Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Proceeds from Sale and Maturity of Marketable Securities			$ 3.1
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 146.6	$ 447.9	146.6	$ 447.9	$ 125.4	$ 151.6
Operating Activities
Net Income (Loss) Attributable to Parent	91.0	82.5	171.2	120.7
Net (loss) income attributable to noncontrolling interest	0.9	$ (0.5)	1.2	(0.6)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			70.8	66.8
Loss on sale of assets			0.9	(1.1)
Deferred income tax provision			0.1	7.7
Stock-based compensation expense			17.8	10.4
Pension and other postretirement expense			1.6	9.9
Pension contributions and other postretirement benefit payments			(8.8)	(12.2)
Changes in operating assets and liabilities:
Accounts receivable			(86.4)	(46.0)
Increase (Decrease) in Unbilled Receivables			(27.8)	0.0
Inventories			(79.9)	(38.1)
Accounts payable, trade			8.4	(50.5)
Other accrued expenses			2.4	(2.0)
Income taxes			3.8	56.7
Other, net			11.7	1.2
Net Cash Provided by Operating Activities			57.8	114.5
Investing Activities
Capital expenditures			(39.6)	(39.9)
Acquisitions, net of cash received			0.0	64.1
Proceeds from disposals of property, plant and equipment			0.2	2.5
Common Stock, Value, Outstanding				(7.1)
Other			0.3	(0.3)
Net Cash Used by Investing Activities			(36.0)	(108.9)
Financing Activities
Cash dividends paid to shareholders			(42.7)	(41.4)
Purchase of treasury shares			(49.6)	(27.0)
Net proceeds from common share activity			10.6	25.7
Payments Related to Tax Withholding for Share-based Compensation			5.0	9.4
Proceeds from Accounts Receivable Securitization			52.1	46.1
Repayments of Accounts Receivable Securitization			18.6	12.1
Proceeds from Issuance of Long-term Debt			130.0	478.3
Payments on long-term debt			(94.2)	(186.4)
Short-term debt activity, net			26.3	6.2
Proceeds from (Payments for) Other Financing Activities			(1.0)	0.0
Net Cash Used by Financing Activities			7.9	280.0
Effect of exchange rate changes on cash			(8.5)	10.7
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect			21.2	$ 296.3
Cash and cash equivalents beginning of period			121.6
Cash and cash equivalents end of period	$ 145.2		$ 145.2		$ 121.6