Quarterly Financial Data (Unaudited)- Textuals (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Oct. 01, 2020	Jul. 02, 2020	Apr. 02, 2020	Dec. 31, 2019	Sep. 26, 2019	Jun. 27, 2019	Mar. 28, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Information [Line Items]
Change In Accounting Estimate, aggregate, affecting earnings from continuing operations	$ 400.7	$ 123.8	$ (231.8)	$ 27.9	$ 55.2	$ 41.8	$ 10.9	$ 0.5	$ (400.7)	$ (65.5)	$ 0.1
Provision For Loss On Contracts	184.6				$ 83.9				184.6	83.9
Restructuring Charges	4.6	19.5	6.3	42.6					73.0	0.0	0.0
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
Gain (Loss) on Disposition of Property Plant Equipment			$ 22.9						(22.9)	$ 0.0	$ 0.0
Valuation Allowance - U.S. Deferred Tax Asset	$ 150.2								$ 150.2