Losses During the three months ended March 28, 2024, there have been no significant changes in the factors that influenced management’s current estimate of expected credit losses, nor changes to the Company’s accounting policies or Current Expected Credit Losses methodology. The beginning balances, current period activity, and ending balances of the allocation for credit losses on accounts receivable and contract assets were not material.

Leases (Policies)

Leases (Policies)	3 Months Ended
	Mar. 28, 2024
Leases [Abstract]
Lessee, Leases [Policy Text Block]	The Company determines if an arrangement is a lease at the inception of a signed agreement. Operating leases are included in right-of-use (“ROU”) assets (long-term), short-term operating lease liabilities, and long-term operating lease liabilities on the Company’s Condensed Consolidated Balance Sheets. Finance leases are included in Property, Plant and Equipment, current maturities of long-term debt, and long-term debt. ROU assets represent the right of the Company to use an underlying asset for the length of the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the lease commencement date based on the estimated present value of lease payments over the lease term. To determine the present value of lease payments, the Company uses its estimated incremental borrowing rate or the implicit rate, if readily determinable. The estimated incremental borrowing rate is based on information available at the lease commencement date, including any recent debt issuances and publicly available data for instruments with similar characteristics. The ROU asset also includes any lease payments made and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease and, when it is reasonably certain that an option will be exercised, those options are included in the net present value calculation. Leases with a term of 12 months or less, which are primarily related to automobiles and manufacturing equipment, are not recorded on the Condensed Consolidated Balance Sheets. The aggregate amount of lease cost for leases with a term of 12 months or less is not material. The Company has lease agreements that include lease and non-lease components, which are generally accounted for separately. For certain leases (primarily related to IT equipment), the Company does account for the lease and non-lease

Changes in Estimates Changes in

Changes in Estimates Changes in Estimates (Tables)	3 Months Ended
	Mar. 28, 2024
Accounting Changes and Error Corrections [Abstract]
Schedule of Change in Accounting Estimate [Table Text Block]	Changes in estimates are summarized below: For the Three Months Ended Changes in Estimates March 28, 2024 March 30, 2023 (Unfavorable) Favorable Cumulative Catch-up Adjustment by Segment Commercial $ (38.9) $ (11.0) Defense & Space (0.3) (0.9) Aftermarket — — Total (Unfavorable) Favorable Cumulative Catch-up Adjustment $ (39.2) $ (11.9) Changes in Estimates on Loss Programs (Forward Loss) by Segment Commercial $ (493.8) $ (109.9) Defense & Space (1.6) (0.1) Aftermarket — — Total Changes in Estimates (Forward Loss) on Loss Programs $ (495.4) $ (110.0) Total Change in Estimate $ (534.6) $ (121.9) EPS Impact (diluted per share based upon applicable forecasted effective tax rate) $ (4.68) $ (1.14)

Accounts Receivable, net (Table

Accounts Receivable, net (Tables)	3 Months Ended
	Mar. 28, 2024
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts Receivable, Net	Accounts receivable, net consists of the following: March 28, December 31, Trade receivables $ 552.1 $ 555.8 Other 40.5 42.0 Less: allowance for credit losses (15.1) (12.3) Accounts receivable, net $ 577.5 $ 585.5

Revenue (Tables)

Revenue (Tables) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 1,702.8	$ 1,431.4
Boeing [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,088.6	921.1
Airbus [Member]
Disaggregation of Revenue [Line Items]
Revenues	317.1	267.6
Other Customer [Member]
Disaggregation of Revenue [Line Items]
Revenues	297.1	242.7
UNITED STATES
Disaggregation of Revenue [Line Items]
Revenues	1,350.7	1,149.7
UNITED KINGDOM
Disaggregation of Revenue [Line Items]
Revenues	157.3	170.3
Other International [Member]
Disaggregation of Revenue [Line Items]
Revenues	194.8	111.4
Total International [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 352.1	$ 281.7

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 28, 2024
Property, Plant and Equipment [Abstract]
Property, plant and equipment, net	Property, plant and equipment, net consists of the following: March 28, December 31, Land $ 30.5 $ 30.5 Buildings (including improvements) 1,314.0 1,307.6 Machinery and equipment 2,481.7 2,460.6 Tooling 1,071.9 1,064.8 Capitalized software 338.6 338.4 Construction-in-progress 110.6 119.0 Total 5,347.3 5,320.9 Less: accumulated depreciation (3,307.2) (3,236.7) Property, plant and equipment, net $ 2,040.1 $ 2,084.2

Other Assets (Tables)

Other Assets (Tables)	3 Months Ended
	Mar. 28, 2024
Other Assets, Noncurrent [Abstract]
Schedule of Other Assets	Other current assets are summarized as follows: March 28, December 31, Prepaid expenses $ 46.6 $ 34.8 Income tax receivable 2.6 5.3 Other assets - short-term 7.7 12.4 Total other current assets $ 56.9 $ 52.5 Other assets are summarized as follows: March 28, December 31, Deferred financing Deferred financing costs $ 0.9 $ 0.9 Less: Accumulated amortization - deferred financing costs (0.9) (0.9) Deferred financing costs, net $ — $ — Other Supply agreements (1) $ 2.4 $ 3.5 Equity in net assets of affiliates 0.7 0.8 Restricted cash - collateral requirements 27.7 22.3 Rotables 45.4 44.0 Other 30.1 29.3 Total other long-term assets $ 106.3 $ 99.9 (1) Certain payments accounted for as consideration paid by the Company to a customer are being amortized as reductions to net revenues.

Other Assets Intangible Assets

Other Assets Intangible Assets (Tables)	3 Months Ended
	Mar. 28, 2024
Finite-Lived Intangible Assets [Line Items]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	Intangible assets are summarized as follows: March 28, December 31, Intangible assets Favorable leasehold interests $ 2.8 $ 2.8 Developed technology asset 103.1 103.1 Customer relationships intangible asset 139.6 139.6 Total intangible assets 245.5 245.5 Less: Accumulated amortization - favorable leasehold interest (2.2) (2.1) Accumulated amortization - developed technology asset (23.6) (21.9) Accumulated amortization - customer relationship (27.3) (25.3) Intangible assets, net $ 192.4 $ 196.2 Amortization expense was $3.8 and $3.7 for the for the three months ended March 28, 2024 and March 30, 2023, respectively.
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	The amortization for each of the five succeeding years relating to intangible assets currently recorded in the Condensed Consolidated Balance Sheets and the weighted average amortization is estimated to be the following as of March 28, 2024: Year Customer relationships Favorable leasehold interest Developed technology Total remaining in 2024 $ 6.2 $ 0.1 $ 5.2 $ 11.5 2025 8.2 0.1 6.9 15.2 2026 8.2 0.1 6.9 15.2 2027 8.2 0.1 6.9 15.2 2028 8.2 0.1 6.9 15.2 2029 7.8 0.1 6.9 14.8 Weighted average amortization period 14.2 years 5.3 years 11.6 years 13.1 years

Other Assets Goodwill (Tables)

Other Assets Goodwill (Tables)	3 Months Ended
	Mar. 28, 2024
Goodwill [Abstract]
Goodwill Disclosure [Text Block]	Goodwill is summarized as follows: Changes in Goodwill Balance Balance at Balance at Segment December 31, Acquisitions Adjustments/Other Currency Exchange March 28, Commercial $ 296.6 $ — $ — $ — $ 296.6 Defense & Space $ 13.2 $ — $ — $ — $ 13.2 Aftermarket $ 321.4 $ — $ — $ — $ 321.4 $ 631.2 $ — $ — $ — $ 631.2 The total goodwill value includes no a ccumulated impairment loss in any of the periods present ed. The Company assesses goodwill for impairment annually or more frequently if events or circumstances indicate that the fair value of a reporting unit that includes goodwill may be lower than its carrying value. F

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 28, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	The guidance discloses three levels of inputs that may be used to measure fair value: Level 1 Quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 1 assets and liabilities include debt and equity securities and derivative contracts that are traded in an active exchange market. Level 2 Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 2 assets and liabilities include debt securities with quoted prices that are traded less frequently than exchange-traded instruments and derivative contracts whose value is determined using a pricing model with inputs that are observable in the market or can be derived principally from or corroborated by observable market data. Observable inputs, such as current and forward interest rates and foreign exchange rates, are used in determining the fair value of the interest rate swaps and foreign currency hedge contracts. Level 3 Unobservable inputs that are supported by little or no market activity and are significant to the fair value of assets and liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation.
Carrying Amount And Estimated Fair Value Of Long Term Debt	The following table presents the carrying amount and estimated fair value of long-term debt. See also Note 13 Derivative and Hedging Activities and Note 15 Pension and Other Post-Retirement Benefits. March 28, 2024 December 31, 2023 Carrying Fair Carrying Fair Senior secured term loan B (including current portion) $ 572.3 $ 575.1 (2) $ 571.0 $ 573.1 (2) Exchangeable senior notes due 2028 222.5 313.7 (2) 222.2 292.6 (2) Senior notes due 2025 20.8 20.8 (1) 20.8 20.7 (1) Senior secured noted due 2026 299.2 288.1 (1) 299.1 288.0 (1) Senior notes due 2028 696.7 652.9 (1) 696.6 616.8 (1) Senior secured first lien notes due 2029 888.8 970.2 (1) 888.4 973.0 (1) Senior secured second lien notes due 2030 1,180.3 1,320.8 (1) 1,180.0 1,273.1 (1) Total $ 3,880.6 $ 4,141.6 $ 3,878.1 $ 4,037.3 (1) Level 1 Fair Value hierarchy (2)

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 28, 2024
Debt Disclosure [Abstract]
Long Term Debt And Capital Lease Obligations Current And Non Current	Total debt shown on the Condensed Consolidated Balance Sheets is comprised of the following: March 28, 2024 December 31, 2023 Current Noncurrent Current Noncurrent Senior secured term loan B $ 5.8 $ 566.5 $ 5.8 $ 565.2 Exchangeable senior notes due 2028 — 222.5 — 222.2 Senior notes due 2025 20.8 — — 20.8 Senior secured notes due 2026 — 299.2 — 299.1 Senior notes due 2028 — 696.7 — 696.6 Senior secured first lien notes due 2029 — 888.8 — 888.4 Senior secured second lien notes due 2030 — 1,180.3 — 1,180.0 Present value of finance lease obligations 46.6 86.2 48.3 95.0 Other 7.8 51.0 10.7 51.4 Total $ 81.0 $ 3,991.2 $ 64.8 $ 4,018.7

Pension and Other Post-Retire_2

Pension and Other Post-Retirement Benefits (Tables)	3 Months Ended
	Mar. 28, 2024
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Change in projected benefit obligations	Defined Benefit Plans For the Three Components of Net Periodic Pension Expense (Income) March 28, March 30, Service cost $ 0.6 $ 0.8 Interest cost 17.7 20.1 Expected return on plan assets (21.6) (21.8) Amortization of net loss — 0.1 Settlement loss (gain) (1) — 64.6 Net periodic pension expense (income) $ (3.3) $ 63.8 Other Benefits For the Three Components of Other Benefit Expense (Income) March 28, March 30, Service cost $ 0.2 $ 0.2 Interest cost 0.4 0.4 Amortization of prior service cost 0.3 (0.2) Amortization of net gain (0.4) (0.5) Net periodic other benefit income $ 0.5 $ (0.1) (1) Includes a $64.6 settlement charge for PVP A during the three months ended March 30, 2023. The components of net periodic pension expense (income) and other benefit income, other than the service cost component, are included in Other income (expense), net in the Company’s Condensed Consolidated Statements of Operations. See Note 20 Other Income (Expense), Net. Effective October 1, 2021, the Company spun off a portion of the existing PVP A, to a new plan called PVP B (“PVP B ” ). As part of the PVP B plan termination process, a lump sum offering was provided during 2021 for PVP B participants and the final asset distribution was completed in the first quarter of 2022. At March 28, 2024, a pension reversion asset of $50.0 is recorded on the Restricted plan assets line item on the Company’s Condensed Consolidated Balance Sheets. Restricted plan assets are expected to be reduced over the next five years as they are distributed to employees under a qualified compensation and benefit program. Restricted plan assets are valued at fair value with gain or loss on fair value adjustments recognized within other income. The underlying investments’ fair value measurement levels under the FASB’s authoritative guidance on fair value measurements are Level 2, see Note 12 Fair Value Measurements. Separately, during the three months ended March 30, 2023, the Company received an excess plan asset reversion of $179.5 of cash from PVP A. This transaction was accounted for as a negative contribution, and is included on the Pension plans employer contributions line item on the Company’s Condensed Consolidated Statement of Cash Flows for the three months ended March 30, 2023. Excise tax of $35.9 related to the reversion of excess plan assets was separately recorded to the Other (expense) income, net line item on the Company’s Condensed Consolidated Statements of Operations for the three months ended March 30, 2023. See also Note 20 Other Income (Expense), Net . I n July 2022, the Company adopted and communicated to participants a plan to terminate the PVP A. During the three months ended March 30, 2023, the Company r ecognized non-cash, pre-tax non-operating accounting charges of $64.6 related to the plan termination, primarily reflecting the accounting for a group annuity purchase made in the first quarter of 2023, which resulted in a settlement charge related to the accelerated recognition of the actuarial losses for the PVP A plan that were previously included in the Accumulated other comprehensive loss

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 28, 2024
Stockholders' Equity Note [Abstract]
Basic and Diluted Earnings per share	The following table sets forth the computation of basic and diluted earnings per share: For the Three Months Ended March 28, 2024 March 30, 2023 Income Shares Per Share Income Shares Per Share Basic EPS Loss available to common stockholders $ (616.7) 116.2 $ (5.31) $ (281.2) 104.9 $ (2.68) Income allocated to participating securities — — — — Net loss $ (616.7) $ (281.2) Diluted potential common shares — — Diluted EPS Net loss $ (616.7) 116.2 $ (5.31) $ (281.2) 104.9 $ (2.68) Included in the outstanding Common Stock were 0.0 million and 0.1 million of issued but unvested shares at March 28, 2024 and March 30, 2023, respectively, which are excluded from the basic Earnings Per Share (“EPS”) calculation. Shares of Common Stock of 9.6 million were excluded from diluted EPS as a result of incurring a net loss for the three months ended March 28, 2024 , as the effect would have been antidilutive. Additionally, diluted EPS for the three months ended March 28, 2024 excludes 0.2 million shares that may be dilutive shares of Common Stock in the future but were not included in the computation of diluted EPS because the effect was either antidilutive or the performance condition was not met. Shares of Common Stock of 0.9 million were excluded from diluted EPS as a result of incurring a net loss for the three months ended March 30, 2023, as the effect would have been antidilutive. Additionally, diluted EPS for the three months ended March 30, 2023 excludes 0.2 million shares that may be dilutive shares of Common Stock in the future but were not included in the computation of diluted EPS because the effect was either antidilutive or the performance condition was not met.
Schedule of Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Loss is summarized by component as follows: As of As of March 28, 2024 December 31, 2023 Pension $ (18.4) $ (18.7) SERP/Retiree medical 6.7 6.8 Derivatives - foreign currency hedge — 2.2 Foreign currency impact on long-term intercompany loan (14.9) (14.6) Currency translation adjustment (70.6) (65.3) Total accumulated other comprehensive loss $ (97.2) $ (89.6)

Commitments, Contingencies an_2

Commitments, Contingencies and Guarantees (Tables)	3 Months Ended
	Mar. 28, 2024
Commitments Contingencies And Guarantees [Abstract]
Service warranty roll forward	The following is a roll forward of the service warranty and extraordinary rework balance at March 28, 2024: Balance, December 31, 2023 $ 82.7 Charges (release) to costs and expenses 1.0 Payouts (1.2) Exchange rate (0.1) Balance, March 28, 2024 $ 82.4

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	3 Months Ended
	Mar. 28, 2024
Other Nonoperating Income (Expense) [Abstract]
Other Income Expense Net	Other income (expense), net is summarized as follows: For the Three March 28, March 30, Kansas Development Finance Authority bond $ 0.9 $ 0.7 Interest income 4.3 2.9 Foreign currency (losses) gains (1) 3.1 (8.5) (Loss) gain on foreign currency forward contract 1.2 (3.4) Loss on sale of accounts receivable (10.6) (11.2) Pension (expense) income (2) 3.6 (62.7) Excise tax on pension assets reversion (3) — (35.9) Other (0.2) 0.7 Total $ 2.3 $ (117.4)

Changes in Estimates (Details)

Changes in Estimates (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Change In Estimate [Line Items]
Changes in Contract Estimates, aggregate, Affecting earnings from Continuing Operations, per Share diluted	$ (4.68)	$ (1.14)
Change In Accounting Estimate, aggregate	$ (534.6)	$ (121.9)
Cost of Goods and Services Sold	2,138.3	1,432.2
Cumulative catch-up adjustment [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(39.2)	(11.9)
Forward Loss [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(495.4)	(110)
Commercial Segment [Member] | Cumulative catch-up adjustment [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(38.9)	(11)
Commercial Segment [Member] | Forward Loss [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(493.8)	(109.9)
Defense & Space Segment [Member] | Cumulative catch-up adjustment [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(0.3)	(0.9)
Defense & Space Segment [Member] | Forward Loss [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(1.6)	(0.1)
Aftermarket Segment [Member] | Cumulative catch-up adjustment [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	0	0
Aftermarket Segment [Member] | Forward Loss [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	$ 0	$ 0

Accounts Receivable, net (Detai

Accounts Receivable, net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Transfer of Financial Assets Accounted for as Sales, Amount Derecognized	$ 814
Trade receivables	552.1		$ 555.8
Other	40.5		42
Less: allowance for doubtful accounts	(15.1)		(12.3)
Accounts receivable, net	577.5		$ 585.5
Gain (Loss) on Sale of Accounts Receivable	$ 10.6	$ 11.2

Contract with customer, asset_2

Contract with customer, asset and liability (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenues	$ 1,702.8	$ 1,431.4
Contract with Customer, Liability, Revenue Recognized	$ 49.5	25.8
Disaggregation of Revenue [Table Text Block]	Disaggregation of Revenue The Company disaggregates revenue based on the method of measuring satisfaction of the performance obligation either over time or at a point in time, based upon the location where products and services are transferred to the customer, and based upon major customer. The Company’s principal operating segments and related revenue are noted in Note 22 Segment Information . The following tables show disaggregated revenues for the periods ended March 28, 2024 and March 30, 2023: For the Three Revenue March 28, March 30, Contracts with performance obligations satisfied over time $ 1,282.1 $ 1,112.8 Contracts with performance obligations satisfied at a point in time 420.7 318.6 Total Revenue $ 1,702.8 $ 1,431.4 The following table disaggregates revenue by major customer: For the Three Customer March 28, March 30, Boeing $ 1,088.6 $ 921.1 Airbus 317.1 267.6 Other 297.1 242.7 Total Revenue $ 1,702.8 $ 1,431.4 The following table disaggregates revenue based upon the location where control of products is transferred to the customer: For the Three Location March 28, March 30, United States $ 1,350.7 $ 1,149.7 International United Kingdom 157.3 170.3 Other 194.8 111.4 Total International 352.1 281.7 Total Revenue $ 1,702.8 $ 1,431.4
Contract with Customer, Liability, Revenue Recognized	$ 49.5	25.8
Contract with Customer, Asset, before Allowance for Credit Loss	832.3	525.6	$ 522.9	$ 502.2
change in contract asset	309.4	23.4
Contract with Customer, Liability	(305.8)	(342.8)	(353.9)	(356.4)
change in contract liability	48.1	13.6
change in contract assets (liabilities), net	357.5	37
Contract with Customer Asset (Liability), Net	526.5	182.8	$ 169	$ 145.8
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,282.1	1,112.8
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 420.7	$ 318.6

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Disaggregation of Revenue [Table Text Block]	Disaggregation of Revenue The Company disaggregates revenue based on the method of measuring satisfaction of the performance obligation either over time or at a point in time, based upon the location where products and services are transferred to the customer, and based upon major customer. The Company’s principal operating segments and related revenue are noted in Note 22 Segment Information . The following tables show disaggregated revenues for the periods ended March 28, 2024 and March 30, 2023: For the Three Revenue March 28, March 30, Contracts with performance obligations satisfied over time $ 1,282.1 $ 1,112.8 Contracts with performance obligations satisfied at a point in time 420.7 318.6 Total Revenue $ 1,702.8 $ 1,431.4 The following table disaggregates revenue by major customer: For the Three Customer March 28, March 30, Boeing $ 1,088.6 $ 921.1 Airbus 317.1 267.6 Other 297.1 242.7 Total Revenue $ 1,702.8 $ 1,431.4 The following table disaggregates revenue based upon the location where control of products is transferred to the customer: For the Three Location March 28, March 30, United States $ 1,350.7 $ 1,149.7 International United Kingdom 157.3 170.3 Other 194.8 111.4 Total International 352.1 281.7 Total Revenue $ 1,702.8 $ 1,431.4
Revenues	$ 1,702.8	$ 1,431.4
Remaining in Current Year [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	4,766.4
2021 [Member] [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	3,152.2
2022 [Member] [Member] [Domain]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	1,299.7
2021 and after [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	754.5
Transferred over Time [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	1,282.1	1,112.8
Transferred at Point in Time [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	420.7	318.6
Boeing [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	1,088.6	921.1
Airbus [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	317.1	267.6
Other Customer [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	$ 297.1	$ 242.7

Inventory (Details)

Inventory (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023
Summary Of Inventories [Abstract]
Raw materials	$ 423.7		$ 414.4
Work-in-process	1,300.5		1,283.7
Finished goods	53		48.4
Product inventory	1,777.2		1,746.5
Capitalized pre-production	20.3		20.8
Total inventory, net	1,797.5		1,767.3
Inventory Valuation Reserves	154.6		150.2
Costs Incurred in Anticipation of Contracts	232.4		$ 262
Excess Capacity Costs- B737MAX and A320 Production Schedules	26.1	$ 43.3
Inventories [Line Items]
Excess Capacity Costs- B737MAX and A320 Production Schedules	$ 26.1	$ 43.3

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Millions	Mar. 28, 2024	Dec. 31, 2023
Property, plant and equipment, net
Land	$ 30.5	$ 30.5
Buildings (including improvements)	1,314	1,307.6
Machinery and equipment	2,481.7	2,460.6
Tooling	1,071.9	1,064.8
Capitalized software	338.6	338.4
Construction-in-progress	110.6	119
Total	5,347.3	5,320.9
Less: accumulated depreciation	(3,307.2)	(3,236.7)
Property, plant and equipment, net	$ 2,040.1	$ 2,084.2

Property, Plant and Equipment_3

Property, Plant and Equipment (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Property Plant And Equipment Textuals [Abstract]
Capitalized interest related to construction-in-progress	$ 1.2	$ 1.6
Repair and maintenance costs	44.1	42.7
Depreciation expense related to capitalized software	$ 4.4	$ 6.1

Leases (Details)

Leases (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023
Lessee Disclosure [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	33 years 6 months		33 years 2 months 12 days
Finance Lease, Weighted Average Remaining Lease Term	4 years 4 months 24 days		4 years 8 months 12 days
Assets and Liabilities, Lessee [Abstract]
Operating Lease, Liability, Current	$ 9.4		$ 9.1
Operating Lease, Liability, Noncurrent	83.5		84.3
Operating Lease, Liability	92.9
finance lease, Right-of-Use Asset, gross	336.4		336.9
Finance Lease, Right-of-Use Asset, Accumulated Amortization	(145.4)		(135.8)
Finance Lease, Right-of-Use Asset, after Accumulated Amortization	191		201.1
Finance Lease, Liability, Current	46.6		48.3
Finance Lease, Liability, Noncurrent	86.2		$ 95
Finance Lease, Liability	132.8
Lessee, Operating Lease, Lease Not yet Commenced, Description	0.4
Lessee, Finance Lease, Lease Not yet Commenced, Description	$ 15.2
Operating Lease, Weighted Average Discount Rate, Percent	6.20%		6.20%
Finance Lease, Weighted Average Discount Rate, Percent	6.40%		6.30%
Finance Lease, Liability, Payment, Due [Abstract]
Finance Lease, Liability, to be Paid, Remainder of Fiscal Year	$ 41.4
Finance Lease, Liability, to be Paid, Year Two	42.8
Finance Lease, Liability, to be Paid, Year Three	27.5
Finance Lease, Liability, to be Paid, Year Four	12.8
Finance Lease, Liability, to be Paid, Year Five	6.9
Finance Lease, Liability, to be Paid, after Year Five	22.3
Finance Lease, Liability, Payment, Due	153.7
Lease Imputed Interest Due- Financing	(20.9)
Cash Flow, Operating Activities, Lessee [Abstract]
Operating lease cost	3.7	$ 3.5
Finance Lease, Interest Payment on Liability	2.1	1.9
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	0.2	0.1
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year	11.1
Lessee, Operating Lease, Liability, to be Paid, Year Two	14.7
Lessee, Operating Lease, Liability, to be Paid, Year Three	12.2
Lessee, Operating Lease, Liability, to be Paid, Year Four	9.7
Lessee, Operating Lease, Liability, to be Paid, Year Five	8.8
Lessee, Operating Lease, Liability, to be Paid, after Year Five	174.1
Lessee, Operating Lease, Liability, to be Paid	230.6
Lease Imputed Interest Due- Operating	(137.7)
Lease, Cost [Abstract]
Operating Lease, Cost	3.5	3.7
Finance Lease, Right-of-Use Asset, Amortization	9.6	8.6
Finance Lease, Interest Expense	2.1	1.8
Lease, Cost	15.2	14.1
Cash Flow, Financing Activities, Lessee [Abstract]
Finance Lease, Principal Payments	13.3	$ 11.3
Lessee, Finance Lease, Not yet Commenced, Description [Abstract]
Lessee, Operating Lease, Lease Not yet Commenced, Description	0.4
Lessee, Finance Lease, Lease Not yet Commenced, Description	$ 15.2
Lessee, Finance Lease, Lease Not yet Commenced, Description	for manufacturing equipment, software, and facilities that are in various phases of construction or customization for the Company’s ultimate use, with lease terms between 3 and 9 years. The Company’s involvement in the construction and design process for these assets is generally limited to project management.

Other Assets (Details)

Other Assets (Details) - USD ($) $ in Millions	Mar. 28, 2024	Dec. 31, 2023	Mar. 30, 2023	Dec. 31, 2022
Other Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	$ 245.5	$ 245.5
Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year	11.5
Finite-Lived Intangible Asset, Expected Amortization, Year One	15.2
Finite-Lived Intangible Asset, Expected Amortization, Year Two	15.2
Finite-Lived Intangible Asset, Expected Amortization, Year Three	15.2
Finite-Lived Intangible Asset, Expected Amortization, Year Four	15.2
Finite-Lived Intangible Asset, Expected Amortization, Year Five	$ 14.8
Finite-Lived Intangible Assets, Remaining Amortization Period	13 years 1 month 6 days
Intangible assets
Deferred financing costs, net	$ 0	0
Goodwill	631.2	631.2
Equity in net assets of affiliates	0.7	0.8
Customer Supply Agreement	2.4	3.5
Restricted Cash, Noncurrent	27.7	22.3	$ 22.1	$ 19.6
Rotable assets	45.4	44
Other	30.1	29.3
Total other long-term assets	106.3	99.9
Prepaid Expense, Current	46.6	34.8
Income Taxes Receivable, Current	2.6	5.3
Other Assets, Miscellaneous, Current	7.7	12.4
Intangible Assets, Net (Excluding Goodwill)	192.4	196.2
Other Assets, Current	56.9	52.5
Patents [Member]
Other Assets [Line Items]
Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year	6.2
Finite-Lived Intangible Asset, Expected Amortization, Year One	8.2
Finite-Lived Intangible Asset, Expected Amortization, Year Two	8.2
Finite-Lived Intangible Asset, Expected Amortization, Year Three	8.2
Finite-Lived Intangible Asset, Expected Amortization, Year Four	8.2
Finite-Lived Intangible Asset, Expected Amortization, Year Five	$ 7.8
Finite-Lived Intangible Assets, Remaining Amortization Period	14 years 2 months 12 days
Favorable Leasehold [Member]
Other Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	$ 2.8	2.8
Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year	0.1
Finite-Lived Intangible Asset, Expected Amortization, Year One	0.1
Finite-Lived Intangible Asset, Expected Amortization, Year Two	0.1
Finite-Lived Intangible Asset, Expected Amortization, Year Three	0.1
Finite-Lived Intangible Asset, Expected Amortization, Year Four	0.1
Finite-Lived Intangible Asset, Expected Amortization, Year Five	$ 0.1
Finite-Lived Intangible Assets, Remaining Amortization Period	5 years 3 months 18 days
Intangible assets
Less: Accumulated amortization	$ (2.2)	(2.1)
Debt issuance costs [Member]
Intangible assets
Deferred financing costs	0.9	0.9
Less: Accumulated amortization-deferred financing costs	(0.9)	(0.9)
Developed Technology [Member]
Other Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	103.1	103.1
Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year	5.2
Finite-Lived Intangible Asset, Expected Amortization, Year One	6.9
Finite-Lived Intangible Asset, Expected Amortization, Year Two	6.9
Finite-Lived Intangible Asset, Expected Amortization, Year Three	6.9
Finite-Lived Intangible Asset, Expected Amortization, Year Four	6.9
Finite-Lived Intangible Asset, Expected Amortization, Year Five	$ 6.9
Finite-Lived Intangible Assets, Remaining Amortization Period	11 years 7 months 6 days
Intangible assets
Less: Accumulated amortization	$ (23.6)	(21.9)
Customer Relationships
Other Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	139.6	139.6
Intangible assets
Less: Accumulated amortization	$ (27.3)	$ (25.3)

Other Assets (Details Textuals)

Other Assets (Details Textuals) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023
Goodwill [Line Items]
Goodwill	$ 631.2		$ 631.2
Goodwill, Acquired During Period	0
Goodwill, Other Increase (Decrease)	0
Goodwill, Period Increase (Decrease)	0
Amortization of Intangible Assets	3.8	$ 3.7
Aftermarket Segment [Member]
Goodwill [Line Items]
Goodwill	321.4		321.4
Goodwill, Acquired During Period	0
Goodwill, Other Increase (Decrease)	0
Goodwill, Period Increase (Decrease)	0
Defense & Space Segment [Member]
Goodwill [Line Items]
Goodwill	13.2		13.2
Goodwill, Acquired During Period	0
Goodwill, Other Increase (Decrease)	0
Goodwill, Period Increase (Decrease)	0
Commercial Segment [Member]
Goodwill [Line Items]
Goodwill	296.6		$ 296.6
Goodwill, Acquired During Period	0
Goodwill, Other Increase (Decrease)	0
Goodwill, Period Increase (Decrease)	0
T.E.A.M., Inc. Acquisition
Goodwill [Line Items]
Goodwill	$ 7.7

Advance Payments and Deferred_2

Advance Payments and Deferred Revenue/Credits (Details) $ in Millions	Mar. 28, 2024 USD ($)
advance payments [Line Items]
Customer advances- B787 program	$ 183.2
Customer advances- Irkut program	18.9
Customer Advances - Boeing 2023 MOA	32.2
Customer advances - A220 term sheet agreement	17
First installment of net advance payment
advance payments [Line Items]
Customer Advances - A350 program	$ 100

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	Mar. 28, 2024	Dec. 31, 2023
Carrying amount and estimated fair value of long term debt
Carrying Amount	$ 3,880.6	$ 3,878.1
Fair Value	4,141.6	4,037.3
Senior Secured Notes Due 2025 [Member]
Carrying amount and estimated fair value of long term debt
Carrying Amount	20.8	20.8
Fair Value	20.8	20.7
Secured Debt Term B [Member]
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	566.5	565.2
Carrying amount and estimated fair value of long term debt
Carrying Amount	572.3	571
Fair Value	575.1	573.1
Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	299.2	299.1
Carrying amount and estimated fair value of long term debt
Carrying Amount	299.2	299.1
Fair Value	288.1	288
Senior Unsecured Notes Due 2028 [Member]
Carrying amount and estimated fair value of long term debt
Carrying Amount	696.7	696.6
Fair Value	652.9	616.8
Senior Secured Notes Due 2025
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	0	20.8
Senior Secured First Lien Notes due 2029
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	888.8	888.4
Carrying amount and estimated fair value of long term debt
Carrying Amount	888.8	888.4
Fair Value	970.2	973
Exchangeable Notes Due 2028
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	222.5	222.2
Carrying amount and estimated fair value of long term debt
Carrying Amount	222.5	222.2
Fair Value	313.7	292.6
Senior Secured Second Lien Notes due 2030
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	1,180.3	1,180
Carrying amount and estimated fair value of long term debt
Carrying Amount	1,180.3	1,180
Fair Value	$ 1,320.8	$ 1,273.1

Derivative and Hedging Activi_2

Derivative and Hedging Activities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023
Interest Rate Swaps
Foreign Currency Cash Flow Hedge Asset at Fair Value	$ 0		$ 3
Foreign Currency Cash Flow Hedge Liability at Fair Value	0		0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(1.8)	$ 2.5
Derivative, Notional Amount	161.8		$ 169.1
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 0
Maximum Length of Time Hedged in Cash Flow Hedge	9 months
Derivative, Credit Risk Related Contingent Features, Existence and Nature	Generally, the Company has agreements with its counterparties that contain a provision whereby if the Company defaults on its existing credit facilities and payment of the loans extended under such facilities is accelerated, the Company could be declared in default under its agreements, which may result in the early termination of the outstanding derivatives governed by such agreements and the payment of an early termination amount.
General Cash Flow Hedge Information [Abstract]
Objectives for Using Cash Flow Hedging Instruments	The Company has entered into currency forward contracts, each designated as a cash flow hedge upon the date of execution, for the purpose of reducing the variability of cash flows and hedging against the foreign currency exposure for forecasted payroll, pension and vendor disbursements that are expected to be made in the British Pound Sterling. The hedging program implemented is intended to reduce foreign currency exposure, and the associated forward currency contracts hedge forecasted transactions through December 2024.
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 1.2	$ (3.4)

Derivative and Hedging Activi_3

Derivative and Hedging Activities (Details 1)	3 Months Ended
	Mar. 28, 2024
Derivative [Line Items]
Maximum Length of Time Hedged in Cash Flow Hedge	9 months

Derivative and Hedging Activi_4

Derivative and Hedging Activities (Details Textual) $ in Millions	3 Months Ended
	Mar. 28, 2024 USD ($)
Derivatives Fair Value [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 0
Maximum Length of Time Hedged in Cash Flow Hedge	9 months

Debt (Details)

Debt (Details) - USD ($) $ in Millions	Mar. 28, 2024	Dec. 31, 2023
Long Term Debt And Capital Lease Obligations Current And Non Current [Abstract]
Other Long-term Debt, Current	$ 7.8	$ 10.7
Other Long-term Debt, Noncurrent	51	51.4
Long-term Debt and Lease Obligation, Current	81	64.8
Long-term Debt and Lease Obligation	3,991.2	4,018.7
Total Debt [Member]
Long Term Debt And Capital Lease Obligations Current And Non Current [Abstract]
Long-term Debt and Lease Obligation, Current	81	64.8
Long-term Debt and Lease Obligation	$ 3,991.2	$ 4,018.7

Debt (Details Textual)

Debt (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023
Debt Instrument [Line Items]
Proceeds from Lines of Credit	$ 0	$ 0.7
Long-term Debt	3,880.6		$ 3,878.1
Finance Lease, Liability, Noncurrent	86.2		95
Finance Lease, Liability, Current	46.6		48.3
Other Long-term Debt, Current	7.8		10.7
Other Long-term Debt, Noncurrent	$ 51		51.4
Senior Unsecured Notes Due 2023 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.95%
Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.85%
Long-term Debt	$ 299.2		299.1
Long-term Debt, Current Maturities	0		0
Secured Long-term Debt, Noncurrent	$ 299.2		299.1
Senior Secured Notes Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.50%
Long-term Debt	$ 20.8		20.8
Senior Unsecured Notes Due 2028 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.60%
Long-term Debt	$ 696.7		696.6
Long-term Debt, Current Maturities	0		0
Unsecured Long-term Debt, Noncurrent	696.7		696.6
Secured Debt Term B [Member]
Debt Instrument [Line Items]
Long-term Debt	572.3		571
Long-term Debt, Current Maturities	5.8		5.8
Secured Long-term Debt, Noncurrent	566.5		565.2
Senior Secured Notes Due 2025
Debt Instrument [Line Items]
Long-term Debt, Current Maturities	20.8		0
Secured Long-term Debt, Noncurrent	$ 0		20.8
Senior Secured First Lien Notes due 2029
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	9.375%
Long-term Debt	$ 888.8		888.4
Long-term Debt, Current Maturities	0		0
Secured Long-term Debt, Noncurrent	888.8		888.4
Senior Secured Notes Due 2029
Debt Instrument [Line Items]
Long-term Debt	$ 888.8
Exchangeable Notes Due 2028
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.25%
Long-term Debt	$ 222.5		222.2
Long-term Debt, Current Maturities	0		0
Secured Long-term Debt, Noncurrent	$ 222.5		222.2
Senior Secured Second Lien Notes due 2030
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	9.75%
Long-term Debt	$ 1,180.3		1,180
Long-term Debt, Current Maturities	0		0
Secured Long-term Debt, Noncurrent	$ 1,180.3		$ 1,180

Pension and Other Post-Retire_3

Pension and Other Post-Retirement Benefits Pension and Other Post-Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 0.2	$ 0.2
Defined Benefit Plan, Interest Cost	0.4	0.4
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0.3	(0.2)
Defined Benefit Plan, Amortization of Gain (Loss)	(0.4)	(0.5)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	0.5	(0.1)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	0.6	0.8
Defined Benefit Plan, Interest Cost	17.7	20.1
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0.1
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(21.6)	(21.8)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	64.6
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ (3.3)	$ 63.8

Stock Compensation (Details)

Stock Compensation (Details) - USD ($)	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
LTIA AND Prior Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company recognized total stock compensation expense, net of forfeitures	$ 10,100,000	$ 9,000,000
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Ownership Plan (ESOP), Compensation Expense	$ 700,000	$ 0
Class A [Member] | Long Term Incentive Plan RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	409,170
Fair Value Of Shares Granted	$ 11,900,000
Class A [Member] | Performance Based LTIP RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	388,386
Fair Value Of Shares Granted	$ 14,900,000
Class A [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Vested	384,734
Grant date value of shares vested	$ 16,000,000

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent	(1.82%)	1.50%
Valuation Allowance [Line Items]
Deferred Income Tax Liabilities, Net	$ 16.5		$ 9.1
Rotable assets	45.4		$ 44
Domestic Tax Authority
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Net	1.5
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance	595.2
Deferred Tax Assets, Net	1.5
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	87.1
Deferred Tax Assets, Gross	593.7
Foreign Tax Authority
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Net	13.3
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance	431.5
Deferred Tax Assets, Net	13.3
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	72.3
Deferred Tax Assets, Gross	$ 418.2

Equity (Details)

Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 925
Common Stock, Dividends, Per Share, Declared	$ 0	$ 0
Basic EPS
Income available to common shareholders	$ (616.7)	$ (281.2)
Income available to common shareholders, shares	116,200,000	104,900,000
Income available to common shareholders, per share amount	$ (5.31)	$ (2.68)
Income allocated to participating securities, shares	0	0
Net Income (Loss) Attributable to Parent	$ (616.7)	$ (281.2)
Diluted potential common shares	0	0
Diluted EPS
Net Income (Loss) Attributable to Parent	$ (616.7)	$ (281.2)
Shares	116,200,000	104,900,000
Diluted (in dollars per share)	$ (5.31)	$ (2.68)
Equity Textuals [Abstract]
Common shares outstanding issued but unvested	0	100,000
Noncontrolling interest	$ 3.9	$ 3.6	$ 3.8	$ 3.7
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(97.2)		(89.6)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax	$ 0.1	$ (64)
Class of Stock [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	9,600,000	0.9
Earnings Per Share, Potentially Dilutive Securities	0.2	0.2
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	0	100,000
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	$ 0	$ 0
Pension [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(18.4)		(18.7)
SERP and Retiree medical [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	6.7		6.8
Foreign currency impact on long term intercompany loan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(14.9)		(14.6)
Currency translation adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(70.6)		(65.3)
Accumulated Foreign Exchange Forward [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 0		$ 2.2

Commitments, Contingencies an_3

Commitments, Contingencies and Guarantees (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Dec. 31, 2023	Mar. 30, 2023	Dec. 31, 2022
Commitments Contingencies And Guarantees [Abstract]
Restricted Cash, Noncurrent	$ 27.7	$ 22.3	$ 22.1	$ 19.6
Service warranty roll forward
Product Warranty And Extraordinary Rework	82.7
Charges to costs and expenses	(1)
Product Warranty Accrual, Payments	(1.2)
Product Warranty And Extraordinary Rework	82.4
Product Warranty Extraordinary Rework Accrual Currency Translation Increase Decrease	(0.1)
Commitments Contingencies And Guarantees Textuals [Abstract]
Outstanding amount of guarantees	22.7	$ 23.1
Product Liability Accrual, Component Amount	2.3
Product Liability Contingency, Loss Exposure in Excess of Accrual, Best Estimate	$ 3.4

Other Income (Expense), Net (De

Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Other Income (Loss) [Line Items]
Kansas Development Finance Authority bond	$ 0.9	$ 0.7
Interest Income, Other	4.3	2.9
Foreign currency (losses) gains (1)	3.1	(8.5)
Gain (Loss) on Foreign Currency Derivatives Recorded in Earnings, Net	1.2	(3.4)
Gain (Loss) on Sale of Accounts Receivable	(10.6)	(11.2)
Pension Income (Expense) without Service Cost	3.6	(62.7)
Taxes, Miscellaneous	0	(35.9)
Other Nonoperating Income		0.7
Other Nonoperating Expense	(0.2)
Amortization of Intangible Assets	3.8	3.7
Total	$ 2.3	$ (117.4)

Other Liabilities (Details)

Other Liabilities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Other Liabilities Disclosure [Abstract]
Proceeds from Other Debt	$ 180

Segment Information (Details)

Segment Information (Details) $ in Millions	3 Months Ended
	Mar. 28, 2024 USD ($) segment	Mar. 30, 2023 USD ($)
Segment Reporting Information [Line Items]
Restructuring Charges	$ 0	$ 6.3
Excess Capacity Costs- B737MAX and A320 Production Schedules	26.1	43.3
Cost of Goods and Services Sold	2,138.3	1,432.2
Segment Revenues
Segment Revenues	1,702.8	1,431.4
Segment Operating Income
Business Segment Operating Income	(435.5)	(7.1)
Segment Information Unallocated Corporate Selling General And Administrative	(81.5)	(77.4)
Segment Information Unallocated Research And Development	(10.6)	(10.6)
Operating loss	$ (527.6)	(95.1)
Segment Reporting Information, Additional Information [Abstract]
Number Of Principal Segments | segment	3
Percentage Of Net Revenue Derived From Two Largest Customers	83%
Commercial Segment [Member]
Segment Reporting Information [Line Items]
Excess Capacity Costs- B737MAX and A320 Production Schedules	$ 24.9	40.9
Segment Revenues
Segment Revenues	1,356.1	1,148.5
Segment Operating Income
Business Segment Operating Income	$ (484.9)	(45.5)
Segment Reporting Information, Additional Information [Abstract]
Segment Reporting, Disclosure of Major Customers	Approximately 71% and 70% of Commercial segment net revenues came from the Company’s contracts with Boeing for the three months ended March 28, 2024, and March 30, 2023, respectively. Approximately 23% and 23% of Commercial segment net revenues came from the Company’s contracts with Airbus for the three months ended March 28, 2024, and March 30, 2023, respectively.
Restructuring Costs		5.4
Defense & Space Segment [Member]
Segment Reporting Information [Line Items]
Excess Capacity Costs- B737MAX and A320 Production Schedules	$ 1.2	2.4
Segment Revenues
Segment Revenues	250.8	188.4
Segment Operating Income
Business Segment Operating Income	$ 32.2	19.2
Segment Reporting Information, Additional Information [Abstract]
Segment Reporting, Disclosure of Major Customers	A significant portion of Defense & Space segment net revenues came from the Company’s contracts with two individual customers for the three months ended March 28, 2024, and March 30, 2023.
Restructuring Costs		0.9
Aftermarket Segment [Member]
Segment Revenues
Segment Revenues	$ 95.9	94.5
Segment Operating Income
Business Segment Operating Income	$ 17.2	$ 19.2
Segment Reporting Information, Additional Information [Abstract]
Segment Reporting, Disclosure of Major Customers	Approximately 58% and 45% of Aftermarket segment net revenues came from the Company’s contracts with a single customer for the three months ended March 28, 2024, and March 30, 2023, respectively.

Restructuring Charges (Details)

Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 0	$ 6.3
Commercial Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs		5.4
Defense & Space Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs		$ 0.9

Payables and Accruals (Details)

Payables and Accruals (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2024	Mar. 30, 2023	Dec. 31, 2023
Supplier Finance Program [Line Items]
Supplier Finance Program, Obligation	$ 137.8	$ 110.6	$ 155.6
Supplier Finance Program, Obligation, Period Increase (Decrease)	$ (17.8)	$ 8.6

Business Combinations and Ass_2

Business Combinations and Asset Acquisitions (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
	Nov. 23, 2022	Mar. 28, 2024	Dec. 31, 2023	Dec. 31, 2023
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired			$ 31.3
Goodwill		$ 631.2	$ 631.2	$ 631.2
T.E.A.M., Inc. Acquisition
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Nov. 23, 2022
Business Acquisition, Description of Acquired Entity				a Rhode Island corporation, which is engaged in the business of manufacturing and engineering textiles, composites, and textile and composite products
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		8.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets		1.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		13.5
Goodwill		7.7
Goodwill, Purchase Accounting Adjustments		0.6
Business Acquisition, Transaction Costs		$ 0