Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net earnings	$ 214.5	$ 185.9	$ 119.6
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	72.1	79.4	89.2
Loss from disposal of discontinued operations before income tax	31.2	19.3	109.3
Write-off debt refinancing fees	2.7
Deferred income taxes	14.0	(3.8)	(12.3)
Share-based compensation	9.5	14.0	10.2
Equity earnings from joint venture	(96.6)	(74.9)	(67.0)
U.S. pension (credit)	(7.5)	(26.3)	(4.5)
Other non-cash adjustments, net	2.5	2.9	(0.4)
Changes in operating assets and liabilities:
Receivables	(1.1)	13.2	(37.1)
Inventories	(7.2)	(8.9)	3.6
Other current assets	(6.9)	9.4	2.2
Other non-current assets	2.1	(5.5)	(1.6)
Accounts payable and accrued expenses	(19.9)	5.4	(20.0)
Income taxes receivables and payables, net	(8.4)	7.5	(18.8)
Other long-term liabilities	(15.6)	(14.4)	(1.2)
Other, net	(2.7)		(0.8)
Net cash provided by operating activities	182.7	203.2	170.4
Cash flows from investing activities:
Purchases of property, plant and equipment	(71.3)	(71.9)	(89.7)
Return of investment from joint venture	85.2	141.7	69.1
Cash paid for acquisitions	(56.4)	(22.2)	(31.2)
Cash consideration received from Knauf		330.0
Payments of proceeds from Knauf to investment in joint venture		(70.0)
Payments to Knauf upon disposal of discontinued operations	(47.9)
Other investing activities	1.3	2.0	(2.4)
Net cash (used for) provided by investing activities	(89.1)	309.6	(54.2)
Cash flows from financing activities:
Proceeds from revolving credit facility	185.0		103.0
Payments of revolving credit facility	(70.0)		(103.0)
Proceeds from long-term debt	500.0
Payments of long-term debt	(825.4)	(32.5)	(25.0)
Financing costs	(2.9)		(0.6)
Dividend paid	(35.6)	(8.6)
(Payments) proceeds from share-based compensation plans, net of tax	(4.7)	18.4	3.3
Payment for treasury stock acquired	(131.3)	(306.6)	(80.4)
Net cash (used for) financing activities	(384.9)	(329.3)	(102.7)
Effect of exchange rate changes on cash and cash equivalents	0.9	(7.4)	4.2
Net (decrease) increase in cash and cash equivalents	(290.4)	176.1	17.7
Cash and cash equivalents at beginning of year of discontinued operations	10.0
Cash and cash equivalents at beginning of year of continuing operations	325.7	159.6	141.9
Cash and cash equivalents at end of period	45.3	335.7	159.6
Cash and cash equivalents at end of period of discontinued operations		10.0
Cash and cash equivalents at end of period of continuing operations	45.3	325.7	159.6
Supplemental Cash Flow Disclosures:
Interest paid	33.1	29.9	30.7
Income tax payments, net	58.4	51.6	32.1
Amounts in accounts payable for capital expenditures	1.9	1.9	2.6
Restated [Member]
Cash flows from operating activities:
Net earnings	$ 214.5	$ 185.9	119.6
Adjustments to reconcile net earnings to net cash provided by operating activities:
Loss from disposal of discontinued operations before income tax			$ 109.3