Inventory (Details) - USD ($) $ in Millions	Sep. 26, 2019	Dec. 31, 2018
Summary Of Inventories [Abstract]
Raw materials	$ 242.4	$ 240.4
Work-in-process	731.9	727.8
Finished goods	11.0	7.1
Product inventory	985.3	975.3
Capitalized pre-production	29.9	37.3
Total inventory, net	1,015.2	1,012.6
Inventory Valuation Reserves	36.3	55.2
Costs Incurred in Anticipation of Contracts	$ 149.0	$ 151.6