General - Schedule of Adjustments Due to Topic 606 (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Jan. 01, 2018	Dec. 31, 2017
Assets
Accounts receivable, net	$ 387.4		$ 387.4		$ 389.3	$ 388.3
Unbilled receivables, net	164.4		164.4		118.8
Inventories, net	377.6		377.6		375.4	400.2
Liabilities
Accrued liabilities	368.3		368.3		347.2	345.3
Stockholders’ Equity
Retained earnings	2,432.5		2,432.5		2,142.9	2,139.6
Net sales	725.3	$ 662.2	2,153.4	$ 1,899.4
Cost of sales	446.2	408.6	1,331.4	1,186.8
Provision for income taxes	9.9	12.7	44.1	39.1
Net income	90.3	$ 69.0	242.7	$ 159.6
Calculated under Revenue Guidance in Effect before Topic 606
Assets
Accounts receivable, net	386.2		386.2			388.3
Unbilled receivables, net	98.2		98.2			89.8
Inventories, net	424.0		424.0			400.2
Liabilities
Accrued liabilities	362.0		362.0			345.3
Stockholders’ Equity
Retained earnings	2,417.8		2,417.8			$ 2,139.6
Net sales	724.2		2,108.8
Cost of sales	446.4		1,301.9
Provision for income taxes	9.5		40.4
Net income	89.4		231.3
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Assets
Accounts receivable, net	(1.2)		(1.2)		1.0
Unbilled receivables, net	(66.2)		(66.2)		29.0
Inventories, net	46.4		46.4		(24.8)
Liabilities
Accrued liabilities	(6.3)		(6.3)		1.9
Stockholders’ Equity
Retained earnings	(14.7)		(14.7)		$ 3.3
Net sales	(1.1)		(44.6)
Cost of sales	0.2		(29.5)
Provision for income taxes	(0.4)		(3.7)
Net income	$ (0.9)		$ (11.4)