Spirit AeroSystems (SPR) 10-Q 1 Nov 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 28, 2023	Oct. 18, 2023
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	Sep. 28, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
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		105,570,958

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Income Statement [Abstract]
Revenues	$ 1,438.9	$ 1,276.9	$ 4,235	$ 3,709.5
Operating costs and expenses
Cost of sales	1,492.5	1,194	4,320.2	3,611.4
Selling, general and administrative	69.2	69.1	217.2	203.8
Unusual or Infrequent Item, or Both, Net (Gain) Loss	0.8		8.1
Restructuring Charges	0	0	7.2	0.2
Research and development	10.1	9.3	33.9	36.5
Other Expenses	0.8	0	5.7	0
Total operating costs and expenses	1,572.6	1,272.4	4,584.2	3,851.9
Operating income (loss)	(133.7)	4.5	(349.2)	(142.4)
Interest expense and financing fee amortization	(75.1)	(56.8)	(221.1)	(170.8)
Other income (expense), net	(7.3)	42.1	120	(30.2)
Loss before income taxes and equity in net income (loss) of affiliates	(201.5)	(94.4)	(690.3)	(283)
Income tax provision	(2.4)	(32.9)	(1.1)	(18.4)
Loss before equity in net income (loss) of affiliates	(203.9)	(127.3)	(691.4)	(301.4)
Equity in net income (loss) of affiliates	0	(0.3)	(0.2)	(1.2)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(203.9)	(127.6)	(691.6)	(302.6)
Net loss	(204.1)	(127.6)	(691.6)	(302.6)
Net Income (Loss) Attributable to Noncontrolling Interest	$ (0.2)	$ 0	$ 0	$ 0
Loss per share
Earnings Per Share, Basic	$ (1.94)	$ (1.22)	$ (6.58)	$ (2.89)
Diluted (in dollars per share)	$ (1.94)	$ (1.22)	$ (6.58)	$ (2.89)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Statement of Comprehensive Income [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	$ 0.8	$ (100.8)	$ 49.5	$ (98.2)
Other Comprehensive Income Unrealized Gain Loss On Intercompany Loan Net Of Tax	(1.1)	(3.2)	0.4	(7.2)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	(3.8)	6.5	(1.7)	12.1
Total other comprehensive (loss) gain, net of tax	(32.1)	(153)	53.9	(212.3)
Total comprehensive loss	(236)	(280.6)	(637.7)	(514.9)
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	3.8	(6.5)	1.7	(12.1)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	(5.2)	(18.5)	2.5	(35.5)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	(0.2)	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(203.9)	(127.6)	(691.6)	(302.6)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(22.8)	(37)	3.2	(83.5)
Total other comprehensive (loss) gain, net of tax	(32.1)	(153)	53.9	(212.3)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	1.2	31.9	(15.2)	30.9
Unrealized exchange (loss) on intercompany loan, tax	0.6	1.3	(0.2)	3.1
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax	1.2	0	0.1	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax	$ 0	$ 0	$ 0	$ 0

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Unaudited) (Parentheticals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Statement of Comprehensive Income [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	$ 1.2	$ 31.9	$ (15.2)	$ 30.9
Unrealized exchange (loss) on intercompany loan, tax	0.6	1.3	(0.2)	3.1
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax	0	0	0	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax	$ 1.2	$ 0	$ 0.1	$ 0

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Sep. 28, 2023	Dec. 31, 2022
Assets
Cash and cash equivalents	$ 374.1	$ 658.6
Restricted Cash, Current	0.2	0.2
Accounts receivable, net	610.3	489.5
Unbilled Receivables, Current	596	501
Inventory, net	1,690	1,470.7
Other current assets	50.6	38.3
Total current assets	3,321.2	3,158.3
Property, plant and equipment, net	2,084.1	2,205.9
Operating Lease, Right-of-Use Asset	93.5	94.3
Unbilled Receivable, Non Current	20.9	1.2
Pension assets	28.3	196.9
Pension reversion assets	61.4	71.1
Deferred Income Tax Assets, Net	0.1	4.8
Goodwill	631.1	630.5
Intangible Assets, Net (Excluding Goodwill)	200	211.4
Deferred income taxes	97.5	91.8
Other assets	6,538.1	6,666.2
Liabilities, Current [Abstract]
Accounts Payable, Current	1,030.3	919.8
Accrued Liabilities, Current	479.5	411.7
Deferred Compensation Liability, Current	18.1	40.5
Long-term Debt and Lease Obligation, Current	64.2	53.7
Operating Lease, Liability, Current	8.4	8.3
Customer Advances, Current	36.5	24.9
Contract with Customer, Liability, Current	157.2	111.1
Provision for Loss on Contracts	335.3	305.9
Deferred Credits and Other Liabilities, Current	48.4	21.7
Other Liabilities, Current	172.1	54.9
Liabilities Noncurrent
Long-term debt	3,811	3,814.9
Operating Lease, Liability, Noncurrent	84.9	85.4
Advance payments, long-term	276.9	199.9
Pension/OPEB obligation	22.2	25.2
Contract with Customer, Liability, Noncurrent	195.6	245.3
Provision for Loss on Contacts, Non Current	289.4	369.2
Deferred Credits and Other Liabilities, Noncurrent	87.2	49
Deferred grant income liability - non-current	25.4	25.7
Deferred Income Tax Liabilities, Net	8.2	1.3
Deferred income taxes	243	141.6
Additional Paid in Capital [Abstract]
Additional paid-in capital	1,205.3	1,179.5
AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract
Accumulated other comprehensive loss	(150)	(203.9)
Retained Earnings Accumulated Deficit [Abstract]
Retained earnings	$ 540.9	$ 1,232.5
Treasury Stock, Shares	41,587,480	41,587,480
Treasury Stock, Value	$ (2,456.7)	$ (2,456.7)
Total stockholders' equity	(859.4)	(247.5)
Noncontrolling interest	3.7	3.7
Total equity	(855.7)	(243.8)
Total liabilities and equity	6,538.1	6,666.2
Liabilities, Current	2,350	1,952.5
Class A [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Common stock	$ 1.1	$ 1.1
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) - $ / shares	Sep. 28, 2023	Dec. 31, 2022
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
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	105,304,482	105,252,421
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	9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022
Operating activities
Net loss	$ (691.6)	$ (302.6)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	236.9	253.2
Amortization of deferred financing fees	5.2	5.6
Accretion of customer supply agreement	1.8	1.6
Employee Benefit and Share-based Payment Arrangement, Noncash	29.3	28.7
Loss on Derivative Instruments, Pretax	(1.7)	10.5
Loss (gain) from foreign currency transactions	(4)	(36.9)
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property	(0.9)	(0.8)
Deferred taxes	(3.8)	15.7
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	61.8	17.2
Grant liability amortization	(0.9)	(1.1)
Unrealized Gain (Loss) on Investments	0.2	1.2
Increase (Decrease) in Forward Provision	(50.7)	(115.3)
Changes in assets and liabilities
Accounts receivable, net	(127)	(89)
Inventory, net	(227)	(47.9)
Accounts payable and accrued liabilities	222.2	210.6
Profit sharing/deferred compensation	(22.5)	(47.6)
Advance payments	87.4	(99.3)
Income taxes receivable/payable	1.1	17.8
Pension plans employer contributions	67.4	(44.4)
Other	19.7	(6.3)
Net cash used in operating activities	(339.5)	(367.4)
Investing activities
Purchase of property, plant, and equipment	(76.5)	(82.7)
Payments for (Proceeds from) Other Investing Activities	0	(6.1)
Net cash used in investing activities	(76.5)	(88.8)
Financing activities
Proceeds from (Repayments of) Other Debt	180	0
Proceeds from Lines of Credit	1.6	0
Proceeds from Issuance of Senior Long-term Debt	12.7	0
Principal payments of debt	(47.2)	(33.7)
Repayments of Debt	(3)	(3)
Payment, Tax Withholding, Share-based Payment Arrangement	(6.1)	(7)
Proceeds from Stock Plans	2.6	1.9
Debt issuance and financing costs	(0.5)	0
Proceeds from Other Debt	180
Payments of Dividends	0	(3.2)
Proceeds from (Payments for) Other Financing Activities	0	(289.5)
Net cash provided by (used in) financing activities	134.1	(334.5)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(281.9)	(808.2)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning Balance	678.4	1,498.4
Cash, cash equivalents, and restricted cash, end of period	396.5	690.2
Cash and Cash Equivalents, at Carrying Value, Ending Balance	374.1	670.5
Reconciliation of Cash, Cash Equivalents, and Restricted Cash [Abstract]
Restricted Cash, Current	0.2	0.2
Restricted Cash, Noncurrent	22.2	19.5
Increase (Decrease) in Income Taxes Payable	1.1	17.8
Increase (Decrease) in Contract with Customer, Liability	(3.9)	(25.1)
Defined Benefit Plan, Plan Assets, Contributions by Employer		19.1
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Assets Transferred to (from) Plan	178
Proceeds from Issuance of Senior Long-term Debt	12.7	0
Proceeds from (Payments for) Other Financing Activities	0	(289.5)
Increase (Decrease) in Contract with Customer, Asset	114.5	112.5
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations	0	(17.5)
Gain (Loss) on Contract Termination	(1.4)	21.4
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	(2.4)	0
Increase (Decrease) in Deferred Liabilities	67.4	(44.4)
Proceeds from Lines of Credit	1.6	0
Increase (Decrease) in Customer Advances	87.4	(99.3)
Asset Acquisition, Consideration Transferred	$ (6)	$ 0

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	$ 448.8
Stockholders' Equity Attributable to Noncontrolling Interest	0.5
Common Stock, Shares, Outstanding at Dec. 31, 2021			105,037,845
Common Stock, Value, Outstanding at Dec. 31, 2021			$ 1.1
Additional Paid in Capital, Common Stock at Dec. 31, 2021				$ 1,146.2
Treasury Stock, Value at Dec. 31, 2021						$ (2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Dec. 31, 2021							$ (23.7)
Retained Earnings (Accumulated Deficit) at Dec. 31, 2021					$ 1,781.4
Net Income (Loss) Attributable to Parent	(175)				(175)
Dividends, Common Stock, Cash	(2.2)				(2.2)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			294,175
Shares Granted, Value, Share-based Payment Arrangement, before Forfeiture			$ 0
Stock Issued During Period, Value, Restricted Stock Award, Gross	18.2			18.2
Shares Issued, Shares, Share-based Payment Arrangement, Forfeited			(91,196)
Shares Granted, Value, Share-based Payment Arrangement, Forfeited			$ 0
Payment, Tax Withholding, Share-based Payment Arrangement	(6.5)		$ 0	(6.5)
Stock Issued During Period, Shares, Employee Stock Purchase Plans			40,078
Stock Issued During Period, Value, Employee Stock Purchase Plan	1.9			1.9
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation			(142,743)
Stockholders' Equity, Other	0.1				0.1
Other Comprehensive Income (Loss), Net of Tax	$ (59.3)						(59.3)
Common Stock, Shares, Outstanding at Jun. 30, 2022			105,138,159
Additional Paid in Capital, Common Stock at Jun. 30, 2022				1,159.8
Treasury Stock, Value at Jun. 30, 2022						(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Jun. 30, 2022							(83)
Retained Earnings (Accumulated Deficit) at Jun. 30, 2022					1,604.3
Common Stock, Value, Outstanding at Jun. 30, 2022			$ 1.1
Common Stock, Shares, Outstanding at Dec. 31, 2021			105,037,845
Common Stock, Value, Outstanding at Dec. 31, 2021			$ 1.1
Additional Paid in Capital, Common Stock at Dec. 31, 2021				1,146.2
Treasury Stock, Value at Dec. 31, 2021						(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Dec. 31, 2021							(23.7)
Retained Earnings (Accumulated Deficit) at Dec. 31, 2021					1,781.4
Common Stock, Dividends, Per Share, Declared	$ 0.03
Net Income (Loss) Attributable to Parent	$ (302.6)
Payment, Tax Withholding, Share-based Payment Arrangement	(7)
Other Comprehensive Income (Loss), Net of Tax	(212.3)
Common Stock, Shares, Outstanding at Sep. 29, 2022			105,159,585
Additional Paid in Capital, Common Stock at Sep. 29, 2022				1,169.8
Treasury Stock, Value at Sep. 29, 2022						(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Sep. 29, 2022							(236)
Retained Earnings (Accumulated Deficit) at Sep. 29, 2022					1,475.7
Common Stock, Value, Outstanding at Sep. 29, 2022			$ 1.1
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	226
Stockholders' Equity Attributable to Noncontrolling Interest	$ 0.5
Common Stock, Shares, Outstanding at Jun. 30, 2022			105,138,159
Additional Paid in Capital, Common Stock at Jun. 30, 2022				1,159.8
Treasury Stock, Value at Jun. 30, 2022						(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Jun. 30, 2022							(83)
Retained Earnings (Accumulated Deficit) at Jun. 30, 2022					1,604.3
Common Stock, Dividends, Per Share, Declared	$ 0.01
Net Income (Loss) Attributable to Parent	$ (127.6)				(127.6)
Dividends, Common Stock, Cash	(1)				(1)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			36,890
Shares Granted, Value, Share-based Payment Arrangement, before Forfeiture			$ 0
Stock Issued During Period, Value, Restricted Stock Award, Gross	10.5			10.5
Shares Issued, Shares, Share-based Payment Arrangement, Forfeited			(1,574)
Shares Granted, Value, Share-based Payment Arrangement, Forfeited			$ 0
Payment, Tax Withholding, Share-based Payment Arrangement	(0.5)		$ 0	(0.5)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation			(13,890)
Other Comprehensive Income (Loss), Net of Tax	(153)						(153)
Common Stock, Shares, Outstanding at Sep. 29, 2022			105,159,585
Additional Paid in Capital, Common Stock at Sep. 29, 2022				1,169.8
Treasury Stock, Value at Sep. 29, 2022						(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Sep. 29, 2022							(236)
Retained Earnings (Accumulated Deficit) at Sep. 29, 2022					1,475.7
Common Stock, Value, Outstanding at Sep. 29, 2022			$ 1.1
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(45.6)
Stockholders' Equity Attributable to Noncontrolling Interest	0.5
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	$ 1.1
Additional Paid in Capital, Common Stock at Dec. 31, 2022	1,179.5			1,179.5
Treasury Stock, Value at Dec. 31, 2022	2,456.7					(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Dec. 31, 2022	(203.9)						(203.9)
Retained Earnings (Accumulated Deficit) at Dec. 31, 2022	1,232.5				1,232.5
Net Income (Loss) Attributable to Parent	(487.5)				(487.5)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			360,884
Shares Granted, Value, Share-based Payment Arrangement, before Forfeiture			$ 0
Stock Issued During Period, Value, Restricted Stock Award, Gross	19.2			19.2
Shares Issued, Shares, Share-based Payment Arrangement, Forfeited			(230,612)
Shares Granted, Value, Share-based Payment Arrangement, Forfeited			$ 0
Payment, Tax Withholding, Share-based Payment Arrangement	(5.8)		$ 0	(5.8)
Stock Issued During Period, Shares, Employee Stock Purchase Plans			79,840
Stock Issued During Period, Value, Employee Stock Purchase Plan	3.2			3.2
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation			(173,639)
Stockholders' Equity, Other	(0.2)				0
Other Comprehensive Income (Loss), Net of Tax	86						86
Common Stock, Shares, Outstanding at Jun. 29, 2023			105,288,894
Additional Paid in Capital, Common Stock at Jun. 29, 2023				1,196.1
Treasury Stock, Value at Jun. 29, 2023						(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Jun. 29, 2023							(117.9)
Retained Earnings (Accumulated Deficit) at Jun. 29, 2023					745
Common Stock, Value, Outstanding at Jun. 29, 2023			$ 1.1
Other retained earnings								$ (0.2)
Common Stock, Shares, Outstanding at Dec. 31, 2022			105,252,421
Common Stock, Value, Outstanding at Dec. 31, 2022		$ 1.1	$ 1.1
Additional Paid in Capital, Common Stock at Dec. 31, 2022	1,179.5			1,179.5
Treasury Stock, Value at Dec. 31, 2022	2,456.7					(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Dec. 31, 2022	(203.9)						(203.9)
Retained Earnings (Accumulated Deficit) at Dec. 31, 2022	$ 1,232.5				1,232.5
Common Stock, Dividends, Per Share, Declared	$ 0
Net Income (Loss) Attributable to Parent	$ (691.6)
Payment, Tax Withholding, Share-based Payment Arrangement	(6.1)
Other Comprehensive Income (Loss), Net of Tax	53.9
Common Stock, Shares, Outstanding at Sep. 28, 2023			105,304,482
Additional Paid in Capital, Common Stock at Sep. 28, 2023	1,205.3			1,205.3
Treasury Stock, Value at Sep. 28, 2023	2,456.7					(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Sep. 28, 2023	(150)						(150)
Retained Earnings (Accumulated Deficit) at Sep. 28, 2023	540.9				540.9
Common Stock, Value, Outstanding at Sep. 28, 2023			$ 1.1
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(628.9)
Stockholders' Equity Attributable to Noncontrolling Interest	$ 3.5
Common Stock, Shares, Outstanding at Jun. 29, 2023			105,288,894
Additional Paid in Capital, Common Stock at Jun. 29, 2023				1,196.1
Treasury Stock, Value at Jun. 29, 2023						(2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Jun. 29, 2023							(117.9)
Retained Earnings (Accumulated Deficit) at Jun. 29, 2023					745
Common Stock, Dividends, Per Share, Declared	$ 0
Net Income (Loss) Attributable to Parent	$ (204.1)				(204.1)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			8,055
Shares Granted, Value, Share-based Payment Arrangement, before Forfeiture			$ 0
Stock Issued During Period, Value, Restricted Stock Award, Gross	8.6			8.6
Shares Granted, Value, Share-based Payment Arrangement, Forfeited			$ 0
Payment, Tax Withholding, Share-based Payment Arrangement	(0.3)			(0.3)
Stock Issued During Period, Shares, Employee Stock Purchase Plans			0
Stock Issued During Period, Value, Employee Stock Purchase Plan	0.9			0.9
Supplemental Retirement Plan Shares Issued			16,023
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation			(8,490)
Stockholders' Equity, Other	0.2
Other Comprehensive Income (Loss), Net of Tax	(32.1)						(32.1)
Common Stock, Shares, Outstanding at Sep. 28, 2023			105,304,482
Additional Paid in Capital, Common Stock at Sep. 28, 2023	1,205.3			$ 1,205.3
Treasury Stock, Value at Sep. 28, 2023	2,456.7					$ (2,456.7)
Accumulated Other Comprehensive Income (Loss), Net of Tax at Sep. 28, 2023	(150)						$ (150)
Retained Earnings (Accumulated Deficit) at Sep. 28, 2023	540.9				$ 540.9
Common Stock, Value, Outstanding at Sep. 28, 2023			$ 1.1
Other retained earnings								$ 0.2
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(855.7)
Stockholders' Equity Attributable to Noncontrolling Interest	$ 3.7

Organization and Basis of Inter

Organization and Basis of Interim Presentation	9 Months Ended
	Sep. 28, 2023
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 nine months ended September 28, 2023, are not necessarily indicative of the results that may be expected for the year ending December 31, 2023. 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 2022 Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on February 17, 2023 (the “2022 Form 10-K”). The Company's significant accounting policies are described in Note 3 Summary of Significant Accounting Policies

Adoption of New Standard (Notes

Adoption of New Standard (Notes)	9 Months Ended
	Sep. 28, 2023
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update and Change in Accounting Principle [Text Block]	In September 2022, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU No. 2022-04, Liabilities-Supplier Finance Programs (Subtopic 405-50) . The amendments in the update require additional qualitative and quantitative disclosure about supplier finance programs. The guidance does not affect the recognition, measurement, or financial statement presentation of supplier finance program obligations. ASU No. 2022-04 is effective on a retrospective basis for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, except for an amended disclosure requirement related to certain rollforward information, which is effective on a prospective basis for fiscal years beginning after December 15, 2023. The adoption of this guidance did not have a significant impact on the Company's consolidated financial statements, and the Company does not expect this guidance to have a material impact prospectively.

Changes in Estimates

Changes in Estimates	9 Months Ended
	Sep. 28, 2023
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 2022 Form 10-K. The risk particularly applies to products such as the B787, A220, and A350, which are in forward loss positions. During the third quarter ended September 28, 2023, the Company recognized unfavorable changes in estimates of $165.1, which included net forward loss charges of $101.1, and unfavorable cumulative catch-up adjustments related to periods prior to the third quarter of 2023 of $64.0. The forward losses in the third quarter were primarily driven by labor and production cost growth on the A350 program, additional labor and supply chain cost growth on the B787 program, increased factory performance and supply chain costs on the B767 program, and production costs incurred on the Sikorsky CH-53K program. The unfavorable cumulative catch-up adjustments primarily relate to increased factory performance costs and rework costs related to the quality issue on the B737 aft pressure bulkhead on the B737 program, and production cost overruns and foreign currency movements on the A320 program. During the third quarter ended September 29, 2022, the Company recognized unfavorable changes in estimates of $54.0, which included net forward loss charges of $49.1, and unfavorable cumulative catch-up adjustments related to periods prior to the third quarter of 2022 of $4.9. The forward losses in the quarter ended September 29, 2022 were primarily driven by losses on the A350, B787, and RB3070 programs. Increased cost estimates for production on the A350 program resulted in a forward loss reflecting additional labor, freight, and other cost requirements driven by parts shortages and production and quality issues. The B787 program forward loss was driven by increased cost estimates for supply chain, rework, and fixed cost absorption. The RB3070 nacelle program forward loss was driven by increased engineering cost estimates. The unfavorable cumulative catch-up adjustments primarily relate to adjustments for production schedule changes and increased costs on the A320 program. Changes in estimates are summarized below: For the Three Months Ended For the Nine Months Ended Changes in Estimates September 28, 2023 September 29, 2022 September 28, 2023 September 29, 2022 (Unfavorable) Favorable Cumulative Catch-up Adjustment by Segment Commercial $ (59.1) $ (6.9) $ (40.7) $ (27.8) Defense & Space (4.9) 2.0 (8.7) 1.6 Aftermarket — — — — Total (Unfavorable) Favorable Cumulative Catch-up Adjustment $ (64.0) $ (4.9) $ (49.4) $ (26.2) Changes in Estimates on Loss Programs (Forward Loss) by Segment Commercial $ (86.5) $ (47.4) $ (298.3) $ (132.6) Defense & Space (14.6) (1.7) (17.5) (4.0) Aftermarket — — — — Total Changes in Estimates (Forward Loss) on Loss Programs $ (101.1) $ (49.1) $ (315.8) $ (136.6) Total Change in Estimate $ (165.1) $ (54.0) $ (365.2) $ (162.8) EPS Impact (diluted per share based upon applicable forecasted effective tax rate) $ (1.57) $ (0.55) $ (3.48) $ (1.66)

Accounts Receivable and Allowan

Accounts Receivable and Allowance for Credit Losses Accounts Receivable and Allowance for Credit Loss (Notes)	9 Months Ended
	Sep. 28, 2023
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: September 28, December 31, Trade receivables $ 579.4 $ 477.9 Other 43.8 19.7 Less: allowance for credit losses (12.9) (8.1) Accounts receivable, net $ 610.3 $ 489.5 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 nine months ended September 28, 2023, $2,657.0 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 $36.5 for the nine months ended September 28, 2023 and is included in other income and expense. See Note 21 Other Income (Expense), Net . Allowance for Credit Losses During the nine months ended September 28, 2023, 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)	9 Months Ended
	Sep. 28, 2023
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 September 28, 2023 or the period ended September 29, 2022. See also Note 5 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. September 28, 2023 December 31, 2022 Change Contract assets $ 616.9 $ 502.2 $ 114.7 Contract liabilities (352.8) (356.4) 3.6 Net contract assets (liabilities) $ 264.1 $ 145.8 $ 118.3 For the period ended September 28, 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 $66.4 of revenue that was included in the contract liability balance at the beginning of the period. September 29, 2022 December 31, 2021 Change Contract assets $ 547.4 $ 443.2 $ 104.2 Contract liabilities (361.7) (387.0) 25.3 Net contract assets (liabilities) $ 185.7 $ 56.2 $ 129.5 For the period ended September 29, 2022, 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 $63.2 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]	September 28, 2023 December 31, 2022 Change Contract assets $ 616.9 $ 502.2 $ 114.7 Contract liabilities (352.8) (356.4) 3.6 Net contract assets (liabilities) $ 264.1 $ 145.8 $ 118.3

Revenue (Notes)

Revenue (Notes)	9 Months Ended
	Sep. 28, 2023
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 23 Segment Information . The following tables show disaggregated revenues for the periods ended September 28, 2023 and September 29, 2022: For the Three For the Nine Revenue September 28, September 29, September 28, September 29, Contracts with performance obligations satisfied over time $ 1,064.1 $ 970.6 $ 3,176.2 $ 2,733.3 Contracts with performance obligations satisfied at a point in time 374.8 306.3 1,058.8 976.2 Total Revenue $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5 The following table disaggregates revenue by major customer: For the Three For the Nine Customer September 28, September 29, September 28, September 29, Boeing $ 883.9 $ 824.3 $ 2,640.6 $ 2,233.7 Airbus 274.5 237.2 816.8 822.2 Other 280.5 215.4 777.6 653.6 Total Revenue $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5 The following table disaggregates revenue based upon the location where control of products is transferred to the customer: For the Three Months Ended For the Nine Location September 28, September 29, September 28, September 29, United States $ 1,156.0 $ 1,037.0 $ 3,379.8 $ 2,768.0 International United Kingdom 163.5 145.5 505.3 473.5 Other 119.4 94.4 349.9 468.0 Total International 282.9 239.9 855.2 941.5 Total Revenue $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5 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 2023 2024 2025 2026 and after Unsatisfied performance obligations $ 1,533.7 $ 5,286.1 $ 1,758.5 $ 278.3

Inventory

Inventory	9 Months Ended
	Sep. 28, 2023
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. September 28, December 31, Raw materials $ 395.4 $ 332.7 Work-in-process (1) 1,226.2 1,044.9 Finished goods 46.8 69.4 Product inventory 1,668.4 1,447.0 Capitalized pre-production 21.6 23.7 Total inventory, net $ 1,690.0 $ 1,470.7 (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 September 28, 2023 and December 31, 2022, work-in-process inventory includes $256.3 an d $392.2, 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 $148.3 and $136.8 as of September 28, 2023 and December 31, 2022, 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 and nine months ended September 28, 2023 includes period expense of $56.4 and $152.9, respectively, for

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 28, 2023
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, net	Property, Plant and Equipment, net Property, plant and equipment, net consists of the following: September 28, December 31, Land $ 30.1 $ 30.1 Buildings (including improvements) 1,292.3 1,269.1 Machinery and equipment 2,439.6 2,365.1 Tooling 1,061.4 1,055.9 Capitalized software 338.3 336.1 Construction-in-progress 86.0 102.2 Total 5,247.7 5,158.5 Less: accumulated depreciation (3,163.6) (2,952.6) Property, plant and equipment, net $ 2,084.1 $ 2,205.9 Capitalized interest was $0.4 and $1.0 for the three months ended September 28, 2023 and September 29, 2022, respectively, and $3.8 and $2.9 for the nine months ended September 28, 2023 and September 29, 2022, respectively. Repair and maintenance costs are expensed as incurred. The Company recognized repair and maintenance costs of $32.1 and $43.7 for the three months ended September 28, 2023 and September 29, 2022, respectively, and $124.4 and $115.0 for the nine months ended September 28, 2023 and September 29, 2022, 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 $5.6 and $5.0 for the three months ended September 28, 2023 and September 29, 2022, respectively, and $17.5 and $16.5 for the nine months ended September 28, 2023 and September 29, 2022, 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 September 28, 2023, there were no events which would require the Company to update its impairment analysis .

Leases (Notes)

Leases (Notes)	9 Months Ended
	Sep. 28, 2023
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 15 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 For the Nine September 28, September 29, September 28, September 29, Operating lease cost $ 3.6 $ 3.2 $ 10.8 $ 9.8 Finance lease cost: Amortization of assets 9.5 8.3 26.6 24.6 Interest on lease liabilities 2.1 1.7 5.9 5.0 Total net lease cost $ 15.2 $ 13.2 $ 43.3 $ 39.4 Supplemental cash flow information related to leases was as follows: For the Three For the Nine September 28, September 29, September 28, September 29, Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 3.5 $ 3.2 $ 10.5 $ 9.5 Operating cash flows from finance leases $ 2.1 $ 1.7 $ 5.9 $ 5.0 Financing cash flows from finance leases $ 13.0 $ 11.2 $ 36.9 $ 33.7 ROU assets obtained in exchange for lease obligations: Operating leases $ 5.1 $ 0.1 $ 5.6 $ 1.3 Supplemental balance sheet information related to leases: September 28, 2023 December 31, 2022 Finance leases: Property and equipment, gross $ 333.5 $ 295.4 Accumulated amortization (129.6) (103.4) Property and equipment, net $ 203.9 $ 192.0 The weighted average remaining lease term as of September 28, 2023 for operating and finance leases was 32.5 years and 4.7 years, respectively. The weighted average discount rate as of September 28, 2023 for operating and finance leases was 6.2% and 5.8%, respectively. The weighted average remaining lease term as of December 31, 2022 for operating and finance leases was 31.7 years and 5.3 years, respectively. The weighted average discount rate as of December 31, 2022 for operating and finance leases was 5.8% and 5.0%, respectively. See Note 15 Debt for current and non-current finance lease obligations. As of September 28, 2023, remaining maturities of lease liabilities were as follows: 2023 2024 2025 2026 2027 2028 and thereafter Total Lease Payments Less: Imputed Interest Total Lease Obligations Operating Leases $ 3.6 $ 13.9 $ 14.0 $ 11.9 $ 9.3 $ 177.2 $ 229.9 $ (136.6) $ 93.3 Financing Leases $ 14.7 $ 51.5 $ 37.8 $ 22.8 $ 9.6 $ 26.8 $ 163.2 $ (21.3) $ 141.9 As of September 28, 2023, the Company had additional operating and financing lease commitments that have not yet commenced of approximately $2.2 and $28.7, 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	9 Months Ended
	Sep. 28, 2023
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 September 28, Commercial $ 296.5 $ — $ — $ — $ 296.5 Defense & Space $ 12.6 $ — $ 0.6 (1) $ — $ 13.2 Aftermarket $ 321.4 $ — $ — $ — $ 321.4 $ 630.5 $ — $ 0.6 $ — $ 631.1 (1) As a result of certain purchase price allocation adjustments recorded during the purchase price accounting measurement period based on additional information obtained, the goodwill resulting from the T.E.A.M., Inc. acquisition was adjusted by $0.6, from $7.1 that was reported at December 31, 2022, to $7.7 as of September 28, 2023. See also Note 26 Acquisitions. 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	9 Months Ended
	Sep. 28, 2023
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 will resume at a lower rate of $0.45 per shipset at line number 1135 and 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 due on December 15th of each year until the advance payments have been fully recovered by Boeing. As of September 28, 2023, the amount of advance payments received from Boeing under the B787 Supply Agreement and not yet repaid was approximately $194.5. Advances on the B737 Program. In an effort to minimize the disruption to Spirit's operations and its supply chain, Spirit and Boeing entered into a Memorandum of Agreement on April 12, 2019 (the “2019 MOA”), which included the terms and conditions for an advance payment to be made from Boeing to Spirit in the amount of $123.0, which was received during the third quarter of 2019. Spirit and Boeing entered into a Memorandum of Agreement on February 6, 2020, which extended the repayment date of the $123.0 advance received by Spirit under the 2019 MOA to 2022. $0.0 and $92.3 of advance payments received from Boeing were repaid in the nine months ended September 28, 2023 and September 29, 2022, respectively. There was no balance due as of September 28, 2023. Advances on the A350 Program . During the three months ended June 29, 2023, the Company received an advance payment from Airbus of $50.0 under an agreement between Airbus S.A.S. and Spirit AeroSystems (Europe) Limited (“Spirit Europe”) signed on June 23, 2023 (the “A350 Agreement”). During the three months ended September 28, 2023, the Company received a second advance payment from Airbus of $50.0. These advances 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. Other. The Advance payments, long-term line item on the Condensed Consolidated Balance Sheets for the period ended September 28, 2023 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	9 Months Ended
	Sep. 28, 2023
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 September 28, 2023, the Company’s long-term debt includes a senior secured term loan and senior notes described further under Note 15 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 14 Derivative and Hedging Activities and Note 16 Pension and Other Post-Retirement Benefits. September 28, 2023 December 31, 2022 Carrying Fair Carrying Fair Senior secured term loan B (including current portion) $ 572.6 $ 571.2 (2) $ 571.7 $ 564.5 (2) Senior notes due 2025 20.8 20.5 (1) 20.7 20.8 (1) Senior secured second lien notes due 2025 1,193.8 1,165.9 (1) 1,191.0 1,179.0 (1) Senior notes due 2026 299.0 278.4 (1) 298.8 272.8 (1) Senior notes due 2028 696.4 538.9 (1) 695.9 562.3 (1) Senior secured first lien notes due 2029 888.0 903.8 (1) 887.2 935.7 (1) Total $ 3,670.6 $ 3,478.7 $ 3,665.3 $ 3,535.1 (1) Level 1 Fair Value hierarchy

Derivative and Hedging Activiti

Derivative and Hedging Activities	9 Months Ended
	Sep. 28, 2023
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 June 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 September 28, 2023, and December 31, 2022. The foreign currency exchange contracts are measured within Level 1 of the Fair Value hierarchy. See Note 13 Fair Value Measurements . Notional amount Other assets Other liabilities September 28, 2023 December 31, 2022 September 28, 2023 December 31, 2022 September 28, 2023 December 31, 2022 Derivatives designated as hedging instruments: Foreign currency exchange contracts $ 160.3 $ 157.1 $ — $ — $ 6.3 $ 2.4 Total derivatives at fair value $ — $ — $ 6.3 $ 2.4 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 Nine Months Ended September 28, 2023 September 29, 2022 September 28, 2023 September 29, 2022 Recognized in total other comprehensive loss: Foreign currency exchange contracts $ (6.3) $ (15.5) $ (2.2) $ (32.5) The following table summarizes the gains/(losses) associated with our hedging transactions reclassified from AOCI to earnings: Three Months Ended Nine Months Ended September 28, 2023 September 29, 2022 September 28, 2023 September 29, 2022 Foreign currency exchange contracts: Other income (expense) $ 3.8 $ (6.5) $ 1.7 $ (12.1) Within the next 12 months, the Company expects to recognize a loss of ($6.3) in earnings related to the foreign currency forward contracts. As of September 28, 2023, 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. Derivatives Not Accounted for as Hedges During the nine months ended September 28, 2023, all foreign currency forward contracts were designated as hedges, and the Company applied hedge accounting to all foreign currency forward contracts. During the nine months ended September 29, 2022, the Company entered into foreign currency forward contracts in the amount of $291.5 to minimize the risk of currency exchange rate movements on the Company's planned settlement of the repayable investment agreement between the Company and the U.K.'s Department for Business, Energy and Industrial Strategy. During the nine-month period ended September 29, 2022, these foreign currency forward contracts were settled, and new contracts were entered into in the amount of $293.7, which were also settled during the period. The Company did not designate these forward contracts as hedges or apply hedge accounting to the forward contracts. For the nine months ended September 29, 2022, the Company recorded a net gain of $1.6 to other income on the Condensed Consolidated Statements of Operations related to the foreign currency forward contracts.

Debt

Debt	9 Months Ended
	Sep. 28, 2023
Debt Disclosure [Abstract]
Debt	Debt Total debt shown on the Condensed Consolidated Balance Sheets is comprised of the following: September 28, 2023 December 31, 2022 Current Noncurrent Current Noncurrent Senior secured term loan B $ 5.7 $ 566.9 $ 5.7 $ 566.0 Senior notes due 2025 — 20.8 — 20.7 Senior secured second lien notes due 2025 — 1,193.8 — 1,191.0 Senior notes due 2026 — 299.0 — 298.8 Senior notes due 2028 — 696.4 — 695.9 Senior secured first lien notes due 2029 — 888.0 — 887.2 Present value of finance lease obligations 47.9 94.0 42.2 102.3 Other 10.6 52.1 5.8 53.0 Total $ 64.2 $ 3,811.0 $ 53.7 $ 3,814.9 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 the Company (“Spirit NC” and, collectively, the “Guarantors”) and each existing and future, direct and indirect, wholly-owned material domestic subsidiary of Spirit, 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 September 28, 2023 , the outstanding balance of the Amended Credit Agreement was $589.5 and the carrying value was $572.6. As of September 28, 2023 , the Company was in compliance with all covenants in the Amended Credit Agreement. 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 each existing and future, direct and indirect, wholly-owned material domestic subsidiary of the Company that guarantee the Company's 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 September 28, 2023 , the outstanding balance of the First Lien 2029 Notes was $900.0 and the carrying value was $888.0. 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 September 28, 2023 , 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 April 17, 2020, Spirit entered into a Third Supplemental Indenture (the “Third 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 Third Supplemental Indenture, the holders of the 2026 Notes were granted security on an equal and ratable basis with the holders of the Second Lien 2025 Notes. 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. As of September 28, 2023, the outstanding balance of the 2026 Notes was $300.0 and the carrying value was $299.0. The 2026 Notes mature on June 15, 2026. Second Lien 2025 Notes On April 17, 2020, Spirit entered into an Indenture (the “Second Lien 2025 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 7.500% Senior Secured Second Lien Notes due 2025 (the “Second Lien 2025 Notes”). The Second Lien 2025 Notes are guaranteed by the Guarantors, and each existing and future, direct and indirect, wholly-owned material domestic subsidiary of the Company that guarantee the Company's obligations under the Amended Credit Agreement and certain other indebtedness. The Second Lien 2025 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 September 28, 2023 , the outstanding balance of the Second Lien 2025 Notes was $1,200.0 and the carrying value was $1,193.8. The Second Lien 2025 Notes mature on April 15, 2025. 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 September 28, 2023 , the outstanding balance of the 2028 Notes was $700.0 and the carrying value was $696.4. As of September 28, 2023, the Company was in compliance with all covenants contained in the indentures governing the First Lien 2029 Notes, 2025 Notes, 2026 Notes, Second Lien 2025 Notes, and 2028 Notes. The 2028 Notes mature on June 15, 2028.

Pension and Other Post-Retireme

Pension and Other Post-Retirement Benefits Defined Benefit Plan (Notes)	9 Months Ended
	Sep. 28, 2023
Retirement Benefits [Abstract]
Retirement Benefits [Text Block]	Pension and Other Post-Retirement Benefits Defined Benefit Plans For the Three Months Ended For the Nine Components of Net Periodic Pension Expense (Income) September 28, September 29, September 28, September 29, Service cost $ 0.8 $ 0.5 $ 2.4 $ 1.7 Interest cost 18.8 13.1 57.4 42.2 Expected return on plan assets (20.3) (28.9) (62.3) (99.2) Amortization of net loss (1) — 71.7 0.1 73.8 Settlement loss (gain) (2) — 0.9 64.6 (0.5) Net periodic pension expense (income) $ (0.7) $ 57.3 $ 62.2 $ 18.0 Other Benefits For the Three For the Nine Components of Other Benefit Expense (Income) September 28, September 29, September 28, September 29, Service cost $ 0.1 $ 0.2 $ 0.4 $ 0.6 Interest cost 0.4 0.1 1.1 0.4 Amortization of prior service cost (0.2) (0.2) (0.6) (0.6) Amortization of net gain (0.4) (0.3) (1.3) (1.0) Net periodic other benefit income $ (0.1) $ (0.2) $ (0.4) $ (0.6) (1) In July 2022, the Company adopted and communicated to participants a plan to terminate the Company's Pension Value Plan A ( “ PVP A”). As further described in the Company's 2021 Form 10-K, the PVP A consists of pension plans which were frozen as of the date Holdings became a standalone company and commenced operations. During the three months ended September 29, 2022, the PVP A plan was amended, providing for an enhancement to benefits the Company is providing to certain U.S. employees in conjunction with the plan termination. The estimated liability impact of this plan amendment, $71.7, was recognized immediately as a non-cash, pre-tax non-operating charge for amortization of prior service costs. (2) Includes a $64.6 settlement charge for the PVP A during the nine months ended September 28, 2023. Includes a $0.9 settlement charge for the PVP A during the three months ended September 29, 2022, and a ($1.4) settlement credit for PVP B related to final asset distribution in the nine months ended September 29, 2022. 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 21 Other Income (Expense), Net. As disclosed in the Company's 2022 Form 10-K, 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 September 28, 2023, a pension reversion asset of $61.4 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 six 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 13 Fair Value Measurements. Separately, during the nine months ended September 28, 2023, the Company received an excess plan asset reversion of $179.5 of cash from PVP A. During the nine months ended September 29, 2022, the Company withdrew $34.0 of cash from PVP B, which represented an excess plan assets reversion. These transactions were accounted for as a negative contribution and are included on the Pension plans employer contributions line item on the Condensed Consolidated Statements of Cash Flows for the nine months ended September 28, 2023 and September 29, 2022. Excise tax of $35.9 and $6.8 related to the reversion of excess plan assets was separately recorded to the Other income (expense), net line item on the Company's Condensed Consolidated Statements of Operations for the nine months ended September 28, 2023 and September 29, 2022, respectively. See also Note 21 Other Income (Expense), Net. As disclosed in the Company's 2022 Form 10-K, i n July 2022, the Company adopted and communicated to participants a plan to terminate the PVP A. During the nine months ended September 28, 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. In connection with the special accounting related to the termination of the PVP A plan, discussed above, a subsequent interim measurement of the Company's U.S. pension and other postretirement plan assets and obligations was completed during the three months ended September 29, 2022. The interim measurement, including the estimated impact of the plan termination liability and enhanced benefits liability noted above, prior to the current period settlement loss and amortization of prior service cost impacts included in Net Periodic Pension Expense above, was recorded to the Accumulated other comprehensive loss line item in the Stockholders' Equity section of the Company's Condensed Consolidated Balance Sheet for the period ended September 29, 2022. Employer Contributions

Stock Compensation

Stock Compensation	9 Months Ended
	Sep. 28, 2023
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 $8.6 and $10.4 of stock compensation expense for the three months ended September 28, 2023 and September 29, 2022, respectively, and a net total of $27.8 and $28.7 of stock compensation expense for the nine months ended September 28, 2023 and September 29, 2022, respectively. During the nine months ended September 28, 2023, 560,190 time or service-based restricted stock units (“RSUs”) were granted with an aggregate date fair values of $18.8 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 nine months ended September 28, 2023, 231,927 performance-based restricted stock units (“PBRSUs”) were granted with an aggregate grant date fair value of $12.0 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 nine months ended September 28, 2023, 116,006 PBRSUs were granted with an aggregate grant date fair value of $4.0 under the Company’s LTIP. T hese awards are earned based on pre-established 2024 - 2025 free cash flow goals. Values for these awards are based on the dividend adjusted value of Common Stock on the grant date. During the nine months ended September 28, 2023, 116,006 PBRSUs were granted with an aggregate grant date fair value of $4.0 under the Company’s LTIP. These awards are earned based on pre-established goals of revenue growth o ver a three-year performance period. Values for these awards are based on the dividend adjusted value of Common Stock on the grant date. During the nine months ended September 28, 2023, 42,065 shares of restricted Common Stock and 39,005 non-employee director restricted stock units (“DRSUs”) were granted to the Board of Directors of the Company (the “Board”) with an aggregate grant date fair value of $2.0. Both types of awards vest if the non-employee director remains continuously in service for the entire one-year term to which the grant relates. If the non-employee director incurs a termination for any reason before the end of the term (before the annual meeting of stockholders following the grant), the awards are forfeited. Upon vesting, shares relating to restricted Common Stock awards are delivered to the director free of restriction; however, vested shares of Common Stock underlying DRSUs are not delivered to the director until the date that the director leaves the Board. Values for these awards are based on the value of Common Stock on the grant date. During the nine months ended September 28, 2023, 466,597 shares of Common Stock with an aggregate grant date value of $22.5 vested under the Company's LTIP. Additionally, 41,096 shares of Common Stock previously granted to the Board vested with an aggregate grant date fair value of $1.3, and 22,155 DRSUs previously awarded to the Board vested with an aggregate grant date fair value of $0.7. 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 $0.9 and $1.5 of stock compensation expense related to the ESPP for the three and nine months ended September 28, 2023. The Company recognized no stock compensation expense related to the ESPP for the three and nine months ended September 29, 2022.

Income Taxes (Notes)

Income Taxes (Notes)	9 Months Ended
	Sep. 28, 2023
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 nine months ended September 28, 2023 were $112.6. This is comprised of ($0.4) related to other comprehensive income (“OCI”) and $113.0 from continuing operations. As of September 28, 2023, the total net U.S. deferred tax asset before the valuation allowance was $544.9 and the total net U.S. valuation allowance was $547.7. The net U.S. deferred tax liability after valuation allowances was $2.8. 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 nine-month period ended September 28, 2023 were $46.9. This is comprised of $0.0 related to other comprehensive income (“OCI”) and $46.9 from continuing operations, including utilization of net operating losses. As of September 28, 2023, the total net U.K. deferred tax asset before the valuation allowance was $322.1 and the total net U.K. valuation allowance was $326.2. The net U.K. deferred tax liability after valuation allowance was $4.1. 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 (0.16%) effectiv e tax rate for the nine months ended September 28, 2023 differs from the (6.49%) effective tax rate for the same period of 2022 primarily due to changes in the valuation allowances recorded on U.S. and U.K. deferred tax assets, nondeductible interest expense and nondeductible excise tax. As the Company is currently reporting a pre-tax loss for the nine months ended September 28, 2023, 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 September 28, 2023 is $2.2. The Company's federal audit is conducted under the Internal Revenue Service Compliance Assurance Process (“CAP”) program and is essentially complete for the 2020 tax year. The Company will continue to participate in the CAP program for 2021 through 2023. 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.

Equity

Equity	9 Months Ended
	Sep. 28, 2023
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 September 28, 2023, 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 nine-month period ended September 28, 2023, 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 September 28, 2023 September 29, 2022 Income Shares Per Share Income Shares Per Share Basic EPS Loss available to common stockholders $ (204.1) 105.2 $ (1.94) $ (127.6) 104.7 $ (1.22) Income allocated to participating securities — — — — Net loss $ (204.1) $ (127.6) Diluted potential common shares — — Diluted EPS Net loss $ (204.1) 105.2 $ (1.94) $ (127.6) 104.7 $ (1.22) For the Nine Months Ended September 28, 2023 September 29, 2022 Income Shares Per Share Income Shares Per Share Basic EPS Loss available to common stockholders $ (691.6) 105.1 $ (6.58) $ (302.6) 104.6 $ (2.89) Income allocated to participating securities — — — — Net loss $ (691.6) $ (302.6) Diluted potential common shares — — Diluted EPS Net loss $ (691.6) 105.1 $ (6.58) $ (302.6) 104.6 $ (2.89) Included in the outstanding Common Stock were 0.1 million and 0.4 million of issued but unvested shares at September 28, 2023 and September 29, 2022, respectively, which are excluded from the basic Earnings Per Share (“EPS”) calculation. Shares of Common Stock of 0.6 million and 0.7 million, respectively, were excluded from diluted EPS as a result of incurring a net loss for the three and nine months ended September 28, 2023 , as the effect would have been antidilutive. Additionally, diluted EPS for the three and nine months ended September 28, 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. Shares of Common Stock of 0.5 million and 0.6 million, respectively, were excluded from diluted EPS as a result of incurring a net loss for the three and nine months ended September 29, 2022, as the effect would have been antidilutive. Additionally, diluted EPS for the three and nine months ended September 29, 2022 excludes 0.3 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 September 28, 2023 December 31, 2022 Pension $ (44.4) $ (95.4) SERP/Retiree medical 11.2 12.7 Derivatives - foreign currency hedge (6.2) (7.1) Foreign currency impact on long-term intercompany loan (16.1) (16.4) Currency translation adjustment (94.5) (97.7) Total accumulated other comprehensive loss $ (150.0) $ (203.9) Amortization or settlement cost recognition of the pension plans’ net gain/(loss) reclassified from accumulated other comprehensive loss and realized into costs of sales and selling, general and administrative on the Condensed Consolidated Statements of Operations was $0.7 and $0.5 for the three months ended September 28, 2023 and September 29, 2022, respectively and ($62.7) and $1.7 for the nine months ended September 28, 2023 and September 29, 2022, respectively.

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 28, 2023
Commitments Contingencies And Guarantees [Abstract]
Commitments and Contingencies Disclosure	20. Commitments, Contingencies and Guarantees Litigation On February 10, 2020, February 24, 2020, and March 24, 2020, three separate private securities class action lawsuits were filed against the Company in the U.S. District Court for the Northern District of Oklahoma, its former Chief Executive Officer, Tom Gentile III, former Chief Financial Officer, Jose Garcia, and former Controller (principal accounting officer), John Gilson. On April 20, 2020, the Class Actions were consolidated by the court (the “Consolidated Class Action”), and on July 20, 2020, the plaintiffs filed a Consolidated Class Action Complaint which added Shawn Campbell, the Company’s former Vice President for the B737NG and B737 MAX program, as a defendant. Allegations in the Consolidated Class Action include (i) violations of Section 10(b) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and Rule 10b-5 promulgated thereunder against the Company and Messrs. Gentile, Garcia, and Gilson, (ii) violations of Section 20(a) of the Exchange Act against the individual defendants, and (iii) violations of Section 10(b) of the Exchange Act and Rule 10b-5(a) and (c) promulgated thereunder against all defendants. On June 11, 2020, a shareholder derivative lawsuit (the “Derivative Action 1”) was filed against the Company (as nominal defendant), all members of the Company’s then serving Board of Directors, and Messrs. Garcia and Gilson in the U.S. District Court for the Northern District of Oklahoma. Allegations in the Derivative Action 1 include (i) breach of fiduciary duty, (ii) abuse of control, and (iii) gross mismanagement. On October 5, 2020, a shareholder derivative lawsuit (the “Derivative Action 2” and, together with Derivative Action 1, the “Derivative Actions”) was filed against the Company (as nominal defendant), all then serving members of the Company’s Board of Directors, and Messrs. Garcia and Gilson in the Eighteenth Judicial District, District Court of Sedgwick County, Kansas. Allegations in the Derivative Action 2 include (i) breach of fiduciary duty, (ii) waste of corporate assets, and (iii) unjust enrichment. The Company and the individual defendants have denied, and continue to deny, the allegations in the Derivative Actions. The facts underlying the Consolidated Class Action and Derivative Actions relate to the accounting process compliance independent review (the “Accounting Review”) discussed in the Company’s January 30, 2020 press release and described under Management's Discussion and Analysis of Financial Condition and Results of Operations - Accounting Review in Part II, Item 7 of the Annual Report on Form 10-K for the year ended December 31, 2019, and its resulting conclusions. The Company voluntarily reported to the SEC the determination that, with respect to the third quarter of 2019, the Company did not comply with its established accounting processes related to potential third quarter contingent liabilities received after the quarter-end. On March 24, 2020, the Staff of the SEC Enforcement Division informed the Company that it had determined to close its inquiry without recommending any enforcement action against the Company. In addition, the facts underlying the Consolidated Class Action and Derivative Actions relate to the Company’s disclosures regarding the B737 MAX grounding and Spirit’s production rate (and related matters) after the grounding. On September 18, 2020, the Company and individual defendants filed a motion to dismiss the Consolidated Class Action. That motion was granted by the U.S. District Court on January 7, 2022, which denied leave to amend and dismissed the Consolidated Class Action with prejudice. On February 4, 2022, the plaintiffs in the Consolidated Class Action appealed this decision to the Tenth Circuit Court of Appeals (the “ Appellate Court ” ). On August 21, 2023, the Appellate Court affirmed the dismissal of the Consolidated Class Action. The Derivative Actions remain stayed at this point. 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. 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 the alleged incorrect installation of fittings on certain B737 MAX planes (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. Lead plaintiff and counsel in the Securities Class Action were appointed on October 20, 2023. 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 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 has appealed the District Court’s latest decision, and filed his opening appellate brief before the Appellate Court on October 20, 2023. 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, 2022 and September 28, 2023. From time to time, in the ordinary course of business and similar to others in the industry, the Company receives requests for information from government agencies in connection with their regulatory or investigational authority. Such requests can include subpoenas or demand letters for documents to assist the government in audits or investigations. 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. 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 these 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. The Company has evaluated and refined management’s original estimate of costs related to rework on the B787 aircraft, including a preliminary assessment related to rework on the forward section of the fuselage, for which the Company identified an additional fit and finish issue in the prior year. The Company continues to coordinate with Boeing to complete the necessary rework. As described in Note 27 Subsequent Events , on October 12, 2023, the Company entered into a Memorandum of Agreement (the “MOA”) with Boeing. Among other things, the MOA includes a broad release of liability and claims through October 12, 2023, by both parties relating to Boeing's Commercial Airplanes division and its airplane programs under the General Terms Agreement for the B787 program and the General Terms Agreement for the B737, B747, B767, and B777 programs. Contingencies As described in Note 27 Subsequent Events , on October 12, 2023, the Company entered into the MOA with Boeing. Among other things, the MOA establishes certain recurring shipset price increases for the B787, and as a result the Company will reverse certain liabilities, including a certain amount of forward losses and material right obligation related to the B787 program in the fourth quarter of 2023. In the third quarter of 2023, the Company updated its estimated cost to satisfy all customer firm orders on the A350 and A220 production programs. Based on forecasted backlog and rates of production, each of these programs anticipates production will extend beyond the period of time for which the Company has recorded forward losses. The Company has recorded forward losses for forecasted production on the A220 and A350 programs through the end of 2025. The Company is in active negotiations with its A220 and A350 customer, regarding, among other things, elements of price. Management has evaluated the probability that the unexercised options to complete the performance obligations for periods beyond the period of time for which it has recorded forward losses is not currently probable. While the Company does not currently believe incremental losses are evident on these programs, if negotiations with its customer do not achieve a result which eliminates or reduces the potential for incremental losses, or other strategic alternatives are abandoned, the Company believes it is reasonably possible it would record cumulative incremental losses across these programs between $0.0 and $255.0 million. On April 12, 2023, the Company issued a notice of escapement to Boeing related to the quality issue on the B737 Vertical Fin Attach Fittings. The remediation of the quality issue requires the Company to rework B737 units within its production system and reimburse Boeing for repairs on previously delivered units in their factory and warranty costs related to units in service. As of June 29, 2023, the Company had completed the required rework on available units located at its factory in Wichita, KS. The impact to production costs is reflected within the reported total gross margins and did not materially change from the preliminary cost estimate of approximately $31.0 estimated as of March 31, 2023. Based upon informal communications to date with our customer, we believe Boeing has completed the required rework on approximately half of the affected units within its factory. The Company has not received a claim from Boeing for rework completed to date. However, the Company has made an estimate of the cost to Boeing for the units repaired to date of $23.0 for the period ended June 29, 2023. This amount is recorded as contra revenue. As described in Note 27 Subsequent Events , on October 12, 2023, the Company entered into the MOA with Boeing. Among other things, the MOA includes a broad release of liability and claims through October 12, 2023, by both parties relating to Boeing's Commercial Airplanes division and its airplane programs under the General Terms Agreement for the B787 program and the General Terms Agreement for the B737, B747, B767, and B777 programs. As a result, the Company will reverse the $23.0 contra revenue adjustment recorded in the three months ended June 29, 2023 during the three months ending December 31, 2023. Guarantees Contingent liabilities in the form of letters of guarantee have been provided by the Company. Outstanding guarantees were $22.8 and $13.9 at September 28, 2023 and December 31, 2022, respectively. Restricted Cash - Collateral Requirements The Company was required to maintain $22.2 and $19.6 of restricted cash as of September 28, 2023 and December 31, 2022, 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. Pursuant to the terms of the bylaws and, with respect to Jose Garcia, his employment agreement, the Company is providing Messrs. Garcia and Gilson and all other individual defendants with defense costs and provisional indemnity with respect to the Consolidated Class Action and Derivative Actions, as well as for Mr. Gentile with regard to the Securities Class Action, as appropriate. Under the bylaws and any applicable agreements, the Company agrees to indemnify each of these 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 September 28, 2023 and December 31, 2022. 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 September 28, 2023 and December 31, 2022. The following is a roll forward of the service warranty and extraordinary rework balance at September 28, 2023: Balance, December 31, 2022 $ 74.9 Charges (release) to costs and expenses 0.1 Payouts (2.2) Exchange rate (0.2) Balance, September 28, 2023 $ 72.6

Other Income (Expense), Net

Other Income (Expense), Net	9 Months Ended
	Sep. 28, 2023
Other Nonoperating Income (Expense) [Abstract]
Other Income (Expense), Net	Other Income (Expense), Net Other income (expense), net is summarized as follows: For the Three For the Nine September 28, September 29, September 28, September 29, Kansas Development Finance Authority bond $ 0.7 $ 0.5 $ 2.1 $ 1.8 Interest income 2.4 2.3 8.0 3.5 Foreign currency (losses) gains (1) 12.9 13.4 (0.4) 40.6 (Loss) gain on foreign currency forward contract 3.8 (6.5) 1.7 (10.5) Loss on sale of accounts receivable (13.2) (6.0) (36.5) (12.8) Pension (expense) income (2) 1.7 (56.4) (59.0) (15.1) Excise tax on pension assets reversion (3) — — (35.9) (6.8) Gain on settlement of financial instrument (4) — — — 20.7 Other (5) (1.0) 10.6 — 8.8 Total $ 7.3 $ (42.1) $ (120.0) $ 30.2 (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 16 Pension and Other Post-Retirement Benefits. Pension expense for the nine months ended September 28, 2023 includes a $64.6 non-cash, pre-tax non-operating settlement charge related to the PVP A termination. Pension expense for the three and nine months ended September 29, 2022 includes a $71.7 non-cash, pre-tax non-operating charge for amortization of prior service costs. (3) Excise tax related to the reversion of excess plan assets for the nine months ended September 28, 2023 and the nine months ended September 29, 2022. See Note 16 Pension and Other Post-Retirement Benefits. (4) The nine-month period ended September 29, 2022 include a $20.7 gain related to a deed of release and related cash payment that fully settled the existing repayable investment agreement between the Company and the U.K.'s Department for Business, Energy and Industrial Strategy. The repayable investment obligation, which was denominated in GBP, was included on the Company’s Condensed Consolidated Balance Sheet as of December 31, 2021, as $41.7 recorded to the Other current liabilities line item and $301.9 recorded to the Other non-current liabilities line item. In January 2022, the Company made repayments of $25.6 to the UK’s Department for Business Energy and Industrial Strategy for units sold, including interest, in respect to the agreement. In April 2022, the deed of release settled the remaining outstanding repayment obligation, including current year interest accrual and foreign currency measurement impacts, in exchange for a payment of $292.8. The portion of the payments related to interest expense and the portion of the payments related to principal repayment are included in net cash used in operating activities and net cash used in financing activities, respectively, on the Company's Condensed Consolidated Statement of Cash Flows for the period ended September 29, 2022.

Other Liabilities

Other Liabilities	9 Months Ended
	Sep. 28, 2023
Other Liabilities Disclosure [Abstract]
Other Liabilities Disclosure	22. Other Liabilities Included on the Company's Condensed Consolidated Balance Sheet for the nine months ended September 28, 2023 is a liability related to the customer financing of $180.0 from Boeing received in the nine months ended September 28, 2023. Per the original terms of the agreement, $90.0 of the advance was to be repaid in the first quarter of 2024 and the other $90.0 of the advance was to be repaid in 2025. Given those terms, $90.0 of the advance is included in the Other current liabilities line item and the additional $90.0 is included in the Other non-current liabilities line item as of September 28, 2023. Per the terms of the MOA signed with Boeing on October 12, 2023 (see Note 27 Subsequent Events ), the repayment dates have been amended to delay the payments such that $90.0 is payable in December 2025 and the remaining $90.0 is payable in equal $45.0 installments in December 2026 and 2027.

Segment Information

Segment Information	9 Months Ended
	Sep. 28, 2023
Segment Reporting [Abstract]
Segment Information	Segment Information The Company operates in three principal segments: Commercial, Defense & Space and Aftermarket. Approximately 81% and 82% of the Company's net revenues for the three and nine months ended September 28, 2023 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 69% and 65% of Commercial segment net revenues came from the Company's contracts with Boeing for the nine months ended September 28, 2023, and September 29, 2022, respectively. Approximately 24% and 27% of Commercial segment net revenues came from the Company's contracts with Airbus for the nine months ended September 28, 2023, and September 29, 2022, 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, C40, 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 nine months ended September 28, 2023, and September 29, 2022. 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 47% and 47% of Aftermarket segment net revenues came from the Company's contracts with a single customer for the nine months ended September 28, 2023, and September 29, 2022, 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 nine months ended September 28, 2023 and September 29, 2022: Three Months Ended Nine Months Ended September 28, September 29, September 28, September 29, Segment Revenues Commercial $ 1,136.4 $ 1,034.9 $ 3,367.9 $ 3,004.4 Defense & Space 205.7 161.7 583.7 466.6 Aftermarket 96.8 80.3 283.4 238.5 $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5 Segment Operating Income (Loss) Commercial (1) $ (82.1) $ 45.0 $ (200.5) $ (3.5) Defense & Space (2) 9.8 18.4 41.0 52.1 Aftermarket (3) 17.9 19.5 61.4 49.3 $ (54.4) $ 82.9 $ (98.1) $ 97.9 SG&A (69.2) (69.1) (217.2) (203.8) Research and development (10.1) (9.3) (33.9) (36.5) Total operating loss $ (133.7) $ 4.5 $ (349.2) $ (142.4) (1) The three and nine months ended September 28, 2023 include excess capacity production costs of $54.3 and $147.0, respectively, related to the temporary B737 MAX, A320 and A220 production schedule changes, costs of $0.8 and $7.9, respectively, related to temporary production pause, and $0.0 and $6.3, respectively, of restructuring costs. The nine months ended September 29, 2022 includes the impact of $23.9 of the total charge in relation to the suspension of activities in Russia as described in Management's Discussion and Analysis of Financial Condition and Results of Operations - Global Economic Conditions and COVID-19 . The three and nine months ended September 29, 2022 include $29.9 and $119.8, respectively, of excess capacity costs related to the temporary B737 MAX, A320 and A220 production schedule changes, abnormal costs of $0.3 and $9.8, respectively, of temporary workforce adjustment costs as a result of the COVID-19 pandemic, net of U.S. employee retention credit and U.K government subsidies, and net $0.0 and ($25.5), respectively, of restructuring costs and other costs, including partial offset related to the Aviation Manufacturing Jobs Protection ("AMJP") Program. (2) The three and nine months ended September 28, 2023 include excess capacity production costs of $2.1 and $5.9 related to the temporary B737 production schedule changes, costs of $0.0 and $0.2, respectively, related to temporary production pause, and $0.0 and $0.9, respectively, of restructuring costs. The three and nine months ended September 29, 2022 include excess capacity costs of $1.5 and $6.3, respectively, related to temporary B737 production schedule changes, and $0.0 and ($2.3), respectively, of restructuring costs and partial offset related to AMJP. (3) The three and nine months ended September 28, 2023 include $0.0 and $0.0, respectively, of restructuring costs and $0.0 and ($2.4), respectively, of benefit related to the settlement of a contingent consideration obligation related to the Applied Aerodynamics acquisition. The nine months ended September 29, 2022 includes $4.2 of the total charge in relation to the suspension of activities in Russia as described in Management's Discussion and Analysis of Financial Condition and Results of Operations - Global Economic Conditions and COVID-19

Restructuring Charges (Notes)

Restructuring Charges (Notes)	9 Months Ended
	Sep. 28, 2023
Restructuring Costs [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	Restructuring Costs The Company's results of operations for the nine months ended September 28, 2023 include 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. 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 and nine months ended September 28, 2023 were $0.0 and $7.2, respectively, of which, $6.3 was included in segment operating margins for the Commercial Segment and $0.9 was included in segment operating margins for the Defense & Space Segment. The Company's results of operations for the nine months ended September 29, 2022 includes restructuring costs related to actions the Company has taken to align costs to updated production levels that have been directed by the Company's customers (restructuring activity). Largely beginning in the first quarter of 2020, the Company's customers, including Boeing and Airbus, significantly reduced their overall production rates as a result of the COVID-19 pandemic and, in the case of Boeing, the B737 MAX grounding. The restructuring activity materially affected the scope of operations and manner in which business is conducted by the Company compared to periods prior to the restructuring activities. The total restructuring costs for the three and nine months ended September 29, 2022 were $0.0 and $0.2, respectively, and are included in segment operating margins for the Commercial Segment.

Payables and Accruals

Payables and Accruals	9 Months Ended
	Sep. 28, 2023
Payables and Accruals [Abstract]
Supplier Finance Program	25. Supplier Financing The Company has provided certain suppliers with access to a supply chain financing program through a facility with a third-party financing institution. 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. This program was primarily entered into as a result of the Company seeking payment term extensions with production suppliers, and 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 $97.0 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. 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 September 28, 2023, the balance of confirmed obligations outstanding was $112.7, an increase of $10.7 over the balance as of December 31, 2022 of $102.0. In the comparable prior year period, confirmed obligations outstanding were $103.5 as of September 29, 2022, an increase of $44.6 over the balance as of December 31, 2021. The changes in each period primarily reflect purchases from suppliers related to production levels during the respective periods.

Business Combinations and Asset

Business Combinations and Asset Acquisitions	9 Months Ended
	Sep. 28, 2023
Business Combination and Asset Acquisition [Abstract]
Business Acquisition, Description of Acquired Entity	26. 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 third quarter of 2023 was immaterial and reported within the Defense & Space segment. There were no acquisition-related expenses for the nine months ended September 28, 2023. Acquisition-related expenses were $0.5 and $0.6 for the for the three and nine months ended September 29, 2022, respectively.

Subsequent Event (Notes)

Subsequent Event (Notes)	9 Months Ended
	Sep. 28, 2023
Subsequent Event [Line Items]
Subsequent Events [Text Block]	Subsequent Events On October 12, 2023, Spirit and The Boeing Company executed the MOA to support production stability. The MOA establishes recurring shipset price increases for the B787 program effective for LN 1164 through LN 1605, recurring shipset price adjustments on the B737 program effective from the first delivery in 2026 through June 2033, releases of liabilities and claims through the effective date of the MOA by both parties relating to Boeing’s Commercial Airplanes division and its airplane programs under the General Terms Agreement for the B787 program and the General Terms Agreement for the B737, B747, B767 and B777 programs unless explicitly excluded within the MOA, Boeing provided funding for tooling and capital through 2025 for certain planned and potential B737 and B787 rate increases, amendment of repayment dates for outstanding customer financing, and changes to terms governing assignments. Regarding the tooling and capital funding, approximately $100.7 was received during the fourth quarter of 2023. As a result of the MOA, which was executed in the fourth quarter, we expect to reverse liabilities, including previously recorded forward losses and material right obligation on the B787 program of between approximately $350.0 to $370.0 in the fourth quarter of 2023 which represents a preliminary estimate which could be subject to change based on certain performance during the fourth quarter. Regarding the $180.0 of advances received as customer financing in the quarter ended June 29, 2023, per the terms of the MOA, the repayment dates were amended. The amended repayment dates require repayment of $90.0 in December 2025 and equal payments of $45.0 in December 2026 and 2027. Additionally and separate from the range above, related to the release of claims, we will be reversing liabilities for certain claims received and other anticipated claims on our balance sheet in the fourth quarter of 2023 including the $23.0 of anticipated claims related to the Boeing 737 Vertical Fin Attach Fittings previously disclosed.

New Accounting Pronouncements (

New Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 28, 2023
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.

Accounts Receivable and Allow_2

Accounts Receivable and Allowance for Credit Losses Allowance for Credit Losses (Policies)	9 Months Ended
	Sep. 28, 2023
Credit Loss [Abstract]
Credit Loss, Financial Instrument [Text Block]	Allowance for Credit Losses During the nine months ended September 28, 2023, 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)	9 Months Ended
	Sep. 28, 2023
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.

Changes in Estimates Changes in

Changes in Estimates Changes in Estimates (Tables)	9 Months Ended
	Sep. 28, 2023
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 For the Nine Months Ended Changes in Estimates September 28, 2023 September 29, 2022 September 28, 2023 September 29, 2022 (Unfavorable) Favorable Cumulative Catch-up Adjustment by Segment Commercial $ (59.1) $ (6.9) $ (40.7) $ (27.8) Defense & Space (4.9) 2.0 (8.7) 1.6 Aftermarket — — — — Total (Unfavorable) Favorable Cumulative Catch-up Adjustment $ (64.0) $ (4.9) $ (49.4) $ (26.2) Changes in Estimates on Loss Programs (Forward Loss) by Segment Commercial $ (86.5) $ (47.4) $ (298.3) $ (132.6) Defense & Space (14.6) (1.7) (17.5) (4.0) Aftermarket — — — — Total Changes in Estimates (Forward Loss) on Loss Programs $ (101.1) $ (49.1) $ (315.8) $ (136.6) Total Change in Estimate $ (165.1) $ (54.0) $ (365.2) $ (162.8) EPS Impact (diluted per share based upon applicable forecasted effective tax rate) $ (1.57) $ (0.55) $ (3.48) $ (1.66)

Accounts Receivable, net (Table

Accounts Receivable, net (Tables)	9 Months Ended
	Sep. 28, 2023
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts Receivable, Net	Accounts receivable, net consists of the following: September 28, December 31, Trade receivables $ 579.4 $ 477.9 Other 43.8 19.7 Less: allowance for credit losses (12.9) (8.1) Accounts receivable, net $ 610.3 $ 489.5

Revenue (Tables)

Revenue (Tables) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Disaggregation of Revenue [Line Items]
Revenues	$ 1,438.9	$ 1,276.9	$ 4,235	$ 3,709.5
Boeing [Member]
Disaggregation of Revenue [Line Items]
Revenues	883.9	824.3	2,640.6	2,233.7
Airbus [Member]
Disaggregation of Revenue [Line Items]
Revenues	274.5	237.2	816.8	822.2
Other Customer [Member]
Disaggregation of Revenue [Line Items]
Revenues	280.5	215.4	777.6	653.6
UNITED STATES
Disaggregation of Revenue [Line Items]
Revenues	1,156	1,037	3,379.8	2,768
UNITED KINGDOM
Disaggregation of Revenue [Line Items]
Revenues	163.5	145.5	505.3	473.5
Other International [Member]
Disaggregation of Revenue [Line Items]
Revenues	119.4	94.4	349.9	468
Total International [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 282.9	$ 239.9	$ 855.2	$ 941.5

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 28, 2023
Inventory Disclosure [Abstract]
Summary Of Inventories	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 September 28, 2023 and December 31, 2022, work-in-process inventory includes $256.3 an d $392.2, 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 $148.3 and $136.8 as of September 28, 2023 and December 31, 2022, 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 and nine months ended September 28, 2023 includes period expense of $56.4 and $152.9, respectively, for

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 28, 2023
Property, Plant and Equipment [Abstract]
Property, plant and equipment, net	Property, plant and equipment, net consists of the following: September 28, December 31, Land $ 30.1 $ 30.1 Buildings (including improvements) 1,292.3 1,269.1 Machinery and equipment 2,439.6 2,365.1 Tooling 1,061.4 1,055.9 Capitalized software 338.3 336.1 Construction-in-progress 86.0 102.2 Total 5,247.7 5,158.5 Less: accumulated depreciation (3,163.6) (2,952.6) Property, plant and equipment, net $ 2,084.1 $ 2,205.9

Other Assets (Tables)

Other Assets (Tables)	9 Months Ended
	Sep. 28, 2023
Other Assets, Noncurrent [Abstract]
Schedule of Other Assets	Other current assets are summarized as follows: September 28, December 31, Prepaid expenses $ 39.6 $ 27.5 Income tax receivable 2.7 3.9 Other assets - short-term 8.3 6.9 Total other current assets $ 50.6 $ 38.3 Other assets are summarized as follows: September 28, December 31, Deferred financing Deferred financing costs $ 0.9 $ 0.9 Less: Accumulated amortization - deferred financing costs (0.8) (0.8) Deferred financing costs, net $ 0.1 $ 0.1 Other Supply agreements (1) $ 4.1 $ 6.4 Equity in net assets of affiliates 0.9 1.1 Restricted cash - collateral requirements 22.2 19.6 Rotables 43.6 39.0 Other 26.6 25.6 Total other long-term assets $ 97.5 $ 91.8 (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)	9 Months Ended
	Sep. 28, 2023
Finite-Lived Intangible Assets [Line Items]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	Intangible assets are summarized as follows: September 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 (2.1) (2.1) Accumulated amortization - developed technology asset (20.2) (15.0) Accumulated amortization - customer relationship (23.2) (17.0) Intangible assets, net $ 200.0 $ 211.4 Amortization expense was $3.8 and $3.6 for the for the three months ended September 28, 2023 and September 29, 2022, respectively and $11.4 and $10.9 for the nine months ended September 28, 2023 and September 29, 2022, 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 September 28, 2023: Year Customer relationships Favorable leasehold interest Developed Technology Total remaining in 2023 $ 2.1 $ — $ 1.7 $ 3.8 2024 8.2 0.1 6.9 15.2 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 Weighted average amortization period 14.7 years 5.8 years 12.1 years 13.6 years

Other Assets Goodwill (Tables)

Other Assets Goodwill (Tables)	9 Months Ended
	Sep. 28, 2023
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 September 28, Commercial $ 296.5 $ — $ — $ — $ 296.5 Defense & Space $ 12.6 $ — $ 0.6 (1) $ — $ 13.2 Aftermarket $ 321.4 $ — $ — $ — $ 321.4 $ 630.5 $ — $ 0.6 $ — $ 631.1 (1) As a result of certain purchase price allocation adjustments recorded during the purchase price accounting measurement period based on additional information obtained, the goodwill resulting from the T.E.A.M., Inc. acquisition was adjusted by $0.6, from $7.1 that was reported at December 31, 2022, to $7.7 as of September 28, 2023. See also Note 26 Acquisitions. 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)	9 Months Ended
	Sep. 28, 2023
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 14 Derivative and Hedging Activities and Note 16 Pension and Other Post-Retirement Benefits. September 28, 2023 December 31, 2022 Carrying Fair Carrying Fair Senior secured term loan B (including current portion) $ 572.6 $ 571.2 (2) $ 571.7 $ 564.5 (2) Senior notes due 2025 20.8 20.5 (1) 20.7 20.8 (1) Senior secured second lien notes due 2025 1,193.8 1,165.9 (1) 1,191.0 1,179.0 (1) Senior notes due 2026 299.0 278.4 (1) 298.8 272.8 (1) Senior notes due 2028 696.4 538.9 (1) 695.9 562.3 (1) Senior secured first lien notes due 2029 888.0 903.8 (1) 887.2 935.7 (1) Total $ 3,670.6 $ 3,478.7 $ 3,665.3 $ 3,535.1 (1) Level 1 Fair Value hierarchy

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 28, 2023
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: September 28, 2023 December 31, 2022 Current Noncurrent Current Noncurrent Senior secured term loan B $ 5.7 $ 566.9 $ 5.7 $ 566.0 Senior notes due 2025 — 20.8 — 20.7 Senior secured second lien notes due 2025 — 1,193.8 — 1,191.0 Senior notes due 2026 — 299.0 — 298.8 Senior notes due 2028 — 696.4 — 695.9 Senior secured first lien notes due 2029 — 888.0 — 887.2 Present value of finance lease obligations 47.9 94.0 42.2 102.3 Other 10.6 52.1 5.8 53.0 Total $ 64.2 $ 3,811.0 $ 53.7 $ 3,814.9

Pension and Other Post-Retire_2

Pension and Other Post-Retirement Benefits (Tables)	9 Months Ended
	Sep. 28, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Change in projected benefit obligations	Defined Benefit Plans For the Three Months Ended For the Nine Components of Net Periodic Pension Expense (Income) September 28, September 29, September 28, September 29, Service cost $ 0.8 $ 0.5 $ 2.4 $ 1.7 Interest cost 18.8 13.1 57.4 42.2 Expected return on plan assets (20.3) (28.9) (62.3) (99.2) Amortization of net loss (1) — 71.7 0.1 73.8 Settlement loss (gain) (2) — 0.9 64.6 (0.5) Net periodic pension expense (income) $ (0.7) $ 57.3 $ 62.2 $ 18.0 Other Benefits For the Three For the Nine Components of Other Benefit Expense (Income) September 28, September 29, September 28, September 29, Service cost $ 0.1 $ 0.2 $ 0.4 $ 0.6 Interest cost 0.4 0.1 1.1 0.4 Amortization of prior service cost (0.2) (0.2) (0.6) (0.6) Amortization of net gain (0.4) (0.3) (1.3) (1.0) Net periodic other benefit income $ (0.1) $ (0.2) $ (0.4) $ (0.6) (1) In July 2022, the Company adopted and communicated to participants a plan to terminate the Company's Pension Value Plan A ( “ PVP A”). As further described in the Company's 2021 Form 10-K, the PVP A consists of pension plans which were frozen as of the date Holdings became a standalone company and commenced operations. During the three months ended September 29, 2022, the PVP A plan was amended, providing for an enhancement to benefits the Company is providing to certain U.S. employees in conjunction with the plan termination. The estimated liability impact of this plan amendment, $71.7, was recognized immediately as a non-cash, pre-tax non-operating charge for amortization of prior service costs. (2) Includes a $64.6 settlement charge for the PVP A during the nine months ended September 28, 2023. Includes a $0.9 settlement charge for the PVP A during the three months ended September 29, 2022, and a ($1.4) settlement credit for PVP B related to final asset distribution in the nine months ended September 29, 2022. 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 21 Other Income (Expense), Net. As disclosed in the Company's 2022 Form 10-K, 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 September 28, 2023, a pension reversion asset of $61.4 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 six 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 13 Fair Value Measurements. Separately, during the nine months ended September 28, 2023, the Company received an excess plan asset reversion of $179.5 of cash from PVP A. During the nine months ended September 29, 2022, the Company withdrew $34.0 of cash from PVP B, which represented an excess plan assets reversion. These transactions were accounted for as a negative contribution and are included on the Pension plans employer contributions line item on the Condensed Consolidated Statements of Cash Flows for the nine months ended September 28, 2023 and September 29, 2022. Excise tax of $35.9 and $6.8 related to the reversion of excess plan assets was separately recorded to the Other income (expense), net line item on the Company's Condensed Consolidated Statements of Operations for the nine months ended September 28, 2023 and September 29, 2022, respectively. See also Note 21 Other Income (Expense), Net. As disclosed in the Company's 2022 Form 10-K, i n July 2022, the Company adopted and communicated to participants a plan to terminate the PVP A. During the nine months ended September 28, 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. In connection with the special accounting related to the termination of the PVP A plan, discussed above, a subsequent interim measurement of the Company's U.S. pension and other postretirement plan assets and obligations was completed during the three months ended September 29, 2022. The interim measurement, including the estimated impact of the plan termination liability and enhanced benefits liability noted above, prior to the current period settlement loss and amortization of prior service cost impacts included in Net Periodic Pension Expense above, was recorded to the Accumulated other comprehensive loss line item in the Stockholders' Equity section of the Company's Condensed Consolidated Balance Sheet for the period ended September 29, 2022.

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 28, 2023
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 September 28, 2023 September 29, 2022 Income Shares Per Share Income Shares Per Share Basic EPS Loss available to common stockholders $ (204.1) 105.2 $ (1.94) $ (127.6) 104.7 $ (1.22) Income allocated to participating securities — — — — Net loss $ (204.1) $ (127.6) Diluted potential common shares — — Diluted EPS Net loss $ (204.1) 105.2 $ (1.94) $ (127.6) 104.7 $ (1.22) For the Nine Months Ended September 28, 2023 September 29, 2022 Income Shares Per Share Income Shares Per Share Basic EPS Loss available to common stockholders $ (691.6) 105.1 $ (6.58) $ (302.6) 104.6 $ (2.89) Income allocated to participating securities — — — — Net loss $ (691.6) $ (302.6) Diluted potential common shares — — Diluted EPS Net loss $ (691.6) 105.1 $ (6.58) $ (302.6) 104.6 $ (2.89) Included in the outstanding Common Stock were 0.1 million and 0.4 million of issued but unvested shares at September 28, 2023 and September 29, 2022, respectively, which are excluded from the basic Earnings Per Share (“EPS”) calculation. Shares of Common Stock of 0.6 million and 0.7 million, respectively, were excluded from diluted EPS as a result of incurring a net loss for the three and nine months ended September 28, 2023 , as the effect would have been antidilutive. Additionally, diluted EPS for the three and nine months ended September 28, 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. Shares of Common Stock of 0.5 million and 0.6 million, respectively, were excluded from diluted EPS as a result of incurring a net loss for the three and nine months ended September 29, 2022, as the effect would have been antidilutive. Additionally, diluted EPS for the three and nine months ended September 29, 2022 excludes 0.3 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 September 28, 2023 December 31, 2022 Pension $ (44.4) $ (95.4) SERP/Retiree medical 11.2 12.7 Derivatives - foreign currency hedge (6.2) (7.1) Foreign currency impact on long-term intercompany loan (16.1) (16.4) Currency translation adjustment (94.5) (97.7) Total accumulated other comprehensive loss $ (150.0) $ (203.9)

Commitments, Contingencies an_2

Commitments, Contingencies and Guarantees (Tables)	9 Months Ended
	Sep. 28, 2023
Commitments Contingencies And Guarantees [Abstract]
Service warranty roll forward	The following is a roll forward of the service warranty and extraordinary rework balance at September 28, 2023: Balance, December 31, 2022 $ 74.9 Charges (release) to costs and expenses 0.1 Payouts (2.2) Exchange rate (0.2) Balance, September 28, 2023 $ 72.6

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	9 Months Ended
	Sep. 28, 2023
Other Nonoperating Income (Expense) [Abstract]
Other Income Expense Net	Other income (expense), net is summarized as follows: For the Three For the Nine September 28, September 29, September 28, September 29, Kansas Development Finance Authority bond $ 0.7 $ 0.5 $ 2.1 $ 1.8 Interest income 2.4 2.3 8.0 3.5 Foreign currency (losses) gains (1) 12.9 13.4 (0.4) 40.6 (Loss) gain on foreign currency forward contract 3.8 (6.5) 1.7 (10.5) Loss on sale of accounts receivable (13.2) (6.0) (36.5) (12.8) Pension (expense) income (2) 1.7 (56.4) (59.0) (15.1) Excise tax on pension assets reversion (3) — — (35.9) (6.8) Gain on settlement of financial instrument (4) — — — 20.7 Other (5) (1.0) 10.6 — 8.8 Total $ 7.3 $ (42.1) $ (120.0) $ 30.2

Changes in Estimates (Details)

Changes in Estimates (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Change In Estimate [Line Items]
Changes in Contract Estimates, aggregate, Affecting earnings from Continuing Operations, per Share diluted	$ (1.57)	$ (0.55)	$ (3.48)	$ (1.66)
Change In Accounting Estimate, aggregate	$ (165.1)	$ (54)	$ (365.2)	$ (162.8)
Cost of Goods and Services Sold	1,492.5	1,194	4,320.2	3,611.4
Cumulative catch-up adjustment [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(64)	(4.9)	(49.4)	(26.2)
Forward Loss [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(101.1)	(49.1)	(315.8)	(136.6)
Commercial Segment [Member] | Cost of Sales | Russia and Ukraine Conflict
Change In Estimate [Line Items]
Cost of Goods and Services Sold				23.9
Commercial Segment [Member] | Cumulative catch-up adjustment [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(59.1)	(6.9)	(40.7)	(27.8)
Commercial Segment [Member] | Forward Loss [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(86.5)	(47.4)	(298.3)	(132.6)
Defense & Space Segment [Member] | Cumulative catch-up adjustment [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(4.9)	2	(8.7)	1.6
Defense & Space Segment [Member] | Forward Loss [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	(14.6)	(1.7)	(17.5)	(4)
Aftermarket Segment [Member] | Cost of Sales | Russia and Ukraine Conflict
Change In Estimate [Line Items]
Cost of Goods and Services Sold				4.2
Aftermarket Segment [Member] | Cumulative catch-up adjustment [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	0	0	0	0
Aftermarket Segment [Member] | Forward Loss [Member]
Change In Estimate [Line Items]
Change in Accounting Estimate - Contract Accounting	$ 0	$ 0	$ 0	$ 0

Accounts Receivable, net (Detai

Accounts Receivable, net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022	Dec. 31, 2022
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Transfer of Financial Assets Accounted for as Sales, Amount Derecognized	$ 2,657		$ 2,657
Trade receivables	579.4		579.4		$ 477.9
Other	43.8		43.8		19.7
Less: allowance for doubtful accounts	(12.9)		(12.9)		(8.1)
Accounts receivable, net	610.3		610.3		$ 489.5
Gain (Loss) on Sale of Accounts Receivable	$ 13.2	$ 6	$ 36.5	$ 12.8

Contract with customer, asset_2

Contract with customer, asset and liability (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 1,438.9	$ 1,276.9	$ 4,235	$ 3,709.5
Contract with Customer, Liability, Revenue Recognized			$ 66.4	63.2
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 23 Segment Information . The following tables show disaggregated revenues for the periods ended September 28, 2023 and September 29, 2022: For the Three For the Nine Revenue September 28, September 29, September 28, September 29, Contracts with performance obligations satisfied over time $ 1,064.1 $ 970.6 $ 3,176.2 $ 2,733.3 Contracts with performance obligations satisfied at a point in time 374.8 306.3 1,058.8 976.2 Total Revenue $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5 The following table disaggregates revenue by major customer: For the Three For the Nine Customer September 28, September 29, September 28, September 29, Boeing $ 883.9 $ 824.3 $ 2,640.6 $ 2,233.7 Airbus 274.5 237.2 816.8 822.2 Other 280.5 215.4 777.6 653.6 Total Revenue $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5 The following table disaggregates revenue based upon the location where control of products is transferred to the customer: For the Three Months Ended For the Nine Location September 28, September 29, September 28, September 29, United States $ 1,156.0 $ 1,037.0 $ 3,379.8 $ 2,768.0 International United Kingdom 163.5 145.5 505.3 473.5 Other 119.4 94.4 349.9 468.0 Total International 282.9 239.9 855.2 941.5 Total Revenue $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5
Contract with Customer, Liability, Revenue Recognized			$ 66.4	63.2
Contract with Customer, Asset, before Allowance for Credit Loss	616.9	547.4	616.9	547.4	$ 502.2	$ 443.2
change in contract asset			114.7	104.2
Contract with Customer, Liability	(352.8)	(361.7)	(352.8)	(361.7)	(356.4)	(387)
change in contract liability			3.6	25.3
change in contract assets (liabilities), net			118.3	129.5
Contract with Customer Asset (Liability), Net	264.1	185.7	264.1	185.7	$ 145.8	$ 56.2
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,064.1	970.6	3,176.2	2,733.3
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 374.8	$ 306.3	$ 1,058.8	$ 976.2

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
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 23 Segment Information . The following tables show disaggregated revenues for the periods ended September 28, 2023 and September 29, 2022: For the Three For the Nine Revenue September 28, September 29, September 28, September 29, Contracts with performance obligations satisfied over time $ 1,064.1 $ 970.6 $ 3,176.2 $ 2,733.3 Contracts with performance obligations satisfied at a point in time 374.8 306.3 1,058.8 976.2 Total Revenue $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5 The following table disaggregates revenue by major customer: For the Three For the Nine Customer September 28, September 29, September 28, September 29, Boeing $ 883.9 $ 824.3 $ 2,640.6 $ 2,233.7 Airbus 274.5 237.2 816.8 822.2 Other 280.5 215.4 777.6 653.6 Total Revenue $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5 The following table disaggregates revenue based upon the location where control of products is transferred to the customer: For the Three Months Ended For the Nine Location September 28, September 29, September 28, September 29, United States $ 1,156.0 $ 1,037.0 $ 3,379.8 $ 2,768.0 International United Kingdom 163.5 145.5 505.3 473.5 Other 119.4 94.4 349.9 468.0 Total International 282.9 239.9 855.2 941.5 Total Revenue $ 1,438.9 $ 1,276.9 $ 4,235.0 $ 3,709.5
Revenues	$ 1,438.9	$ 1,276.9	$ 4,235	$ 3,709.5
Remaining in Current Year [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	1,533.7		1,533.7
2021 [Member] [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	5,286.1		5,286.1
2022 [Member] [Member] [Domain]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	1,758.5		1,758.5
2021 and after [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	278.3		278.3
Transferred over Time [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	1,064.1	970.6	3,176.2	2,733.3
Transferred at Point in Time [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	374.8	306.3	1,058.8	976.2
Boeing [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	883.9	824.3	2,640.6	2,233.7
Airbus [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	274.5	237.2	816.8	822.2
Other Customer [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	$ 280.5	$ 215.4	$ 777.6	$ 653.6

Inventory (Details)

Inventory (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 28, 2023	Sep. 28, 2023	Dec. 31, 2022
Summary Of Inventories [Abstract]
Raw materials	$ 395.4	$ 395.4	$ 332.7
Work-in-process	1,226.2	1,226.2	1,044.9
Finished goods	46.8	46.8	69.4
Product inventory	1,668.4	1,668.4	1,447
Capitalized pre-production	21.6	21.6	23.7
Total inventory, net	1,690	1,690	1,470.7
Inventory Valuation Reserves	148.3	148.3	136.8
Costs Incurred in Anticipation of Contracts	256.3	256.3	$ 392.2
Excess Capacity Costs- B737MAX and A320 Production Schedules	56.4	152.9
Inventories [Line Items]
Excess Capacity Costs- B737MAX and A320 Production Schedules	$ 56.4	$ 152.9

Inventory (Details 2)

Inventory (Details 2) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 28, 2023	Sep. 28, 2023
Block And Order Detail [Abstract]
Unusual or Infrequent Item, or Both, Net (Gain) Loss	$ 0.8	$ 8.1

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Millions	Sep. 28, 2023	Dec. 31, 2022
Property, plant and equipment, net
Land	$ 30.1	$ 30.1
Buildings (including improvements)	1,292.3	1,269.1
Machinery and equipment	2,439.6	2,365.1
Tooling	1,061.4	1,055.9
Capitalized software	338.3	336.1
Construction-in-progress	86	102.2
Total	5,247.7	5,158.5
Less: accumulated depreciation	(3,163.6)	(2,952.6)
Property, plant and equipment, net	$ 2,084.1	$ 2,205.9

Property, Plant and Equipment_3

Property, Plant and Equipment (Details Textual) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Property Plant And Equipment Textuals [Abstract]
Capitalized interest related to construction-in-progress	$ 0.4	$ 1	$ 3.8	$ 2.9
Repair and maintenance costs	32.1	43.7	124.4	115
Depreciation expense related to capitalized software	$ 5.6	$ 5	$ 17.5	$ 16.5

Leases (Details)

Leases (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022	Dec. 31, 2022
Lessee Disclosure [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	32 years 6 months		32 years 6 months		31 years 8 months 12 days
Finance Lease, Weighted Average Remaining Lease Term	4 years 8 months 12 days		4 years 8 months 12 days		5 years 3 months 18 days
Assets and Liabilities, Lessee [Abstract]
Operating Lease, Liability, Current	$ 8.4		$ 8.4		$ 8.3
Operating Lease, Liability, Noncurrent	84.9		84.9		85.4
Operating Lease, Liability	93.3		93.3
finance lease, Right-of-Use Asset, gross	333.5		333.5		295.4
Finance Lease, Right-of-Use Asset, Accumulated Amortization	(129.6)		(129.6)		(103.4)
Finance Lease, Right-of-Use Asset, after Accumulated Amortization	203.9		203.9		192
Finance Lease, Liability, Current	47.9		47.9		42.2
Finance Lease, Liability, Noncurrent	94		94		$ 102.3
Finance Lease, Liability	141.9		141.9
Lessee, Operating Lease, Lease Not yet Commenced, Description	2.2		2.2
Lessee, Finance Lease, Lease Not yet Commenced, Description	$ 28.7		$ 28.7
Operating Lease, Weighted Average Discount Rate, Percent	6.20%		6.20%		5.80%
Finance Lease, Weighted Average Discount Rate, Percent	5.80%		5.80%		5%
Finance Lease, Liability, Payment, Due [Abstract]
Finance Lease, Liability, to be Paid, Remainder of Fiscal Year	$ 14.7		$ 14.7
Finance Lease, Liability, to be Paid, Year Two	51.5		51.5
Finance Lease, Liability, to be Paid, Year Three	37.8		37.8
Finance Lease, Liability, to be Paid, Year Four	22.8		22.8
Finance Lease, Liability, to be Paid, Year Five	9.6		9.6
Finance Lease, Liability, to be Paid, after Year Five	26.8		26.8
Finance Lease, Liability, Payment, Due	163.2		163.2
Lease Imputed Interest Due- Financing	(21.3)		(21.3)
Cash Flow, Operating Activities, Lessee [Abstract]
Operating lease cost	3.5	$ 3.2	10.5	$ 9.5
Finance Lease, Interest Payment on Liability	2.1	1.7	5.9	5
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	5.1	0.1	5.6	1.3
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year	3.6		3.6
Lessee, Operating Lease, Liability, to be Paid, Year Two	13.9		13.9
Lessee, Operating Lease, Liability, to be Paid, Year Three	14		14
Lessee, Operating Lease, Liability, to be Paid, Year Four	11.9		11.9
Lessee, Operating Lease, Liability, to be Paid, Year Five	9.3		9.3
Lessee, Operating Lease, Liability, to be Paid, after Year Five	177.2		177.2
Lessee, Operating Lease, Liability, to be Paid	229.9		229.9
Lease Imputed Interest Due- Operating	(136.6)		(136.6)
Lease, Cost [Abstract]
Operating Lease, Cost	3.6	3.2	10.8	9.8
Finance Lease, Right-of-Use Asset, Amortization	9.5	8.3	26.6	24.6
Finance Lease, Interest Expense	2.1	1.7	5.9	5
Lease, Cost	15.2	13.2	43.3	39.4
Cash Flow, Financing Activities, Lessee [Abstract]
Finance Lease, Principal Payments	13	$ 11.2	36.9	$ 33.7
Lessee, Finance Lease, Not yet Commenced, Description [Abstract]
Lessee, Operating Lease, Lease Not yet Commenced, Description	2.2		2.2
Lessee, Finance Lease, Lease Not yet Commenced, Description	$ 28.7		$ 28.7
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 2 and 5 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	Sep. 28, 2023	Dec. 31, 2022	Sep. 29, 2022	Dec. 31, 2021
Other Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	$ 245.5	$ 245.5
Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year	3.8
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	$ 15.2
Finite-Lived Intangible Assets, Remaining Amortization Period	13 years 7 months 6 days
Intangible assets
Deferred financing costs, net	$ 0.1	0.1
Goodwill	631.1	630.5
Equity in net assets of affiliates	0.9	1.1
Customer Supply Agreement	4.1	6.4
Restricted Cash, Noncurrent	22.2	19.6	$ 19.5	$ 19.5
Rotable assets	43.6	39
Other	26.6	25.6
Total other long-term assets	97.5	91.8
Prepaid Expense, Current	39.6	27.5
Income Taxes Receivable, Current	2.7	3.9
Other Assets, Miscellaneous, Current	8.3	6.9
Intangible Assets, Net (Excluding Goodwill)	200	211.4
Other Assets, Current	50.6	38.3
Patents [Member]
Other Assets [Line Items]
Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year	2.1
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	$ 8.2
Finite-Lived Intangible Assets, Remaining Amortization Period	14 years 8 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
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 9 months 18 days
Intangible assets
Less: Accumulated amortization	$ (2.1)	(2.1)
Debt issuance costs [Member]
Intangible assets
Deferred financing costs	0.9	0.9
Less: Accumulated amortization-deferred financing costs	(0.8)	(0.8)
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	1.7
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	12 years 1 month 6 days
Intangible assets
Less: Accumulated amortization	$ (20.2)	(15)
Customer Relationships
Other Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	139.6	139.6
Intangible assets
Less: Accumulated amortization	$ (23.2)	$ (17)

Other Assets (Details Textuals)

Other Assets (Details Textuals) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Dec. 31, 2022	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Goodwill [Line Items]
Goodwill	$ 630.5	$ 631.1		$ 631.1
Goodwill, Acquired During Period				0
Goodwill, Other Increase (Decrease)				0.6
Goodwill, Period Increase (Decrease)				0
Amortization of Intangible Assets		3.8	$ 3.6	11.4	$ 10.9
Aftermarket Segment [Member]
Goodwill [Line Items]
Goodwill	321.4	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	12.6	13.2		13.2
Goodwill, Acquired During Period				0
Goodwill, Other Increase (Decrease)				0.6
Goodwill, Period Increase (Decrease)				0
Commercial Segment [Member]
Goodwill [Line Items]
Goodwill	296.5	296.5		296.5
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		7.7
T.E.A.M., Inc. Acquisition | Defense & Space Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period	$ 7.1			$ 7.7

Advance Payments and Deferred_2

Advance Payments and Deferred Revenue/Credits (Details) - USD ($) $ in Millions	Sep. 28, 2023	Jun. 29, 2023	Dec. 31, 2022
advance payments [Line Items]
Customer advances- B787 program	$ 194.5
Customer advances- Irkut program	18.9
First installment of net advance payment
advance payments [Line Items]
Customer Advances - A350 program		$ 50
Second installment of net advance payment
advance payments [Line Items]
Customer Advances - A350 program	$ 50
Total Payment [Member]
advance payments [Line Items]
Customer advances- B737 program			$ 123

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 28, 2023	Dec. 31, 2022
Carrying amount and estimated fair value of long term debt
Carrying Amount	$ 3,670.6	$ 3,665.3
Fair Value	3,478.7	3,535.1
Secured Debt Term B [Member]
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	566.9	566
Carrying amount and estimated fair value of long term debt
Carrying Amount	572.6	571.7
Fair Value	571.2	564.5
Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	299	298.8
Carrying amount and estimated fair value of long term debt
Carrying Amount	299	298.8
Fair Value	278.4	272.8
Senior Secured Second Lien Notes Due 2025
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	1,193.8	1,191
Carrying amount and estimated fair value of long term debt
Carrying Amount	1,193.8	1,191
Fair Value	1,165.9	1,179
Senior Unsecured Notes Due 2028 [Member]
Carrying amount and estimated fair value of long term debt
Carrying Amount	696.4	695.9
Fair Value	538.9	562.3
Senior Secured Notes Due 2025
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	20.8	20.7
Carrying amount and estimated fair value of long term debt
Carrying Amount	20.8	20.7
Fair Value	20.5	20.8
Senior Secured First Lien Notes due 2029
Debt Instrument [Line Items]
Secured Long-term Debt, Noncurrent	888	887.2
Carrying amount and estimated fair value of long term debt
Carrying Amount	888	887.2
Fair Value	$ 903.8	$ 935.7

Derivative and Hedging Activi_2

Derivative and Hedging Activities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022	Dec. 31, 2022
Interest Rate Swaps
Foreign Currency Cash Flow Hedge Asset at Fair Value	$ 0		$ 0		$ 0
Foreign Currency Cash Flow Hedge Liability at Fair Value	6.3		6.3		2.4
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(6.3)	$ (15.5)	(2.2)	$ (32.5)
Derivative, Notional Amount	160.3		160.3		$ 157.1
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months			$ 6.3
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 June 2024.
Description of Foreign Currency Derivative Instruments Not Designated as Hedging Instruments Activities			During the nine months ended September 29, 2022, the Company entered into foreign currency forward contracts in the amount of $291.5 to minimize the risk of currency exchange rate movements on the Company's planned settlement of the repayable investment agreement between the Company and the U.K.'s Department for Business, Energy and Industrial Strategy. During the nine-month period ended September 29, 2022, these foreign currency forward contracts were settled, and new contracts were entered into in the amount of $293.7, which were also settled during the period. The Company did not designate these forward contracts as hedges or apply hedge accounting to the forward contracts.
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments				1.6
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 3.8	$ (6.5)	$ 1.7	$ (12.1)

Derivative and Hedging Activi_3

Derivative and Hedging Activities (Details 1)	9 Months Ended
	Sep. 28, 2023
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	9 Months Ended
	Sep. 28, 2023 USD ($)
Derivatives Fair Value [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 6.3
Maximum Length of Time Hedged in Cash Flow Hedge	9 months

Debt (Details)

Debt (Details) - USD ($) $ in Millions	Sep. 28, 2023	Dec. 31, 2022
Long Term Debt And Capital Lease Obligations Current And Non Current [Abstract]
Other Long-term Debt, Current	$ 10.6	$ 5.8
Other Long-term Debt, Noncurrent	52.1	53
Long-term Debt and Lease Obligation, Current	64.2	53.7
Long-term Debt and Lease Obligation	3,811	3,814.9
Total Debt [Member]
Long Term Debt And Capital Lease Obligations Current And Non Current [Abstract]
Long-term Debt and Lease Obligation, Current	64.2	53.7
Long-term Debt and Lease Obligation	$ 3,811	$ 3,814.9

Debt (Details Textual)

Debt (Details Textual) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Dec. 31, 2022
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities	$ 0	$ (289.5)
Proceeds from Issuance of Senior Long-term Debt	12.7	0
Proceeds from Lines of Credit	1.6	$ 0
Long-term Debt	3,670.6		$ 3,665.3
Finance Lease, Liability, Noncurrent	94		102.3
Finance Lease, Liability, Current	47.9		42.2
Other Long-term Debt, Current	10.6		5.8
Other Long-term Debt, Noncurrent	$ 52.1		53
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		298.8
Long-term Debt, Current Maturities	0		0
Secured Long-term Debt, Noncurrent	$ 299		298.8
Senior Secured Notes Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	550%
Senior Secured Second Lien Notes Due 2025
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.50%
Long-term Debt	$ 1,193.8		1,191
Long-term Debt, Current Maturities	0		0
Secured Long-term Debt, Noncurrent	$ 1,193.8		1,191
Senior Unsecured Notes Due 2028 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.60%
Long-term Debt	$ 696.4		695.9
Long-term Debt, Current Maturities	0		0
Unsecured Long-term Debt, Noncurrent	696.4		695.9
Secured Debt Term B [Member]
Debt Instrument [Line Items]
Long-term Debt	572.6		571.7
Long-term Debt, Current Maturities	5.7		5.7
Secured Long-term Debt, Noncurrent	566.9		566
Senior Secured Notes Due 2025
Debt Instrument [Line Items]
Long-term Debt	20.8		20.7
Long-term Debt, Current Maturities	0		0
Secured Long-term Debt, Noncurrent	20.8		20.7
Senior Secured First Lien Notes due 2029
Debt Instrument [Line Items]
Long-term Debt	888		887.2
Long-term Debt, Current Maturities	0		0
Secured Long-term Debt, Noncurrent	888		$ 887.2
Senior Secured Notes Due 2029
Debt Instrument [Line Items]
Long-term Debt	$ 888

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		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 0.1	$ 0.2	$ 0.4	$ 0.6
Defined Benefit Plan, Interest Cost	0.4	0.1	1.1	0.4
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(0.2)	(0.2)	(0.6)	(0.6)
Defined Benefit Plan, Amortization of Gain (Loss)	(0.4)	(0.3)	(1.3)	(1)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(0.1)	(0.2)	(0.4)	(0.6)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	0.8	0.5	2.4	1.7
Defined Benefit Plan, Interest Cost	18.8	13.1	57.4	42.2
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	71.7	0.1	73.8
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(20.3)	(28.9)	(62.3)	(99.2)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0.9	64.6	(0.5)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ (0.7)	$ 57.3	$ 62.2	$ 18

Stock Compensation (Details)

Stock Compensation (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
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	$ 8,600,000	$ 10,400,000	$ 27,800,000	$ 28,700,000
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Ownership Plan (ESOP), Compensation Expense	$ 900,000		$ 1,500,000	$ 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			560,190
Fair Value Of Shares Granted			$ 18,800,000
Class A [Member] | Board of Directors Plan [Member] | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Vested			22,155
Grant date value of shares vested			$ 700,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			39,005
Class A [Member] | Board of Directors Plan [Member] | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Vested			41,096
Number of shares granted			42,065
Grant date value of shares vested			$ 1,300,000
Class A [Member] | Performance Based LTIP RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted			231,927
Fair Value Of Shares Granted			$ 12,000,000
Class A [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Vested			466,597
Grant date value of shares vested			$ 22,500,000
Class A [Member] | Board of Directors Plan- Pro Rata
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value Of Shares Granted			$ 2,000,000
Class A [Member] | Performance Based RSU - Free Cash Flow goals
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted			116,006
Fair Value Of Shares Granted			$ 4,000,000
Class A [Member] | Performance Based RSU - 3yr Revenue Growth goals
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted			116,006
Fair Value Of Shares Granted			$ 4,000,000

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent	(0.16%)	(6.49%)
Valuation Allowance [Line Items]
Deferred Income Tax Liabilities, Net	$ 8.2		$ 1.3
Rotable assets	43.6		$ 39
Domestic Tax Authority
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Net	2.8
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance	547.7
Deferred Tax Assets, Net	2.8
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	112.6
Deferred Tax Assets, Gross	544.9
Foreign Tax Authority
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Net	4.1
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance	326.2
Deferred Tax Assets, Net	4.1
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	46.9
Deferred Tax Assets, Gross	$ 322.1

Equity (Details)

Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Jun. 29, 2023	Jun. 30, 2022	Sep. 28, 2023	Sep. 29, 2022	Dec. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 925				$ 925
Common Stock, Dividends, Per Share, Declared	$ 0	$ 0.01			$ 0	$ 0.03
Basic EPS
Income available to common shareholders	$ (204.1)	$ (127.6)			$ (691.6)	$ (302.6)
Income available to common shareholders, shares	105,200,000	104,700,000			105,100,000	104,600,000
Income available to common shareholders, per share amount	$ (1.94)	$ (1.22)			$ (6.58)	$ (2.89)
Income allocated to participating securities, shares	0	0
Net Income (Loss) Attributable to Parent	$ (204.1)	$ (127.6)	$ (487.5)	$ (175)	$ (691.6)	$ (302.6)
Diluted potential common shares	0	0
Diluted EPS
Net Income (Loss) Attributable to Parent	$ (204.1)	$ (127.6)	(487.5)	(175)	$ (691.6)	$ (302.6)
Shares	105,200,000	104,700,000			105,100,000	104,600,000
Diluted (in dollars per share)	$ (1.94)	$ (1.22)			$ (6.58)	$ (2.89)
Equity Textuals [Abstract]
Common shares outstanding issued but unvested	100,000	400,000			100,000	400,000
Noncontrolling interest	$ 3.7	$ 0.5	$ 3.5	$ 0.5	$ 3.7	$ 0.5	$ 3.7	$ 0.5
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(150)				(150)		(203.9)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax	$ 0.7	$ (0.5)			$ (62.7)	$ 1.7
Class of Stock [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	600,000	0.5			700,000	0.6
Earnings Per Share, Potentially Dilutive Securities	0.2	0.3				0.3
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	100,000	400,000			100,000	400,000
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	(44.4)				$ (44.4)		(95.4)
SERP and Retiree medical [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	11.2				11.2		12.7
Foreign currency impact on long term intercompany loan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(16.1)				(16.1)		(16.4)
Currency translation adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(94.5)				(94.5)		(97.7)
Accumulated Foreign Exchange Forward [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (6.2)				$ (6.2)		$ (7.1)

Commitments, Contingencies an_3

Commitments, Contingencies and Guarantees (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2023	Dec. 31, 2022	Sep. 29, 2022	Dec. 31, 2021
Commitments Contingencies And Guarantees [Abstract]
Restricted Cash, Noncurrent	$ 22.2	$ 19.6	$ 19.5	$ 19.5
Service warranty roll forward
Product Warranty And Extraordinary Rework	74.9
Charges to costs and expenses	(0.1)
Product Warranty Accrual, Payments	(2.2)
Product Warranty And Extraordinary Rework	72.6
Product Warranty Extraordinary Rework Accrual Currency Translation Increase Decrease	(0.2)
Commitments Contingencies And Guarantees Textuals [Abstract]
Outstanding amount of guarantees	22.8	$ 13.9
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		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Other Income (Loss) [Line Items]
Kansas Development Finance Authority bond	$ 0.7	$ 0.5	$ 2.1	$ 1.8
Interest Income, Other	2.4	2.3	8	3.5
Foreign currency (losses) gains (1)	12.9	13.4	(0.4)	40.6
Gain (Loss) on Foreign Currency Derivatives Recorded in Earnings, Net	3.8	(6.5)	1.7	(10.5)
Gain (Loss) on Sale of Accounts Receivable	(13.2)	(6)	(36.5)	(12.8)
Pension Income (Expense) without Service Cost	1.7	(56.4)	(59)	(15.1)
Taxes, Miscellaneous	0	0	(35.9)	(6.8)
Gain on settlement of financial instrument	0	0	0	20.7
Other Nonoperating Income		10.6	0	8.8
Other Nonoperating Expense	(1)
Amortization of Intangible Assets	3.8	3.6	11.4	10.9
Total	$ 7.3	$ (42.1)	$ (120)	$ 30.2

Other Liabilities (Details)

Other Liabilities (Details) $ in Millions	9 Months Ended
	Sep. 28, 2023 USD ($)
Other Liabilities Disclosure [Abstract]
Proceeds from Other Debt	$ 180

Segment Information (Details)

Segment Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023 USD ($)	Sep. 29, 2022 USD ($)	Sep. 28, 2023 USD ($) segment	Sep. 29, 2022 USD ($)
Segment Reporting Information [Line Items]
Restructuring Charges	$ 0	$ 0	$ 7.2	$ 0.2
Excess Capacity Costs- B737MAX and A320 Production Schedules	56.4		152.9
Cost of Goods and Services Sold	1,492.5	1,194	4,320.2	3,611.4
Segment Revenues
Segment Revenues	1,438.9	1,276.9	4,235	3,709.5
Segment Operating Income
Business Segment Operating Income	(54.4)	82.9	(98.1)	97.9
Segment Information Unallocated Corporate Selling General And Administrative	(69.2)	(69.1)	(217.2)	(203.8)
Segment Information Unallocated Research And Development	(10.1)	(9.3)	(33.9)	(36.5)
Operating income (loss)	$ (133.7)	4.5	$ (349.2)	(142.4)
Segment Reporting Information, Additional Information [Abstract]
Number Of Principal Segments | segment			3
Percentage Of Net Revenue Derived From Two Largest Customers	81%		82%
Commercial Segment [Member]
Segment Revenues
Segment Revenues	$ 1,136.4	1,034.9	$ 3,367.9	3,004.4
Segment Operating Income
Business Segment Operating Income	(82.1)	45	$ (200.5)	(3.5)
Segment Reporting Information, Additional Information [Abstract]
Segment Reporting, Disclosure of Major Customers			Approximately 69% and 65% of Commercial segment net revenues came from the Company's contracts with Boeing for the nine months ended September 28, 2023, and September 29, 2022, respectively. Approximately 24% and 27% of Commercial segment net revenues came from the Company's contracts with Airbus for the nine months ended September 28, 2023, and September 29, 2022, respectively.
Commercial Segment [Member] | Cost of Sales | Russia and Ukraine Conflict
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold				23.9
Defense & Space Segment [Member]
Segment Revenues
Segment Revenues	205.7	161.7	$ 583.7	466.6
Segment Operating Income
Business Segment Operating Income	9.8	18.4	$ 41	52.1
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 nine months ended September 28, 2023, and September 29, 2022.
Aftermarket Segment [Member]
Segment Revenues
Segment Revenues	96.8	80.3	$ 283.4	238.5
Segment Operating Income
Business Segment Operating Income	$ 17.9	$ 19.5	$ 61.4	49.3
Segment Reporting Information, Additional Information [Abstract]
Segment Reporting, Disclosure of Major Customers			Approximately 47% and 47% of Aftermarket segment net revenues came from the Company's contracts with a single customer for the nine months ended September 28, 2023, and September 29, 2022, respectively.
Aftermarket Segment [Member] | Cost of Sales | Russia and Ukraine Conflict
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold				$ 4.2

Restructuring Charges (Details)

Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Sep. 28, 2023	Sep. 29, 2022
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 0	$ 0	$ 7.2	$ 0.2

Payables and Accruals (Details)

Payables and Accruals (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2023	Sep. 29, 2022	Dec. 31, 2022
Supplier Finance Program [Line Items]
Supplier Finance Program, Obligation	$ 112.7	$ 103.5	$ 102
Supplier Finance Program, Obligation, Period Increase (Decrease)	$ 10.7	$ 44.6

Business Combinations and Ass_2

Business Combinations and Asset Acquisitions (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended	9 Months Ended
	Nov. 23, 2022	Jun. 29, 2023	Jun. 29, 2023	Sep. 28, 2023	Dec. 31, 2022	Sep. 29, 2022
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired		$ 31.3
Goodwill				$ 631.1	$ 630.5
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		$ 0.6