Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 26, 2019	Sep. 27, 2018
Operating activities
Net income	$ 462.4	$ 439.4
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation expense	186.9	171.3
Amortization expense	0.1	0.4
Amortization of deferred financing fees	2.6	17.3
Accretion of customer supply agreement	3.3	3.0
Employee stock compensation expense	22.6	19.9
Loss on Derivative Instruments, Pretax	8.1	3.4
Gain from foreign currency transactions	17.2	0.8
Gain (Loss) on Disposition of Property Plant Equipment	0.7	1.7
Deferred taxes	29.4	(37.8)
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(9.7)	(25.1)
Grant liability amortization	(13.8)	(15.9)
Equity in net income of affiliate	0.0	(0.6)
Increase (Decrease) in Forward Provision	(7.5)	(134.0)
Changes in assets and liabilities
Accounts receivable	(167.8)	(122.3)
Inventory, net	(3.3)	26.7
Increase (Decrease) in Unbilled Receivables	(67.5)	(50.4)
Accounts payable and accrued liabilities	149.3	279.9
Profit sharing/deferred compensation	(12.2)	(67.4)
Advance payments	120.8	(73.2)
Income taxes receivable/payable	4.9	(28.3)
Increase (Decrease) in Billing in Excess of Cost of Earnings	(16.7)	188.0
Deferred revenue and other deferred credits	6.2	(1.1)
Other	2.6	(28.3)
Net cash provided by operating activities	718.6	567.4
Investing activities
Purchase of property, plant and equipment	(118.8)	(170.9)
Payments for (Proceeds from) Other Investing Activities	0.1	2.8
Net cash used in investing activities	(118.7)	(168.1)
Financing activities
Proceeds from Lines of Credit	100.0	0.0
Proceeds from Issuance of Debt	250.0
Proceeds from Issuance of Senior Long-term Debt		1,300.0
Principal payments of debt	(8.5)	(4.9)
Repayments of Debt	(5.2)	(256.3)
Repayments of Lines of Credit	(100.0)	0.0
Early Repayment of Senior Debt	0.0	(300.0)
Payments Related to Tax Withholding for Share-based Compensation	(12.1)	(15.5)
Proceeds from Stock Plans	1.3	0.0
Debt issuance and financing costs	0.0	(23.2)
Payments for Repurchase of Common Stock	(75.0)	(805.8)
Payments of Dividends	(37.8)	(35.4)
Proceeds from (Payments for) Other Financing Activities	0.8	0.0
Net cash provided by (used in) financing activities	113.5	(141.1)
Effect of exchange rate changes on cash and cash equivalents	(13.5)	0.2
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	699.9	258.4
Cash, cash equivalents, and restricted cash, beginning of period	794.1	445.5
Cash, cash equivalents, and restricted cash, end of period	1,477.3	683.4
Reconciliation of Cash, Cash Equivalents, and Restricted Cash [Abstract]
Restricted Cash, Current	0.3	0.3
Restricted Cash, Noncurrent	$ 16.4	$ 20.2