Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Assets
Cash and cash equivalents	$ 1,151.8	$ 1,478.6
Restricted Cash, Current	0.3	0.3
Accounts receivable, net	580.0	461.6
Contract with Customer, Asset, after Allowance for Credit Loss, Current	449.0	443.2
Inventory, net	1,387.8	1,382.6
Other current assets	41.1	39.7
Total current assets	3,610.0	3,806.0
Property, plant and equipment, net	2,327.9	2,385.5
Operating Lease, Right-of-Use Asset	83.6	85.3
Contract with Customer, Asset, after Allowance for Credit Loss, Noncurrent	4.2	0.0
Pension assets	530.4	532.5
Deferred Tax Assets, Net of Valuation Allowance	7.9	0.4
Goodwill	623.6	623.7
Intangible Assets, Net (Excluding Goodwill)	208.6	212.3
Deferred income taxes	94.4	91.6
Other assets	7,490.6	7,737.3
Liabilities, Current [Abstract]
Accounts Payable, Current	762.9	720.3
Accrued Liabilities, Current	409.0	376.1
Deferred Compensation Liability, Current	19.7	63.7
Long-term Debt and Lease Obligation, Current	49.1	49.5
Operating Lease, Liability, Current	8.4	8.2
Customer Advances, Current	128.0	137.8
Contract with Customer, Liability, Current	76.2	97.9
Provision for Loss on Contracts	262.6	244.6
Deferred Revenue, Current	21.6	72.7
Other Liabilities, Current	87.4	105.2
Liabilities Noncurrent
Long-term debt	3,734.0	3,742.7
Operating Lease, Liability, Noncurrent	76.4	78.8
Advance payments, long-term	198.6	201.3
Pension/OPEB obligation	53.1	74.8
Contract with Customer, Liability, Noncurrent	284.8	289.1
Provision for Loss on Contacts, Non Current	469.6	521.6
Deferred grant income liability - non-current	25.5	26.4
Deferred Tax Liabilities, Net	1.2	21.8
Deferred revenue and other deferred credits	30.3	32.1
Deferred income taxes	410.0	423.9
Additional Paid in Capital [Abstract]
Additional paid-in capital	1,151.1	1,146.2
AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract
Accumulated other comprehensive loss	(41.3)	(23.7)
Retained Earnings Accumulated Deficit [Abstract]
Retained earnings	$ 1,727.5	$ 1,781.4
Treasury Stock, Shares	41,587,480	41,523,470
Treasury Stock, Value	$ (2,456.7)	$ (2,456.7)
Total stockholders' equity	381.7	448.3
Noncontrolling interest	0.5	0.5
Total equity	382.2	448.8
Total liabilities and equity	7,490.6	7,737.3
Liabilities, Current	1,824.9	1,876.0
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