Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Assets
Cash and cash equivalents	$ 770.2	$ 1,478.6
Restricted Cash, Current	0.2	0.3
Accounts receivable, net	581.3	461.6
Unbilled Receivables, Current	482.7	443.2
Inventory, net	1,345.8	1,382.6
Other current assets	31.4	39.7
Total current assets	3,211.6	3,806.0
Property, plant and equipment, net	2,260.9	2,385.5
Operating Lease, Right-of-Use Asset	82.3	85.3
Unbilled Receivable, Non Current	0.9	0.0
Pension assets	432.1	532.5
Pension reversion assets	70.3	0.0
Deferred Income Tax Assets, Net	3.5	0.4
Goodwill	623.4	623.7
Intangible Assets, Net (Excluding Goodwill)	205.0	212.3
Deferred income taxes	99.3	91.6
Other assets	6,989.3	7,737.3
Liabilities, Current [Abstract]
Accounts Payable, Current	810.7	720.3
Accrued Liabilities, Current	390.3	376.1
Deferred Compensation Liability, Current	19.5	63.7
Long-term Debt and Lease Obligation, Current	347.7	49.5
Operating Lease, Liability, Current	8.3	8.2
Customer Advances, Current	98.2	137.8
Contract with Customer, Liability, Current	84.2	97.9
Provision for Loss on Contracts	309.2	244.6
Deferred Credits and Other Liabilities, Current	22.1	72.7
Other Liabilities, Current	89.7	105.2
Liabilities Noncurrent
Long-term debt	3,424.8	3,742.7
Operating Lease, Liability, Noncurrent	73.2	78.8
Advance payments, long-term	194.1	201.3
Pension/OPEB obligation	32.5	74.8
Contract with Customer, Liability, Noncurrent	276.2	289.1
Provision for Loss on Contacts, Non Current	402.5	521.6
Deferred Credits and Other Liabilities, Noncurrent	27.0	32.1
Deferred grant income liability - non-current	26.6	26.4
Deferred Income Tax Liabilities, Net	9.5	21.8
Deferred income taxes	117.1	423.9
Additional Paid in Capital [Abstract]
Additional paid-in capital	1,159.8	1,146.2
AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract
Accumulated other comprehensive loss	(83.0)	(23.7)
Retained Earnings Accumulated Deficit [Abstract]
Retained earnings	$ 1,604.2	$ 1,781.4
Treasury Stock, Shares	41,587,480	41,523,470
Treasury Stock, Value	$ (2,456.7)	$ (2,456.7)
Total stockholders' equity	225.4	448.3
Noncontrolling interest	0.5	0.5
Total equity	225.9	448.8
Total liabilities and equity	6,989.3	7,737.3
Liabilities, Current	2,179.9	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