CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Operating activities:
Net income attributable to common shareholders	$ 56.6		$ 72.5		$ 134.2	$ 245.9
Noncontrolling interests in subsidiaries’ earnings	0.0		0.1		0.0	0.2
Net income before allocation to noncontrolling interests	56.6	$ 62.8	72.6	$ 82.5	134.2	246.1
Loss on deconsolidation of joint venture					0.0	1.2
Realized gain on marketable securities					0.0	(1.1)
Depreciation and amortization					95.3	84.2
Stock-based compensation expense					16.2	16.8
Defined benefit plans and postretirement credit					(4.5)	(0.4)
Deferred income taxes					7.5	18.8
Cash used for operating working capital					(8.2)	(157.1)
Defined benefit plans and postretirement contributions					(3.1)	(6.0)
Environmental payments, net of reimbursements					(2.9)	(6.5)
Asbestos related payments, net of insurance recoveries					(23.7)	(29.0)
Other					(2.7)	4.0
Total provided by operating activities					208.1	171.0
Investing activities:
Payment for acquisition - net of cash acquired					(169.2)	0.0
Purchase of marketable securities					(60.0)	(8.8)
Proceeds from sale of marketable securities					0.0	9.9
Proceeds from disposition of capital assets					3.9	1.3
Capital expenditures					(20.6)	(50.9)
Impact of deconsolidation of joint venture					0.0	(0.2)
Total used for investing activities					(245.9)	(48.7)
Financing activities:
Dividends paid					(75.4)	(70.1)
Reacquisition of shares on open market					(70.0)	0.0
Stock options exercised - net of shares reacquired					4.2	2.6
Debt issuance costs					(1.3)	0.0
Proceeds received from issuance of long-term debt					0.0	3.0
Repayment of long-term debt					0.0	(4.5)
Proceeds from issuance of commercial paper with maturities greater than 90 days					251.3	0.0
Repayments of commercial paper with maturities greater than 90 days					(188.6)	0.0
Net repayments of commercial paper with maturities of 90 days or less					(76.8)	0.0
Proceeds from revolving credit facility					77.2	0.0
Repayments from revolving credit facility					(77.2)	0.0
Proceeds from term loan					343.9	0.0
Total provided by (used for) financing activities					187.3	(69.0)
Effect of exchange rates on cash and cash equivalents					1.2	(7.9)
Increase in cash and cash equivalents					150.7	45.4
Cash and cash equivalents at beginning of period		$ 393.9		$ 343.4	393.9	343.4	$ 343.4
Cash and cash equivalents at end of period	$ 544.6		$ 388.8		544.6	388.8	$ 393.9
Detail of cash used for operating working capital:
Accounts receivable					123.6	(24.1)
Inventories					6.7	(48.9)
Other current assets					(18.8)	3.7
Accounts payable					(90.9)	(69.2)
Accrued liabilities					(19.7)	(38.5)
U.S. and foreign taxes on income					(9.1)	19.9
Cash used for operating working capital					(8.2)	(157.1)
Supplemental disclosure of cash flow information:
Interest paid					35.2	31.7
Income taxes paid					$ 42.0	$ 32.7