Condensed Consolidating Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 26, 2019	Sep. 27, 2018	Sep. 26, 2019	Sep. 27, 2018	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 1,919.9	$ 1,813.7	$ 5,903.8	$ 5,386.7
Operating costs and expenses
Cost of sales	1,647.6	1,543.1	5,029.1	4,601.3
Selling, general and administrative	53.6	37.3	173.6	154.5
Research and development	12.6	10.8	36.0	31.3
Total operating costs and expenses	1,713.8	1,591.2	5,238.7	4,787.1
Operating income	206.1	222.5	665.1	599.6
Interest expense and financing fee amortization	(23.6)	(24.2)	(66.1)	(60.3)
Other expense, net	(9.5)	7.4	(11.9)	(0.8)
Income (loss) before income taxes and equity in net loss of affiliates and subsidiaries	173.0	205.7	587.1	538.5
Income tax provision	(41.7)	(36.9)	(124.7)	(99.7)
Income (loss) Before Equity In Net Income (Loss) Of Affiliates and Subsidiaries	131.3	168.8	462.4	438.8
Equity in net income of affiliate	0.0	0.0	0.0	0.6
Equity in net income of subsidiaries	0.0	0.0		0.0
Net income	131.3	168.8	462.4	439.4
Total other comprehensive income (loss)	21.5	(0.6)	16.7	(16.5)
Comprehensive Income, Net of Tax, Attributable to Parent	152.8	168.2	479.1	422.9
Assets
Cash and cash equivalents	1,494.0	703.9	1,494.0	703.9	$ 794.1	$ 445.5
Restricted Cash and Cash Equivalents	0.3		0.3		0.3
Accounts receivable, net	708.6		708.6		545.1
Unbilled Receivables, Current	579.0		579.0		469.4
Inventory	1,015.2		1,015.2		1,012.6
Other current assets	58.3		58.3		48.3
Total current assets	3,838.7		3,838.7		2,849.3
Property, plant and equipment, net	2,199.8		2,199.8		2,167.6
Operating Lease, Right-of-Use Asset	49.7		49.7		0.0
Unbilled Receivable, Non Current	9.7		9.7		54.1
Pension assets	385.3		385.3		326.7
Other assets	218.4		218.4		288.2
Total assets	6,701.6		6,701.6		5,685.9
Liabilities
Accounts payable	1,140.5		1,140.5		902.6
Accrued expenses	319.8		319.8		313.1
Profit sharing	55.9		55.9		68.3
Current portion of long-term debt	37.6		37.6		31.4
Operating Lease, Liability, Current	6.2		6.2
Advance payments, short-term	19.8		19.8		2.2
Billings in Excess of Cost, Noncurrent	340.4		340.4		369.8
Billings in Excess of Cost, Current	170.5		170.5		157.9
Provision for Loss on Contracts	37.2		37.2		12.4
Deferred revenue and other deferred credits, short-term	17.2		17.2		20.0
Deferred grant income liability - current	5.6		5.6		16.0
Other current liabilities	55.4		55.4		58.2
Total current liabilities	1,865.7		1,865.7		1,582.1
Long-term debt	2,132.2		2,132.2		1,864.0
Operating Lease, Liability, Noncurrent	43.6		43.6
Advance payments, long-term	335.1		335.1		231.9
Pension/OPEB obligation	32.6		32.6		34.6
Provision for Loss on Contacts, Non Current	161.9		161.9		170.6
Deferred grant income liability - non-current	28.0		28.0		28.0
Deferred revenue and other deferred credits	32.4		32.4		31.2
Other liabilities	112.7		112.7		135.6
Total equity	1,617.0		1,617.0		1,238.1
Total liabilities and equity	6,701.6		6,701.6		5,685.9
Operating activities
Net cash (used in) 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)
Proceeds from Issuance of Debt			250.0
Proceeds from Lines of Credit			100.0	0.0
Proceeds from Issuance of Senior Long-term Debt				1,300.0
Financing activities
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 (payments) from subsidiary for purchase of treasury stock			0.0
Debt issuance and financing costs			0.0	(23.2)
Proceeds from (Payments for) Other Financing Activities			(0.8)	0.0
Payments for Repurchase of Common Stock			(75.0)	(805.8)
Proceeds from subsidiary (payments to Parent) to pay dividends			0.0	0.0
Payments of Dividends			(37.8)	(35.4)
Proceeds from Stock Plans			1.3	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 and cash equivalents, beginning of period			773.6	423.3
Cash, cash equivalents, and restricted cash, end of period	1,477.3	683.4	1,477.3	683.4
Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues	(142.3)	(128.0)	(504.9)	(462.2)
Operating costs and expenses
Cost of sales	(142.3)	(128.0)	(504.9)	(462.2)
Selling, general and administrative				0.0
Research and development				0.0
Total operating costs and expenses	(142.3)	(128.0)	(504.9)	(462.2)
Interest expense and financing fee amortization	0.9	1.2	2.8	3.8
Other expense, net	(0.9)	(1.2)	(2.8)	(3.8)
Equity in net income of affiliate				(0.6)
Equity in net income of subsidiaries	(160.7)	(190.1)	(556.2)	(510.1)
Net income	(160.7)	(190.1)	(556.2)	(510.7)
Total other comprehensive income (loss)	(7.6)	0.5	1.3	31.2
Comprehensive Income, Net of Tax, Attributable to Parent	(168.3)	(189.6)	(554.9)	(479.5)
Assets
Restricted Cash and Cash Equivalents	0.0		0.0		0.0
Accounts receivable, net	(319.0)		(319.0)		(358.1)
Unbilled Receivables, Current	0.0		0.0		0.0
Inventory					0.0
Total current assets	(319.0)		(319.0)		(358.1)
Operating Lease, Right-of-Use Asset	0.0		0.0
Unbilled Receivable, Non Current	0.0		0.0		0.0
Investment in subsidiary	(2,383.7)		(2,383.7)		(1,937.0)
Other assets	(191.3)		(191.3)		(196.4)
Total assets	(2,894.0)		(2,894.0)		(2,491.5)
Liabilities
Accounts payable	(320.4)		(320.4)		(358.2)
Accrued expenses	1.4		1.4		0.1
Operating Lease, Liability, Current	0.0		0.0
Billings in Excess of Cost, Noncurrent	0.0		0.0		0.0
Billings in Excess of Cost, Current	0.0		0.0		0.0
Provision for Loss on Contracts	0.0		0.0		0.0
Total current liabilities	(319.0)		(319.0)		(358.1)
Long-term debt	(90.7)		(90.7)		(95.8)
Operating Lease, Liability, Noncurrent	0.0		0.0
Provision for Loss on Contacts, Non Current	0.0		0.0		0.0
Other liabilities	(100.6)		(100.6)		(100.6)
Total equity	(2,383.7)		(2,383.7)		(1,937.0)
Total liabilities and equity	(2,894.0)		(2,894.0)		(2,491.5)
Investing activities
Payments for (Proceeds from) Other Investing Activities			0.0	0.0
Proceeds from Issuance of Debt			0.0
Proceeds from Lines of Credit			0.0
Financing activities
Principal payments of debt				0.0
Repayments of Debt				0.0
Early Repayment of Senior Debt				0.0
Payments Related to Tax Withholding for Share-based Compensation			0.0	0.0
Proceeds (payments) from subsidiary for purchase of treasury stock			0.0
Debt issuance and financing costs				0.0
Proceeds from (Payments for) Other Financing Activities				0.0
Payments for Repurchase of Common Stock				0.0
Proceeds from subsidiary (payments to Parent) to pay dividends			0.0	0.0
Payments of Dividends			0.0	0.0
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues	0.0	0.0	0.0	0.0
Operating costs and expenses
Cost of sales				0.0
Selling, general and administrative	2.6	2.3	9.6	8.0
Research and development				0.0
Total operating costs and expenses	2.6	2.3	9.6	8.0
Operating income	(2.6)	(2.3)	(9.6)	(8.0)
Interest expense and financing fee amortization				0.0
Other expense, net				0.0
Income (loss) before income taxes and equity in net loss of affiliates and subsidiaries	(2.6)	(2.3)	(9.6)	(8.0)
Income tax provision	0.6	0.4	2.2	1.5
Income (loss) Before Equity In Net Income (Loss) Of Affiliates and Subsidiaries	(2.0)	(1.9)	(7.4)	(6.5)
Equity in net income of affiliate				0.6
Equity in net income of subsidiaries	133.3	170.7	469.8	445.3
Net income	131.3	168.8	462.4	439.4
Total other comprehensive income (loss)	21.5	(0.6)	16.7	(16.5)
Comprehensive Income, Net of Tax, Attributable to Parent	152.8	168.2	479.1	422.9
Assets
Restricted Cash and Cash Equivalents	0.0		0.0		0.0
Accounts receivable, net
Unbilled Receivables, Current	0.0		0.0		0.0
Inventory					0.0
Operating Lease, Right-of-Use Asset	0.0		0.0
Unbilled Receivable, Non Current	0.0		0.0		0.0
Investment in subsidiary	1,617.0		1,617.0		1,238.0
Total assets	1,617.0		1,617.0		1,238.0
Liabilities
Billings in Excess of Cost, Noncurrent	0.0		0.0		0.0
Billings in Excess of Cost, Current	0.0		0.0
Provision for Loss on Contracts	0.0		0.0		0.0
Long-term debt
Provision for Loss on Contacts, Non Current	0.0		0.0		0.0
Total equity	1,617.0		1,617.0		1,238.0
Total liabilities and equity	1,617.0		1,617.0		1,238.0
Investing activities
Payments for (Proceeds from) Other Investing Activities			0.0	0.0
Financing activities
Repayments of Debt				0.0
Early Repayment of Senior Debt				0.0
Payments Related to Tax Withholding for Share-based Compensation			0.0	0.0
Proceeds (payments) from subsidiary for purchase of treasury stock			(75.0)
Debt issuance and financing costs				0.0
Proceeds from (Payments for) Other Financing Activities				805.8
Payments for Repurchase of Common Stock			(75.0)	(805.8)
Proceeds from subsidiary (payments to Parent) to pay dividends			37.8	35.4
Payments of Dividends			(37.8)	(35.4)
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues	314.7	305.6	1,062.2	1,017.6
Operating costs and expenses
Cost of sales	278.3	275.2	941.5	915.7
Selling, general and administrative	4.6	3.6	14.5	13.4
Research and development	1.6	1.6	4.7	3.5
Total operating costs and expenses	284.5	280.4	960.7	932.6
Operating income	30.2	25.2	101.5	85.0
Interest expense and financing fee amortization	(0.9)	(1.2)	(3.0)	(4.0)
Other expense, net	3.5	(1.0)	4.6	(3.6)
Income (loss) before income taxes and equity in net loss of affiliates and subsidiaries	32.8	23.0	103.1	77.4
Income tax provision	(5.4)	(3.6)	(16.7)	(12.6)
Income (loss) Before Equity In Net Income (Loss) Of Affiliates and Subsidiaries	27.4	19.4	86.4	64.8
Equity in net income of affiliate				0.6
Equity in net income of subsidiaries				0.0
Net income	27.4	19.4	86.4	65.4
Total other comprehensive income (loss)	(13.9)	0.1	(18.0)	(14.7)
Comprehensive Income, Net of Tax, Attributable to Parent	13.5	19.5	68.4	50.7
Assets
Cash and cash equivalents	133.8	61.9	133.8	61.9	68.6	58.2
Restricted Cash and Cash Equivalents	0.0		0.0		0.0
Accounts receivable, net	316.1		316.1		310.2
Unbilled Receivables, Current	59.1		59.1		48.6
Inventory	311.2		311.2		316.6
Other current assets	11.9		11.9		3.0
Total current assets	832.1		832.1		747.0
Property, plant and equipment, net	475.1		475.1		496.8
Operating Lease, Right-of-Use Asset	7.1		7.1
Unbilled Receivable, Non Current	0.0		0.0		0.0
Pension assets	20.0		20.0		19.7
Other assets	110.3		110.3		127.5
Total assets	1,444.6		1,444.6		1,391.0
Liabilities
Accounts payable	407.8		407.8		405.6
Accrued expenses	26.1		26.1		36.3
Profit sharing	4.2		4.2		5.7
Current portion of long-term debt	1.1		1.1		0.9
Operating Lease, Liability, Current	0.8		0.8
Billings in Excess of Cost, Noncurrent	0.0		0.0		0.0
Billings in Excess of Cost, Current	0.0		0.0		0.6
Provision for Loss on Contracts	0.0		0.0		0.0
Deferred revenue and other deferred credits, short-term	0.3		0.3		0.5
Deferred grant income liability - current	5.6		5.6		16.0
Other current liabilities	6.6		6.6		5.8
Total current liabilities	452.5		452.5		471.4
Long-term debt	97.6		97.6		103.2
Operating Lease, Liability, Noncurrent	6.3		6.3
Provision for Loss on Contacts, Non Current	0.0		0.0		0.0
Deferred grant income liability - non-current	18.6		18.6		22.1
Deferred revenue and other deferred credits	2.3		2.3		2.4
Other liabilities	20.5		20.5		12.9
Total equity	846.8		846.8		779.0
Total liabilities and equity	1,444.6		1,444.6		1,391.0
Operating activities
Net cash (used in) operating activities			147.3	81.3
Investing activities
Purchase of property, plant and equipment			(24.8)	(28.0)
Payments for (Proceeds from) Other Investing Activities			0.0	(0.5)
Net cash used in investing activities			(24.8)	(27.5)
Proceeds from Issuance of Debt			0.0
Proceeds from Lines of Credit			0.0
Financing activities
Principal payments of debt			(0.7)	0.6
Repayments of Debt				0.0
Early Repayment of Senior Debt				0.0
Collection on (repayment of) intercompany debt			(56.1)	(49.7)
Payments Related to Tax Withholding for Share-based Compensation			0.0	0.0
Proceeds (payments) from subsidiary for purchase of treasury stock			0.0
Debt issuance and financing costs				0.0
Proceeds from (Payments for) Other Financing Activities				0.0
Payments for Repurchase of Common Stock				0.0
Proceeds from subsidiary (payments to Parent) to pay dividends			(0.2)	0.0
Payments of Dividends			0.0	0.0
Net cash provided by (used in) financing activities			(57.0)	(50.3)
Effect of exchange rate changes on cash and cash equivalents			(0.3)	0.2
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect			65.2	3.7
Cash and cash equivalents, beginning of period			68.6
Cash, cash equivalents, and restricted cash, end of period	133.8		133.8
Subsidiary Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues	1,747.5	1,636.1	5,346.5	4,831.3
Operating costs and expenses
Cost of sales	1,511.6	1,395.9	4,592.5	4,147.8
Selling, general and administrative	46.4	31.4	149.5	133.1
Research and development	11.0	9.2	31.3	27.8
Total operating costs and expenses	1,569.0	1,436.5	4,773.3	4,308.7
Operating income	178.5	199.6	573.2	522.6
Interest expense and financing fee amortization	(23.6)	(24.2)	(65.9)	(60.1)
Other expense, net	(12.1)	9.6	(13.7)	6.6
Income (loss) before income taxes and equity in net loss of affiliates and subsidiaries	142.8	185.0	493.6	469.1
Income tax provision	(36.9)	(33.7)	(110.2)	(88.6)
Income (loss) Before Equity In Net Income (Loss) Of Affiliates and Subsidiaries	105.9	151.3	383.4	380.5
Equity in net income of affiliate				0.0
Equity in net income of subsidiaries	27.4	19.4	86.4	64.8
Net income	133.3	170.7	469.8	445.3
Total other comprehensive income (loss)	21.5	(0.6)	16.7	(16.5)
Comprehensive Income, Net of Tax, Attributable to Parent	154.8	170.1	486.5	428.8
Assets
Cash and cash equivalents	1,360.2	$ 642.0	1,360.2	642.0	725.5	$ 387.3
Restricted Cash and Cash Equivalents	0.3		0.3		0.3
Accounts receivable, net	711.5		711.5		593.0
Unbilled Receivables, Current	519.9		519.9		420.8
Inventory	704.0		704.0		696.0
Other current assets	46.4		46.4		45.3
Total current assets	3,325.6		3,325.6		2,460.4
Property, plant and equipment, net	1,724.7		1,724.7		1,670.8
Operating Lease, Right-of-Use Asset	42.6		42.6
Unbilled Receivable, Non Current	9.7		9.7		54.1
Pension assets	365.3		365.3		307.0
Investment in subsidiary	766.7		766.7		699.0
Other assets	299.4		299.4		357.1
Total assets	6,534.0		6,534.0		5,548.4
Liabilities
Accounts payable	1,053.1		1,053.1		855.2
Accrued expenses	292.3		292.3		276.7
Profit sharing	51.7		51.7		62.6
Current portion of long-term debt	36.5		36.5		30.5
Operating Lease, Liability, Current	5.4		5.4
Advance payments, short-term	19.8		19.8		2.2
Billings in Excess of Cost, Noncurrent	340.4		340.4		369.8
Billings in Excess of Cost, Current	170.5		170.5		157.3
Provision for Loss on Contracts	37.2		37.2		12.4
Deferred revenue and other deferred credits, short-term	16.9		16.9		19.5
Other current liabilities	48.8		48.8		52.4
Total current liabilities	1,732.2		1,732.2		1,468.8
Long-term debt	2,125.3		2,125.3		1,856.6
Operating Lease, Liability, Noncurrent	37.3		37.3
Advance payments, long-term	335.1		335.1		231.9
Pension/OPEB obligation	32.6		32.6		34.6
Provision for Loss on Contacts, Non Current	161.9		161.9		170.6
Deferred grant income liability - non-current	9.4		9.4		5.9
Deferred revenue and other deferred credits	30.1		30.1		28.8
Other liabilities	192.8		192.8		223.3
Total equity	1,536.9		1,536.9		1,158.1
Total liabilities and equity	6,534.0		6,534.0		$ 5,548.4
Operating activities
Net cash (used in) operating activities			571.3	486.1
Investing activities
Purchase of property, plant and equipment			(94.0)	(142.9)
Payments for (Proceeds from) Other Investing Activities			0.1	(2.3)
Net cash used in investing activities			(93.9)	(140.6)
Proceeds from Issuance of Debt			250.0
Proceeds from Lines of Credit			100.0
Proceeds from Issuance of Senior Long-term Debt				(1,300.0)
Financing activities
Principal payments of debt			(7.8)	4.3
Repayments of Debt			(5.2)	(256.3)
Repayments of Lines of Credit			100.0
Early Repayment of Senior Debt				(300.0)
Collection on (repayment of) intercompany debt			56.1	49.7
Payments Related to Tax Withholding for Share-based Compensation			(12.1)	(15.5)
Proceeds (payments) from subsidiary for purchase of treasury stock			75.0
Debt issuance and financing costs				23.2
Proceeds from (Payments for) Other Financing Activities			(0.8)	805.8
Proceeds from subsidiary (payments to Parent) to pay dividends			(37.6)	(35.4)
Payments of Dividends			0.0	0.0
Proceeds from Stock Plans			1.3
Net cash provided by (used in) financing activities			170.5	(90.8)
Effect of exchange rate changes on cash and cash equivalents			(13.2)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect			634.7	$ 254.7
Cash and cash equivalents, beginning of period			705.0
Cash, cash equivalents, and restricted cash, end of period	$ 1,343.5		$ 1,343.5