Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net Income (Loss)	$ 223.8	$ 202.9	$ 183.2
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	89.2	83.7	96.5
Write-off of debt refinancing fees	0.0	0.6	0.0
Loss on disposal of discontinued operations	0.0	0.0	0.4
Deferred income taxes	(0.8)	(1.6)	8.7
Share-based compensation	18.8	14.3	11.3
Equity earnings from joint venture	(89.3)	(77.6)	(87.7)
Loss (gain) from change in fair value of contingent consideration	0.1	11.0	(4.1)
Payments of contingent consideration in excess of acquisition date fair value	(5.0)	(1.9)	0.0
Other non-cash adjustments, net	0.5	0.3	1.0
Changes in operating assets and liabilities:
Receivables	(1.6)	(12.4)	(30.9)
Inventories	6.1	(19.7)	(10.6)
Accounts payable and accrued expenses	8.0	(1.8)	38.6
Income taxes receivable and payable, net	3.2	(6.9)	(2.0)
Other assets and liabilities	(18.5)	(8.5)	(17.2)
Net cash provided by operating activities	233.5	182.4	187.2
Cash flows from investing activities:
Purchases of property, plant and equipment	(83.8)	(74.8)	(79.8)
Return of investment from joint venture	96.9	104.5	78.3
Cash paid for acquisitions, net of cash acquired	(26.5)	(2.8)	(0.7)
Proceeds from the sale of assets	0.0	0.0	0.1
Payments to Knauf upon disposal of discontinued operations	0.0	0.0	(11.8)
Proceeds from company-owned life insurance, net	3.0	1.3	0.0
Net cash (used for) provided by investing activities	(10.4)	28.2	(13.9)
Cash flows from financing activities:
Proceeds from revolving credit facility	55.0	355.0	95.0
Payments of revolving credit facility	(120.0)	(315.0)	(155.0)
Proceeds from long-term debt	0.0	450.0	0.0
Payments of long-term debt	0.0	(468.7)	(25.0)
Financing costs	0.0	(3.1)	0.0
Dividends paid	(46.9)	(44.2)	(41.4)
Payments from share-based compensation plans, net of tax	(1.8)	(2.0)	(3.6)
Payments for finance leases	(2.7)	(2.2)	(2.1)
Payments of acquisition related contingent consideration	(10.2)	(6.7)	0.0
Payments for treasury stock acquired	(132.0)	(165.0)	(80.0)
Net cash (used for) financing activities	(258.6)	(201.9)	(212.1)
Effect of exchange rate changes on cash and cash equivalents	0.3	(0.8)	0.0
Net (decrease) increase in cash and cash equivalents	(35.2)	7.9	(38.8)
Cash and cash equivalents at beginning of year	106.0	98.1	136.9
Cash and cash equivalents at end of year	70.8	106.0	98.1
Supplemental Cash Flow Disclosures:
Interest paid	33.9	26.9	21.5
Income tax payments, net	72.1	63.2	52.5
Amounts in accounts payable for capital expenditures	$ 2.4	$ 2.8	$ 0.3