Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net earnings (loss)	$ 90.5	$ (175.9)
Adjustments to reconcile net earnings (loss) to net cash provided by operating activities:
Depreciation and amortization	51.3	37.5
Deferred income taxes	5.4	(89.9)
Share-based compensation	5.5	3.8
Loss on disposal of discontinued operations	0.4	4.2
Gain related to sale of fixed and intangible assets		(14.1)
Equity earnings from joint venture	(44.7)	(33.0)
U.S. pension cost	0.1	369.7
Change in fair value of contingent consideration	(9.5)
Other non-cash adjustments, net	0.5	0.5
Changes in operating assets and liabilities:
Receivables	(14.3)	(1.3)
Inventories	(3.3)	(6.4)
Accounts payable and accrued expenses	8.2	(26.2)
Income taxes receivable and payable, net	2.6	21.3
Other assets and liabilities	(10.8)	(11.5)
Net cash provided by operating activities	81.9	78.7
Cash flows from investing activities:
Purchases of property, plant and equipment	(30.7)	(18.5)
Return of investment from joint venture	36.4	42.4
Payments of proceeds from Knauf to investment in joint venture		(20.0)
Payments to Knauf upon disposal of discontinued operations	(11.8)
Other investing activities	(0.7)	6.4
Net cash (used for) provided by investing activities	(6.8)	10.3
Cash flows from financing activities:
Proceeds from short-term debt		30.0
Payments for finance leases	(1.0)
Proceeds from revolving credit facility	75.0	100.0
Payments of revolving credit facility	(100.0)	(85.0)
Payments of long-term debt	(12.5)
Dividends paid	(20.4)	(19.5)
Proceeds from share-based compensation plans, net of tax	(4.5)	(7.8)
Payments for treasury stock acquired	(30.0)	(34.4)
Net cash (used for) financing activities	(93.4)	(16.7)
Effect of exchange rate changes on cash and cash equivalents	0.4	(0.5)
Net (decrease) increase in cash and cash equivalents	(17.9)	71.8
Cash and cash equivalents at beginning of year	136.9	45.3
Cash and cash equivalents at end of period	119.0	117.1
Supplemental Cash Flow Disclosures:
Interest paid	11.1	12.6
Income tax payments, net	25.1	$ 1.1
Amounts in accounts payable for capital expenditures	$ 1.9