Inventory (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2020	Oct. 01, 2020	Jul. 02, 2020	Apr. 02, 2020	Dec. 31, 2020	Dec. 31, 2019
Summary Of Inventories [Abstract]
Raw materials	$ 337.3				$ 337.3	$ 253.1
Work-in-process(1)	1,000.6				1,000.6	822.8
Finished goods	58.1				58.1	14.5
Product inventory	1,396.0				1,396.0	1,090.4
Capitalized pre-production	26.3				26.3	28.4
Total inventory, net	1,422.3				1,422.3	$ 1,118.8
Inventory [Line Items]
Excess Capacity Costs- B737MAX and A320 Production Schedules	50.1	$ 72.6	$ 82.8	$ 73.4	278.9
Abnormal Costs- COVID19 production suspension	$ (0.1)	$ (10.9)	$ 19.3	$ 25.4	$ 33.7

Abnormal Costs- COVID19 production suspension

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Excess Capacity Costs- B737MAX and A320 Production Schedules

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Net Inventory Raw Materials Finished Goods And Work In Process

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of unprocessed items to be consumed in the manufacturing or production process.

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Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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Amount, before valuation and last-in first out (LIFO) reserves, of costs capitalized in inventory classified as other, expected to be sold, or consumed within one year or operating cycle, if longer.

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